Market doesn’t justify reusable launchers, expendable rocket makers argue, Ars Technica
“Monday evening in Salt Lake City, some aerospace industry officials sat down to discuss this new development. The panel at an American Institute of Aeronautics and Astronautics forum on propulsion had a provocative title, “Launch Vehicle Reusability: Holy Grail, Chasing Our Tail, or Somewhere in Between?” Moderator Dan Dumbacher said of the panel, “We purposefully tried to get a good cross-section of those who have been working on it.” However, the panel included no one actually building reusable rockets and relied heavily on the old-guard perspective. Dumbacher himself, now a professor at Purdue University, previously managed development of the Space Launch System rocket for NASA, and he expressed doubt about the viability of reusable launch vehicles in 2014 by essentially saying that because NASA couldn’t do it, it was difficult to see how others could.”
Keith’s note: Well of course SLS-hugger and former NASA SLS manager Dan Dumbacher can’t see a world where the launch market is diverse in terms of customers, payloads, launch vehicles, and financing. He only has wetware that lets him see giant government-built rockets – so that is all that he can see.
The author of the piece (Berger) nailed it with his closing paragraph. As some folks toss around analyses and future projections about the viability of doing things in new ways, others are actually bending metal and exploring those new ways in the jurisdiction of the final arbiter: reality.
One name: Dumbacher
All I need to know. The guy is an absolute train wreck when it comes to policy. Sadly, this guy still has a lot of clout and when the private sector laps NASA he will be saying its a mistake.
No one wants to design missions with SLS. Everyone knows it is just a matter of time before the crushing weight of political oversight ruins any real chance SLS had.
This is so typical of the “inside the 495” crowd. Oh we invited them but they didn’t show. Whatever.
Consider that 70% of NASA’s mass is dirt cheap, Class D propellant. HSF Mission mass to lunar and mars is 200 to 500mT/yr!
There is no ‘what next’ until launch costs drop 10X – reuse and flight rate. Take risks with cheap payload and demonstrate reliability.
Missions/tech demos are paid for by LV $$ to payloads.
“Boeing’s new gas stations would leverage rockets that are three to five times cheaper than NASA ($10,000/kg) launch systems” http://nextbigfuture.com/20…
Make a change or keep building and operating decades old stuff?
“If a problem cannot be solved, enlarge it” Dwight D. Eisenhower
Next Big Future indeed.
I think you’re missing the point (or making the point) by talking about “Class D” propellant. According to some, there is no such thing.
If propellant is necessary for a high-priority mission, then it is of equal priority as the mission. Propellant for a class A mission is, by this logic, a class A payload.
If launching the propellant is not necessary for some specific mission, then why are you launching it? Some people feel you should only expend resources (including money) on things necessary to accomplish a specific, approved goal (with documented flow down from goals to requirements to actions.)
I’m not saying I agree with this logic. It is, however, fairly common and gets in the way of saying “well, it would really help some, unspecified, future missions.”
Class D refers to the value. The cost of propellant is a few million. The cost of the hardware is 100s of millions to billions, even though it only makes up 30% of the mass or less. Class A is for expensive hardware/crew.
Why ‘package’ them together?
Basically, one is simply filling the departure stage in space and decoupling Class A from Class D, allowing more risk taking to reduce costs for 70% of the mass.
One could launch Class D propellant on a reuseable LV, and only lose the cost of the LV. Stage the 100s mT of propellant first. Launch the upper stage empty, or offload propellant to increase the hardware mass. ISRU could help too, especially since the crew needs prepositioned propellant to reduce the trip time.
Ares V, 140mT, had to increase the number of flights from five to 6 for one leg of the Mars mission due to 70 tons of boiloff. Simply build a near zero boiloff gas station. With a depot, one does not require heavy lift, and increases the flight rate of the smaller fleet.
Many other advantages of depots here, besides Boeings Amplification factor link above.
http://www.spaceref.com/new…
Assuming we are talking about the same A to D classications, I think you are incorrect. There have been discussions of the at public NASA meetings, the presentations are on line, and I can dig up the references if you like.
Class A missions are not defined by cost. They are missions which are critical to high-level NASA goals or missions who’s success or failure would significantly impact our national reputation. Class D missions are, by definition, ones which can fail without having those sorts of reproductions. The cost follows the classification, not the other way around.
The beauty of prepositioned supplies and propellant is that the billion dollar hardware with a small launch window can be launched in a few flights (30% mass). In contrast, near zero boiloff propellant only has to be ready every year or so, so it has low priority per Appendix B. The DOD fleet can launch lower priority cheap propellant when not required to meet a high priority national security need.
The safety requirements, and hence costs, are significantly reduced for Class D vs Class payloads too. Multiple LVs including IPs can fill this need and reduce the costs of deep space exploration as long as it delivered “within a year or so”, not within a 20 second window.
http://nodis3.gsfc.nasa.gov…
I take your point and while I also get why you are breaking out the fuel from the payload, I’d point out that the orbital gas stations that everybody is so keen about require lifting fuel to fill the tank. Yes, smaller rockets are involved, but still.
I suppose that there’s a break point someplace: bigger rockets carrying mega tons of fuel vs. smaller rockets that carry fuel to the gas station and thence onwards towards wherever. The notion of orbital refueling only makes sense, at least in the terms of the argument you have posed, when somehow the fuel is not also lifted from the planet.
Making the issue larger: the cycler concept sheds ever more pieces of the lifting rocket.
Am I missing something here?
Simply stated, one is reducing the amount of hardware (cost and mass) that needs to be pushed through the LEO (and cycler) dV, along with other advantages (risk, availability, reuse …) “Amplification factor” ***
1) Depots reduce the size of the LV required and allow optimization of DOD, NASA, comm. mission classes for cost and reliability.
1A) Greater mission flexibility. Need 2mT more payload? simply offload 2mT of propellant and top off at the depot, similar to using EP for the trip to GEO. Why even use a heavy variant?
1B) ULA needs 10 flights to achieve 100M, otherwise its a simply excess capacity. Depots easy allow multiple LV ‘customers’, even IPs.
Reduced mass thru dV
A depot is simply an upper stage with stretched tanks launched empty with power, refrigerators and attitude control. The allows the expensive, long life equipment to be decoupled from the dumb tankers.
2) reduces mass of boiloff mitigation on tanker
2A) transfer stage can be designed for on-orbit loads with propellant, not launch loads
2B) MMOD on LEO depot, not tankers
2C) depot performs prox ops
2D) Reuse: cyclers pull depots to preposition supplies; debris cleanup refuels at depot
Reduced costs
3) Class D payload–less ops/certs costs
3A) Reuse missions to demonstrate reliability
3B) fuel transfer/storage enables reuse (cars, planes, trains)
Mission LOC/LOC
4) Propellant decoupled from mission elements reduces LOM
4A) more cargo flights perhaps find the unknown unknown LOC
4B) MMOD shifted to depot, not hardware elements, especially when staging 400mT
4C) reduced trip time mitigates crew health
The ability to stage hardware sent directly to L2 almost eliminates all MMOD mass, and EP uses the slower transfer rate to reduce costs at the expense of time. A depot near Mars enables faster trip times back to earth and for beyond Mars science.
*** Boeing’s Amplification Factor
“Because most of the mass necessary to get to the moon is propellant (though Boeing would never say so), a space gas station might even eliminate the need for a heavy-lift launcher altogether, increasing the launch rate of smaller, cheaper vehicles, which in turn could cut costs for getting to the moon and, eventually, Mars. “
http://webcache.googleuserc…
http://www.lpi.usra.edu/mee…
http://images.spaceref.com/…
It’s a big paradigm shift, as they say.
Perhaps an analogy with modern Air Force/ Navy practices is apt? Building B1 and other bombers and fighters with the range needed to get to target without refueling would fatally compromise aircraft design.
It’s pretty much the current situation with lifters, although it is also true that the Smart People at SPX are thinking of the BFR. There’s a fly in the ointment (err, argument) someplace. Maintenance of in situ depots? Complexity?
Maintenance…HSF flight rate…..if all else fails launch another one, will need many anyway. Pull the filled depot one way, pick up the empty from the previous mission…bring back for repair if necessary.
I could still make a case that propellant could still be class “D”, for a class A mission, as it’s all fungible. The propellant for a class A mission or a D is all the same, and more propellant is always arriving at the node, depot, gas station (whatever the concept is). The availability at the gas station would be critical to the Class A though, the availability there at the interface at the ready would be an “A” unto itself, but incentives there at the gas station (or stations, plural) should be to always have the propellant at the ready, to best manage traffic efficiently, both coming leaving propellant, and providing delivery thereof. A gas stations operations and reliability would improve from having many customers, Class A or otherwise (the private sector wants to have their items succeed just as much).
You could make that argument, and I wouldn’t disagree. My point was that many people, many within NASA, would. There is a tendency to focus on _one_ mission, the one you are working on. From that perspective, fuel launched is either critical to the mission (making it class A payload if the mission is class A) or irrelevant.
What you are suggesting is to make fuel on orbit a general resource, available to any mission which needs it. That could be compared to the Deep Space Network, which provides telecommunications services to any mission which needs it. That is not a bad idea. I am simply pointing out that that would require a significant change in the way the people involved think about things. If the idea was considered by people thinking in the traditional manner, it would be rejected.
I think people need to get a grip on a new paradigm (although I dislike that term) before they will accept the sort of thing you are suggesting.
Way, way back in the 1990s, the strategic goal of NASA space launch technology R&D efforts was to lower the cost of access to space for government and commercial missions. NASA abandoned that goal a year or two after the turn of the century, and turned its focus to launchers for its own purposes. That was when the argument emerged (recognizable to students of Aesop fables) of the fox who failed to reach the grapes: they must be sour…! It is a great shame: there no reason that NASA might not play the same role for astronautics that it plays for aeronautics — AND still pursue R&D / systems for its own missions where needed.
This panel seemed to reflect the ‘moñeyd’ (contractor, old space) interests; part of the corruption of NASA that seemed to begin around the time of the Shuttle consolidation contracts. NASA and its benefactors really need to figure out NASAs role in HSF,then señd some people to get to work.definitely a management problem.
Dr. Dumbacher’s point that if NASA couldn’t do it then reusability couldn’t be done is/was a good one; many were in that camp not so long ago.
Now we see that someone else can do it, which came as a surprise to a lot of people. Recall for instance Gerst’s comments regarding the investigation of SpaceX rocket failure, pointing out that at NASA six months would pass before he could even field a team to investigate the cause of the crash, and that all NASA had to do in that instance was get out of the way.
These two examples are challenging many suppositions of this old Democrat.