ptfrd

joined 8 months ago
[–] ptfrd@sh.itjust.works 1 points 8 hours ago

Yeah. One possibility is that SpaceX were indeed underperforming, and the story was placed to put public pressure on them to improve. (A bit like the 2019-09-27 Bridenstine tweet.)

[–] ptfrd@sh.itjust.works -2 points 10 hours ago

(And just to be clear, I have many problems and potential concerns about Musk. I'm just saying I'd choose him over, say, a Maoist, or a Stalinist, and over "Burn_The_Right".)

[–] ptfrd@sh.itjust.works 2 points 16 hours ago (2 children)

I’m sure he could block the Starlink terminals Russian army is using, if he wanted to try, for example.

I remember a story coming out about Russians using Starlink but it seemed a bit vague to me. Has anyone reliable actually asserted that SpaceX are significantly underperforming in the job of blocking captured terminals (once notified), or other aspects of the day-to-day operations that the Ukrainians would do if they controlled it themselves?

[–] ptfrd@sh.itjust.works 2 points 1 day ago

Though at least they've already proved they can relight during a belly flop.

[–] ptfrd@sh.itjust.works 2 points 1 day ago* (last edited 1 day ago)

I would not have thought it could float in a different orientation

Me either. But they call that orientation "Stable 1", possibly implying they've accounted for other stable orientations, and some non-stable situations.

Here was the first time I heard that term (with Bob & Doug): https://www.youtube.com/live/tSJIQftoxeU?t=6h29m34s

The commentator then gives some explanation.

[–] ptfrd@sh.itjust.works 3 points 1 day ago

Post-splashdown news conference: https://youtu.be/gOUoI-UYi2Y

They mentioned that Cargo Dragon sometimes reuses parachutes, which I didn't know.

[–] ptfrd@sh.itjust.works 2 points 1 day ago (2 children)

Watched some of the official coverage: https://www.youtube.com/live/5CRB3FHV9Dw

Things that were new to me:

  • 1:40:50 Drone footage of the capsule lift
  • 34:42 Jones explains that the same set of 12 hooks secures Dragon to either its nosecone or to the ISS. Makes perfect sense; I'd just never thought about it before.
  • 1:35:57 "There are multiple options so if Dragon were to splash down in a different orientation they could egress from the top hatch as well."
    • Would this be a last resort after they'd tried & failed to correct the orientation?
    • Would it only be used when Dragon was still in the sea or would they ever lift Dragon onto the boat in an orientation that necessitated top hatch egress?

And all this talk of Dragon orientation, combined with the extensive weather delays in Crew-8's departure, got me wondering ... How would Dragon fare if it was left in very rough seas for an extended period? (Imagine the recovery vessel broke down a minute after splash-down and then a big multi-day storm blew in, or something.)

[–] ptfrd@sh.itjust.works 2 points 1 day ago

Plausible. It's not how I imagine them engaging with their defence contractors but I don't actually have a clue how it works. One supporting point might be if there were any other companies treated similarly, like if Lockheed Martin was ordered to immediately ramp up production of relevant types of military hardware, and told that the details (contracts / payment / etc.) would be sorted out later.

An opposing point would be the fact that the US and its allies knew an invasion was likely well in advance. Yet the initial Starlink 'roll out' seemed pretty ad hoc, with SpaceX organizing its own logistics. But then maybe the allies didn't expect Russia to be so effective in disrupting the existing military comms infrastructure.

[–] ptfrd@sh.itjust.works 2 points 1 day ago (3 children)

that the engines relight multiple times in orbit

Should they do an orbital test next? Or continue with the previously used 'almost orbit' trajectory that ensures the second stage re-enters safely with no need for a relight?

[–] ptfrd@sh.itjust.works 6 points 1 day ago* (last edited 1 day ago) (5 children)

The SpaceX officials in the audio said they were “trying to focus on booster risk reduction versus ship envelope expansion” for the next flight.

For the "ship envelope expansion", do you think they will/should do an in-space engine relight test? Or are the seemingly successful flip-landing maneuvers on flights 4 and 5 sufficient? (Has this been covered elsewhere?)

[–] ptfrd@sh.itjust.works 8 points 1 day ago* (last edited 1 day ago)

Interesting! They're talking about unnecessary aborts, and how they want to do as much analysis as possible of the abort criteria, to prevent them.

This will remain an issue for Flight 6 which, it seems, will happen the moment SpaceX decides it's sufficiently ready. Unlike previous flights ...

"Given this is the first launch in a long time ... well really ever ... that we've not been FAA driven ..."

 

Steve Stich states at today's Crew-9 news conference that Dragon has a new contingency capability if all 4 parachutes fail; the SuperDracos will ignite prior to splashdown.

The Crew-8 return to Earth will also have this capability.

(He said this about 20 minutes after the start of the stream.)

 

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?

 

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.

 

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.

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submitted 3 months ago* (last edited 3 months ago) by ptfrd@sh.itjust.works to c/spacex@sh.itjust.works
 

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.

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