ptfrd

joined 5 months ago
[–] ptfrd 3 points 2 days ago* (last edited 2 days ago)

the host says they’re going to higher altitudes than the Apollo program

Ah, yes, well normally that would be my opportunity to remind people of Gell-Mann amnesia.

But this time it's unfair to the host. Isaacman has made that mistake himself on (I think) multiple occasions. She might have got it from him. (Perhaps indirectly.) Here's one: https://youtu.be/aASZ2rKdS6I?t=1m2s (He meant "since", not "than".)

this one doesn’t really have anything that makes it fundamentally unsafe.

You're probably right, but we'll see. The altitude and the spacewalk are the first big new initiatives for SpaceX's human spaceflight work that haven't been done under close NASA supervision. That's probably a good thing but ... I'm nervous.

Talking of the altitude, this is from the article:

The mission is scheduled to launch between 3:30 and 7 a.m. Eastern Aug. 26 in one of three instantaneous launch windows. Isaacman said the launch times were selected by SpaceX to minimize the micrometeoroid and orbital debris impact risk to the mission given its unconventional orbit.

He said it during the event (which is available to watch here), and I don't think any further explanation was given for why certain launch times are better than others for MMOD. Does anyone understand why? Is it obvious? Any resources I could check out to learn more?

Talking of the article, they still haven't fixed the first sentence!:

spacewalk on a is ready

If Jeff or anyone else from Space News is reading this, hire me as your proofreader!

[–] ptfrd 3 points 3 days ago (2 children)

Interesting title on the video about this, just uploaded to YT by CBS News: SpaceX sending private citizens on risky mission that includes spacewalk attempt

I find myself agreeing with the sentiment. I'm fairly nervous about this mission.

Don't get me wrong, I'd jump at the chance to join it. I'd choose it over a routine trip on Starliner, but not for the reason you might be thinking. ... I can't help wondering if Polaris Dawn is both higher risk and reward than a routine trip on Starliner.

[–] ptfrd 6 points 3 days ago (2 children)

No, that's this one, funded by a crypto billionaire, announced a week ago and launching in ~4 months.

Polaris Dawn is funded by a payments processing billionaire, announced 2.5 years ago, and launching this month.

[–] ptfrd 4 points 4 days ago

That has to be a requirement regardless I guess since a depressurization could happen on any flight.

Yes, this has been pointed out by the crew (IIRC) in an interview about the mission. (Not to suggest that no work was needed on the issue, just less work than people might expect. Obviously it can be the case that taking an unlikely contingency scenario and making it a deliberate part of a mission, raises the level of assurance needed.)

[–] ptfrd 1 points 1 week ago* (last edited 1 week ago)

Scenario 4

Well, consider various lesser versions of Scenario 1. What if the crew was only partially reduced in their capabilities?

Perhaps they were both suffering from the symptoms of carbon monoxide poisoning (including headaches, dizziness, and confusion). Or perhaps one was serously injured, and the other was fine but needed to focus all her attention on tending to her crewmate?

Then it would come down to the question of just how complex and time-consuming the required manual step(s) are. If there's just a big red button that says "TAKE US HOME" then, it shouldn't be a problem. But we don't know.

And if there was just a big red button, couldn't they try bypassing the current 4-week delay, by coming up with some ways of pressing it without humans on board? ;) Shove an astrobee in there and give it a try. If it doesn't work, no harm done ...

[–] ptfrd 7 points 1 week ago

Aren’t there several realistic scenarios ...

Scenario 1

Emergency on board ISS. 1) One aspect of the emergency (e.g. noxious air) has incapacitated many of the crew, including all the ones trained to operate Starliner. 2) Another aspect of the problem (e.g. electrical faults that are expected to lead to fire) leaves no doubt that evacuation is essential.

Those ISS crew who managed to don emergency breathing apparatus quickly enough now move the incapacitated Starliner crew to their seats, strap them in and exit Starliner (closing the hatches on their way out), before proceeding to their own vehicle(s).

Scenario 2

Serious MMOD strike upon a docked vehicle, causing damage that makes it very unlikely to be safe for its crew to return in, and also at significant risk of posing a danger to the ISS.

Wouldn't the least bad option be to command an uncrewed undocking and hope for the best?

Scenario 3

During a flight test, a spacecraft is able to dock with ISS, but only after encountering significant problems. The first job of engineers is to consider whether it is sufficiently safe for the crew to return to Earth in, in the event of an emergency. Their decision is either 'no', or 'barely'.

An alternative provider of crewed LEO access services, known for its proficiency and speed of operations, announces that they will be able ready to send a replacement vehicle by the time of a suitable launch opportunity in 4 days' time.

There are no spare docking ports.

 

A Youtuber called Ellie in Space claims that a NASA source sent her the following message. It was in response to a question about when NASA knew that the Boe-CFT mission's Starliner vehicle would not be able to undock and return to Earth autonomously without being reconfigured.

So if you want to know when??? Well always, but it wasn't a reasonable consideration to retain the unmanned Starliner capsule software to work in the manned version of the capsule as a contingency. Would you call that a mistake?? Maybe, but let's think about the need to really ever plan to send folks up to space and leave them there with no way to fly home... they would always chose to risk the ride vs having no way home.

No one really considered this very unique and dynamic situation would happen.

Background

I believe this issue was first brought to light by Eric Berger.

Regardless, sources described the process to update the software on Starliner as "non-trivial" and "significant," and that it could take up to four weeks. This is what is driving the delay to launch Crew 9 later next month.

A couple of days later, NASA held a press teleconference in which they emphasized that what was needed was merely a "data load", not a software change. But they indicated timelines that do seem consistent with the "up to four weeks" claim by Berger's source.

My questions

Aren't there several realistic scenarios where you'd want to undock a crew vehicle, without its crew (or at least without them being in a fit state to operate the vehicle), in less than 4 weeeks?

Can Crew Dragon do it? Soyuz?

[–] ptfrd 2 points 2 weeks ago* (last edited 2 weeks ago)

In the implication here that it is Congress who want a diversity of suppliers, whereas NASA doesn’t care as much?

Yes, I think that's the implication. I realized it's not correct but decided to leave it like that. I'm a big picture kinda guy; someone else can sort out the details!

I guess it might be more like a combined NASA / Space Force high level strategic fund providing the subsidy. So that individual 'low level' programmes within NASA / Space Force then don't have to worry too much about the long term strategic goals like dissimilar redundancy, and can mostly just focus on their own needs.

[–] ptfrd 4 points 2 weeks ago

If NASA decides to send Starliner back empty, it's a vote of no confidence in Boeing that may lead the company to cut its losses and withdraw from the program.

How would this work, contractually? Would they have to give back the whole $4.1 billion (or whatever)? And pay penalties on top to cover NASA's costs?

[–] ptfrd 4 points 2 weeks ago* (last edited 2 weeks ago) (1 children)

the most likely alternative would be to bring the astronauts back using SpaceX's Crew Dragon by removing two astronauts from the Crew-9 mission

The most likely? Not convinced. Wouldn't anyone removed from Crew-9 just be shifted to Crew-10? So it'd seem silly to announce Crew-10 only to have to change it a week later.

And even if they don't care about looking silly in that way, they might instead just go with one empty seat 'uphill' for each of Crew 9 and 10. Because that's a less drastic change to make to Crew 9 at such short notice.

But maybe I'm wrong. So, assuming the quoted scenario actually is what happens ...

I guess they'd have to keep the Russian (Gorbunov)?

And keep the capsule commander (Cardman)? But she's never been to space, so maybe the pilot (Hague)? I can't immediately see if he was expected to be the ISS commander, but if so, I guess that would give them a good excuse to 'promote' him over Cardman?

Wilson has had more launches than Hague (3 versus 2ish) but a lot less time in space, and I don't know if she would be as well trained for Dragon as the commander & pilot.

[–] ptfrd 3 points 2 weeks ago

They say they really like Starliner, and I think they mean it. After all, it's not that bad! If you offered me a free trip to space in it, I'd jump at the chance.

In fact I'd offer to pay at least 1/3 of my net worth. (Sadly this doesn't quite equate to the current cost-per-astronaut of, what, $150m?)

[–] ptfrd 5 points 3 weeks ago (1 children)

Turns out that some of the later parts of the video I posted largely negated my above comment.

What do you think will happen to the other one? Do you think they’ll maintain a Florida splashdown capability indefinitely, as a backup

Question at 43:08.

43:56 "There may be a small transition period as we're moving vessels through the Panama Canal ... where we can support either Coast ..." (implying not indefinite)

e.g. in case of bad weather in all the new West Coast splashdown zones

51:15 "one benefit of moving to the West Coast is much better weather"

Also of interest ...

30:39. Sounds like they didn't bother with a Public Safety Determination in the end, and just went directly to full(?) approval.

[–] ptfrd 3 points 3 weeks ago

And I see that the Soyuz TMA-11 crew included Peggy Whitson. We wouldn't want the same kind of thing to happen to her twice!

(Her 2nd Axiom mission is NET November this year, so that shouldn't be affected by this change, but any subsequent Axiom missions might be.)

21
submitted 3 weeks ago* (last edited 3 weeks ago) by ptfrd to c/spacex
 

Relevant portion of the video is 18:06 - 22:22.

Key quote: "We'll move a Dragon recovery vessel to the Pacific some time next year, and we'll use SpaceX facilities in the Port of Long Beach for initial post-flight processing".

Although this was revealed in a Crew-9 briefing, it doesn't actually apply to Crew-9.

The announcement has just now been posted to the SpaceX website.

Key excerpts:

During Dragon’s first 21 missions, the trunk remained attached to the vehicle’s pressurized section until after the deorbit burn was completed. Shortly before the spacecraft began reentering the atmosphere, the trunk was jettisoned to ensure it safely splashed down in unpopulated areas in the Pacific Ocean.

After seven years of successful recovery operations on the U.S. West Coast, Dragon recovery operations moved to the East Coast in 2019, enabling teams to unpack and deliver critical cargo to NASA teams in Florida more efficiently and transport crews more quickly to Kennedy Space Center. Additionally, the proximity of the new splashdown locations to SpaceX’s Dragon processing facility at Cape Canaveral Space Force Base in Florida allowed SpaceX teams to recover and refurbish Dragon spacecraft at a faster rate [...]

This shift required SpaceX to develop what has become our current Dragon recovery operations, first implemented during the Demo-1 and CRS-21 missions. Today, Dragon’s trunk is jettisoned prior to the vehicle’s deorbit burn while still in orbit, passively reentering and breaking up in the Earth’s atmosphere in the days to months that follow. [...]

When developing Dragon’s current reentry operations, SpaceX and NASA engineering teams used industry-standard models to understand the trunk’s breakup characteristics. These models predicted that the trunk would fully burn up due to the high temperatures created by air resistance during high-speed reentries into Earth’s atmosphere, leaving no debris. The results of these models was a determining factor in our decision to passively deorbit the trunk and enable Dragon splashdowns off the coast of Florida.

In 2022, however, trunk debris from NASA’s Crew-1 mission to the International Space Station was discovered in Australia, indicating the industry models were not fully accurate with regards to large, composite structures such as Dragon’s trunk. [...]

After careful review and consideration of all potential solutions – coupled with the new knowledge about the standard industry models and that Dragon trunks do not fully burn-up during reentry – SpaceX teams concluded the most effective path forward is to return to West Coast recovery operations.

To accomplish this, SpaceX will implement a software change that will have Dragon execute its deorbit burn before jettisoning the trunk, similar to our first 21 Dragon recoveries. Moving trunk separation after the deorbit burn places the trunk on a known reentry trajectory, with the trunk safely splashing down uprange of the Dragon spacecraft off the coast of California.

27
submitted 4 weeks ago* (last edited 4 weeks ago) by ptfrd to c/spacex
 

That's 27 hours from now.

SpaceX is targeting Saturday, July 27 for a Falcon 9 launch of 23 Starlink satellites to low-Earth orbit from Launch Complex 39A (LC-39A) at NASA’s Kennedy Space Center in Florida. Liftoff is targeted for 12:21 a.m. ET, with backup opportunities available until 4:21 a.m. ET.

And here is their blogpost, dated 2024-07-25, announcing that the mishap report has been submitted to the FAA, and discussing some of the details.

During the first burn of Falcon 9’s second stage engine, a liquid oxygen leak developed within the insulation around the upper stage engine. The cause of the leak was identified as a crack in a sense line for a pressure sensor attached to the vehicle’s oxygen system. This line cracked due to fatigue caused by high loading from engine vibration and looseness in the clamp that normally constrains the line.

38
submitted 1 month ago* (last edited 1 month ago) by ptfrd to c/spacex
 

During tonight’s Falcon 9 launch of Starlink from Space Launch Complex 4 East at Vandenberg Space Force Base in California, the second stage engine did not complete its second burn. As a result, the Starlink satellites were deployed into a lower than intended orbit. SpaceX has made contact with five of the satellites so far and is attempting to have them raise orbit using their ion thrusters.

There's also a tweet saying the same thing in fewer words.

This is the affected mission: Starlink 9-3 launch bulletin

Let's hope it was due to SpaceX pushing the envelope on their in-house Starlink missions in some way, though I have no specific guesses along those lines. Perhaps a manufacturing defect or an operational mistake are more likely to be the leading candidates for the cause.

13
submitted 5 months ago* (last edited 5 months ago) by ptfrd to c/spacex
 

Quote from Bill Nelson:

... SpaceX, by having the return of the first stage, has brought the cost down significantly. That has affected the entire launch industry. We'll be seeing attempts at bringing the second stage down on some missions.

The key sentence is (currently) 52 minutes and 48 seconds into the video. Approximately 49 minutes after the event started.

No other mention is made of this. Should we assume he's specifically referring to the 2nd Stage of the Falcon 9? What is the likelihood that he is mistaken? Could he just be thinking of the existing deorbit procedure? Or could SpaceX be putting parachutes on some of their 2nd Stages in the near future?

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