this post was submitted on 20 Nov 2024
191 points (97.5% liked)

News

23361 readers
3630 users here now

Welcome to the News community!

Rules:

1. Be civil


Attack the argument, not the person. No racism/sexism/bigotry. Good faith argumentation only. This includes accusing another user of being a bot or paid actor. Trolling is uncivil and is grounds for removal and/or a community ban. Do not respond to rule-breaking content; report it and move on.


2. All posts should contain a source (url) that is as reliable and unbiased as possible and must only contain one link.


Obvious right or left wing sources will be removed at the mods discretion. We have an actively updated blocklist, which you can see here: https://lemmy.world/post/2246130 if you feel like any website is missing, contact the mods. Supporting links can be added in comments or posted seperately but not to the post body.


3. No bots, spam or self-promotion.


Only approved bots, which follow the guidelines for bots set by the instance, are allowed.


4. Post titles should be the same as the article used as source.


Posts which titles don’t match the source won’t be removed, but the autoMod will notify you, and if your title misrepresents the original article, the post will be deleted. If the site changed their headline, the bot might still contact you, just ignore it, we won’t delete your post.


5. Only recent news is allowed.


Posts must be news from the most recent 30 days.


6. All posts must be news articles.


No opinion pieces, Listicles, editorials or celebrity gossip is allowed. All posts will be judged on a case-by-case basis.


7. No duplicate posts.


If a source you used was already posted by someone else, the autoMod will leave a message. Please remove your post if the autoMod is correct. If the post that matches your post is very old, we refer you to rule 5.


8. Misinformation is prohibited.


Misinformation / propaganda is strictly prohibited. Any comment or post containing or linking to misinformation will be removed. If you feel that your post has been removed in error, credible sources must be provided.


9. No link shorteners.


The auto mod will contact you if a link shortener is detected, please delete your post if they are right.


10. Don't copy entire article in your post body


For copyright reasons, you are not allowed to copy an entire article into your post body. This is an instance wide rule, that is strictly enforced in this community.

founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
[–] sp3tr4l 71 points 3 days ago* (last edited 3 days ago) (24 children)

Starship's upper stage will make a partial orbit of Earth, re-enter the atmosphere and splash down in the Indian Ocean...

Also known as not an orbit, or a suborbital flight / trajectory.

Saying a suborbital flight is a partial orbit is like saying a cessna can partially achieve hypersonic velocities.

NASA is also counting on a specialized version of Starship to ferry astronauts to the lunar surface later this decade under its Artemis program.

There is no public information indicating design on this variant has even begun.

... And Starship+Heavy Booster was supposed to have completed a succesful orbital flight in Q2 2022, per NASA's contract with SpaceX.

Which it still has not done, in Q4 2024.

If SpaceX somehow completes an orbital flight of this thing in say Q2 2025, and keeps to the originally agreed contract timeline, well thats only 3 years behind schedule.

But this is Musk. Not the best track record on delivering on promises, more of a 'pray i do not alter the deal further' kinda vibe, but spoken with all the menacing intimidation of Darth Helmet.

So far he's gotten a banana to suborbit in this thing.

...

I'll eat a sock if a SpaceX launcher and lander gets human beings to the moon and back safely by the end of 2030.

Did I forget to mention Musk's plan for a moon mission requires the Starship Lunar Lander variant to remain in Earth orbit, rendevouz and dock with and refuel from something like 12 or 16 other Starships?

... And there is also no publicly available information indicating actual design of this refuelling system either, just vague cgi concept arts of a plan?

I'll eat two fucking socks.

[–] [email protected] 9 points 2 days ago (5 children)

I'm a space systems propulsion design engineer by profession. I worked on a project which I will not name that requires on-orbit refuelling. (It's not this one and I don't and will never work for Elon Musk).
The technology for in-orbit refuelling doesn't exist, and there's a whole lot of new technology required. Remotely docking is akin to self-driving in complexity; don't forget to factor in the signal delay if you're in a lunar or translunar orbit. If you make this a crewed activity only, then the problem becomes one of pneumatics. A pressure system that can reliably contain and transfer pressure up to the levels of spacecraft fuel (around 300 psi for liquid, 3000 for gas) repeatedly, in both directions is very, very heavy. The valves are heavy, the tanks are heavy, the control systems are heavy. Too heavy to be considered viable for spaceflight. Even less so for a mission whose payload is "as much transfer fuel as we can possibly get up there". A huge amount of innovation has to take place before this can become real. As of 2022, when I last worked on this, none of the technology was even being researched, that is to say it was not even at TRL 3. Typically these things take on the order of a decade or so to get to TRL 9, if they are successful and quick.
I'm not saying it's impossible, I'm saying I'll be fascinated to see which solutions they come up with, and that I'm sceptical that they do have current solutions which are feasible and useful, rather than something like a one-shot refueling subsystem that weighs 250kg and delivers 15 litres of hydrazine.

[–] sp3tr4l 3 points 2 days ago* (last edited 2 days ago) (1 children)

I appreciate your expert input!

Yeah the only stuff I could find about actual orbital refueling was basically some tests with cryogenic fuel pumping on the ISS, which had some fairly serious problems, and a few times that basically a small satellite was refueled / serviced by another small satellite, which yeah as you say, just deliver a tiny amount of hydrazine, an exceptionally less volatile and easier fuel to deal with.

[–] [email protected] 2 points 2 days ago* (last edited 2 days ago) (1 children)

Hydrazine isn't less volatile or easy to deal with. Not unless your point of comparison is that one fluorine test rocket.

Here's the MSDS on hydrazine: https://nj.gov/health/eoh/rtkweb/documents/fs/1006.pdf

[–] [email protected] 1 points 2 days ago* (last edited 2 days ago)

It's easier to store. Aside from it being the single most hazardous chemical substance known to man, that is

load more comments (3 replies)
load more comments (21 replies)