Virtual STS-131 stranded into orbit, any ideas ?

[N_Molson]

Ok, while trying to replay the STS-131 mission I made some calculation errors on my launch azimuth. With a 1.3 DEG RInc with the ISS, I burned a lot more fuel that I should have. The date in the scenario is May 1st (yeah, STS-131 was really in late, so STS-132 has to be delayed anyway).

Docking was a success, I used a super-low fuel consumption trajectory to get to the ISS (it took a whole week !). But now I've only 2350 kg of propellant left, which is not enough for de-orbit. :embarrassed: Let's say there has been a fuel leak.

I made calculations with the Tsiolkovsky rocket equation and here are my conclusions : I need a strict minimum of 3050 kg of propellant to lower my orbital speed (7691 m/s) from the 90 m/s I need. And I'm not taking into account the amount of fuel that will be needed for RCS reentry manoeuvers (I would guess 300 kg to be safe).

So what can I try (while staying realistic) ?

• There is a Progress docked to the station with 325 kg of propellant left. I considered docking it to Atlantis (if it's possible to build with the on-board materials some kind of adapter). But that's just giving me 6.5 m/s (even worse, some fuel is lost because the Shuttle has to use the RCS to keep it's attitude during the thrust). I tried, my calculations were right, it doesn't work.

• STS-132 could be converted to a contingency mission. The 1st objective would be to bring the other crew back (which means, according to NASA, a 40 days delay to bring modifications to the orbiter (add seats, re-train the crew, adapt the life support system...). Could the Rassvet Module still be delivered, as a 2nd objective ? I doubt of it. Discovery would be put on a parking orbit (anyway it was it's last flight). The ISS-Shuttle assembly can, from what I read, provide life support to a crew of 12 for 80 days.

• STS-132 could, with the Rassvet module, bring a booster that could provide the needed Delta-V. But I didn't found the mass of the Rassvet. And I think there are no man-rated boosters available. Maybe some SRM like the STAR-48B ? It seems very dangerous to put a SRM in the Shuttle bay... And I doubt it's powerful enough (didn't made the calculations). Anyway the Shuttle docking port won't be available until STS-131 moves !

• A rocket (maybe AtlasV) could be launched to rendez-vous with STS-131 in orbit, bringing a restartable liquid-fueled booster. But still we need at least 40 days to plan & launch the mission. And this means delaying STS-132 (which is possible, I think). But can the STS-131 systems be shut down and powered again 40 days later ? Could the ISS solar panels bring enough power to the Shuttle to keep it "alive" while waiting the booster ? I think that a AtlasV or DeltaIV upper stage mated with a docking module would provide enough Delta-V (a Proton-DM would work too, but it seems much more expensive).

So feel free to give your opinions

 

[garyw]

Move to the crew to the station and implement CSCS. The orbiter will not survive because there is no method (in real life) of getting prop into the Orbiter whilst it's in orbit.

Launching another rocket such as a delta is not an option either. it'll take too long to prepare the rocket and there is no way of getting the booster to the ISS. By the time those problems are worked out the Orbiters fuel cells would have died, even with powering down as much as possible and usings SSPTS (unless it's Atlantis).

You should have landed as soon as you realised how out of plane you were. Simsup would not be happy. :lol:

 

[Urwumpe]

But now I've only 2350 kg of propellant left, which is not enough for de-orbit.

Lets check the options according to the SCOM. Is it total propellant or only OMS propellant?

If it is just OMS propellant: I get 5300 lb fuel from your calculations, that means 42% OMS fuel (2x21% or 1x42%). With that amount of OMS fuel, I can reduce the speed by 252 ft/s and lower the orbit by approximately 126 n.mi (235 km), just as a quick calculation. Theoretically even enough for a good deorbit burn.

If I still have RCS fuel left, I can also use the RCS for lowering the orbit even more, ensuring deorbit and still have enough RCS for a safe reentry maybe.

Since I would have to dump a lot of FRCS propellant anyway, in such a scenario I could use the forward RCS thrusters to exhaustion for deorbit. The forward RCS is disabled in a real space shuttle during reentry.

 

[N_Molson]

I'm using default "Martins" Atlantis with a Discovery skin

 

[astrosammy]

Maybe build a small adapter to dock PMA-3 to Zvezdas aft port.
Send it up with STS-132, move STS-131 away from PMA-2 to allow STS-132 docking, move the adapter and PMA-3 to Zvezdas and redock STS-131 to it.
Now both shuttles are safely docked and STS-132 can install Rassvet.
The limitation is that one Russian docking port is unavailable, so one Soyuz would have to be removed (or are there more than three Russian ports on the ISS?).

Now you'd have enough time to find a solution to boost STS-131 out of orbit. I'd say use some simple boost module that can be installed into the bay, with the engine pointing out of the bay. But if the payload bay is unable to close it would mean a LOCV. An unmanned entry would be the only safe solution.

As Gary said, fuel cells would be another problem to deal with...

After the shuttle has landed you'd still have 13 shuttle crw members onboar ISS, I'd say get the STS-131 crew with the STS-132 shuttle (because they propably had a long time in space). To get the STS-132 crew home, maybe fly STS-133 with a reduced crew and use it to return them. Or fly STS-132 with a reduced crew to allow a much faster return of all the astronauts.

As this would mean months of development and production, causing major delays (into 2012 or even 2013) this wouldn't be an option in real life. But hey, it's Orbiter, you don't have to deal with problems of money and politics and could just do it.

In RL, it would propably mean an uncontrolled decay and reentry of Discovery, maybe into populated areas. But I'd be proud to be killed by debris from such a great spaceship.

 

[N_Molson]

Yeah, fuel cells are the n°1 problem... And since the orbiter already 7 days into orbit, they will be dead in less than 10 days. Which is a too short delay to save the Orbiter. For now I consider moving the crew to ISS, then remotely undock Discovery and use the remaining propellant to raise the orbit as much as possible (2 burns). Then, in the following years (I think orbit decay would be slow at 400kms), send a little ionic thruster to park it forever or deorbit it in a controlled fashion... I would prefer the 1st option, being in space forever is a nice end for a Space Shuttle. And a testimony of today's technology (the most complex machine ever built by humanity)

:idea: Another idea, how much can the ISS change it's orbit ? Contrary to the Shuttle, it can be refuelled with Progress-M...

From Wiki :

"In the case of an abort to orbit, where the shuttle is unable to reach the ISS orbit and the thermal protection system inspections suggest the shuttle cannot return to earth safely, the ISS can be brought down to meet the shuttle. Such a procedure is known as a joint underspeed recovery."

 

[garyw]

:idea: Another idea, how much can the ISS change it's orbit ? Contrary to the Shuttle, it can be refuelled with Progress-M...

Not by much. too much delta-v is bad for the truss and it'll shake itself apart. By the time you are in the right plane the shuttle would long have run out of consumables.

A joint underspeed recovery isn't a plane change, it's a deorbit where the ISS swoops down on the shuttle. I'll admit, it's something I'd be fascinated to see but hope I never do.

 

[Urwumpe]

Correction:

Not by much. too much delta-v/delta-t is bad for the truss and it'll shake itself apart.

 

[garyw]

I know that would get me but I'm so used to typing "delta-v" - thanks Urwumpe.

 

[Urwumpe]

I know that would get me but I'm so used to typing "delta-v" - thanks Urwumpe.

Thats what computer scientists are for... fixing math problems. :lol:

(For those who still wonder what the joke is: delta-v/delta-t means "change of velocity during a change of time" or simpler: Acceleration)

 

[N_Molson]

Plane change isn't my first concern, I think a controlled unmanned ditching into the Pacific would be the best option at this point, with a recovery fleet in the projected area to prevent the Shuttle from sinking (floatation bags, etc...). With no crew aboard, most of the life support systems could be switched off. That's basically what is said in the official CSCS procedure :

The following timeline is presented with respect to the flight day (FD) of the mission to be rescued:

• FD-10 A decision on the requirement for Contingency Shuttle Crew Support (CSCS) is expected by flight day 10 of a nominal mission.
• FD-10 Shortly after the need for CSCS operations a group C powerdown of the shuttle will take place.
• FD-11->21 During flight days 11 ~ 21 of the mission the shuttle will remain docked to the international space station (ISS) with the hatch open. Various items will be transferred between the shuttle and ISS.
• FD-21 Hatch closure will be conducted from the ISS side. The shuttle crew remains on the ISS, leaving the shuttle unmanned
• FD-21 Deorbit Burn - Burn occurs four hours after separation. Orbiter lands at Vandenberg Air Force Base under remote control from Houston. (Prior to STS-121, the payload bay doors would have been left open to promote vehicle breakup.)
• FD-45 Launch of rescue flight. 35 days from call-up to Launch for the rescue flight is a best-estimate of the minimum time it will take before a rescue flight is launched.[2]
• FD-45->47 The rescue flight catches up with the ISS, conducting heat shield inspections en-route.
• FD-47 The rescue flight docks with the station, on day three of its mission.
• FD-48 Shuttle crew enters the rescue orbiter. Vehicle with a crew complement of 11 undocks from ISS.
• FD-49 Rescue orbiter re-enters atmosphere over Indian or Pacific Ocean for landing at either Kennedy Space Center or Edwards Air Force Base. A Russian Progress resupply spacecraft is launched at later date to resupply ISS crew. ISS precautionary de-crew preparations begin.
• FD-58 De-crew ISS due to ECLSS O2 exhaustion in event Progress unable to perform resupply function.

And it looks like there is a very intersting cable aboard the ISS (that allows Ground Control to control Fuel Cell reactant valve).

"The Remote Control Orbiter (RCO), also known as the Autonomous Orbiter Rapid Prototype (AORP), is a term used by NASA to describe a Shuttle that could perform entry and landing without a human crew onboard. To this end, NASA developed the RCO in-flight maintenance (IFM) cable. The cable is approximately 28 feet (8.5 m) long, weighs over 5 lb (2.3 kg), and has 16 connectors.[10]
The purpose of the RCO IFM cable is to provide an electrical signal connection between the Ground Command Interface Logic (GCIL) and the flight deck panel switches. With this system, signals could be sent from the Mission Control Center to the unmanned Shuttle to control the following systems:

• Auxiliary Power Unit (APU) start and run
• Air Data Probe (ADP) deployment
• Main Landing Gear (MLG) arming and deployment
• Drag chute arming and deployment
• Fuel cell reactant valve closure

The RCO IFM cable first flew aboard STS-121 and was transferred to the ISS for stowage during the mission. The cable will remain aboard the ISS until the end of the Shuttle program at which time it will be brought back to Earth on the final Shuttle flight.
Prior to STS-121 the plan was for the damaged shuttle to be abandoned and allowed to burn up on reentry. The prime landing site for an RCO orbiter would be Vandenberg Air Force Base in California[11]. Edwards Air Force Base, a site already used to support shuttle landings, was the prime RCO landing site for the first missions carrying the equipment; however Vandenberg was later selected as the prime site as it is nearer the coast, and the shuttle can be ditched in the Pacific should a problem develop that would make landing dangerous. White Sands Missile Range in New Mexico is a likely alternate site.[12] A major consideration in determining the landing site would be the desire to perform a high-risk re-entry far away from populated areas. The flight resource book, and flight rules in force during STS-121 suggest that the damaged shuttle would reenter on a trajectory such that if it should break up, it would do so with debris landing in the South Pacific Ocean."http://en.wikipedia.org/wiki/STS-3xx#cite_note-CSCSResourceBook-1

 

[dre120v]

What about sending down Soyuz (with a few crew members)that is attached to the ISS(if it is in this scenerio) and sending up fuel with the next automated soyuz craft?

 

[jinglesassy]

What about sending down Soyuz (with a few crew members)that is attached to the ISS(if it is in this scenerio) and sending up fuel with the next automated soyuz craft?

Since when has there been an automated soyuz?

 

[dre120v]

Since when has there been an automated soyuz?

http://en.wikipedia.org/wiki/Automated_Transfer_Vehicle

 

[Urwumpe]

Since when has there been an automated soyuz?

Pretty often:

http://en.wikipedia.org/wiki/Soyuz_TM-1

 

[IronRain]

in fact, Soyuz was kind of build to be automated, right?

 

[Urwumpe]

in fact, Soyuz was kind of build to be automated, right?

Yes, it is like all Russian spacecraft, heavily automated. You could let a Soyuz TMA land yourself automatically, with only minimal knowledge about it.

And it looks like there is a very intersting cable aboard the ISS (that allows Ground Control to control Fuel Cell reactant valve).

such control over the valve is needed for safing the orbiter AFTER a safe landing.

 

[dre120v]

Also:
http://www.nasa.gov/mission_pages/station/expeditions/expedition23/p37_launch.html

 

[ddom2006]

What about gradually lowering the orbit of the ISS over the mission duration as long as possible and then undocking the shuttle fully manned and de-orbit as gradually as possible to avoid heavy fuel usage? You could then launch a Progress re-supply vessel loaded with fuel for the ISS and use the Progress to re-boost the ISS to a more stable orbit again.

 

[Marcvs101]

I suggest you to launch a progress spacecraft to the ISS filled with fuel and with an adapter for docking with the Shuttle.

Once at the ISS dock the progress to the shuttle that will undock one minute before the progress arrival so you wont waste rcs fuel for the shuttle (in this phase do not use rcs on the shuttle, let the progress do the work).

After refueling, re-enter with the progress inside the shuttle cargo bay, or make them re-enter separately