SpaceX is doing it again

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pjknibbs
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Re: Europe is starting to freak out about the launch dominance of SpaceX

Post by pjknibbs » Thu, 25. Mar 21, 12:11

mr.WHO wrote:
Thu, 25. Mar 21, 09:59
If you burn pure hydrogen with Oxygen, there is little to none enviromental dammage.
Surprisingly few rockets use hydrox in their first stages. SpaceX engines use RP-1 (slightly modified kerosene aka paraffin) and oxygen, for example, as did the Saturn V. Space shuttle main engines used hydrox, but the solid rocket boosters obviously did not. The only rocket I can think of offhand that definitely has a pure hydrogen/oxygen first stage is the Ariane 5.

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mr.WHO
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Re: Europe is starting to freak out about the launch dominance of SpaceX

Post by mr.WHO » Thu, 25. Mar 21, 12:24

pjknibbs wrote:
Thu, 25. Mar 21, 12:11
mr.WHO wrote:
Thu, 25. Mar 21, 09:59
If you burn pure hydrogen with Oxygen, there is little to none enviromental dammage.
Surprisingly few rockets use hydrox in their first stages. SpaceX engines use RP-1 (slightly modified kerosene aka paraffin) and oxygen, for example, as did the Saturn V. Space shuttle main engines used hydrox, but the solid rocket boosters obviously did not. The only rocket I can think of offhand that definitely has a pure hydrogen/oxygen first stage is the Ariane 5.
Interesting - then it means we actually have a development potential to make rockets more-ECO :)
Especially if Elon want's to launch 1'000 Starships to colonize Mars.

I read somewhere that hydrox is the most efficient weight-thrust ratio, but logistic, maitenance and safety is more complex than kerosene (which makes kerosene cheaper and better for inital stages - aparently you don't want hydrox to blow up in your launch pad).

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Re: Europe is starting to freak out about the launch dominance of SpaceX

Post by pjknibbs » Thu, 25. Mar 21, 13:31

The biggest problem with liquid hydrogen is its density, or lack thereof. You need enormous fuel tanks for the stuff. Even though RP-1 is somewhat less efficient you can use a much smaller tank for it, which makes the rocket smaller and lighter and means you need less fuel to get into space.

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Re: Europe is starting to freak out about the launch dominance of SpaceX

Post by Ethan13 » Thu, 25. Mar 21, 22:48

Nuclear engines may be the most environmentally friendly. Fuel takes up little space. There are no emissions.
What about a plasma thruster?

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Re: SpaceX is doing it again

Post by Ethan13 » Thu, 25. Mar 21, 22:59

mr.WHO wrote:
Tue, 23. Mar 21, 13:03
Redvers Ganderpoke wrote:
Sat, 6. Mar 21, 13:00
I'm still waiting for Elon to go to Mars. I can think of a few other people who could accompany him.
I recall his said he won't be moving to Mars even if he could, but he will allow his kids if they will want to (which I doubt - as a child of billionare I wouldn't want to go to cold desert wasteland of Mars).
I think he has the conditions for that. Perhaps he will allow his children to do this, but only with proper preparation and upon reaching the age of 21.

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Re: Europe is starting to freak out about the launch dominance of SpaceX

Post by BaronVerde » Thu, 25. Mar 21, 23:16

Ethan13 wrote:
Thu, 25. Mar 21, 22:48
Nuclear engines may be the most environmentally friendly. Fuel takes up little space. There are no emissions.
Nope. Nuclear thermal propulsion has a high specific impulse ISP (roughly double that of the best chemical rockets driven by hydrogen/oxygen) but a low thrust, too low to get off the pad. They must be launched by chemical rockets and would then propel a spacecraft on its transfer to Mars. There is no environmental gain unfortunately for the atmospheric part.

When something goes wrong at launch with an NTR motor on bord and the reactor breaks open on impact that'll be more or less bad, depending on how the nuclear fuel is stored and who finds it first and does what with it. For a taste of a bad case search Kosmos 954, though there are techniques to avoid such a scenario. Nasa has studies for the risks involved with a launch of the probes that have radioisotopic generators on bord. It is not super bad, but not exactly in the comfort zone either.

Plasma thrusters, like the ion thrusters belong to the family of electric propulsion, have a too low thrust for a manned spacecraft. They are among the most effective propulsion methods (2-40 times the ISP even of an NTR) that exist with current tech, and used for spacecarft who have years to decades time, use multiple gravity assists, etc. They need, though a lot of electric energy, making them almost useless beyond Jupiter if driven by solar panels.

For the significance of the ISP let me point to Tsiolkovski's rocket equation.

:-)

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SpaceX rocket debris creates a fantastic light show in the Pacific Northwest sky

Post by Ethan13 » Fri, 26. Mar 21, 17:56

SpaceX rocket debris creates a fantastic light show in the Pacific Northwest sky
https://www.theverge.com/2021/3/26/2235 ... ket-debris

Is the space debris problem becoming more and more urgent?
Many devices are already being created to combat space debris in orbit.
What are we going to do with such things as described in this article?

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Re: SpaceX is doing it again

Post by CBJ » Fri, 26. Mar 21, 18:01

I've merged several SpaceX threads together. I know there are plenty of space enthusiasts here, for obvious reasons, but we don't need a new thread every time they do something. :)

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Re: SpaceX rocket debris creates a fantastic light show in the Pacific Northwest sky

Post by BaronVerde » Sat, 27. Mar 21, 20:33

Ethan13 wrote:
Fri, 26. Mar 21, 17:56
Is the space debris problem becoming more and more urgent?
Many devices are already being created to combat space debris in orbit.
What are we going to do with such things as described in this article?
If I understand that correctly those were the remains of the second stage of a Falcon 9. When it has delivered its payload, it deliberately de-orbits to get out of the way. I think that's 'best practice' these days (but better check that if you want to be sure, not everybody may stick to it).

But generally, yes, it is becoming more and more of a problem, ISS performing evasive maneouvers, etc. I Think ESA and JAXA have some proposals, but overall it seems to me as if noone really takes it serious. There are catalogues of the bigger parts that float around in earth orbit, but smaller mm things go 'through'. There were already collisions, also multiple examples of damage so satellites as well as spacecraft returning from orbit, done by sub-mm parts, and even unexplained failures may have their cause already in debris hits.

The problem is known by the name 'Kessler syndrome'. When it starts it might kick loose a cascade in low earth orbit.

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Re: SpaceX rocket debris creates a fantastic light show in the Pacific Northwest sky

Post by Ethan13 » Mon, 29. Mar 21, 12:59

BaronVerde wrote:
Sat, 27. Mar 21, 20:33
Ethan13 wrote:
Fri, 26. Mar 21, 17:56
Is the space debris problem becoming more and more urgent?
Many devices are already being created to combat space debris in orbit.
What are we going to do with such things as described in this article?
If I understand that correctly those were the remains of the second stage of a Falcon 9. When it has delivered its payload, it deliberately de-orbits to get out of the way. I think that's 'best practice' these days (but better check that if you want to be sure, not everybody may stick to it).

But generally, yes, it is becoming more and more of a problem, ISS performing evasive maneouvers, etc. I Think ESA and JAXA have some proposals, but overall it seems to me as if noone really takes it serious. There are catalogues of the bigger parts that float around in earth orbit, but smaller mm things go 'through'. There were already collisions, also multiple examples of damage so satellites as well as spacecraft returning from orbit, done by sub-mm parts, and even unexplained failures may have their cause already in debris hits.

The problem is known by the name 'Kessler syndrome'. When it starts it might kick loose a cascade in low earth orbit.
Japanese experts have proposed creating wooden satellites to solve this problem. They can greatly reduce the design of satellites. (But it sounds very strange somehow. Wooden structures in the harsh conditions of space.)
I like the offer of skyrora.com. Their space tug has already been tested. The company recently received additional funding from ESA, which will allow them to speed up the development process. Perhaps this will be an effective solution to some of the problems in orbit.

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Re: SpaceX is doing it again

Post by Observe » Thu, 1. Apr 21, 01:42

I'm surprised no comments on SpaceX doing it again - explosions that is. Still, I guess that's what prototypes are for. I hope Starship doesn't turn out to be a dead-end strategy to be abandoned as a bad idea. One thing we know about Musk though, is his tenacity and determination. If it's technically feasible, he will likely make it work.

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Re: SpaceX is doing it again

Post by Mightysword » Thu, 1. Apr 21, 02:12

I think it's pretty much rountine for SpaceX at this point. They blew up a few Falcon back in the day too before successful at landing it. The success of both the Falcon and Dragon program proved that the financial benefit to be the first platform is huge. So between that and Musk's own stubbornness, I don't see them quitting anytime soon.
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Re: SpaceX is doing it again

Post by Observe » Thu, 1. Apr 21, 02:47

Mightysword wrote:
Thu, 1. Apr 21, 02:12
I think it's pretty much rountine for SpaceX at this point. They blew up a few Falcon back in the day too before successful at landing it. The success of both the Falcon and Dragon program proved that the financial benefit to be the first platform is huge. So between that and Musk's own stubbornness, I don't see them quitting anytime soon.
All true. If SpaceX can develop a fully reusable heavy-lift solution, they will dominate the launch market for years to come. There may still be some market for other companies like Rocket Lab, but they too are seeking the re-usability route.

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Re: SpaceX is doing it again

Post by Jacob68 » Mon, 5. Apr 21, 10:56

RegisterMe wrote:
Thu, 4. Mar 21, 00:53
SpaceX is the living embodiment of try, fail, learn, try again, repeat.

They deserve a lot of respect for that.
What a pleasure to see a person who understands that an unsuccessful landing is okay. The more people I meet, the more often I get upset because they think SpaceX doesn't progress and has to stop their tests. I always try to prove that it's necessary to consider the aim SpaceX wants to achieve — landing a rocket isn't that easy, and only blind people can't see progress. I remember that Falcon rockets also exploded during testing, but now they are the most successful reusable rockets of our time. Fails help them learn, and it's a key.

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Re: SpaceX rocket debris creates a fantastic light show in the Pacific Northwest sky

Post by Jacob68 » Mon, 5. Apr 21, 11:32

Ethan13 wrote:
Fri, 26. Mar 21, 17:56
SpaceX rocket debris creates a fantastic light show in the Pacific Northwest sky
https://www.theverge.com/2021/3/26/2235 ... ket-debris

Is the space debris problem becoming more and more urgent?
Many devices are already being created to combat space debris in orbit.
What are we going to do with such things as described in this article?
Was anyone lucky to see it for yourself? This "show" is better than any other firework, I think. Space debris is an important problem, of course, but those remnants described in the article burned up in the atmosphere. SpaceX is known for its quest for creating reusable spacecraft, and the amount of space debris they leave is minimal. I won't be surprised if it turns out that they are working on the spacecraft to remove space debris from LEO.

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Re: SpaceX is doing it again

Post by red assassin » Fri, 16. Apr 21, 22:52

https://www.nasa.gov/press-release/as-a ... ns-on-moon
This is a pretty big vote of confidence - NASA has picked Starship for the Artemis program's lunar lander. (They're still intending on using Orion and the SLS to get to the Moon, which seems a bit daft, but I guess when you've sunk your sunk costs...)
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Re: SpaceX is doing it again

Post by Vertigo 7 » Sat, 17. Apr 21, 01:23

I imagine it's too late for NASA to back out of the SLS program now. Congress has already given NASA about 20billion USD for the SLS and more already budgeted. It's a net loss no matter how things go, but it'd be better to see something come of it than wasted years and stupid amounts of cash. I expect they'll get their currently planned missions funded and finalized and that'll be the end of the SLS.
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Re: SpaceX is doing it again

Post by exogenesis » Sat, 17. Apr 21, 12:19

There are other launch methods ...
https://www.smbc-comics.com/comic/the-space-fountain

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