Recovering upper stages - in orbit?

[DDE]

1 hour ago, mikegarrison said:

There was a proposal back in the Apollo days to make a space station out of a Saturn IIb stage. https://en.wikipedia.org/wiki/Wet_workshop But in the end, the US decided to make Skylab a "dry workshop", in other words a space station purpose-built on the ground rather than assembled out of the hulk of a lifting stage.

Nitpick: no, Skylab was originally designed as a wet workshop, the only reason it ended up dry was because NASA had a spare Saturn V; they'd have gone with that if they had to, plus the manned Venus flyby project was a thing.

Edited September 23, 2017 by DDE

[mikegarrison]

20 minutes ago, DDE said:

Nitpick: no, Skylab was originally designed as a wet workshop, the only reason it ended up dry was because NASA had a spare Saturn V; they'd have gone with that if they had to, plus the manned Venus flyby project was a thing.

And what do you think is different about what you said from what I said?

[ModZero]

No recycling until we have a propulsion system that's at once cheap, high dV, and has a decent thrust. Right now that's a bit of a "pick one" situation. VASIMR people tried to "advertise" their thingie as a potential "space junk cleaner" engine (totally worth watching for music that somehow makes me feel like I'm watching a truck advertising. That might be intentional. Also, extremely KSP-ey spacecraft), but, uh, they don't really have anything to show for it, and considering the power needs, I don't think they'd get past "pick two" if they somehow succeed.

[StrandedonEarth]

About the only real value in recovering (not de-orbiting) stages in space is to refill (near term) or recycle (long term). Bringing them back down the well would be prohibitively difficult and expensive, to the point of being pointless. Anything already in orbit has the sunk value of already being up the hill and halfway to anywhere.

[Bill Phil]

On ‎9‎/‎23‎/‎2017 at 4:44 PM, DDE said:

Nitpick: no, Skylab was originally designed as a wet workshop, the only reason it ended up dry was because NASA had a spare Saturn V; they'd have gone with that if they had to, plus the manned Venus flyby project was a thing.

I'm not so sure if it was designed at all up until mid 1969 or so beyond concepts. McDonnell Douglas got the contract in August 1969. By late 1968 it was likely that they would gain access to a Saturn V, and later it was guaranteed by the cancellation of the last three landings.

And, even then, if we're being technical, the Orbital Workshop was not named Skylab until 1970, meaning that from the beginning "Skylab" was designed as a dry workshop. The Orbital Workshop, of course, was proposed as a wet workshop and ultimately became a dry workshop.

[kerbiloid]

(Just because somebody would leave this here)
https://en.wikipedia.org/wiki/Manned_Venus_Flyby#Background

Edited September 25, 2017 by kerbiloid

[NSEP]

I'd love to live in a SLS fuel tank, but im not sure on how difficult it is to actually make liveable and safe. Im not sure if the SLS fuel tank or pretty much any fuel tank has micrometeorite protection. The point of a rocket stage is to send something somewhere in space and just be destroyed afterwards right? Its like using a plastic plates as a full time dishware (if im right)

Correct me if im wrong.

[kerbiloid]

According to wiki, big orange tank from shuttle is 46.9 x 8.4 m large.
If they were collecting them in orbit (attaching with struts), there was a bunch of ~130 tanks, with total volume 300 000 m³. Already paid, btw.

[NSEP]

Just now, kerbiloid said:

According to wiki, big orange tank from shuttle is 46.9 x 8.4 m large.
If they were collecting them in orbit (attaching with struts), there was a bunch of ~130 tanks, with total volume 300 000 m³. Already paid, btw.

But are they still in orbit? I think most of them (if not all) have burned up by now.

[kerbiloid]

All of them have burned. But they were so close to the orbit. Just 50 m/s more or so.

Edited September 25, 2017 by kerbiloid

[Nibb31]

The whole "repurposing Shuttle ETs" was always a bit of a myth. The ET would have needed a major redesign to actually use it for anything. You would need an airlock, attitude control, docking system, internal hatches between the tanks, removable baffles, etc, etc, etc...  A lot of engineering that would make them more complex, heavier, and less reliable. Just leaving in them orbit, the orange foam would outgas, degrade, and end up as a giant cloud of orange debris around the tank. Yuck.

The whole idea was utterly impractical.

Edited September 25, 2017 by Nibb31

[wumpus]

1 hour ago, Nibb31 said:

The whole "repurposing Shuttle ETs" was always a bit of a myth. The ET would have needed a major redesign to actually use it for anything. You would need an airlock, attitude control, docking system, internal hatches between the tanks, removable baffles, etc, etc, etc...  A lot of engineering that would make them more complex, heavier, and less reliable. Just leaving in them orbit, the orange foam would outgas, degrade, and end up as a giant cloud of orange debris around the tank. Yuck.

The whole idea was utterly impractical.

I'd suspect that there was enough residue oxygen left in the tank to make it worth pumping out (at reduced pressure/flow requirements).  Presumably there would also be hydrogen, but it certainly wouldn't last long enough to be useful.

I'd also assume they could be used as some sort of ISS backbone/struts (don't try to change anything inside).  It wouldn't help the outgassing problem (although you could presumably time orbital correction maneuvers to escape your outgas). 

But all this mostly assumes planning that would have to happen in the 1970s when NASA managed a miracle in getting the Shuttle to perform nearly all of its crazy requirments (cost/launch wasn't even close, but the cares about cost were borne by all Congress, while the committee members could veto the whole thing if their pet requirement was ignored).  I doubt they would bother making sure the fuel tank could be delivered into orbit for some hypothetical future use.  And I have no idea if you could fit a CanadARM capable of working with such a thing inside the Shuttle (where it was originally attached).

[DerekL1963]

20 hours ago, wumpus said:

I'd also assume they could be used as some sort of ISS backbone/struts (don't try to change anything inside). 

You still have to change the outside, and that's not really going to be much easier than changing the inside.  You don't have to worry about taking a cryogenic bath, but you do have to worry about supersonic and hypersonic airflow.  (Not just over the added/changed parts, but the interactions with the rest of the stack too.)

[wumpus]

2 hours ago, DerekL1963 said:

You still have to change the outside, and that's not really going to be much easier than changing the inside.  You don't have to worry about taking a cryogenic bath, but you do have to worry about supersonic and hypersonic airflow.  (Not just over the added/changed parts, but the interactions with the rest of the stack too.)

Still, ISS masses over 400 tons.  Using available material for struts would presumably be a net gain.  The catch is that they would have to change the status of the space station in 1980 from "canceled" to "canceled, but still a design requirement of the shuttle".  That would only lead to more worms than that program needed, and I'd expect more to pile on until designing a working shuttle would be impossible.

I love the idea that you could bring "free" mass to orbit.  I just can't imagine the political nightmare that might follow from attempting to justify the changes necessary to bring it.  They did change the external tank twice (both to make it lighter).  I'm guessing that combining one of those changes with the CanadARM might make such a thing possible, but I don't know what the space station status would be at the time (it wouldn't make much sense to have one without a space station).

On second thought, they would have to increase the maneuvering engine fuel supply (to get the whole thing into orbit), that is probably to much of an ECO for too little benefit.

[DerekL1963]

6 hours ago, wumpus said:

I love the idea that you could bring "free" mass to orbit.

TANSTAAFL.

The ET isn't "free" mass - it's cargo to orbit, carried externally in place of internal cargo in the bay.

[scottadges]

On 9/23/2017 at 1:08 AM, kerbiloid said:

gather the upper stages and move them to the orbital scrapyard.

Isn't that a little bit like this though, but for space? 

[Rakaydos]

I;ve always felt that the GEO Graveyard orbit would be a prime canidate orbit for a garbage collection scow. Not only is there a lot of trash there now, but every satelite in GEO is programmed to put itself into the graveyard orbit before it dies.

[kerbiloid]

There is no orbital graveyard, there are orbitally canned goods.

[ModZero]

7 hours ago, scottadges said:

Isn't that a little bit like this though, but for space? 

The graveyard orbit is pretty big, though, even compared to the oceans, and unlike GEO you usually don't particularly care about your neighbors and their EM emissions. Also, last time I checked in space there were no cute purple octopuses that would get sick because of the trash.

[wumpus]

13 hours ago, DerekL1963 said:

TANSTAAFL.

The ET isn't "free" mass - it's cargo to orbit, carried externally in place of internal cargo in the bay.

You have to pay what, 50m/s compared to what you absolutely have to pay just to keep firing the engine into space, compared to paying 9000m/s to launch it from the ground?  That counts as free to me.  The TANSTAAFL part is finding *any* use for it that doesn't make you want to pay 9000m/s for exactly what you want.

[DerekL1963]

1 hour ago, wumpus said:

You have to pay what, 50m/s compared to what you absolutely have to pay just to keep firing the engine into space, compared to paying 9000m/s to launch it from the ground?  That counts as free to me. 

No, you have to pay the entire cost of a Shuttle launch to place the ET into orbit - and that's the only cargo that can be carried on that launch.

That's not free.

[kerbiloid]

12 hours ago, DerekL1963 said:

No, you have to pay the entire cost of a Shuttle launch to place the ET into orbit

Shuttle mass 105 t, External Tank dry mass 27 t.
Just spend +30% hydrazine+NTO more, and Shuttle never had started with full payload.

You already almost had put ET into orbit, -9500 m/s.

Edited September 28, 2017 by kerbiloid

[Pand5461]

Spending +30% OMS fuel for orbital insertion would've left the Shuttle without fuel to deorbit.

However, the ET could probably hold enough hydrogen and oxygen to get it into orbit. The main reason not to do it was to avoid leaving a huge uncontrollable piece of debris that could later fall anywhere and cause damage.

[sevenperforce]

If I recall correctly, the circularization burn with the OMS system was quite some time after the ET jettison. Using the SSMEs for full orbital insertion and circularization would have required a different flight profile. What was the minimum throttle range of the SSMEs? Since they couldn't be restarted in-flight, you'd have to figure out a way to keep them burning all the way through circularization...but cutting off two of the engines and dropping the remaining one to minimum throttle might still have burned through all the propellant before the proper circularization height was reached.

[Pand5461]

@sevenperforce, you are right, OMS circularization started about 30 minutes after MECO (according to Wikipedia). This basically means that MECO was almost at the perigee of a suborbital trajectory at around 120 km altitude.

There's a thread discussing the Shuttle guidance algorithm.

I looked at the equations - the guidance does not intrinsically rely on the coast between MECO and circularization. But a coast phase was explicitly specified, so that was what guidance algorithm should adapt the ascent trajectory to. I'm not sure what could happen if the algorithm was told to insert the whole thing into 200 km circular orbit. I think it could find a suitable pitch program, question is how much more fuel such trajectory would require (given the increased gravity losses because Shuttle would need to climb at a steeper angle to get to 200 km in basically the same time it climbed to 120 km in the real flights).