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58 votes
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Evacuating the ISS but wait, there's only one Spacecraft?

By design that will never happen. There are always enough return seats for the crew. This is exactly why the whole crew of one of the visiting vehicles gets in it whenever it undocks, even when it is ...
Organic Marble's user avatar
50 votes
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Soyuz landing ground detection

Earlier Voskhod models used a retractable metal probe, but it was unreliable, especially in windy conditions. So in Soyuz, as the other answers have pointed out, a gamma-ray source is pointed at the ...
Rikki-Tikki-Tavi's user avatar
49 votes
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Why do we only use Soyuz to send humans to the ISS?

Why do we only use Soyuz to send humans to the ISS? Because other than Chinese spacecraft (which aren't allowed), the Soyuz is currently the only one that can send humans to the International Space ...
David Hammen's user avatar
47 votes
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What eliminates the velocity when occupants return from ISS to earth, and how much?

Nearly all the velocity is cancelled by atmospheric deceleration of the descent module, before its parachutes are deployed. ISS orbital velocity is around 7700 m/s. An initial retro-burn of the ...
Russell Borogove's user avatar
40 votes

Soyuz landing ground detection

Soyuz uses gamma rays altimeter "Cactus", which starts soft landing engines just 1 meter before ground. Translation from russian wikipedia: The altimeter uses a source of gamma radiation (usually -...
Pavel Bernshtam's user avatar
38 votes
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How could the 2018-08-30 Soyuz MS-09 / ISS leak be so slow?

The ISS is at 1 bar, i.e. 1 kgf/cm2, or 10 gramsf/mm2. So the pressure on that 2 mm hole is 31.4 gramsf, well within the range a human finger can handle. Also, the ISS is really big compared to the ...
Hobbes's user avatar
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35 votes
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So with Soyuz being retired, what gets people up to the ISS and back down now?

Soyuz the booster and Soyuz the person carrying spacecraft are different. Soyuz the booster is based on the original R-7 ICBM and has seen a series of upgrades. Sometimes to engines, sometimes to ...
geoffc's user avatar
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35 votes
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Has the ISS ever not had a lifeboat?

It never actually happened, but there was a case when this situation had the potential for happening. That was the last shuttle flight, STS-135. If a critical flaw in the thermal protection system ...
Organic Marble's user avatar
33 votes

Did the soft-landing rockets malfunction in the Soyuz (expedition 50 crew) landing?

The "three second" item is incorrect. In general (and this can be confirmed by watching multiple landings), the rockets fire approximately half a second before landing. Maybe they meant to say "...
Tristan's user avatar
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31 votes
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Was the LES used in the MS-10 abort?

Yes, the launch escape system was used, contrary to earlier reports based on assumptions and ignorance of Soyuz hardware. However, it was not the tower that we are familiar with on Mercury and Apollo ...
Ghedipunk's user avatar
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30 votes
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Soyuz Steering during Re-Entry

By itself the roll doesn't generate lift. But the Soyuz descent module (DM) enters with a non-axial center of mass that results in a non-zero angle of attack, and hence some lift. Several spacecraft, ...
Tom Spilker's user avatar
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29 votes
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Where can I download the Soyuz Crew Operations Manual?

I can't recall where I got them from, so let me just re-host. Crew-ops manual Users manual
SF.'s user avatar
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28 votes

Evacuating the ISS but wait, there's only one Spacecraft?

What would happen if there was a freak accident in which that the ISS needed to be evacuated and there was ONLY one space craft available? Carrying that to an even greater extreme, what would happen ...
David Hammen's user avatar
26 votes

What are the reasons Soyuz's lifespan in orbit is limited?

Scott Manley answers this question here. Basically, it is due to the "shelf life" of the hydrogen peroxide propellant used by the attitude control thrusters of the Soyuz descent module. When hydrogen ...
Anthony X's user avatar
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25 votes
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Did the soft-landing rockets malfunction in the Soyuz (expedition 50 crew) landing?

ESA has a nice 3-part video series on YouTube that explains on a high-level ascent, rendezvous, and re-entry. These are actual training videos that are shown to ESA astronauts during their training. ...
Jörg W Mittag's user avatar
25 votes
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How did the attitude system of the uncrewed Soyuz 7K-OK No.1 fail on the launch pad in 1966, killing ground staff as LES was activated?

Rocket guidance systems generally use a fixed inertial platform based on gyroscopes to determine their orientation in space; an accelerometer solution would be useless to determine orientation (though ...
Russell Borogove's user avatar
25 votes

What eliminates the velocity when occupants return from ISS to earth, and how much?

The process is described here, which answers nearly all of your question. The reentry burn removes about 120 m/s of velocity from the capsule (that's your 1) and the final impact is 15 miles per hour ...
Steve Linton's user avatar
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25 votes
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Can a Soyuz-MS still propel itself back to earth if all its Hydrogen Peroxide decomposed?

Most thrusters on the Soyuz-MS spacecraft use Dinitrogen Tetroxide1 (N2O4, oxidizer) and Unsymmetrical Dimethylhydrazine2 (UDMH, fuel). These are stored (and burned) on the service module and both ...
Alex Hajnal's user avatar
  • 1,981
24 votes
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August 30th 2018 Soyuz leak, any dangers for re-entry?

The leak is in the Orbital Module (OM), which is jettisoned prior to re-entry, so there is no concern there. Source: link in the question. Image source: spaceflight101.com
Organic Marble's user avatar
21 votes

Why doesn't Roscosmos launch Soyuz spacecraft with only Russians on board?

As of 24 April 2020, the Russians & Chinese are the only ones capable of sending people into orbit. The Chinese crewed space program is still in its early stages & only sends Chinese people ...
Fred's user avatar
  • 13.1k
20 votes

How could the 2018-08-30 Soyuz MS-09 / ISS leak be so slow?

This is the image of the hole (news source, although the image is from NASA) The hole is 2mm in diameter. Even with a total vacuum on the other side, you're not talking a lot of volume getting ...
Machavity's user avatar
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20 votes
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Microgravity indicators

As Organic Marble points out, yes the US space program had G meters. They're likely to include these in future manned missions, as well. As for the true purpose of the toys: To humans, any sudden ...
Ghedipunk's user avatar
  • 1,167
19 votes
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Why does the Soyuz parachute pulsate?

Thanks to the paper linked by Jan Doggen in the comments we can say that it is a natural outcome of the shape of the parachute. In particular, the shape, together with the near absence of wind and ...
Federico's user avatar
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19 votes
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Is this smoke from Expedition 53 returning Soyuz capsule?

It's a purge of remnant hydrogen peroxide from the "secondary control system".1 "On the “ОТСТРЕЛ ЛОБОВОЙ ТЕПЛОЗАЩИТЫ” (Bottom Shield Jettison) all УРМД thruster valves are opened and ...
Organic Marble's user avatar
19 votes

Soyuz landing ground detection

Just to add a better source: From the Soyuz Crew Operations Manual The АКСП consists of barostatic and time mechanisms and the Гамма-лучевой высотомер (ГЛВ) (Gamma Ray Altimeter). The barostatic ...
Organic Marble's user avatar
19 votes
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Soyuz MS spacecraft battery voltage?

"Soyuz: A Universal Spacecraft" says the electrical system produces 23-34 volts. I saw a reference to a nominal 28VDC supply to the spacecraft in the Soyuz launcher manual; 28VDC is a global standard ...
Russell Borogove's user avatar
18 votes
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Has USSR/Russia launched humans on any rocket not derived from R-7?

No, it never happened. However besides the failed N1 program and cancelled Buran missions the Soviet Union also made several successful (or partially successful) test launches of spacecrafts that ...
OON's user avatar
  • 1,684
17 votes
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Can Soyuz spacecraft operate without the orbital module?

According to Russian Space Web, separating the orbital module prior to reentry burn was not only possible, but it was the normal procedure up to 1988: Originally, the habitation module [i.e. orbital ...
Russell Borogove's user avatar
17 votes
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How do cosmonauts board the Soyuz spacecraft?

Referred to as the боковой загрузочный люк - side loading hatch. Yes, they enter through the fairing, square hatch on the left, next to the Roscosmos logo. Shown in red "Soyuz" (...
blobbymcblobby's user avatar

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