SpaceX Grasshopper Makes a Bigger Leap (with videos)
SpaceX’s Grasshopper Takes Giant Leap Towards Reusability with 40 Meter Flight (with two videos)
“SpaceX’s Grasshopper took a 12-story leap towards full and rapid rocket reusability in a test flight conducted December 17, 2012 at SpaceX’s rocket development facility in McGregor, Texas. Grasshopper, SpaceX’s vertical takeoff and landing vehicle (VTVL), rose 131 feet (40 meters), hovered and landed safely on the pad using closed loop thrust vector and throttle control. The total test duration was 29 seconds.”
2013 is going to be a very good year!
Hopefully:
– Description of SpaceX’s Mars plan (as promised)
– More GH flights
– First controlled re-entries of F9 first stages
– First propulsive test flights of Dragon
MX!
Don’t forget Falcon Heavy’s first flight.
So are they really going to recover the 1st & 2nd stages + Dragon the way they showed in the animation video a while back? I would have thought the rocket equation was so constrained already that the extra fuel would be too costly?
The extra fuel plus the landing legs, and probably also some Draco thrusters for the first stage, will affect performance. So the payload will be smaller. But having to build a whole new first stage is hugely expensive, so that should easily more than make up for the reduced payload.
As I understand it a very well designed rocket of this class can get 3 or maybe 4 percent of its lift-off mass to orbit. That’s not much. I think I read that SpaceX feels they can make a reusable F9 system profitable if the landing systems and structural strengthening modifications to make the stage reusable can be kept to 2 percent of the overall mass.
That would cut the mass of the payloads in half but the cost savings would come with the reusability. Smaller payloads but at a much lesser cost of dollars per pound to orbit. The Falcon Heavy will probably become the SpaceX work horse with the Falcon 9 perhaps fading away.
Just some thoughts.
Seems like there could be an advantage for SpaceX to maintain both reusable and expendable booster types. Then leave it to the customer to decide if they want a lower launch cost using reusable boosters, with some limits on payload, or else pay more for expendable boosters which would allow for a heavier payload.
In theory Falcon Heavy could offer multiple combinations, listed here in ascending order of cost and performance:
3R (three reusable boosters)
2R1E (two reusable, one expendable)
1R2E
3E
One drawback with this method is that SpaceX would have to maintain two types of booster designs. However that might be mitigated if they can find a way to use a common design for each, so that when they are building an expendable version they simply leave off the landing gear, and substitute lighter structural pieces, etc.
I guess we might see a Falcon Heavy with the center core being expendable since it would stage in a higher more dynamic environment. The two side cores, staging lower in a more benign environment, might be the first ones to be recoverable and reusable. Hopefully someday they’ll find a way to get them all back.
I wonder if they’ve looked at inflatable aeroshells/aerofoils as a way to get the boosters back?
If you are going to use inflatables for aero breaking why not design a stage out of a sphere?
What if your engines were on the bottom, and your payload sat on top of a very thin column or truss that tapered out, at the top and bottom like an apple core. Couldn’t your stage be a inflatable sphere? Which used cables from the core that support the bottom half of the spheres skin.
Could thrust be set to slow acceleration down to reduce drag and max q allowing for this less aerodynamic shape?
Seems to me that a sphere could be used to create a lighter vehicle than a cylinder plus the cylinder shape could also be used for aero breaking reducing fuel needed for reducing speed.
Imagine throwing a spinning ball at the atmosphere where the whole surface area could be used to dissipate heat evenly.
Lol the apple core design lol
Maybe you divide your tank like orange segments. Think how strong an orange is. It holds its shape while filled with liquid.
It just seems to me that the concept of balloon like inflatable rocket boosters just might be more practical than one might think, at first.
The skin (and the whole tank) will “flap” in the airflow. Flapping causes drag and instability. I suspect that you couldn’t pressurise a flexible skin enough to offset this problem, even when fully fuelled. It may also just plain wobble, as the fuel sloshes around due to thrust instabilities, which would cause more problems. [Not to mention the cryo-programs from LOx. And LH is out of the question entirely.]
I’d like to see someone have a go at it, though.
(It wouldn’t have to be a sphere. Note that Bigelow’s modules are rounded-end cylinders, same as fuel tanks.)
http://www.projectrho.com/r…
Paul
Thank you for your wise comments!
Merry Christmas
If inflatable rockets is such a poor idea why would you want someone to try it??
How high do you have to go for flapping surfaces to not be a problem. Lol I recall a guy suggesting that rockets be launched from dirigibles. Could you launch a rocket from the height that sky diver jumped from? 3 miles? Would air drag from that height, on an inflatable surface still be a problem??
Vacuum ballon man lol
Bubble world 🙂
Pump up the volume, pump up the volume yeah!
The Atlas ICBM had a
pressure-stabilized tank.
“The Atlas boosters would collapse
under their own weight if not kept pressurized with nitrogen gas in
the tank, even when not fueled. The Atlas booster was unusual in its
use of balloon tanks for holding its fuel. The rockets were made from
very thin stainless steel that offered minimal or no rigid support.
It was pressure in the tanks that gave the rigidity required for
space flight.” http://en.wikipedia.org/wik…
‘FALCON 1
“The primary structure is made of
a space grade aluminum alloy in a graduated monocoque, common
bulkhead, flight pressure stabilized architecture developed by
SpaceX. The design is a blend between a fully pressure stabilized
design, such as Atlas II, and a heavier isogrid design, such as Delta
II. As a result, Falcon 1 first stage is able to capture the mass
efficiency of pressure stabilization, but avoid the ground handling
difficulties of a structure unable to support its own weight.”
http://www.spacex.com/falco…
Sphere’s are hardly aerodynamic. Losing aero efficiency either means increasing fuel load or decreasing up-mass.
I’m not sure what’s lol about either idea.
Robin there is nothing funny about the sad state of our space program. It is fun to float wild ideas here, and just maybe worthwhiled ones.
Sad is to spend tons of money an old fashion throw away rocket like SLS in the name of some crap call exploration when we need to be settling space.
I’m no rocket scientist, but what if rockets were built in a completely different way!
Happy new year!
PS I love too laugh! Lol why not? Better than crying 🙂
“If inflatable rockets is such a poor idea why would you want someone to try it??”
Solving crazy ideas can sometimes inspire more sane ones, and train engineers to push the boundaries.
The Apollo guys learned their craft well enough to build a hundred tonne space plane and actually make it work on the first go, during a period of sharp budget cuts and crushed morale. And before that, they built a giant space station as a make-work project to use up some spare parts.
Modern NASA can’t build a Saturn-like rocket from existing parts. They spent a decade and several billion dollars planning a space station. And another near-decade, and more billions of dollars building it.
I seem to recall tinker saying that three stage vehicles are more effectent anyway. Right?
Shouldn’t falcon heavy drop it’s 3 cores one at a time then double them up to make 6 pack version that delevopes into a 6 core recoverable verision of tinkers recoverable heavy lifter??
Wow! It looks like their control systems keep it rock-steady and land it nice and gently.
It’s quite a contrast with those videos of Morpheus.
I’d say they’re already past most of the hurdles to getting a reusable first stage for Falcon 9/Falcon Heavy. I’m sure they’ll continue to slowly expand the envelope with Grasshopper flights, and once they’re done, they’ll be ready for their first orbital launch with a reusable first stage. As SpaceX has already said, the payload will be somewhat lower with a reusable first stage, since they need to carry extra fuel and landing legs, but that will be well worth it if they don’t have to build a new stage one for every launch.
A reusable Falcon 9 may not be able to launch Dragon because of the reduced payload. Maybe that’s part of the reason for Falcon Heavy. A Falcon Heavy with the three lower stages doing soft landings would almost certainly have enough performance to put Dragon in orbit, and the costs should be well under those for one of the current Falcon 9 launches, since only the second stage and Dragon trunk would be expended.
Welcome to the era of true low-cost access to space.
Spacex is about to upgrade falcon 9 with longer stage tanks and more powerful merlins that have 8 engines in a circle around a center dropped ninth engine that will have enough fuel to launch a dragon.
Tinker add details please, i have not read the latest sources, just parroting what you said earlier.
Chris:
DTARS has it right. The Falcon v1.1 stages will have about 40% more power. Some of that margin can by used for recovery hardware and it would still lift a Dragon to orbit in the Falcon 9 single core configuration.
tinker
There was quite a bit of drift to the left during ascent, maybe 30 feet or so, possibly due to the wind which was blowing in that same direction. But it was interesting to then watch grasshopper come back to center on the way down and land within a few feet of its liftoff point.
If you want to get a good look at this motion here’s a trick you can do, that is if you don’t mind getting a little bit of smudge on your monitor. Just before launch place your fingertip on grasshopper’s nose, and hold it there during the entire event. You’ll see just how far grasshopper drifts to the left, but when it lands the nose winds up almost exactly under your fingertip.
Errr, you can just use your mouse pointer.
Not quite as dramatic but smudge problem solved for those concerned!
My iPod has no mouse pointer 🙂
Dam good Christmas present from spacex. Lolol
Chris:
The Grasshopper’s single Merlin 1d can only lift about sixty tonnes, so it will be limited to the lower end (closer to the ground) of the Reusable Falcon’s flight plan. That will still be tens of thousands of feet in altitude and over a thousand miles per hour though. The other part of the flight test program will happen on future Falcon 9/Heavy launches. First they’ll rotate the first stage after separation and relight the Merlin engines they need for their retro burn. Then they have to fly a flight profile past the densest interface of the atmosphere. When they get that far, SpaceX could probably recover the stage with parachutes like they planned from the beginning. But more importantly, the Falcon stage will be in the envelope tested out by the Grasshopper.
Both flight programs can (and probably will) be carried out in parallel. The extra fuel needed for the ‘high road’ tests won’t have any effect on operational flights (since when have customers cared what happens to a first stage after it separates as long as it doesn’t hit anything important). But once completed, SpaceX will have the data they need to fly the whole flight profile from first stage separation to landing and that will be guide the final design for their reusable Falcon first stage.
Since they fully intend to get that stage back, it’s up front cost can be much higher than SpaceX’s current model. That means they could choose exotic composites that would be much stronger (and maybe even lighter) for the tanks and thrust frame. Because of this, the reusable Falcon first stage will be an entirely new bird for sure. There are untested advantages to this approach, untested because nobody was willing to spent that kind of money on something that would only fly once. This approach alone will greatly improve structural margins on both Falcon stages.
Steve:
I did exactly what you did but on my wide screen TV! Could the drift have been on purpose to minimize having the Merlin’s flame in any one spot on the concrete too long? How do you suppose they’re dealing with rotational torque? The same way the Falcon second stage uses it’s turbine exhaust nozzle on an actuator? Cold gas?
Folks:
I laugh every time I hear that satisfied little ‘pop’ at the very end of the video! 😀
tinker
Should HAVE!!!!!!!! Sad fact!!!!
Tinker
I was reading through your discussion with Ernesto and had another of my goofy ideas.
Have you ever made water balloons as kid?
What if
your tank to orbit was a stretchable material like a balloon and you used your thrust frame to help your inflatable to have tensile structure during launch. Once in orbit unfold your thrust frame for solar collector or mirror use and inflate that balloon!
Wouldn’t it be cool if you could fly your mega-lifter then inflate it to quadruple it’s volume once in orbit.
Mega real restate lifter !!! Lololol
Just what if material dreaming again!!!!
Adding to this thought, would space want to make their lifter wider and use tenion cables inside to keep it light? Wouldn’t that be how they would use aero breaking to make a vehicle/second stage that could fly to mars refuel and return to earth orbit for refueling? More surface area versus weight?
Looking in the other direction, literally, I wonder if the added fuel and control systems for reuse could also be modified to do the opposite — put an expended first and/or second stage into orbit to be used as either real estate or building material, just like we never did with the Shuttle ETs (but could have).
I haven’t even tried the math; this was just an idle thought. But putting a structure several stories high into orbit to use as a shell would be a very significant starting point for building a station, a fuel depot, a BEO tug, or whatever. If the engines are reusable (in the airplane sense) then that would be even better; just refuel it and stick on a new payload. That gives us things like Buzz Adlrin’s proposed cycler and DTARS’s solar system railway a whole lot cheaper and easier.
Maybe, what goes up is sometimes better left up.
Just a thought.
Steve
Steve:
The argument about Single Stage To Orbit (SSTO) has always been that the margins are too small to make it economical. Small to nil, that is. But, if your cargo is your spacecraft, it starts to look pretty good. Your spacecraft could consist of nothing but fuel/oxidizer tanks, thrust frame and motors. Like my MegaLifter, the tank could be delivered to a staging area where it would be secured and then the engine compartment could be detached for return to Earth for reuse. You end up with something large, light and valuable on orbit, ready to be outfitted with hardware brought up by more conventional reusable launch vehicles like the Falcon 9/Heavy R.
Your math will work. In fact, if you do the numbers, you’ll find that the Saturn S-IVB third stage could make it to orbit all by itself (Gary Hudson taught me that). You’ll be amazed to find that something the size of an office tower can easily be placed into orbit if all you’re after is a large volume ready to be completely outfitted in shirt sleeves once it’s up there.
If you recover the engine compartments (Tugs) then you have yet another type of reusable space system. The engine compartments are reflown and the tanks are reused as habitats. There’s a workable business plan if anyone wants to pick up the ball. DTARS? This is right up your alley. Construction contractor is what we need here… not a rocket scientist! 😉
tinker
Thanks Tinker.
I’ve long hoped for construction experts to get more involved in this area. Of course, there are two basic questions — what and how. Someone would have to look seriously at exactly what we could make from (or starting with) orbited stages, then work with construction people to ensure that it can be done, how, and what cost/schedule.
The problem is, we’d probably need a Richard Branson or Paul Allen type taking it seriously and pitching it before anyone else would take it seriously. I don’t think even a large company could sell it alone; look at how little serious attention Planetary Resources got with their asteroid mining announcement.
I will openly admit to being influenced by the science fiction of past decades, but I still firmly believe that we need to start looking at space construction, not just lobbing up finished pieces. That combined with building things in a standardized, modular, reusable way is what will ultimately make space development affordable and sustainable.
Merry Christmas,
Steve
“but I still firmly believe that we need to start looking at space construction, not just lobbing up finished pieces.”
I can’t see any advantage until we’re supplying significant amounts of material from non-terrestrial sources. Otherwise, in general, it all ends up on the same launchers, may as well divide it into completed sections (ie, separate modules), rather than a single large empty shell fitted out in orbit. Once you can manufacture shell and truss components from low cost in-situ material, spun off from in-situ air/fuel industries, things might change.
Put simply, unless you use the shuttle or SLS, launch costs are going to be a small part of the mission development cost, so trying to reuse empty tanks is not something we’re ready for.
Party pooper 🙂
Here we go with another super-skinny reply.
Hi Paul,
I certainly agree that acquiring and processing non-terrestrial materials for use in space is important. In fact, I’m sure it will turn out to be one of the major turning points in space development. I think that the ability and facilities for space construction — the joining of pieces not designed to be simply docked together like Lego — will be even more important than using non-terrestrial materials.
In practice, neither of these activities requires the other in order to happen. If you are constructing a building on Earth, it is not necessary to produce your building materials on site, you only have to have them delivered on time. And further, your construction activities do not depend on where your building materials came from, only that they all meet spec when received. The same applies with space construction; the correct building materials, from anywhere, delivered on time, will suffice to do the job.
Experience has shown us, over and over again, that when you try to combine too many things into one program, you are much less likely to have that program selected and carried out. Also, the more you stuff into one program, the worse the budget and schedule overruns can become, which is something that you always want to head off at the pass if you can, because it’s a tough one to argue. This says to me that we should be aiming to propose and execute these two development programs (they’re both at the development stage) independently of one another. Neither requires the other to happen, and they needn’t even happen at the same time. In fact, risk management and budget cuts both suggest doing them at different times.
The use non-terrestrial materials and space construction have something critical in common — they are both necessary because of the physical limitations of what can be accommodated by a payload fairing. Too many people think only in terms of mass. But volume, L-W-H dimensions, structural stability, center of gravity, shifting center of gravity, and susceptibility to vibration and/or G forces are just some of the other limitations on lifting material, or anything else, from Earth. Anything you send up must be in its final form, and you can’t just add items to the payload until you approach your payload mass limit. The most obvious example of this limitation is the ISS — absolutely every piece of it had to either fit in the Shuttle bay or be balanced on the end of a Russian booster (HTV and ATV excepted). Both of these seriously limited the dimensions and shape of anything that went into the ISS. Even if we still had the Shuttles, the very best we could do today by lifting “finished” modules from Earth is another ISS, or something little different from it.
What we could be doing, instead, is to pack a payload fairing with rolled or preformed, predrilled sheet metal, prefab struts, chemicals to blow foam or mix adhesives, welding equipment, assemble-on-site furniture, electronics boxes with cable harnesses and bezels packed separately and more efficiently, etc… There’s not a lot that can’t be designed for straight-forward final assembly on site and shipped up “broken down” after testing.
Consider one particular physical configuration — a Wernher von Braun/Arthur Clarke/Chesley Bonestell-type rotating space station (as in the 2001 movie). There are a lot of reasons for adopting the torus (or other circular configuration) space station. The same is true for BEO spacecraft any bigger than a bathroom. But sending prefab torus sections from Earth (or a space factory) in a payload fairing to dock together isn’t really doable. You’d end up with sections so small that half (or more) of the station volume would be docking ports/air locks. (Prefabbing torus sections from ISRU processes would be a much harder challenge than producing flat sheet metal and prefab struts.) So, I would say, the only way to build a toroidal station would be with in-space construction, which is the same conclusion that a lot of both fiction and non-fiction writers have come to over the decades.
“trying to reuse empty tanks is not something we’re ready for“
Given my other arguments, why not? It would be important information to know that it can be done, and how difficult it is. And lots of people are constantly proposing much more difficult programs, like sending people to Mars. And this idea goes back to the early Shuttle days (at least). If we did nothing more than make it airtight and installed permanently cycling ECS systems for testing it would be worth the effort. It could also be used for measuring/testing impact protection systems, thermal control systems, and much more. And that’s just a beginning.
Finally, doing construction the way I suggest means that SLS (or equivalent) is not necessary, since you can get a payload fairing almost as big (volume) on much cheaper LVs, and mass is not the limiting factor.
Please seriously consider the fact that much of the mess that the space program is in now stems from people insisting on using existing hardware and concepts to do new jobs for which they weren’t designed (what I call the just-do-it crowd). It’s these same people who tend to turn up their noses at R&D proposals. In my opinion, next to Congress, these people are hands-down the most damaging group that space development faces. We desperately need to be doing new things in new ways. I offer the very impressive MSL landing procedure as an example of new ways for new tasks.
There’s lots more, but I’ve gone on far too long already. In summary:
• Space construction and ISRU are both going to be essential.
• Space construction and ISRU do not depend on one another (but will be complementary in the long run).
• Space construction and ISRU should initially be pursued separately.
• Space construction is the only way to get items of certain size and/or geometry in space.
• Shuttle is gone and SLS, if it ever becomes available, is far too expensive, and not necessary.
All of this is, of course, just my opinion.
Happy holidays.
Steve
Steve
We get trucks of steel each day and just put the puzzle pieces. Easy lol
Building in space can be done in a very similar way once we have to tonka toys to put parts together and the safe tick suits to work. Rather than being all that new. Old techniques can evolve.
Did you know that steel workers rarely walk steel any more? For safety they ride in lifts.
Paul once Elon does his thing the idea of working in space will radially change.
Steve
Lol Mr. Whitfield
The year is 1902
I know the future. I know that soon the Wright Brothers will soon make their bicycles fly and that the whole world will change. All the opportunities that it will bring and only I, and a few others fully understand this secret lolol
Steve, I am amazed that the comments here don’t seem to really understand what is about to happen this decade. The significance of these hopper tests.
I am currently working with a crew of iron workers we are on a large job building a Michelin plant that is going to manufacture LARGE tires for mining equipment which will chew up landscape for our never ending hunger for energy.
In seven weeks the eight to ten of us have erected enough steel to cover an area of about 3 or 4 football fields.
The group I’m with sets the pace for this job. Previously I have only be associated with light commercial, so I am getting quite an education.
What if! Lol
What if. Lol we were building erecting a space station/farm/mars recycler in orbit which would put us on the road to settling space. Maybe I have found my tick pilots.
Steve I’m getting old I’m 57. There is not much time lol,
You and tinker are making suggestions.
How can we help paint the future with words and turn them into reality. PLAN lolol
As consequence said soon Mr. Musk will put that used Merlin on a stand and light it up.
We have to be ready!
Sorry I have not written you in a while but I am gathering my tools. Trying to get my own toolbox back in order. My new relationships may even make what you and tinker are hinting at possible.
For me Mr. Musk is a very inspiring person.
It doesn’t take a rocket scientistt lol
Hi George,
Hope you and yours are having a great holiday season.
I agree with you that the reactions to these recent tests seem much less than I would have expected. Perhaps it’s just that the more excited people are busy with the holidays. Also, I agree that there’s not much time (for us to see results), but I must stress that at 57 you’re not getting old, because that would make me older, and I’m not ready for that yet.
What Tinker and I kicked around above was a possibility. There are lots of people around thinking about lots of possibilities. What we, or someone, need to do is turn one or more of those possibilities into a plan that will deliver something which has genuine benefits — for all the people, or at least a majority of the people, whether the people realize it or not. Just because we can do a thing doesn’t mean we should do it, no matter how cool it is. Everything we do in space (or in life as a population) should be for the purpose of bettering or protecting the welfare of the people as a whole, and that’s the critical factor that I think we’ve all been ignoring. The question of “why” with respect to space has been kicked around endlessly, here and elsewhere. Instead of answering with specifics, which is guaranteed to make people argue it, I think we need to look at it in a more general, but still meaningful way. And the way I see it is as simple as what I’ve said above — it should be for the purpose of bettering or protecting the welfare of the people. If we could get the majority to, more or less, agree on that concept (or another) as “why,” then we can start debating specific proposals and how well they satisfy our why.
In electronics and computer design they have a phrase, “top down design,” which governs how a design is done. I’m sure that you have the same concept in your profession, just worded differently. It simply means that you start any project by defining the performance requirements of the entire completed item. Then you work backwards, each stage/program defining the requirements of those that feed into it. The same concept needs to be applied to thinking about space. Perhaps this is why so many posters push a mission or destination as the important thing.
However, approaching it from the perspective of possibilities, we can’t simply pick a mission or destination, no matter how exciting or beneficial it may be, without considering whether we have the technological (and financial) capability to perform every required action within it. This is another thing that is so commonly ignored, or filled with wrong assumptions, in what people propose, with the “humans to Mars” mission being the most obvious case. There are many people who believe that we could put people on Mars now and bring them home, or even could have 30 years ago. They minimize the problems when they are brought up and insist on believing what isn’t true.
So, the way I see it, we have to propose a plan that is developed taking both of these into account — it must benefit the population and it must be demonstrably doable. One big mistake that NASA has made too often is making the development of things that we can’t yet do part of a mission plan or a product build, with cost and schedule numbers assigned to them (presumably by best guess), when this is not at all realistic. Anything involving science or research cannot be accurately costed and/or scheduled beforehand — these things take as long as they take and cost as much as they cost, and there is absolutely no way to know the final numbers until after the fact. There are too many people (politicians and managers) who refuse to believe this and continue to criticize those who claim it. Of course, none of these know-it-alls have ever had to be the scientists, technologists and technicians who are actually committed to budgets and schedules by their managers; otherwise they’d have a clue. To make it worse, it is too often these same people who argue against spending money on R&D programs (while believing that America still leads the world in everything).
What my long-winded diatribe adds up to is that, as difficult as the technical problems of space development are, it seems that it’s still the non-technical problems that are pulling back on the brake handle. We do a lot of talking about what and how here on NASA Watch, but to develop a plan that will possibly get any attention in the necessary places, we’ve got to nail down the why, and do it in such a way that it almost sells itself without requiring any one-on-one selling. It needs to be presented concisely and clearly so that anyone, newbie or old campaigner, 18 or 80, can read it, understand it, and believe it, without anyone having to spoon feed them. And then we reinforce it throughout the plan, showing how each stage is a positive step in satisfying our agreed upon why. Neither missions nor possibilities can succeed without thoroughly nailing the why first.
For whatever it many be worth, that’s how I see things.
Happy Holidays.
Steve
Steve I was wondering about a different approach. Instead of dealing with the extremely daunting task of fabricating a module on orbit out of a spent stage/fuel tank, how about building on the ground a fully configured module which can also initially perform as a stage or tank. Then on orbit you simple remove the stage/tank hardware. Obviously not a simple thing to do in reality, but here one way that it might work:
I noticed that most of the ISS modules were virtually empty during launch, since the racks were shipped separately to be added after the modules were on orbit. So the idea would be to fill that empty volume with fuel tanks during launch.
Each module would be built in the usual way, outfitting it on the ground with all of the things that modules normally get such as insulation, wiring, plumbing, windows and hatches. Of course windows and hatches would have to be protected somehow during launch, as would anything else on the exterior. The module would be fully completed with the exception that the aft section would not be installed yet.
At this point the fuel tanks would be inserted into the module through the aft opening, filling up virtually all of the empty space. The tanks would be secured to the module through several attachment points located on the walls of the module. Hoses would travel through openings in the aft end of the module. Finally a boattail type of arrangement including engine(s) would be attached to the aft of the module, and the hoses connected. Now it has become a rocket stage!
After the module is on orbit, it’s just a matter of removing the stage/tank hardware to convert the stage into a module. This work would be done by a combination of astronauts doing EVA, as well as Dextre/Robonaut type of assistance. Hoses, electrical would be disconnected. The boattail/engine module would be removed and returned to Earth on an unmanned cargo vehicle.
This would leave a large opening in the aft section of the module, though which the fuel tank could now be disconnected and removed, then sent back into the atmosphere to burn up (the fuel tank would be the only non-reused hardware). After the fuel tank is removed, an aft section would be installed which contains hatch and/or docking adapter.
The module is now ready to start adding racks and putting it to use.
Whether this would really be practical I don’t know, one complication is that the module structure would be handling vertical loads during launch, requiring the module to be heavier than it would otherwise be. But maybe even with that it would still be practical.
“one complication is that the module structure would be handling vertical loads during launch, requiring the module to be heavier than it would otherwise be.”
However, using the right attachment points, the module would essentially “drape over” the pressure-stabilised tank, the tank providing most of the necessary strength.
“though which the fuel tank could now be disconnected and removed, then sent back into the atmosphere to burn up”
Alternatively, you could use DTARS’ inflatable fuel tank as the interior tanks, then the deflated bags would be small enough to be removed via an airlock. That way you don’t have to leave the entire aft of the module open to remove the inner tank. It also means you can return the tank-lining in your cargo capsule for analysis. And, of course, you never expose the interior to the toxic fuel or hard vacuum. (Although you still have to find flexible linings that can handle the fuel and oxidiser.)
“The boattail/engine module would be removed and returned to Earth on an unmanned cargo vehicle.”
I doubt you could fit an engine module, even a small upper-stage engine, inside anything currently used. Or anything smaller than the retired shuttles.
[Michael: You can presumably create a shell of some kind able to recover the engine pod, but you’ve really just invented a new space capsule. Main-engine/RMS/heat-shield/guidance-system/comm-system/ELS/etc. Not exactly, “just return it in a cargo vehicle”.]
“I doubt you could fit an engine module, even a small upper-stage engine, inside anything currently used. Or anything smaller than the retired shuttles.”
There is always the possibility of attaching an inflatable heat shield to these engines for return such as what they tetsted with IRVE-3
Hi Steve,
This is the sort of thinking I like. I’ve had thoughts similar to your proposal before, but I hit on a couple of problems that I couldn’t yet think of how to deal with.
First, everything depends on exactly what fuel and oxidizer you’re using. If either one is cryogenic (still my favorite) then the whole scheme falls apart. If either one is particularly corrosive, requiring thick or time-constrained containment, then we’re adding a lot of mass. If neither of these is an issue, then, like DTARS and Paul, I’d advocate inflatable tanks, since we’d get maximum use of available volume and we wouldn’t have to worry about attachment points or shifting center of gravity, although we’d have to design the module physically so that the CofG, with filled tanks, was at the proper location. There is one down side with inflatable tanks; if our fuel and oxidizer are hypergolic we’d better make damn sure that they can’t ever mix on a tank breach.
Another problem I saw was that our module size is still limited in diameter and we’re still restricted to cylinders.
The third problem I saw was keeping nozzle heat from conducting to the module and either damaging or weakening it. There are several possibilities for dealing with this that I could think of, but they involved adding mass and height — and expense (I’m thinking ceramics).
I feel confident that all of these can be overcome; I just couldn’t see how myself so far, but I can definitely see what you propose as being viable for smaller, cylindrical modules. I’m still going to argue space construction for larger, more massive modules with other geometries, like building a rotating torus.
Ultimately, I’m sure we’ll need several different approaches to this used in combination, where what we need up there will determine how we put it there. I’m very pleased that people are starting to think outside the box more, but we’ve got to push our “different ways” thinking harder, because a lot of people are still stuck on outdated ideas. The one that still baffles me the most is the belief that the BFR is the only answer, people who won’t see that multiple smaller LVs can do the job cheaper and easier.
I definitely like your idea.
Steve
[Moved back to the top of the thread]
Re: Fuel tanks/stages into space station modules.
You mentioned to Steve P about people believing in things like human Mars missions because they minimise or ignore the difficulties and as-yet-absent technologies. I feel the same is true when people talk about turning an empty fuel tank or upper-stage into a space station, or station module. A habitable space station module is not just an aluminium shell with some hatches cut in and a bunch of stuff fitted out inside, the number of changes you would have to make to turn an empty tank into just an empty space-station shell are staggering. In the end, you are doing do much conversion, there wouldn’t really be anything of the original tank left.
My point about ISRU was that the first generation of metal used will, by necessity, be in simple bulk structures. Shells, frames and trusses. That necessitates installing all the complicated bits separately from components launched from Earth.
Until then, both the bulk material and the complex parts are shipped on the same rockets, so you might as well pre-assemble them on the ground. Even if reusable manned SpaceX launches lower the cost of putting DTARS’ construction crew in orbit by an order of magnitude, it’s still more cost effective and practical to manufacture complete modules on the ground and merely assemble in orbit.
One day we’ll be casting steel beams on the moon, or vacuum depositing aluminium onto inflatable shells to make disposable fuel tanks for asteroid sourced fuel, or whatever else we do, and those parts may be so cheap, a mere spin-off of other more profitable activities, that it suddenly makes sense to do orbital construction, rather than just orbital assembly. And I hope we reach that cross-over point in my life-time, it’s partly why I push ISRU-fuel and asteroid-missions so hard; but we are so far from that point today.
Part two:
You said: “Experience has shown us, over and over again, that when you try to combine too many things into one program, you are much less likely to have that program selected and carried out.”
But then you said: “What we could be doing, instead, is to pack a payload fairing with rolled or preformed, predrilled sheet metal, prefab struts, chemicals to blow foam or mix adhesives, welding equipment, assemble-on-site furniture, electronics boxes with cable harnesses and bezels packed separately and more efficiently, etc…”
And every single part of that construction process, individually and together, will need to be created from scratch in horribly complex overlapping/interacting/interfering development program. The worst kind of NASA project.
Does the outgasing from the foam interfere with the welding process, or vice-versa, or with the EVA suits, or with the crew capsule? Does every step of assembly have enough attachment points and hand-holds? is there too much risk of suit-tear/abrasion? Does every step have a frame for holding the parts during welding/gluing, and then how do you assemble the frame…? Etc etc, and for a million other questions I can’t even imagine.
Re: ISRU and construction
“This says to me that we should be aiming to propose and execute these two development programs (they’re both at the development stage) independently of one another. Neither requires the other to happen, and they needn’t even happen at the same time.”
You miss my point. I’m not saying that ISRU should be developed along-side in orbit construction, I’m saying that in-orbit construction (as opposed to assembly) will not occur until after ISRU is well established. It will occur as a spin-off, a by-product. A few achingly simple components, such as simple shielding, being available for less than the cost of launching from Earth. And slowly building up the catalogue of available materials/structures until you find that you’re doing full golden-era SF in-orbit construction.
Considering where robotics technology is today and where it is going I do not see the need for manned EVA’s for in orbit construction. I always imagined creating a shipyard that incorporates a truss structure with a series of SRMS’s (not much different than a modern auto assembly line) and robonaut’s for welding, screwing, etc. Although there would still probably be a necessity for humans on occasion to participate in EVA’s to deal with certain aspects of construction that the robot can’t handle.
As much as I believe that this is the future of structures and ships in space I also believe (initially at least) that bigelow inflatables are going to be the key to filling the gap from the tin can prefabs of today into the more complex and larger structures of tomorrow (i.e. 450 meter diameter toroidal space station spinning at 1 g and not getting people sick).
Michael,
Re robotics in space: You’ve hit on yet another area that we need to do a lot of R&D on, which will certainly pay off over time. Quite aside from radiation and thermal hardening, and similar issues, we have the fact that proven robotic/automation equipment and processes on Earth rely heavily on the presence of gravity. Hardware, mechanics and software will have to be designed and tested that will work in free fall and vacuum. The problem of lubrication (that doesn’t boil off) of continuously moving parts in a vacuum would be a whole program in itself. We may require things like sealed air bearings, improved gaskets, seals for metal parts that are undergoing extreme thermal expansion and contraction, a new method for overload sensors (thermal won’t cut it), and probably a lot of other things. This sounds like a project that one could really sink his teeth into (and it would probably be a lot of fun).
Steve
Re: Orbiting ship-yard.
I love the image. And I’m sure MDA would love the work.
However, roboticising a process usually means you have understood and optimised the entire system. That makes it something that happens long after we’ve been doing it by hand.
That said: I think it is worth… well, maybe not NASA, no funding… maybe DARPA?… to sponsor the development of a kind of automated manufacturing plant that uses a standardised input component (say steel bar, rod or tubing) and automatically cuts and welds together any shape created on the CAD operating system, without any other human intervention. Like giant 3D printing with rebar.
(The next step is then to create one that can create a continuous truss lengths. Then another that can spider-climb over an existing truss to add new elements branching off the main beam. Then one that can attach pre-made elements to a truss. Then start moving the whole process into space.)
Hi Paul,
I follow your logic, but it doesn’t alter my thinking. First off, maybe I shouldn’t be using the word “construction,” or at least I should have defined what I meant. Think about how the roof of a new house is built these days. They can’t prefab an entire roof at the factory and then transport it to the house site. Instead they prefab whole rafter sections, cut the cross beams to length, and do everything that they can do at the factory and still fit the results onto a truck to take to the house site. Assembling the prefab components at the site is a lot easier than building those components from raw lumber and nails on site. This on-site assembling is still called construction, and that’s what I mean when I say space construction. It all comes down to what will fit on the truck, or in the payload fairing. If you want anything bigger or more massive than what your truck/fairing will handle, you can only do it by sending the prefab components to the site and putting them together there.
I certainly won’t argue with you that this is difficult. And I’m not saying we already know how to do it. In fact, I specifically said that both space construction and ISRU are in need of development. These are just two of many things that I’ve been insisting we need to do R&D on.
I think I could get you to agree that we don’t need to do both things at once. ISRU can be developed without involving space construction and vice versa; in fact, in the initial stages of each, they’d have to be kept separate. So why create a major dependency that doesn’t exist. Combining the two means that failure or delay of either one will affect them both. Also consider that ISRU isn’t a single thing: it requires acquisition (usually seen as mining); it requires materials refining and processing; it requires manufacturing of the resources into usable materials or parts; it requires transportation to where it is needed. Each of these is complex, untried, and is going to take considerable time to develop.
Space construction (I’m going to stick with that label unless you have a better one) similarly has many separate, complex aspects. Consider something as simple as welding is space. We have a limited amount of experience with it, so we can’t say for certain which of the methods that will work in vacuum is “best” when you have a lot of it to do, where “best” encompasses ease, cost, reliability, strength, lifetime, which materials can be welded by a welding type, and so on. Is MIG welding inside pressurized containment viable? If so, the equipment will have to be designed and tested. There are all kinds of questions that we can suspect the answers to, based on Earth experience, but can’t know for certain until we do the development and testing.
Everything considered, I’m saying that your statement “in-orbit construction (as opposed to assembly) will not occur until after ISRU is well established” is something I can’t agree with, but as I said above, it may be that I created confusion with the word construction. In terms of building structures, I can see us building things much larger than an ISS module using prefab components (like roof rafter sections, not finished modules) using currently available LVs and their payload fairings, if we’re willing to do construction (assembly) in orbit. If your maximum fairing dimension is 10 meters, then the only way to send up a 15 meter beam is to send it in two pieces to be either welded or bolted together on site. The only way to determine the required time, problem issues, ideal tools, etc. is to actually do this a few times, which can all be done from Earth-launched materials and tools — and could be done right now.
I think we can be, and need to be, building larger structures in space, and doing so long before ISRU is up and running on any significant scale. At some point in the future, non-terrestrial materials for building structures in space are going to be cheaper than materials brought up from Earth, but given the extent of development and costs involved, it is realistically going to be a long time before that happens. Long before then we can be constructing large structures in space which will not only create a market for the ISRU materials, but will also help facilitate the ISRU development process.
Just my take on things.
Steve
“Space construction (I’m going to stick with that label unless you have a better one)”
No, we can call the other ones “manufacture” and “assembly”.
“Think about how the roof of a new house is built these days. They can’t prefab an entire roof at the factory and then transport it to the house site.”
They can. They can transport entire pre-assembled houses. They even re-transport existing houses, including ones that weren’t intended to be moved. So they can certainly design a roof intended to be delivered in one piece, and I’ve seen it done. They mostly don’t because it’s stupidly expensive to move large structures around.
The same is true for orbital assembly vs construction, but with the opposite result. We can probably do what you suggest, build a “flat-pack” space station, with precut parts, shipped disassembled, built in space. But it will always be more expensive that shipping a bunch of pre-built modules, a la ISS. Even if we lower the cost of putting people in space, we’ll lower the cost of putting more modules in space by the same factor too.
Hence, I believe that something outside that is required to change the cost-benefit equation. I can see ISRU being that. It might not do it, but it’s the only thing that can do it.
“I think I could get you to agree that we don’t need to do both things at once. ISRU can be developed without involving space construction and vice versa;”
As I said, I not only see them developing separately, I see ISRU developing first, construction as a later spin-off. But importantly, I don’t see “construction” as the first “product”. It will occur more organically, almost by accident. I used the example of tanks, I can see a situation where the fuel market is large, but so scattered that the cost of recovering old tanks, or shipping new ones from Earth, is a significant drain. So some bright boy invents the tech to allow just shipping disposable deflated balloons which at the ISRU-site get vacuum-deposited with a thin aluminium wall. The tanks are filled and shipped to clients, who dump them wherever is convenient.
That tech then lends itself to another application, say someone using recycled tanks as mud-rooms/open-workshops. And step by step, a new market is created. Instead of tanks, someone makes Whipple-shielded shells, and rad-shielded panels for interiors. You order an inflatable blank in the shape you want, shipped deflated from Earth, it’s then turned into a solid structure by the ISRU guys, shipped to a location of choice, where you fit out the complex stuff from Earth.
Alternatively, crude sintered slabs for lunar landing pads. Becomes sintered bricks for shielding habs. Becomes 3d-printed “sand moulds” for iron casting of mounts/frames for non-essential tasks. Becomes… Or a thousand other possible paths, I have no idea which one will be key.
But one day, you wake up and space construction is the default, because space manufacturing is so cheap, and no one planned it. I honestly can’t see any other way for it to develop. A NASA project to develop orbital construction in order to build an L2 station or Mars-ship would be a total disaster. SLS and JWST, times a thousand.
Worse, I think you need a “place” to do the construction. A solid thing to attach everything to while you work. You will not build a structure in empty space with just a Dragon capsule and a shipment of parts. And ISS is too “delicate” to use, so at the very least we need one more conventionally assembled space station, one that is built as a construction shack. And I can see that feature being dropped early on, just as it was from Freedom/ISS.
Hi again Paul,
I wrote this really late last night and then fell asleep before sending it (I hope it all hangs together).
“They can transport entire pre-assembled houses.“
I think maybe we’re carrying an analogy too far now. We don’t have the equivalent “mover” and processes to move large structures (complete houses) into orbit or within orbit, either from Earth or from elsewhere in space — at any price. Aside from every other consideration, if we want to put anything into space with a single enclosed volume larger than a payload fairing it will have to be constructed/ assembled in place. And I see lots of requirements for large enclosed volumes in LEO and cis-lunar space. One of the most immediate requirements, in my opinion, is facilities for storing and processing ISRU resources and manufacturing what we need from them — unless you’re proposing to do this all on the lunar surface, which I see as a big step backward, or in free fall in open space, which makes it much more difficult, more dangerous, and probably more expensive.
“Hence, I believe that something outside that is required to change the cost-benefit equation. I can see ISRU being that. It might not do it, but it’s the only thing that can do it.“
Again, if you want a large enclosed volume, or something that is structurally too weak to survive a launch completed, then cost is not the controlling factor. The requirements determine the means. Also, until ISRU can be reliably accomplished on a sufficiently large scale, it is not going to be a solution for construction materials. And this goes for processing and manufacturing using ISRU materials as well. So, we see this issue exactly opposite of one another, since I think space construction can be happening long before ISRU for structural materials will be contributing meaningfully to it. I suspect that we will ultimately agree on this particular issue, but right now we’re thinking in two different time frames. Down the road, ISRU will be the ultimate source, but not in the foreseeable future. Part of what I’m advocating these days is, let’s think more now about the things that we can realistically be doing now, and less about the things that are still a long ways down the road. And, very important, let’s try to stop people mixing these two things in current program proposals — what we can do gets disqualified because it includes things we can’t do.
“someone using recycled tanks as mud-rooms/open-workshops“
This is something I advocate doing now, except preferably as closed workshops; and not as a business, but simply as a matter of convenience and common sense. In micro-g it’s going to be a lot easier and safer working inside an old tank, or other structure, than trying to anchor yourself to the outside of something (or nothing). This is why I originally asked if the reusability additions that SpaceX is developing could be used to put an expended stage into orbit. And, whether intact or opened out, the shell of an expended stage is a convenient sun shield for outside work.
“A NASA project to develop orbital construction in order to build an L2 station or Mars-ship would be a total disaster.“
Actually, I think this is much more in line with what NASA can do well and should be doing than foolishness like SLS. I would very much like to eliminate the “L2 station or Mars-ship” reference from your statement, though, and just consider learning to do space construction without tying it to any large programs. The learning process should be a program by itself, not part of another program which will become dependent on it before we have finished learning it. I have the same opinion about developing ISRU. It’s a mistake to try specifying applications before we know how difficult, expensive, time consuming, dangerous, etc. different aspects of these things are. It may well turn out that some ISRU materials are relatively cheap and easy while others are nearly impossible or prohibitively expensive. The same applies for different construction techniques. I strongly believe that it is a huge (and too often repeated) mistake to consider using any of these processes until we have plenty of meaningful first-hand learning experience with them. Consider that school kids have long made things like ashtrays and waste baskets in art class and shop — not because they’re useful or artistic, but because they are appropriate for the kids to start learning about clay and sculpting, sheet metal and welding, wicker and weaving, or whatever materials and processes were involved. And the cost for a school child to make an item is much higher than buying the same thing (in better quality) from a store, but education is an investment that always pays off.
“And ISS is too “delicate” to use“
I agree 100%. For the things that we need to do in LEO and cis-lunar space, we need enclosed working volumes that are considerably larger than anything done to date, structurally sturdy (to the point of surviving orbital repositioning and an onboard centrifuge), and ideally with large, pressurized, shirt-sleeve working areas. If it’s worth doing, then it’s worth doing right! and lives may depend on doing it right.
Even though we’re not converting one another here, I consider this an important set of ideas to be discussing, and I’m enjoying it. I would be a lot happier if I thought these ideas were being discussed, or even recognized, by the people who make the big decisions. So many of these developmental items have been all but ignored for decades; and these are mostly things that we can be doing now (and could have done during the last 20-30 years), and which we will need to learn to do in order to progress much past where we are now. Metaphorically, we need to go back to school and get more education before we’re “going to get a job.”
One final analogy (here I go, looking for trouble again): If we were planning out the courses for our advanced “education,” a lot of our decisions would be driven by prerequisites, learning things in the right order so that we have the necessary background for each new thing as it comes along. And we don’t try jumping straight to the hard courses and final answers (like humans to Mars). A simple example is atomic structure; we learn about it (roughly) in Chemistry class, and before long some student always asks why the like charges of the protons in the nucleus don’t rip the nucleus apart. It’s a good question, but it can be frustrating for a teacher because the answer doesn’t exist anywhere in Chemistry. We have to learn some basic Particle Physics (quark/gluon bonding and the relative strengths of the four forces in the universe) in order to answer it. So our education (R&D by analogy) has to take all of the interdependencies into account, and certain “subjects” end up being iterative, where we learn some but not all of a subject in one class, and then come back to that subject in more detail later, after we’ve learned relevant knowledge from other classes. And whether we’re talking school or real-life R&D, there are no short-cuts. Everything necessary/relevant must be learned, in the order dictated by the various interdependencies, before we can presume to start using our gained “knowledge” and “facts” in the real world.
If we accept this analogy, without trying to carry it too far, it supports the idea that more and better R&D is required before our space activities are going to progress past the point that they’ve basically been stuck at (for the most part) since the mid-1970’s. The way I see it, Americans (and others) are collectively shooting themselves in the foot with the current reluctance to invest in R&D. I think this is far more damaging than the so-called “anti-science” attitude that has taken hold in both upper and lower circles. With the anti-science crowd, we can at least pick them out readily and ignore them, but there’s no way (that I can see) to compensate for the lack of R&D investment. As a start, though, we could be pushing for smaller, more obviously relevant R&D programs which would be easier to sell — if the cost was down in the noise band of the budget; if the risks are minimized by not tying them to some big program; if the arguments for and results from these program were easily understood by anyone; and if they were pursued in a logical order, such that prerequisite are covered and the synergy resulting from successively completed R&D programs further exemplifies the benefits of ongoing related R&D programs.
A final thought about space “construction”: As structures grow larger or less symmetrical (physically and CofG) modular assembly techniques become less reliable and so welding, or at a minimum heavy bolting, becomes necessary to keep the structure intact. For spinning structures, as the angular momentum at any radius increases, again we reach a point where plug n’ play won’t suffice and we have to resort to welding and/or heavy bolting to obtain reliable structural integrity (and bolting requires gaskets, which would have to be replaced on a regular basis as they boil off; not a trivial job at all). So, unless we limit ourselves to ISS-type structures and inflatables, space construction (or assembly if you want to include bolting under assembly) is not optional; we’re going to need it. So we should be learning how to do it, and find the optimal methods, now, so that we can properly estimate cost and schedule when it’s needed. To me, the idea that we won’t/can’t do something because we didn’t do it before doesn’t hold water. We learn how to do it, then we practice it, and then we use it, the same way we learned to write (and so much else) as kids.
Steve
“I wrote this really late last night and then fell asleep before sending it”
I have that effect on people.
“I think maybe we’re carrying an analogy too far now.”
Almost certainly. However, my point was that the housing industry failing to deliver roofs in one piece isn’t because they can’t. It’s because the cost of transporting (and craning) outweighs any advantage. It’s a cost issue, not a capability issue.
Orbital construction has the same logic, but the opposite conclusion. Transport costs are a tiny part of the cost of a space-station project. In-orbit work is hideously more expensive than work on Earth, even ignoring launch costs. Hence the cost of constructing a space station in orbit will always be orders of magnitude more expensive than merely assembling a bunch of modules (a la ISS.)
Going way way way back to my original point: The very nature of a space station module is so fundamentally different from a fuel tank or upper-stage that the idea of converting one to the other is foolish, even if we already had in-orbit construction. An empty space-station “shell” is nothing at all like the skin of a tank. Starting with the tank isn’t actually helping you.
[One solution might be to ship up a “glove” made from Transhab/Bigelow skin shaped to go over the outside of the tank, the tank becomes the inner pressure vessel. But then, why not just use an inflatable Bigelow… the tank adds nothing worth the cost/complexity.]
“then cost is not the controlling factor.”
Cost is always a controlling factor. If NASA tried to do Freedom/ISS as a single-volume constructed in-orbit, rather than a modular assembly, then ISS would never have been built, even if they had spent another two decades at $3b/yr.
I’m not saying that the lack of in-orbit construction isn’t limiting what can be tried in space. And I’m not saying it doesn’t suck. It will continue to limit what we can do. You keep trying to convince me of the need, you don’t have to. I’m not talking about whether we need it, but whether we can get it. “You can’t get there from here.” I’m saying that the sheer cost outweighs any possible advantage of doing all those things. No matter how much R&D we do first, that first real construction project is going to cost more than its worth to its funders.
And unfortunately that will always be the case, whether public or private program; when you are looking at your options, it will always be wildly cheaper, quicker and easier to find a way to avoid doing in-orbit construction.
…Unless something changes the rules of the game. I’m guessing that ISRU might do it, but only long after it is established, and even then it has to develop accidentally as a consequence of other activities that justify themselves, not because someone says “hey let’s develop ISRU to do in-orbit construction!” That won’t happen either. (And here I disagree with a lot of ISRU advocates. “We should be building SPS arrays from lunar metals!” Ummm, no.)
Re: NASA R&D, rather than a major project.
Well, yeah. I think you know me well enough to know I wouldn’t object to a whole crap-load of small research projects looking at different aspects of in-orbit construction (and manufacturing, for that matter.)
In the same way that I’ve disagreed with Dennis Wingo about how mature ISRU is. Dennis believes it should have been factored into any lunar program like Constellation; whereas I really really really don’t. But I think there should be a lander on the moon now, today, last year, a decade ago, sintering bricks out of regolith and making little walls and arches out of them; purely for the experience (and morale) of doing it. (There should also be a lander at the lunar pole, giving us the detailed specs of the ice/regolith mix there. Because one day we are going to want to get that water, we should at least know what we’ll be working with. Also a tele-op humanoid robot on the moon, with a rock hammer… And and and… Enough with the $2.5b Mars missions, let’s go somewhere new, do new things.)
Re: ISS being “delicate”.
I meant that it’s designed as a micro-g research station, it has issues with vapour impingement. Nothing to do with structural delicacy. You could build a “construction shack” using ISS-size modules and methods. And my point was you would need to build the first “construction shack” using current methods before you could do in-orbit construction, because you won’t be able construct one from scratch in open space, hanging out of the back of a Dragon-capsule. You need something to attach to, and somewhere to live. So you need to assemble a construction shack in order to construct a construction shack…
Paul:
If you’re sending a fuel tank into orbit as real estate, you’d build it a whole lot different than an expended stage.
Case in point. When SpaceX masters reusable stages (to get back to the thread topic (after drifting far afield)), they will be quite different than the expendable Falcon stages. For one thing, they’ll be a lot more expensive as exotic composite materials could be used to greatly improve the durability and, thus, the lifespan of the stages.
I’d use the same approach for real estate tankage. On the inside, I would have standard brackets interspersed along the tank stiffeners, ready to receive prefabricated structures; ‘floor’ panels, rack mounts, cable, ventilation and wiring harnesses, to name a few. Insulation strips would be placed between the tank stiffeners for thermal insulation on the inside. On the outside, I would do something unorthodox. Like the Space shuttle tanks, these repurposed tanks would have insulation, but not a thin, delicate layer by any means. It would have a multilayer covering akin to Bigelow’s Genesis Modules: foam insulation between kevlar like material several layers thick. Thermal insulation and meteor shield all in one! Yes, it’ll be heavier but we don’t care because it’s part of the payload.
I call it the ‘stuffed animal’ method of buiding… uh, StarScrapers! (Just thought of that :). Like that one DTARS?)
Forget for a moment about how foolish it might seem to toss a three hundred foot tall, 40 foot diameter (about the minimum size to be useful) almost empty tank into orbit and imagine what you’d have once it got there.
Part of the payload would be an almost solid mass of composites and aluminum that won’t take up much room but once unpacked and assembled would be all the walls, floors, rack mounts and anything else that can be bolted down. This could be done in shirt sleeves from the start because life support would be the first thing installed. If a power/manuevering module is waiting for it, you’d maximize the volume of what you can get into orbit (and folks could start working right away).
Windows and hatches? Built in, baby! Even the Space Shuttle tanks had service access in the form of bolt-on covers.
So, now you have a structure with air, rudimentary power, wall, floors, window, doors. The ‘framing’ is done (DTARS, you know what I’m talkin’ about here! ;)). Now you call in the electricians, the plumbers, the air conditioning folks. Each flight of crew and cargo brings up solar panels so the power needs balance the ever increasing functionality of the StarScraper. Then the furnishings, appliances and other finishing touches
Then you’re open for business!
All that work can be done in shirt sleeves as I said before. This alone would go a long way towards reducing construction cost and time-frame.
Outside work would be done with robot arms and ‘plug and play’ modular units, solar panels, radiators, docking modules, consumable storage units, etc.
Nice, clean, tidy design. At about $50 a cubic meter a day rent, I don’t think I’d have too much problem making a profit as a developer (as in the kind that builds condos down town).
Not a crazy idea at all if you think like a building developer or architect that has to take location, supply lines and placement into account. The location is exotic (on orbit), the supply line is expensive (one big launch, but dozens of little ones) and the placement, getting the initial huge tank into orbit is a major risk for an investor.
But, not insurmountable!
Any thoughts?
tinker
BTW: …and if you think I’m crazy whipping up a pre-fab space station, check out these guys!:
http://news.nationalpost.co…
In response to Paul451 (12/28/2012 07:57 PM)
Paul,
Sorry I haven’t replied. I may be away for a while (medical issues). But I haven’t forgotten this discussion; I have enjoyed it a lot, and I think it’s important that we continue to openly discuss these “thinking outside the box” possibilities, even when they seem far fetched, because I suspect that the good stuff, and the new stuff, that we read and write on NASA Watch does get picked up by people in influential places, directly or indirectly, and can make a difference. The more that the people at the decision levels are presented with new ideas from their staffs, the more likely we are to finally see our space programs dragged out of 1950’s thinking and into the future. We can only try.
I’m reminded, as is often the case, of a line from a Robert Heinlein book: Let the experts tell you what can’t be done, and why, and then do it anyhow. I know from personal experience that this idea is valid. And it seems to me that this is the point that our space programs are at, desperately in need of new approaches.
I read Tinker’s reply to you and agree with it in principle. It’s main strengths to me are: 1) we can do things that haven’t been done before, despite the number of people who are outright afraid to try new things, and 2) never, ever waste usable materials or actions, think “green” in space.
One final comment for now: In reviewing our discussion, and other somewhat similar NW exchanges, I am convinced of two things, collectively: 1) the biggest problem that we have to overcome is the total lack of consensus with regard to what we should be doing in space (which makes “how” discussions almost irrelevant at this time); and 2) the biggest weakness in our various arguments and proposals is inconsistencies in time — Joe argues something that pertains to today and Pete counters with an argument that relates to events decades in the future at the earliest. There is no meaningful exchange because the two points are not related to one another, separated in time as they are. I all too often see this “different time frame” mistake made by a single person (including me) within the same paragraph. For our arguments and proposals to have any meaning, each “idea” has to be assigned to a realistic point in time before one can consider which “ideas” have relationships or dependencies between them. I find that, sometimes, preventing this jumping around in time can be as simple as creating a post off-line and editing it as much as necessary to eliminate invalidating one’s own arguments, but it takes time. However, we need to be clear on what happens at what time, and in what order. It would be ideal if we had a comprehensive time line with all of the major events that we’re likely to undertake assigned to realistic target dates. Then we could more easily see the order of events, the dependencies between them, and when each event could/should be happening.
Thanks again Paul,
Steve
Fantastic Hop! Hopefully this will ultimately lead to the holy grail of spaceflight -CRRATS.
Folks:
😐 Like the cheese, we’ve been had… again!
tinker
A great test by Space X. I am hoping to see some of their RD put to use in the near future.
I thought NASA was suppose to do the r and d?????
They do. But they do R&D for stuff that doesn’t have, and may never have, commercial applications. Of course, many of the things they research do end up benefiting commercial interests, but that’s not the initial goal. Businesses like SpaceX (or Microsoft, or Pfizer), on the other hand, do R&D on things which they believe will result in a profit more often than not. This is one of the reasons that nobody who argues “NASA should be shut down and replaced by private industry” should be taken seriously. There’s no short-term financial benefits to doing the things NASA does.
Who will have to do the Major R and D for radiation shielding. NASA???? Or will Elon have to do that too!!!!!!
And I agree with your words above and I sure wish NASA would stop SLS and turn Orion into something which directly helps us get up there. I don’t buy the whole expensive exploration thing.
Lots of R&D went on before Elon Musk, goes on now without the approval or intervention of Elon Musk, and will continue to go on depsite Elon Musk. It takes very little research to discover as much.
Elon Musk isn’t a god. He’s just a guy with money to spend.
“Elon Musk isn’t a god. He’s just a guy with money to spend.”
I agree he’s not a god but he’s a hell of a lot more than “just a guy with money to spend.”
That remark came across as a bit petty to me.
It’s not petty. The lack of objectivity, however, when talking about Elon Musk is a bit tiresome. I’m a big fan of what SpaceX done, but I’m also wary of promises, like landing on or colonizing Mars within a given amount of time, especially when SpaceX has yet to fly humans, has yet to leave LEO, has yet to announce new radiation shielding for a trip to Mars, life on Mars, and the return trip….. I’m of the “let’s take it one day at a time” school. Reading some comments make it seem as if all of Elon Musk’s plans are faits accomplis.
As someone else alluded to earlier, there are a lot of people in the industry–both in government and the private sector–who are every bit as talented, imaginative, and capable as the people at SpaceX or Elon Musk himself. A little perspective is in order.
He’s not a god?? Well with his own falcons and dragons he surely MUST be some kind of wizard.
Lololol
Robin
I agree with you when you speak about all the other talented people. That’s not the point at all. It is important for people to get excited about space again. And the very fact that Musk is not some super genius makes what he is TRYING to do so note worthy. Like many of us he’s a guy with the dream, and he has a goal and he is formulating a plan and going for it. Succeed or not, that’s the kind of stuff, lol the right stuff we need to ever have a space future.
Seems to me the most important message from Mr. Musk is that any of us can do almost anything if we really want too! And really go after a goal.
Mr. Musk as told the world that dispite myth of how impossible and expensive space flight is, that it IS possible.
Has for all the radiation r and d issues that stuff, should be done by NASA and others with them realizing that there is a good reason to hurry.
I believe I have the perspective you speak of.
Robin,
There is one thing that, I think, makes it easier to like Musk and SpaceX, and that’s the fact that, generally speaking, when Musk says that he/SpaceX is aiming to do such and such by a given date, it has some meaning. They don’t always, or even often, make their dates, but they don’t cancel or redefine their goals when things change. They keep on chugging until they do reach their stated goals. This has certainly not been the case with either NASA or the other aerospace companies.
In project management, when things start deviating from plan, the correct action is to take steps ASAP to get back to the plan. The worst response is to change the plan itself in mid-stream, yet this is what NASA and the big aerospace companies have done over and over, with and without government participation.
Musk is no God, but his word means something, and there are no other people lined up behind him with the power to force his hand. Only money issues can possibly force him to modify his goals.
Steve
I will disagree with your last assertion, Brian. The technology to do this is brand new. SpaceX is inventing it now. Musk himself has commented about the need to use cutting-edge composites and manufacturing technologies in order to carry the fuel and extra gear to pull it off.
Cheers to all the SpaceX team. We can’t wait to see what you do next!
Descending all the way from staging altitude with descent rate controlled by engine thrust alone would consume a great deal of fuel. Using a small guided drogue parasail would allow most of the descent to be made at constant speed without burning any fuel, and keep position above the landing pad. The parasail could be released and the engine could be ignited at a few hundred meters altitude for a controlled landing, as has been done on Mars
V4:
You’d be surprised at how little fuel the stage would need to maintain powered flight. Consider, the Falcon 9 first stage burns for almost three minutes. That means that one engine can burn for over twenty five minutes at full power. So, if they use a sustaining thrust of 30% during powered descent, it could conceivably burn for well over an hour. Now, it couldn’t do that with a full tanks but what does 10% fuel load remaining at separation give us? 80 minutes of 30% thrust from one engine divided by 10 = 8 minutes of flying time to descend and land.
Might be enough to do the job. The new Falcon first stages are 40% longer than the original yet SpaceX has said that the new flight profile will separate the first stage earlier to reduce atmospheric stress. Looks like they’re leaving room for landing fuel.
As recovery systems go, they get it on the cheap. the hardware is mostly already there. The center Merlin engine is repurposed. As for the fuel, all they have to do is add extra barrels sections to the fuel and oxidizer tanks. Done! The only substantially heavy hardware that needs to be added is the landing legs.
Also, restarting the engines means that they’d have to pack compressed helium tanks to restart the Merlin’s turbo pumps. Deep throttling the Merlin saves having to sweat through another flight profile ‘event’ as well as being able to maintain complete control of the stage.
I expect the second stage and Dragon capsules will land using Dracos. They are both about the same weight so what works for one will work for the other.
Interesting that you bring up the drogue chute idea though. If you look at SpaceX’s latest Falcon/Dragon video, you’ll see them show a Dragon landing just like you describe except they appear to keep the parachute right through to landing, firing the Dracos up a few seconds before touch down. Scary, yeah, I know. I’d want to ditch the parachute a few thousand feet up too. 🙂 The idea of being pitched over like a Soyuz doesn’t seen appealing with a spacecraft as big as Dragon.
I think parachutes have a role to play for the Falcon second stage and Dragon capsule reentry, but for the first stage? Not necessary or desirable.
Cheers:
tinker
I almost doesn’t matter what altitude the booster falls from. If you have attitude control you can make it come in with a high drag profile. The booster will reach terminal velocity. I have no idea what that velocity is for the Falcon but I suspect that it isn’t more than a few hundred MPH. You only have to fire up the landing rockets when you have to slow down from that velocity. This may only be a few thousand feet altitude.
Of course, a parachute weights a lot less than the fuel to slow the booster down so it might make sense to use both.
“Of course, a parachute weights a lot less than the fuel to slow the booster down so it might make sense to use both.”
You’d think so, but generally space-craft parachute systems are so complex and multi-stage that they mass as much as the equivalent extra fuel.
That sounds reasonable, I wonder if one can take the parafoil idea all the way to horizontal landing on skids?
James:
Actually NASA tried just that with the X-38!
tinker
Tinker,
Going back even further, the Gemini capsule was originally designed for a parafoil landing. They did some test drop landings.
Steve
That’s not the plan… They will descend at terminal velocity (which is only a few hundreds m/s) and brake at the end – Lunar Lander Style!
Wait a minute!
I heard Elon say with his own mouth that he hoped that the hopper would go hypersonic by the end of the year. He said it was not a prediction but an aspiration.
Behind schedule again!!!! Lol
Have you all caught this latest piece of LockMart arrogance regarding Space X’s comparatively low launch prices/costs?
“Lockheed, SpaceX Trade Jabs in War of Words:
http://www.pcmag.com/articl…
It’s all about the money, but I’m surprised that LM still doesn’t get it. To LM it’s about how much money they can make. For the customer, it’s about how much money what they want costs. The two are not the same thing. SpaceX understands this; apparently LM still doesn’t. The times are not changing — they’ve already changed.
Easy to make scientific progress when you’re not dealing with political/personal agendas. Kudos to SpaceX for getting it done. But it’s not like they’re any smarter than anybody else. Folks have had great ideas for years, but have been shot down for one reason or another. The gift that SpaceX gives us is not what they are doing technically, because there are great minds everywhere. Their gift is reminding us all what unconstrained folks are able to do.
To be fair, though, they were smart enough to structure and operate the company the way they have. It probably would have been just as easy to set themselves up in the same manner as those who work with Boeing and LM, becoming just one more subcontractor car on the gravy train.
Unfortunately Yusef, your analysis is not quite spot-on. Elon and SpaceX are very large contributors to the current regime. So, there are certain games being played, but they are not the same games as the old arsenal space companies. I’m not attacking SpaceX, but facts are facts; it’s good to have friends in high places, and both Elon and SpaceX are very good lobbyists.
You don’t need to be a great lobbyist when you’re selling at a fraction of the price of the other guys.
Tinker Steve Paul
I have not read all your posts thoroughly enough to comment on details.
But tinker I disagree that all these comments are off topic in this Spacex hopper thread. Wouldn’t musk want us to be talking about what will be possible once Space flight is cheaper.
In general I think Tinkers solution to early space construction IS the middle ground between Steves and Pauls arguments about space construction. That’s why I have always been such a fan of his lifter. It’s just common sense.
Tinker lol Starscraper is perfect. You have Joe Qs approval!!!!!
Sorry I couldn’t comment more thoughtfully. I have a lot on my plate, building stuff these days 🙂
Also in general, I think that once Spacex starts dropping that launch price. that all kinds of possibilities will start happening and snowball, Musk will go to mars in his life time, but the business opportunities in Leo, beo and the moon will be far more important. Provided that public /space/government/DOD/congress don’t delay It.
Steve
You say why
To get the resources we need.
More than one place for man kind to live to ensure our survival.
Asteroid defense
You recall even Clem agreed. 🙂
Bottom line is little Mr. Musk is going to mars and flight to Leo will get much much cheaper.
All we need to do is figure the best way to help.
Steve a big fear I have is that our tribalism will make ALL of mans hope of getting of this rock impossible. I have a very general definition for that word.
Lol I confess I planted comments to get you all talking about this kind of stuff lololol
You all fell right into my trap. Lololol
It’s kinda fun to have bright friends that could make a difference if people would only listen to you.
Lololol
Joe Q Public
PS Steve I just read your thank you note to Paul I agree! Even a Joe Q like me can make a difference if he can use the strengths of others in the group for the good off All. Isn’t that the goal?????
Lololol
It sure is fun 🙂
Happy new year Steve 🙂
DTARS:
Careful, your wisdom is beginning to show through… 😉
tinker
Yes Sir! I’ll try to be more careful, I’m just a parrot for good ideas.
Happy New year Tinker
Keith
End of the year 2012
Thank you so much for your blog that gives thoughtful people a place to share ideas
I hope my thoughts have been an asset.
Happy new year!
Folks:
From Steve Whitfield’s post on this page:
“…the biggest problem that we have to overcome is the total lack of
consensus with regard to what we should be doing in space…”
The answer to what we should be doing in space is, of course, everything!
Happy New Year:
tinker
StarScrapers land on Mars
Tinker
I just realized some things about your lifter/StarScrapers and maybe how they should be built and used.
Our welding rods come in rectangular metal boxes, about 5 in by 5 inch and about 18 inches tall, the perfect shape and size to model your to orbit tank.
As I have said before your main tank should be square to maximize useful space in Space lolol.
Your lifter should be powered by methane engines because that is a green Fuel plus it can be gathered on Mars. You told me that the ratio of methane to liquid oxygen fuel is close to one to one. Well regardless of which is more, your on orbit tank should be oxygen and your tugs carry the methane.
Since your tank is basically square it is easy to reinforce using standard X bracing either inside or as part of your external thrust frame.
Your thrust frame can now be square. Standard structural girders that support the tank from underneath like a floor(not just the sides as you have suggested.) on the sides of these floor girders is where you mount your tugs.
I disagree with you that you put your payload underneath. Lololol your payload only goes inside the to orbit tank. To carry standard payloads to orbit you add oxygen tanks to each of your tugs. Turning each tug into Spacex recoverable first stages. So each of your tugs can either fly with one recoverable tank using the on orbit tank for oxygen or it uses it’s own oxygen tank added on top making each tug twice as tall.
Lolol now your thrust frame is used as a basket to carry what ever 40 by 40 foot payload your want to carry.
Also there is no reason to carry your whole thrust frame to orbit, your two second stage tugs could stay attached to the lower heavy part of your thrust frame which has landing legs just like Spacex hopper and bring it back to earth for another flight.
Ok lolol
Soooo
What would it take to get your whole lifter/StarScraper into Leo with legs and enough fuel to land it on mars????
One flight using standard one tank tugs to get the shell up there then you upfit the interior with standard LVs or a couple of payload flights from double tank tugs. Then with your last flight you fly double tank tugs with no payload and you fly all six tugs attached to the lower thrust frame and landing legs, to dock with your MarsScraper which turns it into a GIANT lander. Then you head to mars with enough fuel to land on Mars and maybe make fuel for a return as well.
How many tugs would you want to carry to mars to be part of your mars lander configuration???? My guess would be all of them so that some of your empty tankage could be used for fuel manufacture.
I envision 6 two tank tugs with total 30 engines strapped to the thrust frame with a StarScraper tank filled with settlers already in their mars apartment units And this high rise has the ability to land on Mars and fly back to earth.
Tinker, you didn’t understand before why I was asking about Spacex building engines smaller than a Merlin 2. I think that each of these tugs should have 5 methane Merlin engines the center one dropped down for recovery control. Would 5 merlin 2s be to big or not. Depending on the load couldn’t you leave an engine turned off on each stage if you didn’t need the extra lift??
Didn’t Mr. C say all missions start with a lander??
Isn’t your lifter the cheapest easiest way to build a mars lander/transporter/habitat/ mars return vehicle all in one???
Wouldn’t you take two of your lifters and cable them together and spin them for artificial gravity to mars??? Couldn’t one or two of your lifters be put in mars orbit as space stations.
Couldn’t your lifter BE the engine, railroad cars and stations I’m looking for to build railways to the moon and Mars as well as LEO and BEO.
Isn’t Spacex doing the R and D right now for your lifters tugs????
Shouldn’t Spacex be planning to build your lifter in future to settle the inner solar system?????
Steve
I know you will say that what I want is a millennium falcon and again I will disagree lol. I want a modular vehicle system that can do it all!!! Lol including heavy lift lolol
Maybe StarScrapers/MoonScrapers landers/MarsScrapers landers are just what we need to build the inner solar system railroad.
I’m not sure how to design the lunar version. Maybe it runs on hydrogen. Any suggestions?????
It DTARS
Just a little imagination
Just to be clear you fly this in TWO versions that share the same basic thrust frame.
The real estate version which flies just like Tinkers lifter puts an large empty tank in orbit. The tugs on this version only have one main methane tank.
The payload version
Using the same basic thrust frame this version has tugs with double tanks making each tug twice as tall so the tugs carry the complete fuel load leaving the 40 by 40 thrust frame for GIANT payloads.
Each version could have landing legs where the second stage pair of tugs brings lower part of the thrust frame (the tug collar) back to it’s launch point.
Since the tugs all use the same reusable engine configuration, couldn’t some of the tugs fly double duty as a standard LV???? Perhaps you possibly even just stack your three tugs and put a payload on top letting each tug use it’s recovery tech in the flight profile where it is comfortable????? And upper stage tugs only fire as many engines as needed.
Humm sounds like Tinkers lifter could and should be the standard for a complete rocket fleet to me!!!
PSS and don’t tell me we don’t have the ability to assembly this crap in space, its mostly modular, plus my tick pilots are ready!
Lolol
Of course your lifter lander could also double as hopper. So you could move you whole science colony from One interesting site to another on those early science resourse research missions.
Just want to keep science guys happy lolol
George,
I read through 87 and 88. I have no problems with the concept, but I did scratch my head over a couple of issues. Sorry, but this is just a quick reply for today.
First, for the complex (I consider it complex, others may not) thrust frame configuration you’ve described, you’re going to need a sophisticated, and fast, fuel/oxidizer crossfeed system for all of your tankage in order to maintain your center of gravity. I’m talking about crossfeed performance on par with a fighter jet or an ocean tanker. Without it you’re going to tumble and crash. One problem you face is that crossfeed systems are something that you can’t break into sections after launch. There are several issues to get around with this, but it might be doable (but will probably involve jettisoning some hardware on every launch).
Second, off-hand, I think you’ve got your Tugs doing more than the fuel/oxidizer available for them at launch will manage. Also, the tasks you’ve assigned to the Tugs implies that they are all manned, yet you propose “Turning each tug into SpaceX recoverable first stages.” Have you worked through the details of what a Tug can do (manned or unmanned), where each Tug starts from (all from the thrust frame?), where each Tug ends up and whether you have the fuel/oxidizer and control to recover them all to wherever they’re going? Do you have a scheme for detaching each Tug from the frame as needed that is reliable and reusable (as opposed to pyro bolts)? Do your envisioned mission plans require that a Tug ever “rejoin” the thrust frame? If so, how are you planning to do that?
A general note on Tugs: they often will need to be very maneuverable and work together, much like harbor tugs on water, so how realistic is it to use the “SpaceX recoverable first stage” shape?
I’m not shooting you down here. I’m just pressed for time, so I scribbled down the first thoughts that occurred to me about things needing to be elaborated upon.
Steve