totm nov 2023 SpaceX Discussion Thread

[tater]

That has to refer to the Apollo capsules used for specific Skylab missions since the longest was ~3 months, and Skylab itself was up for a few years.

[tater]

 

[RCgothic]

1 hour ago, tater said:

That has to refer to the Apollo capsules used for specific Skylab missions since the longest was ~3 months, and Skylab itself was up for a few years.

Yes, you're certainly right. I've got to start applying sanity checks before I post.

[mikegarrison]

Yeah, it's a pretty niche "record". The longest time a "US" "crew capsule" has been in space. Because the Shuttle used to just drop people off and come back, it never stayed there that long. The Russians tend to rotate their Soyuz capsules, but they routinely stay up there more than 200 days, so 168 days is only a US record.

The Russians can pretty easily rotate their crews through different capsules, with a departing crew just taking the oldest one up there back home. That might become difficult for the US, if there end up being both Boeing and SpaceX capsules up there, because I don't think crews are being cross-trained to fly in the different types. I don't even know if the space suit hookups are cross-compatible.

Edited May 2, 2021 by mikegarrison

[tater]

Wonder what is the limiting factor of the commercial crew on-orbit duration value. Isn't it like 210 days or something as the requirement?

[mikegarrison]

1 hour ago, tater said:

Wonder what is the limiting factor of the commercial crew on-orbit duration value. Isn't it like 210 days or something as the requirement?

210 was apparently the standard Soyuz upper limit, although when I was looking to find that I saw an article about a 214 day mission from 2007. In that article it mentioned that the standard limit for Soyuz was 210.

[tater]

3 minutes ago, mikegarrison said:

210 was apparently the standard Soyuz upper limit, although when I was looking to find that I saw an article about a 214 day mission from 2007. In that article it mentioned that the standard limit for Soyuz was 210.

Seems like it offers excess capacity for normal operations (~6 months). I still wonder what the actual limit is, and what drives it. Consumable stores? They seem to run flexible ducts in to add it to ISS life support, so presumably they are not expending that from Dragon, perhaps there is some small loss over time regardless?

[mikegarrison]

4 minutes ago, tater said:

Seems like it offers excess capacity for normal operations (~6 months). I still wonder what the actual limit is, and what drives it. Consumable stores? They seem to run flexible ducts in to add it to ISS life support, so presumably they are not expending that from Dragon, perhaps there is some small loss over time regardless?

There are many possible mechanisms for how machines that are supposed to move stop working if they stop moving for too long. However, what seems most likely is that this is simply the envelope of what has been tested. As in, they have high confidence it can last that long, but not much specific proof it can last longer, even if they don't know for sure it can't.

Consider the X-37B, whose orbital durations have been:

• 224 days
• 468 days
• 674 days
• 717 days
• 779 days
• (ongoing)

That's a clear pattern of systematic envelope extension.

[Codraroll]

2 hours ago, mikegarrison said:

The Russians can pretty easily rotate their crews through different capsules, with a departing crew just taking the oldest one up there back home.

Aren't Soyuz seats custom made to fit the astronaut riding them, though? I'm quite sure I can remember reading that somewhere. I guess two astronauts with similar body structures could ride in each other's seats, but you couldn't put anyone in somebody else's seat.

[tater]

Yeah, I actually think the crews come down on the ship that brought them. Unsure about some of the super long duration missions in the past.

[YNM]

11 minutes ago, Codraroll said:

Aren't Soyuz seats custom made to fit the astronaut riding them, though? I'm quite sure I can remember reading that somewhere. I guess two astronauts with similar body structures could ride in each other's seats, but you couldn't put anyone in somebody else's seat.

I think the seats are replaceable... so the seats stick to the astronauts, not to the capsule.

[kerbiloid]

1 hour ago, mikegarrison said:

• 224 days
• 468 days
• 674 days
• 717 days
• 779 days
• (ongoing)

If  x is number and y is duration, till 680 days it was growing linearly.
After that it's linear again, but much more shallow, it  gets slower.

The logarithmic function is the best approximation found (r = 0.98)
T ~= 354.2 ln(N) + 233.2

Its asymptotic ceiling is ~1000 days after ~10 launches.

1 hour ago, Codraroll said:

Aren't Soyuz seats custom made to fit the astronaut riding them, though?

Were. Later they became more standard.

Edited May 2, 2021 by kerbiloid

[mikegarrison]

1 hour ago, Codraroll said:

Aren't Soyuz seats custom made to fit the astronaut riding them, though? I'm quite sure I can remember reading that somewhere. I guess two astronauts with similar body structures could ride in each other's seats, but you couldn't put anyone in somebody else's seat.

The customized part is a foam insert that can be swapped between capsules.

[Jaff]

Soyuz is limited on orbit by its fuels iirc. 
 

scott Manley done a vid on it a few years ago after the MS10(?) launch abort made it look like the crew currently on board may have to extend their stay longer than recommended. 
 

something to do with peroxide rings a bell? 

[tater]

Pretty cool render:

(by @ErcXspace at twitter)

Meanwhile at 39A:

 

[tater]

And at Boca Chica:

 

[tater]

 

[satnet]

6 hours ago, Jaff said:

Soyuz is limited on orbit by its fuels iirc. 
 

scott Manley done a vid on it a few years ago after the MS10(?) launch abort made it look like the crew currently on board may have to extend their stay longer than recommended. 
 

something to do with peroxide rings a bell? 

You remember correctly, they use hydrogen peroxide as a fuel,  which is non-toxic but does spontaneously decompose at an appreciable rate even without a catalyst.

[Nothalogh]

19 hours ago, tater said:

SpaceX told them they earned 68 million miles for their frequent flyer plan.

Only the in atmo miles count.

10 hours ago, mikegarrison said:

if there end up being both Boeing and SpaceX capsules

Big "IF", at this point

[mikegarrison]

2 hours ago, Nothalogh said:

Big "IF", at this point

Really? You think the US government is going to have spent all this money and effort to develop two alternate crew transport providers and then decide they are only going to use one of them?

[Nothalogh]

1 minute ago, mikegarrison said:

Really? You think the US government is going to have spent all this money and effort to develop two alternate crew transport providers and then decide they are only going to use one of them?

The trajectory of Boeing, at this point, is not promising.

[SOXBLOX]

Boeing has slipped up, but that doesn't mean that they're out. I think we'll see Starliner used a few years, at least.

2 hours ago, tater said:

 

Yes! Please fly on Star Wars Day! May the Thrust be with you, SN15! 

[tater]

18 minutes ago, SOXBLOX said:

Yes! Please fly on Star Wars Day! May the Thrust be with you, SN15! 

That has to be intentional.

Also, static fire on the booster for SL#25 heading up Tuesday:

 

[mikegarrison]

1 hour ago, Nothalogh said:

The trajectory of Boeing, at this point, is not promising.

So I guess here is where I point out that the Starliner has been to orbit and returned from orbit safely. Meanwhile people in this thread are super excited about a ship that has blown up every time it has tried to land.

I predict that the Starliner carries crew sooner than the Starship. Wanna take that bet?

(I do hope SpaceX manages to land this test flight. I'm not anti-SpaceX. It's just so annoying that many SpaceX fans seem to think anything not SpaceX is bad.)

Edited May 3, 2021 by mikegarrison

[Flying dutchman]

1 hour ago, mikegarrison said:

 

I predict that the Starliner carries crew sooner than the Starship.

I completely agree.

 

But i think it's pretty much impossible to compare Starship to a capsule. One is a tried and proven concept and the other is quite experimental. 

 

I personally think ss won't Carry crew for a long time (except for lunar ss) but i could be wrong.

Edited May 3, 2021 by Flying dutchman