NASA's Latest Gateway Cartoon Presentation
FYI @JimBridenstine Jason Crusan is trying to be cute saying that Gateway is not a space station (to thwart some criticism that it is) because it has an engine and moves around. Apparently Jason does not know that ISS has engines and that it moves around (reboost) all the time. pic.twitter.com/2sSF0J7hZh
— NASA Watch (@NASAWatch) August 28, 2018
|
|
|
|
|
|
|
|
|
|
|
|
Which raises an interesting question. Just what is the technical difference between a spaceship and a space station? Propulsion of course, but at what point does it have enough to be considered a spaceship?
And just for fun it should be noted that OST, Liability Convention or Registration Convention does not distinguish between space stations or spacecraft, just referring to them as “space objects”. Indeed, if I recall several of the modules and components actually have separate registration numbers as “space objects”.
I don’t believe there is any accepted, technical difference between a spaceship and a space station. Nor is there any between a spacecraft and a spaceship. (And, I suppose there is a logical case for a boat coming somewhere between a craft and a ship. But I can’t recall ever seeing the term spaceboat.) Nor is there any universally accepted definition of terrestrial crafts, boats and ships. There are probably many, in the details of registration and licensing, but not a single, consistent and widespread usage.
For myself, I’d say a spaceship would have enough propulsive capability to go from one place to another, while a space station would only have propulsion for station keeping. But that’s vague, and it isn’t hard to invent exceptions. (Would Aldrin’s concept of an Earth-Mars cycler be a ship or a station?)
So.. .this thing is only occuped part-time?
Hate giving the vehicle yet another potential job, but why not just launch a BFS on need? It’s certainly large enough, will have a large ECLSS system and crew quarters, and gobs of endurance and dV. Need a microgravity “lab” disconnected from twitchy human vibrations? Deploy a small one from the cargo bay, or put a larger one in lunar orbit and rendezvous with it.
You are assuming there is a purpose to LOP-G other than providing SLS with a payload and Orion with a destination…
Even so, using BFR is structurally something NASA would not want to do. As a general rule, a project is supposed to have some sort of responsibility for (and control over) everything in the critical path. What would the managers of the lunar orbital station project do if SpaceX changed their minds and decided not to develop BFR? Or made changes as substantial as when they went from ITS (2016-2017)?
NASA could use the approach that worked well for commercial crew and cargo, a Space Act agreement that would say only that SpaceX would get paid when they provide the capability for human to operate in circumlunar space, without telling them how to do it.
How about “SpaceBarge”? It is sort of like a Space Station but slower. And it would be more fun to say.
Though SpaceBoat does sound better.
I’ll know it when I see it.
Rather than propulsion I think it’s the “station” part of the name that best describes it, based on the definition for that word which comes from the same root word as stationary. Definitions for station include a place where someone is assigned to stand or remain, or a stopping point on a transportation route.
Besides propulsion for station-keeping, a space station could in theory have propulsion enabling it to change its position if needed, similar in concept to how geostationary satellites operate. Even though people might go for the ride during such moves, that would only be incidental, the primary purpose of a space station is not transportation, but instead as a destination for other space vehicles in a permanent or semi-permanent location or orbit.
Perhaps a complementary and equally literal definition could be about ships and crafts. If they are defined as a vehicle, then they are literally a device to move people and goods. That is, a device who’s primary function is transportation. That’s not perfect, but it does differentiate them from a station, something who’s primary goal is not transportation.
Merrium Webster has it as:
“Definition of space station
: a large artificial satellite designed to be occupied for long periods and to serve as a base (as for scientific observation) — called also space platform”
They don’t mention the ability to move… I would think that station keep ability would be a basic function?
is gateway being occupied only 30-60 days of a year considered occupied for long durations?
I suppose that’s relative. When I travel, my definition of a “long” trip is whether or not I have to do laundry while I’m away. I pack light enough that that’s about a week. On the other hand, five or six hours is about when I start thinking of a plane flight a “long” trip.
The station uses its propulsion to, essentially, stay in the same place. Although it is not actually stationary, because it is moving around the Earth in orbit. But the orbit is stationary. No, the orbit precesses. The first Deathstar was called a “battle station” even though it could move between stars. Why wasn’t it a battleship? What about the “HMS Ascension island”? http://www.ascension-island…
My head is starting to hurt.
And what about one of the O’Neill Habitats? Would you call that a space station?
Part of the concept for the O’Neill habitats was that propulsion would not be needed because the L4 and L5 orbits are considered “stable”, low energy points in the gravity field of the Earth and Moon and in a constant orbital location relative to both, however this location was not selected for the Space Gateway. The desire for proximity to the Moon may have been a factor.
And HMS Victory is still a commissioned ship in the Royal Navy (the flagship of First Sea Lord at that), despite the fact that it’s been in dry dock since 1922 and almost certainly can’t float anymore.
And, during the Second World War, several islands were referred to as “unsinkable aircraft carriers.”
We could also talk about weather or scientific stations on icebergs or ice islands (there have been a few) since they do drift over the ocean.
Well, if they would have put some advanced propulsion to test on the ‘Gateway’ and had it cruising between Earth orbit and lunar trajectories, then it might have made some sense, but just keeping it out in a ‘halo orbit’ out in the middle of nowhere, makes no sense at all. Apparently the only goal was that, in an lieu of an asteroid, and unable (and with no reason) to reach a low lunar orbit, it gives Orion a place to fly to every now and again (which is as often as they can afford to fly it). Apparently there goals and strategy are not a part of the program.
Let’s be clear, giving “Orion a place to fly to every now and again” is the primary goal of Gateway. Anything else is a secondary consideration. If the asteroid retrieval mission had been given the green light, Gateway wouldn’t exist.
Except he is talking about using commercial assets for a lunar return. The SLS/Orion may be on the way out.
It’s not yet on the way out. I’ll believe it’s on the way out when, in a public hearing, the NASA Administrator tells Congress it’s not needed and it’s a waste of money. And even then, Congress might balk and continue to fund SLS/Orion over the objections of the Administrator. SLS/Orion is, after all, primarily welfare for engineers. It really doesn’t matter to Congress if it’s needed, or if it even flies, as long as the pork keeps on flowing.
> giving “Orion a place to fly to every now and again”
This rings familiar. Space Station Freedom for Space Transportation System to be useful ?
The 1st rule of sales …
Sell the Sizzle not the Steak
Boy did NASA take that to heart .. because they are sure selling the sizzle ..
What NASA is doing here is commonly called “programming;” this word is used as a technical term in the design world.
http://balberarchitect.com/…
Programming is a normal and proper initial step in design, particularly in cases where the builder/owner and the end users are very different entities. Budget properly isn’t part of this process (but see below).
The process of programming involves listing all of the possible things you want in, for instance, an office building, or a home, a space station, or whatever. Costs are not part of the process for many excellent reasons. There’s no way to know, taking a simple example, how different program elements might functionally overlap: a guest powder room, for instance, might serve as a swimming pool bathroom.
There are exceptions. In the case of this proposed structure, for instance, should the proposed structure be capable of orbiting luna or earth or Neptune? Probably not.
There are sophisticated methodologies for dealing with program elements but most of the time common sense is sufficient, meaning that Neptune is probably a non-starter.
If I understand you correctly, the implication is that there is a builder or owner. That is, someone has property he wishes to develop or at least money he wishes to invest in development. And that the location being developed is sufficiently well known for a realistic list of possible options can be assembled.
If that’s the case, then the implication for LOP-G is that it’s a given that it will be built and they are studying what to do with it, given that fact. I might question that decision (well, I definitely would) but once it’s made, you do have a point. I think the conceptual design is a little too far along for this, since the design ought to follow from the intended uses. And they do need to down select the uses, not try to build it to support every suggested use.
“the design ought to follow from the intended uses”
This would be an abstraction of ‘form follows function’, no?
In the case that Keith is posting about I don’t know what the objection is or what would be a better way to do it. Looking at deep space projects from my (very) outside perspective, for instance, it appears that scientists play quite well together both in programming and in mission selection. Certainly there’s going to be in-fighting that we don’t see out here in the public, but the public-facing part of the process appears to work.
Dr. Woodward’s point about HSF is well-taken and I think he correctly identifies the culprit: confusion over who exactly is the user/ owner.
Even here though I don’t find much that is objectionable; politics is how we run our country. We all get the same vote.
It is not an easy matter to identify actual users for the LOP-G but astronomical observation seems a reasonable choice, since the lack of shadowing by Earth would minimize thermal stress and ease power supply design, and the low gravitational gradient would make it possible to move operating telescopes some distance from the habitat platform without much demand on station-keeping propellant.
When planning planetary spacecraft NASA follows this approach reasonably well. Program management acts as the owner, does periodic surveys of the users, i.e. scientists, announces a program opportunity, i.e. a spacecraft of a given size will be launched to a given planet in a given year, and invites proposals for instruments to be accomodated, like the tenants in an office building.
In human spaceflight and some of the largest unmanned projects like JWST this does not work because political forces and institutions are effectively the customers rather than actual users. Congress would not allow Constellation to be cancelled and created SLS/Orion, a destination was needed and so the Space Gateway was created, and now scentists (i.e. users) are being asked for proposals to do experiments on SG.
To be fair, the same process you describe for planetary missions is also used for complete, competed missions (Discovery and New Frontiers), as well as instruments on large strategic missions. And the results for the larger missions (where the spacecraft is assigned to a center rather than competed) are mixed. Finally, the other science directorates (Astrophysics, Earth Science, and Heliophysics) do similar things. I’d say the distinction is whether the work is competed or assigned to a center, and how much money is involved.
In listening to the explanation that the Administrator gave for the Gateway it appears it will have a SEP attached. So maybe it will have the ability to change orbits as needed, useful given the gravity environment of the Moon.
Well, from the looks of it, that’s 50 kW of solar power, to operate four Hall effect thrusters. That would be great thing to flight test. And it looks like it could give Gateway a few (three or so) km/s of delta v. For the orbit they’re talking about, that’s more than I’d expect they need for station keeping (despite the irregularities in the Moon’s gravitational field.) But I wonder when you write, “ability to change orbits as needed.” What is the actual need? I guess I’m harping on the idea of form following function (again) and wondering what the required function is, and whether the SEP system could be tested equally well on a different spacecraft and at a lower cost.
If the Gateway is going to be used as a transfer point between the Orion and a lunar lander being locked in a single orbit may greatly limit the possible landing sites. The ability to alter the orbital inclination would open up more options. Yes, plane changes are very energy intensive so the changes would have to be limited.
As for testing the SEP, I would recommend it would be tested on the ISS by increasing its orbit to one that will last longer.
Somehow, that just feels wrong. If LOP-G (they really need a better name…) is supposed to be a transportation hub, moving it around to support different landing sites just doesn’t strike me as an elegant solution. Maybe maneuvering the smaller lander, or something clever with orbital precession of the station. I’m not sure what, since I’ve yet to see any details of the planned station’s orbit.
In any case, I also don’t think the artist’s conceptions I’ve seen look like something suitable to be a transportation hub. And I don’t credit anything at the viewgraph-only stage as being a design rather than an artist’s conception.
(And, yes, I do realized that an aircraft carrier is a transportation hub which moves around. But that’s the only example I can think of.)
Nevertheless the purpose of a transportation hub is to reduce the cost of transportation. The first transportation hub that would be logically needed would be in LEO, to serve as the transfer point between vehicles designed for atmospheric flight and vehicles designed for space. In fact when the modern idea of the LEO space station was formulated in the late 70’s that was its primary mission.