Polaris Mission(s) - Commercial Crew prep for Starship

[ecarfan]

I assume that boils down to the space suit/life support system completion.

Could be. That is obviously critical, and something that SpaceX has never done before! And since Dragon has no airlock and the entire crew will be in the new suits, not just Isaacman doing the EVA, they all have to work perfectly.

On the one hand, this EVA could be viewed as just a stunt. The new suits won’t be used on the lunar surface during an Artemis mission. However, the knowledge gained in creating the new suits can serve as a foundation for going on to create suits for Mars surface operations.

 

[ecarfan]

Came across this very short video posted by space.com on the new EVA suite. Can’t find the video at SpaceX.com for some reason.

 

[JB47394]

Can’t find the video at SpaceX.com for some reason.

When it doubt, go to the other SpaceX site.

https://twitter.com/x/status/1786759044948189202

And a graphic from Polaris (the image is only a link to a webm file, so it won't play in place).



It has been observed that these are just EVA suits, so they won't have any onboard capabilities. They'll rely on an umbilical, like the Gemini EVA suits.

 

[ecarfan]

When it doubt, go to the other SpaceX site.

Thanks, but I don’t participate on X, for a variety of reasons.

It has been observed that these are just EVA suits, so they won't have any onboard capabilities. They'll rely on an umbilical, like the Gemini EVA suits.

Because that Polaris mission will depressurize the capsule everyone will need one of those suits. But so far all Dragon missions have had an ascent/descent suit for every astronaut. Is there room in Dragon for 8 suits? I wouldn’t think so. I was assuming that the new EVA suit would do double duty.

 

[JB47394]

Thanks, but I don’t participate on X, for a variety of reasons.

Me either. I just Google stuff

I was assuming that the new EVA suit would do double duty.

That makes sense. They appear to be close-fitted, so they shouldn't present any problems of bulk. And that also matches up with the Gemini missions; they opened the capsule to space and the second astronaut had to have a capable suit.

 

[ecarfan]

At 7:45 in this video Scott talks about the new suit. The breathing gas will be 100% O2 at 0.3atm. He says “When you are going from one atmosphere to one third of an atmosphere you have to worry about the bends.” That is basically true, but since the suit breathing gas in this case will not contain any nitrogen the primary concern is oxygen toxicity, and that is why they will be at reduced pressure. Cabin atmosphere in Dragon is a nitrox mix of 23% O2 / 77% N2 according to this MIT article and I assume that is the case for the Polaris mission.

The suits do slowly leak gas (rate unspecified) because of the very long entry zipper. And each suite has to be custom made. Interestingly, the suit legs do not articulate so it would not be possible to walk in Earth gravity. Of course one doesn’t need to walk inside a Dragon capsule.

No mention by Scott or I assume by SpaceX if these are the only suits onboard but my guess is they are.

 

[scaesare]

HUD: very cool... would like to know what it displays...

As is the integrated camera, but the phrasing in that VideoFromSpace youtube link is odd... it says camera providing temp and humidity data. I would assume those are separate sensors.... and while they may be overlaid on the camera feed, I would also assume they are separate data streams that can be monitored by ground control...

 

[scaesare]

More on the spacesuit: https://polarisprogram.com/wp-conte...Spin_Callouts_Detail_16x9_02.mp4-comp-27.webm

On edit:

https://twitter.com/x/status/1786828966353056082

and

https://twitter.com/x/status/1786829373422837974

 

[JB47394]

As a manned space flight pessimist, I'll throw in here that EVAs, and especially untethered EVAs are a dangerous and ineffective way to work in space. Use teleoperation, remote manipulators, waldos, whatever you want to call them. A robot arm with cameras and manipulators on it that allows someone to work from somewhere nearby in relative comfort and safety. Criminy, put the top of an Optimus robot onto an arm that can walk (or fly) to the work site, then have the guys with Tesla's training rigs do the work from inside their ship or station or whatever.

The only value for suits is depressurization safety, a second line of defense.

 

[Ben W]

At 7:45 in this video Scott talks about the new suit. The breathing gas will be 100% O2 at 0.3atm. He says “When you are going from one atmosphere to one third of an atmosphere you have to worry about the bends.” That is basically true, but since the suit breathing gas in this case will not contain any nitrogen the primary concern is oxygen toxicity, and that is why they will be at reduced pressure. Cabin atmosphere in Dragon is a nitrox mix of 23% O2 / 77% N2 according to this MIT article and I assume that is the case for the Polaris mission.

The bends occur when nitrogen is first breathed at high(er) pressure (1atm in Dragon, 77% nitrogen), then entering a lower pressure (0.3atm) environment; the drop in pressure can cause the dissolved nitrogen in the bloodstream to bubble, like a soda can being opened. So even if the suit gas is pure O2, the astronauts may have to pre-breathe 100% O2 at 1atm for a while (15-30 min) before reducing the pressure, to avoid the bends risk.

Oxygen toxicity shouldn't be a concern here; it manifests when breathing O2 at >1.4atm partial pressure for a short period (a few minutes), or at ~1atm partial pressure for a much longer period (a few hours). With the partial pressures of O2 at 0.23atm and 0.3atm respectively for Dragon and the suit, and with 15-30 min of 1atm O2 pre-breathing (or even just breathing pure O2 while the cabin gradually depressurizes from 1atm to vacuum over a similar timeframe), it shouldn't be a concern.

 

[ecarfan]

I'll throw in here that EVAs, and especially untethered EVAs are a dangerous and ineffective way to work in space. Use teleoperation, remote manipulators, waldos, whatever you want to call them. A robot arm with cameras and manipulators on it that allows someone to work from somewhere nearby in relative comfort and safety.

I agree. I hope that all future deep space crewed vehicles are designed such that basic repairs can be effected without the crew having to leave the ship.

 

[ecarfan]

…the astronauts may have to pre-breathe 100% O2 at 1atm for a while (15-30 min) before reducing the pressure, to avoid the bends risk.

Oxygen toxicity shouldn't be a concern here; it manifests when breathing O2 at >1.4atm partial pressure for a short period (a few minutes), or at ~1atm partial pressure for a much longer period (a few hours). With the partial pressures of O2 at 0.23atm and 0.3atm respectively for Dragon and the suit, and with 15-30 min of 1atm O2 pre-breathing, it shouldn't be a concern.

Yes that is correct. I was assuming that the crew would be pre-breathing 100% O2 before the suit pressure is reduced, so doing that and then reducing the suit pressure would avoid the O2 toxicity risk, which otherwise could be a problem.

 

[Ben W]

Yes that is correct. I was assuming that the crew would be pre-breathing 100% O2 before the suit pressure is reduced, so doing that and then reducing the suit pressure would avoid the O2 toxicity risk, which otherwise could be a problem.

As far as I know, no EVA suit has ever been designed to be used at >0.3atm, because the greater pressure difference would substantially impede movement and flexibility. (Although a pressure suit at 1atm could simply use air, not pure O2, which would sidestep both bends and O2 toxicity entirely.) The ISS procedure has been to pre-breathe pure O2 at 1atm for 4h prior to EVA, which dramatically lowers the bends risk, but edges up to the ~6h mark where O2 toxicity symptoms typically begin to appear. Russian research indicates that 30min O2 pre-breathing at 1atm should be sufficient to mitigate bends risk. Space suit - Wikipedia

If astronauts were to pre-breathe O2 in the EVA suits while matching pressure with Dragon down to 0.3atm, then even though Dragon's low-pressure air would not be breathable below 0.7atm or so, an ordinary oxygen mask in the cabin would still work in the event of an emergency that required suit doffing. I also suspect that re-pressurizing the entire cabin to ~1atm could be done very quickly if needed, given the small volume.

 

[JB47394]

As far as I know, no EVA suit has ever been designed to be used at >0.3atm, because the greater pressure difference would substantially impede movement and flexibility.

This came out back in 2014, and I believe the idea is to fit the suit to the wearer so that the gases inside suit don't get an opportunity to balloon. It's an elegant idea, but I guess they couldn't make it work well enough to convince even SpaceX to go that route.

Shrink-wrapping spacesuits

For future astronauts, the process of suiting up may go something like this: Instead of climbing into a conventional, bulky, gas-pressurized suit, an astronaut may don a lightweight, stretchy garment, lined with tiny, musclelike coils. She would then plug in to a spacecraft’s power supply...

news.mit.edu

 

[ICUDoc]

the top of an Optimus robot onto an arm

GRTEAT idea!
Musk will champion that for sure!

 

[Ben W]

This came out back in 2014, and I believe the idea is to fit the suit to the wearer so that the gases inside suit don't get an opportunity to balloon. It's an elegant idea, but I guess they couldn't make it work well enough to convince even SpaceX to go that route.

Shrink-wrapping spacesuits

For future astronauts, the process of suiting up may go something like this: Instead of climbing into a conventional, bulky, gas-pressurized suit, an astronaut may don a lightweight, stretchy garment, lined with tiny, musclelike coils. She would then plug in to a spacecraft’s power supply...

news.mit.edu

I'd be a bit concerned about what that suit concept would do to my geometrically delicate regions! Talk about solving the issue of space junk...