Flightstar - 5/5/2006 3:31 PMOrbiters can't survive in space for too long. Even if you took away the power requirements, they'd get very ill very fast with the whole enviorment of space.
DaveS - 5/5/2006 3:35 PMNo. The orbiter uses cryogenic propellants(LH2 and LOX) to power to the three fuel cells and once those die the loses it capability to power it's systems like critical heaters for the OMS and RCS.The shuttle was never intended as a long duration spacecraft like the Soyuz and Progress spacecrafts.
DaveS - 5/5/2006 4:02 PMThe orbiter would dead when you undocked it!Edit:Cryogenic fluids boils off so the supplies of LH2 and LOX will decrease even if you power everything off. The orbiter's were simply not designed with a long on-orbit lifetime in mind.
Jamie Young - 10/5/2006 7:08 PM QuoteDaveS - 5/5/2006 4:02 PM The orbiter would dead when you undocked it! Edit: Cryogenic fluids boils off so the supplies of LH2 and LOX will decrease even if you power everything off. The orbiter's were simply not designed with a long on-orbit lifetime in mind. Could they replace them with electrical power units?
DaveS - 5/5/2006 4:02 PM The orbiter would dead when you undocked it! Edit: Cryogenic fluids boils off so the supplies of LH2 and LOX will decrease even if you power everything off. The orbiter's were simply not designed with a long on-orbit lifetime in mind.
What are electrical power units?
also who would fly it home? who would be trained to fly it. Who on the ground would maintain proficency in shuttle systems? How long does it take to power it up. how would the atmosphere be maintained while dormant.
psloss - 12/5/2006 2:00 PMQuoteAvron - 5/11/2005 5:31 PMThanks... so what they basically took the remaining engines out of Auto shutdown mode, that in itself sounds a little dangerous..."position inhibits all automatic shutdowns". That brings up another question, what then would shut down the engines, time... cannot be velocity, lack of gass, but that would be very bad?This would be a good question for the Q & A thread -- particularly that switch...
Avron - 5/11/2005 5:31 PMThanks... so what they basically took the remaining engines out of Auto shutdown mode, that in itself sounds a little dangerous..."position inhibits all automatic shutdowns". That brings up another question, what then would shut down the engines, time... cannot be velocity, lack of gass, but that would be very bad?
Although a shutdown as a result of violating operating limits is normally automatic, the flight crew can, if necessary, inhibit an automatic shutdown through the use of the main engine limit shut dn switch on panel C3. The switch has three positions: enable, auto and inhibit. The enable position allows only the first engine that violates operating limits to be shut down automatically. If either of the two remaining engines subsequently violates operating limits, it would be inhibited from automatically shutting down. The inhibit position inhibits all automatic shutdowns.
psloss - 12/5/2006 5:20 PMMy question is regarding the first call on this after the center engine shutdown, although any explanation of this ascent from the experts would be greatly appreciated. After the center engine shutdown, the crew was told to take the switch to Enable -- this was just after the single engine TAL call. Later on, when one of the two "fuel turbine temp" sensors on the right engine failed (reported in a similar pattern to that of the center engine), the crew was called to take the switch to Inhibit.Given the description from the reference manual and the situation where you already have one engine out, can someone clarify the difference between Enable and Inhibit? (Or perhaps this logic has changed since 51-F?)Also, was the call to take the switch to Enable a function of the failure?Thanks,Philip Sloss
mkirk - 12/5/2006 7:38 PMFor 51-F when the first engine exceeded it’s redline parameter and based on the limit switch being in Auto (always in Auto at launch), the engine controller shut the engine down and the orbiter’s general purpose computers automatically inhibited the limit software for the remaining to engines. Once an engine fails the crew is trained to expect to re-enable the limit software as soon as possible (i.e. abort capability). This is usually called up to the crew by mission control.
psloss - 12/5/2006 6:57 PMQuotemkirk - 12/5/2006 7:38 PMFor 51-F when the first engine exceeded it’s redline parameter and based on the limit switch being in Auto (always in Auto at launch), the engine controller shut the engine down and the orbiter’s general purpose computers automatically inhibited the limit software for the remaining to engines. Once an engine fails the crew is trained to expect to re-enable the limit software as soon as possible (i.e. abort capability). This is usually called up to the crew by mission control.Thanks as always, Mark.So, just to be clear, the call that CapCom Dick Richards made just after the single engine TAL boundary call "...and main engine limits to enable, Gordo" was the call to re-enable the limits, right?Philip Sloss
psloss - 12/5/2006 6:57 PMSo, just to be clear, the call that CapCom Dick Richards made just after the single engine TAL boundary call "...and main engine limits to enable, Gordo" was the call to re-enable the limits, right?Philip Sloss
At 5 minutes 43 seconds after lift-off, both temperature readings for the SSME (Space Shuttle Main Engine) 1 high pressure turbopump indicated above the redline, resulting in a premature shutdown of SSME 1 and the declaration of an ATO (abort-to-orbit) condition. This is the first such abort condition encountered during the Shuttle Program. An OMS (orbital maneuvering system) burn was initiated at 210:21:06:06.0 G.m.t., for 106 seconds and used approximately 4134 lb of propellant. At 8 minutes 13 seconds into the flight, one of two temperature sensors on SSME 3 indicated a high temperature reading and auto shutdown for the remaining two engines was inhibited to assure achieving an acceptable orbit. The OMS (orbital maneuvering system)-2 burn placed the Shuttle in a 143.1- by 108.0-nmi. orbit with an inclination of 49.57 degrees.
psloss - 13/5/2006 12:49 PMOne thing I didn't see in the mission report was when the first sensor reading went over its redline on the center engine, which was earlier in the ascent (if I recall correctly, somewhere around plus 3 and 1/2 minutes)...Whoops, the other thing that I was looking for was how much of an underspeed they ended up with at MECO...Philip Sloss
mkirk - 13/5/2006 2:00 PMAlso here is a link to main engine stuff. It is slighly dated but far more current than the STS News Reference. Page 26 and 27 discuss the engine limit switch. It also discusses the 6 parameter the controller tracks for redline shutdowns. The new Block II engines only use 5 of them.http://www.shuttlepresskit.com/scom/216.pdfMark Kirkman