If there are currently nine crew at the ISS, when will that be reduced? I don’t think the ECLSS can support that number indefinitely.
If there are currently nine crew at the ISS, when will that be reduced? I don’t think the ECLSS can support that number indefinitely.
When Crew-9 arrives there will temporarily be 11, as is typical for a crew handover. Once Crew-8 departs the station will be back to a crew of 7.
There is also a 3-person Soyuz crew rotation in there as well. Scheduled for September 11.
The crew spec was 7 at first launch. It was assumed at late stages, 6 would be available for maintenance and 1 for science. They spent a long time at 6 because that is what you get with 2 Soyuz. 7 was 1 Soyuz and 1 US visiting vehicle (my has that changed over the decades)
I don’t think 9 is as big and impact on ECLSS as it is for other consumables. Remember, there are no washing machines on orbit. You can put more clothes on a supply Dragon, but only taking off other items, which won’t be food and water. It is probably a good thing we can’t smell the interior of the ISS.
Well, it had been my understanding the ECLSS for the USOS was sized for four, and the Russian segment for three. But yes, that’s not the only constraint.
It’s somewhat inaccurate to say the ISS ECLSS is “sized” for anything, although the USOS water reclamation system is said to be sized for 6 (not 4). Instead, the systems can support whatever load they have supplies for. Oxygen is made from water electrolysis, but both segments have makeup gas (compressed air in ROS and oxygen + nidogen tanks in USOS) brought up in supply ships as needed. In addition, ROS stocks perchlorate candles. At a rate of one candle per crew member per day it’d take over 2500 to do the whole job for a year, but a single Cygnus could bring up that many (probably 2 Progresses). The current supply rate is 3 Progress, 3 Cargo Dragons, and 2 Cygnus per year (usually) so that gives you a rough estimate of what it takes (minus all the hardware, it’s not all supplies).
Well I watched Calypso un-dock from the ISS successfully. De-orbit burn in about 3 hours…
It will be interesting to see if Calypso makes it back ok. I think the odds are probably pretty good. Good enough for a crewed return? Well NASA didn’t think so. Who am I to say otherwise?
So crewed next flight? If so as the result of what further testing? Suspect we won’t see another Starliner flight next year. By the time you have to allow for analysis and modifications I’m thinking 2026 at the earliest? And then is NASA going to want another uncrewed test flight? Could they make it a pressurized cargo flight and get something out of it for the ISS? Thoughts?
There’s actually a bit of good news at the moment (just after landing).
Diagnosing the thruster problem is critical, and due to the thrusters that failed being on the service module, they weren’t expecting to get any of the failed thrusters to test. So, the good news (sort of) is that a capsule thruster failed too, so now they’ve got at least one failed thruster to examine.
How did you watch the return? Through a periscope? Or maybe on a monitor at your local Sonic?
BTW what am I going to do with all these tickets? 🙂
@ Davis Spain
Lol. I figured out a few days ago (based on ISS ground track) that it’d be an ascending node reentry, so not over my area. I just stayed put, and managed to get NASA’s youtube channel to work, kinda. 🙂
I really was worried about a loss of control and breakup at max dynamic pressure during reentry. I, for no good technical reason, suspected the capsule thrusters could fail as some of the SM ones had (Even though they are at least a bit dissimilar).
I’m very glad it made it okay, and didn’t scatter dangerous debris over an inhabited area.
The CM thrusters are different from the SM thrusters. CM are monopropellant, SM are bipropellant. So now they have two different kinds of thruster problems. I’d like to see Starliner go into service, but I’m no longer hopeful.
Although there are projections to the contrary, a 2025 return to flight doesn’t sound likely.
@ William Barton
When I was worried about the CM thrusters failing on reentry, I was wrongly assuming they were hypergolic biprop, similar to the SM thrusters. Thanks for the info!
This definitely does not look good for Boeing; two very different systems failing, plus of course other issues, like the helium leaks, the excessive sublimation water usage, etc.
My guess on when it’ll fly again; 50-50 Boeing cancels it, and if not, 50-50 for a 2026 unmanned cargo flight to ISS, assuming they can get the thruster problem solved for sure.
On the other hand, waiting might be Boeing’s least-bad option. After the planned ISS orbit-lowering in 2030, Starliner could reach ISS without thrusters, no problem. 🙂
A question for Mr. Kelly. To date the issue with the bulging Teflon oxidizer line seals (NTO) in the service module’s thrusters have been claimed to be thermal. Due at least in part to the design of the ‘doghouse’ enclosure the thrusters are enveloped in. How would Kalrez respond differently to that kind of stress?
If one were to redesign the seals to use Kalrez, would it be easier to just build new thrusters from scratch from it and then replace the entire thruster assembly in the doghouse rather that try to ‘fix’ the existing thrusters?
Sounds like one of the options being considered by NASA is to use the thruster ‘less’ or ‘less often’, thus avoiding over heating. I wonder about this option, should one have serious reservations about that?
FWIW here’s what ChatGPT has to say:
Key Differences Between Kalrez and Teflon
Material Composition:
Kalrez: Perfluoroelastomer (FFKM) with elastomeric properties.
Teflon: Polytetrafluoroethylene (PTFE), a rigid, non-elastic material.
Temperature Resistance:
Kalrez: Up to 327°C (620°F).
Teflon: Up to 260°C (500°F).
Applications:
Kalrez: Primarily used in sealing applications in harsh chemical environments, high temperatures, or where long-term durability is needed.
Teflon: Used in applications where a low friction, non-stick surface is required, such as cookware, bearings, gaskets, and coating cables.
Mechanical Properties:
Kalrez: Exhibits elastomeric properties, making it suitable for dynamic sealing applications.
Teflon: Has rigid and non-elastic properties, making it better suited for static seals or non-moving parts.
Chemical Resistance:
Both materials are highly chemically resistant, but Kalrez can withstand a broader range of chemicals and conditions, especially in more demanding environments.
In summary, while both Kalrez and Teflon offer excellent chemical resistance, Kalrez is superior in high-temperature stability and dynamic sealing applications, whereas Teflon is known for its non-stick properties and lower cost, making it ideal for consumer products and certain industrial uses.
Btw, I think the CM thrusters are hydrazine/iridium.