View Full Version : ISS escape pod

2003-Feb-14, 01:56 PM
Have been searching a little on line to learn something about the "escape Pod" mentioned on the news as a possible vehicle to return ISS astronauts to Earth and can't find much, except that it's referred to as a Russian Soyuz capsule. Does anyone out there know more? How old is it? Is it really safe or is it only a last resort? What was its oringinal purpose on the ISS? Thanks for any info.

2003-Feb-14, 02:06 PM

2003-Feb-17, 12:42 PM
The Soyuz is the Russian standard crew space vehicle. Versions of the Soyuz have been used since the 1970s. The TMA was the latest incarnation. Not sure specifics of what made TMA better than previous versions.

Back when the space station was dreamed up, it was realized that the Shuttle would not be able to be kept docked for long periods of time (i.e. 6 months), nor be able to be kept ready for immediate launch in case of safety problems on ISS. It was determined they would need an "escape pod" of some sort, an emergency crew return vehicle (CRV). The escape vehicle envisioned went through a couple of incarnations (or at least names). It would have extended on orbit capability (indefinite), with the ability to power up quickly (stand-by mode) and safe return to Earth of a crew of seven people. Then the Russians became one of the international partners, and the Soyuz became available. And then budget problems forced NASA to cut certain upgrade plans for ISS, and one of the decisions was to stop work on the CRV and rely on Soyuz capsules as the emergency return vehicles.

Operationally, this meant either limiting the crew to 3 or keeping multiple Soyuz on station at a time. Also, the Soyuz do not have indefinite life, but need to be replaced periodically (6 months current schedule) because of the fuel used is heavily reactive and corrodes the tanks.

2003-Feb-17, 01:44 PM
Thanks for the info. Let's hope the safety of said Soyuz as an escape vehicle is never really tested.

2003-Feb-17, 01:49 PM
gethen, the reliability is tested every six months, as normally a visiting crew brings a new Sojuz spaceship to the ISS and after some 10 days they return in the old one, leaving a fresh emergency Sojuz at the station.


2003-Feb-17, 09:08 PM
kucharek, that's exactly the info I was looking for. Had a discussion with a friend who was bemoaning the "fact" that the only escape route for the ISS astronauts was "an outdated Soviet Soyuz pod." I was not ready to believe that NASA would consign its astronauts to such a shaky means of escape. The friend was using the argument as evidence of NASA's disregard for safety in general. So thanks again. I knew someone on the board would have the info I was looking for.

2003-Feb-17, 10:40 PM
Soyuz TMA is virtually identical to Soyuz TM in most of its operational aspects. The main differences are that it has a "glass cockpit" replacing the steam gauges and other mechanical instrumentation, allowing a substantial savings in weight and space. This allows Soyuz TMA to not only carry more cargo, but also to accomodate all astronauts meeting NASA's height requirements. (Previously, the tallest NASA astronauts were too tall to fit in a Soyuz couch.)

The one currently docked to ISS is Soyuz TMA-1, the very first of this newest model Soyuz. (All Soyuz spacecraft are numbered in the order in which they fly, not in the order in which they are constructed, and actually there have been subtle changes to the models without changes in the spacecraft designations; I think it mainly depends on how extensive the improvements were.) These are expendable and must be swapped out every six months because of progressive damage to their fuel systems because of the corrosive hypergolic propellants they carry. The first one to visit the ISS was delivered by the Expedition One crew; all subsequent ones have been delivered by "taxi" crews who have then returned to Earth in the old Soyuz. It's a bit of a dance to get everything shifted, but the visiting crews move all of their stuff into the old Soyuz and the resident crew moves all of their stuff into the new Soyuz -- and the most important stuff to swap are the custom-fitted Sokol partial-pressure suits and the custom-fitted seat-liners that protect the crew from injury when the vehicle hits the ground.

The full list of Soyuz capsules (with dates from launch to touchdown) that have visited the ISS is:

Soyuz TM-31 (10/31/00 - 5/6/01)
Soyuz TM-32 (4/29/01 - 10/30/01)
Soyuz TM-33 (10/21/01 - 5/5/02)
Soyuz TM-34 (4/25/02 - 11/9/02)
Soyuz TMA-1 (10/29/02 - undetermined)

Soyuz TMA-1 may end up returning to Earth in a few months with the current ISS crew on board, most likely after their replacements have arrived on board Soyuz TMA-2 -- assuming the supply issues can be resolved enough to allow continuous ISS habitation relying strictly on Russian hardware. As it is, the thinking at NASA seems to be pointing towards the next expedition crew being Gennady Pedalka and an undetermined American astronaut, with the third seat on Soyuz TMA-2 occupied by a cargo cannister to carry more supplies. With only two crew, they can stretch supplies a lot further and hopefully extend the increment long enough to let them be replaced when Soyuz TMA-3 arrives. Or until the Shuttle program resumes, whichever comes first. (In practise, of course, none of this has been decided; it's all contingency planning.)

Incidentally, I realize this is only tangentially related, but STS-114 (the next scheduled flight to the ISS) was sitting in the VAB already stacked. It is now in the process of destacking. I wasn't able to find out *why* it was destacked, but it probably is a combination of two things: they will want to inspect the foam on the ET, and they will need to destack anyway because there are certain preflight tests on the orbiter (Atlantis) which have to be redone if enough time elapses -- and which cannot be done unless the orbiter is in the Orbiter Processing Facility. So, it looks like we won't be seeing another Shuttle launch for a few months at least.

2003-Feb-18, 09:48 AM
Not that I'm adding anything to the discussion, but may I say that I'll take a ride on a Soyuz any day of the week.

2003-Feb-18, 09:25 PM
So now it appears NASA is contracting out it's plans for "space station lifeboat" (http://europe.cnn.com/2003/TECH/space/02/18/sprj.colu.space.plane.ap/). Does this mean X-33 is officially scrapped?

2003-Feb-23, 01:13 PM
X-33 was scrapped some time back.