Polaris Dawn

[darthgently]

 

Polaris Dawn NET Aug 26

[Spaceception]

Is Polaris separate enough to warrant its own thread? Either way, looking forward to this mission, and since SpaceX is using this opportunity to develop better spacesuits, I wonder if we'll eventually see Polaris using suits with their own PLSS instead of needing umbilicals, just a safety tether, since that's likely in the pipeline.

[darthgently]

16 minutes ago, Spaceception said:

Is Polaris separate enough to warrant its own thread?

There is so much traffic in SpaceX and given that PD will launch in a few weeks figured a separate thread would organize better.  Most of the NASA non-routine missions get their own thread it seemed to me, so ..   But I see your point

21 minutes ago, Spaceception said:

I wonder if we'll eventually see Polaris using suits with their own PLSS instead of needing umbilicals, just a safety tether, since that's likely in the pipeline.

I'm wondering if the development and certification gauntlet for a new PLSS  was considered too much to bite into right now.  I doubt they will simply be going with the old design and everyone and their brother at NASA is probably full of ideas on the improvements over the old design that the SpaceX design should incorporate.  Probably a one step at a time thing

[tater]

 

[AckSed]

tl;dw If inspiration 4 was a commercial version of Mercury, Polaris Dawn is commercial Gemini.

Apart from the spacewalk, the thing I'm hoping to see work out is the Starlink test. We've already seen the Starship re-entry, but reliable connectivity? That's potentially a whole new sector of telecommunications that can service other satellites. It also makes the prospect of teleoperated orbital factories that little bit closer to reality.

[Gargamel]

On 8/7/2024 at 7:45 PM, Spaceception said:

Is Polaris separate enough to warrant its own thread?

All missions are worthy of their own thread if there's a chance they'll create additional conversation.   Once my electricity gets restored, I'll add this one and any others to the list.   You can always @ ping me to add a new mission or launch service to the list.    I might not get to it right away, but if you nag me me every 6 months....

[AckSed]

Interview with Scott Poteet: https://mynews13.com/fl/orlando/space/2024/08/16/scott-kidd-poteet-talks-about-polaris-dawn

[AckSed]

Everyday Astronaut livestream (set to start 6:30 AM UTC, 27th August):

 

[AckSed]

Scrubbed till morning of 28th.

[K^2]

Somebody said this mission gives Titan vibes, and I kind of agree. I have no reason to doubt the capsule itself, but everything about the spacewalk plan is sounding very flimsy.

[CBase]

 

[darthgently]

2 hours ago, CBase said:

 

A fairly active storm season is predicted for the Atlantic this summer and fall so we might want to get used to this

[Bioman222]

23 hours ago, K^2 said:

Somebody said this mission gives Titan vibes, and I kind of agree. I have no reason to doubt the capsule itself, but everything about the spacewalk plan is sounding very flimsy.

I agree. It feels a lot more ambitious/risky than other crew dragon flights. A lot could go wrong. Especially having the pure O2 environment in the capsule for an extended period of time, that is worrying to me. It also seems like this all came together very fast, having been announced a little over 2 years ago. And the EVA suits seemed like they just appeared out of the blue. But I suppose fortune favors the bold, and the Dragon flights so far have been very successful.

[darthgently]

2 hours ago, Bioman222 said:

I agree. It feels a lot more ambitious/risky than other crew dragon flights. A lot could go wrong. Especially having the pure O2 environment in the capsule for an extended period of time, that is worrying to me. It also seems like this all came together very fast, having been announced a little over 2 years ago. And the EVA suits seemed like they just appeared out of the blue. But I suppose fortune favors the bold, and the Dragon flights so far have been very successful.

The EVA suits have been in dev since around the announcement, iirc.  Maybe the preliminaries started well before as SpaceX had already dev'd the flight suit and have been planning to dev an EVA suit for HLS for some time and I doubt they haven't started on that.  And it isn't like they are starting from scratch.  I'm guessing the lunar "PLSS" suit will build on this tethered suit.   Would be nice to know more and not be guessing however

[CBase]

3 hours ago, Bioman222 said:

It feels a lot more ambitious/risky than other crew dragon flights.

Maybe because private entrepreneurs like Elon and Isaac are more ambitious than NASA ? They keep pushing, but the steps are not that big and bold like Artemis.

3 hours ago, Bioman222 said:

Especially having the pure O2 environment in the capsule for an extended period of time, that is worrying to me.

But easy to test previously on the ground, so it is likely something they are already comfortable with.

3 hours ago, Bioman222 said:

And the EVA suits seemed like they just appeared out of the blue.

I can not provide a source right now, but I remember to have read that the suits are only intermediate upgrades to IVA suits. They are not rated for extended durations, so might leak a bit more air than full EVA suits. Probably same for cooling, radiation, .... . Less challenging requirements make it faster to iterate from precessor and decrease risks during first mission.

[mikegarrison]

5 hours ago, CBase said:

(100% oxygen) But easy to test previously on the ground, so it is likely something they are already comfortable with.

The concern about pure-oxygen cabins is the risk of fire. However, for the Apollo missions they had pure oxygen in space. Their only cabin fire was the Apollo 1 mission, where they were using pure oxygen at high pressure (16 psi).

In space, Apollo used 100% oxygen at about 5 psi.

[AckSed]

Scott Manley points out a few details I hadn't considered, namely that debris could be an issue higher up, the attitude will be nose down, and the nosecone will point towards the direction of the orbit to act as a shield. Includes Kerbal for illustration:

 

[K^2]

2 hours ago, mikegarrison said:

In space, Apollo used 100% oxygen at about 5 psi.

Pressure isn't as big of a factor for fire risk as it is for, say, breathing. Most of the reduction of reactivity of oxygen in air isn't due to the partial pressure of oxygen being lower, so much as the ballast of nitrogen etc. While it's true that fire hazard of pure oxygen at 0.2 bar is going to be lower than at 1 bar, it is still way higher than for air at 1 bar. A lot of things that won't catch fire in an air mix will catch fire in O2 at 0.2 bar.

 

Unrelated, at least in any direct way, due to the failure of the most recent Falcon 9 launch, NASA has temporarily grounded all F9 flights until further notice. As far as I can tell, nobody really knows how long the grounding is likely to be in effect, but the general consensus seems to be that we should expect Polaris Dawn to be further delayed.

[magnemoe]

5 hours ago, K^2 said:

Pressure isn't as big of a factor for fire risk as it is for, say, breathing. Most of the reduction of reactivity of oxygen in air isn't due to the partial pressure of oxygen being lower, so much as the ballast of nitrogen etc. While it's true that fire hazard of pure oxygen at 0.2 bar is going to be lower than at 1 bar, it is still way higher than for air at 1 bar. A lot of things that won't catch fire in an air mix will catch fire in O2 at 0.2 bar.

Unrelated, at least in any direct way, due to the failure of the most recent Falcon 9 launch, NASA has temporarily grounded all F9 flights until further notice. As far as I can tell, nobody really knows how long the grounding is likely to be in effect, but the general consensus seems to be that we should expect Polaris Dawn to be further delayed.

Who failure, the failed landing. I assume that is an internal issue for SpaceX. 

[darthgently]

7 hours ago, K^2 said:

due to the failure of the most recent Falcon 9 launch

*landing, not launch.

I don't think the delay will be long.  A bigger factor is more likely to be seasonal weather

Edited August 29 by darthgently

[K^2]

Ah, yes, landing. Nonetheless, it seems that because the problem happened as the engines were getting re-lit, NASA opted to ground the flights, presumably out of abundance of caution.

https://www.npr.org/2024/08/28/g-s1-19934/faa-spacex-falcon9-grounded-polaris-dawn

[darthgently]

17 hours ago, K^2 said:

Ah, yes, landing. Nonetheless, it seems that because the problem happened as the engines were getting re-lit, NASA opted to ground the flights, presumably out of abundance of caution.

https://www.npr.org/2024/08/28/g-s1-19934/faa-spacex-falcon9-grounded-polaris-dawn

The engines had been lit for some time for the landing burn.  Scott Manley's analysis points to a leg failing from fatigue or just bad timing with the ocean swell such that the barge rose to meet the booster before it had fully decelerated, or a combination of both. 

The telemetry does seem to show it contacting the pad a few m/s faster than typical, but not outside what other other boosters survived.   

Clearly a leg failed whether it was the proximate cause or not, and once the leg failed an engine bell beat itself silly on the deck with great fireworks and excitement.

The latest Manley vid is good stuff for pondering this event, as usual, imo

[AckSed]

Fun fact: they put the entire Dragon capsule into the vacuum chamber before flight to pre-empt any offgassing of the materials when the spacewalk happens.

[tater]

The current wait is for a long enough weather window. They fly the nominal mission, with recovery weather looking OK for the entire mission duration (however many days it is).

[tater]