I'm looking for:
Mass
Operating pressure
Pressurisation gas mix
Cooling system
Helmet attachment
Thanks!
I'm looking for:
Mass
Operating pressure
Pressurisation gas mix
Cooling system
Helmet attachment
Thanks!
Some of the information you seek is proprietary information. Which is why not even NASA has released that information.
Three pieces of information that are not proprietary:
- Mass is ~10 kg (whole suit, as worn by the astronauts)
- Helmet is not attachable/detachable. It is an integrated part of the one-part suit.
- Cooling system: Nitrox circulation for both breathing AND cooling. Nitrox is chilled via adiabatic expansion. See here:
ICES-2020-333.pdf (tdl.org)How one puts the suit on is beautifully shown in this video from Japanes astronaut Soichi Noguchi:
Another video from his is a nice close-up introduction to the IVA suit:
It also clearly shows that the helmet is an integrated part of the suit.
I'm looking for:
Mass
Operating pressure
Pressurisation gas mix
Cooling system
Helmet attachment
Thanks!
Some of the information you seek is proprietary information. Which is why not even NASA has released that information.
Three pieces of information that are not proprietary:
- Mass is ~10 kg (whole suit, as worn by the astronauts)
- Helmet is not attachable/detachable. It is an integrated part of the one-part suit.
- Cooling system: Nitrox circulation for both breathing AND cooling. Nitrox is chilled via adiabatic expansion. See here: ICES-2020-333.pdf (tdl.org)
How one puts the suit on is beautifully shown in this video from Japanes astronaut Soichi Noguchi: [snip]
Another video from his is a nice close-up introduction to the IVA suit:
snip]
It also clearly shows that the helmet is an integrated part of the suit.
Well, it's a start and quite useful.
The ICES paper indicates that the gas mixture is 23% O2 and 77% N2, and a mean cabin pressure of 99.6 kPa.
In transitioning to an unpressurised environment the ambient N2 partial pressure/internal suit pressure should be <2 to avoid DCS, thus 77.7 kPa/2 = 38.5 kPa. This is similar to Sokol.
The 10 kg mass is also similar to Sokol and more than the 7.2 kg of the Gemini G5C suit of the 60s (worn only on G VII).
The ICES paper indicates that the gas mixture is 23% O2 and 77% N2, and a mean cabin pressure of 99.6 kPa.
In transitioning to an unpressurised environment the ambient N2 partial pressure/internal suit pressure should be <2 to avoid DCS, thus 77.7 kPa/2 = 38.5 kPa. This is similar to Sokol.
This however raises issues of hypoxia. At 23% O2 the partial pressure at 40 kPa is only 9.2 kPa, equivalent to an altitude of ~6,100 m. Unacclimated people are very sick at this altitude. Aircrew are supposed to be on supplemental oxygen above 3,000 m (14.2 kPa partial pressure O2). In Sokol people are on pure O2 in an emergency.
So either the SpaceX suit has an even higher pressure than 400 kPa (the ICES paper indicates minimum acceptable cabin pressurisation is 55 kPa) or the suit provides supplemental oxygen (which is not mentioned). A pressure of 55 kPa and 23% O2 gives a partial pressure of 12.65 kPa, equivalent to about 4,100, which is tolerable for short periods without acclimation, although people will be feeling poorly. A suit pressure of 55 kPa is going to be though to move in, it's roughly equivalent to an inflated basketball. However, this is a get you down suit, not one to work in, let alone to do an EVA.
So either the SpaceX suit has an even higher pressure than 400 kPa (the ICES paper indicates minimum acceptable cabin pressurisation is 55 kPa) or the suit provides supplemental oxygen (which is not mentioned).
From ICES-2020-333.pdf (tdl.org)
Page 3:
B. Oxygen and Nitrox System
Dragon stores gaseous oxygen for metabolic consumption and for use in the space suit during an emergency
involving a depressurized cabin. It uses nitrox, ...
Page 4:
2. Oxygen and Nitrox Delivery
...
For larger hole sizes, Dragon will stop
feeding the leak when a nitrox reserve mass is reached and allow the cabin to depressurize, feeding oxygen to the
suits. When reentering with a depressurized cabin, the repress valves flow nitrox into the cabin as the external
pressure increases.
Yes. The ICES paper clearly mentions that the suits are fed oxygen, instead of nitrox, when the cabin is allowed to depressurize. That kills the O2 partial pressure issue.
Yes. The ICES paper clearly mentions that the suits are fed oxygen, instead of nitrox, when the cabin is allowed to depressurize. That kills the O2 partial pressure issue.
The language is a bit ambiguous to me. The statement is:
"For larger hole sizes, Dragon will stop
feeding the leak when a nitrox reserve mass is reached and allow the cabin to depressurize, feeding oxygen to the
suits."
To me this suggests that the suits are topped up with O2 once closed when the critical threshold is reached. or am I missing something?