I'm so excited about this. I used to watch old space mission videos and I think how could it would've been to watch them live back in the day. Now SpaceX has brought this excitement back.
I definitely feel like a kid watching this.
SpaceX successfully launches two humans into orbit
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Re: SpaceX successfully launches two humans into orbit
#32Earlier quoted context omitted.
Hypergolic fuels have TONS of advantages, including extremely reliable ignition. Basically all crewed orbital spacecraft have used hypergols in some ways. SpaceX's Starship will not use hypergols, although it probably won't be available for years.
> Basically all crewed orbital spacecraft have used hypergols in some ways. Right, but Soyuz spacecraft is flying since 1960-s, has a half a year orbital storage time, and yet it has no toxic RCS for the capsule. At least that simplifies handling after landing. And it was long since proven RCS doesn't need to use toxic components. The fact that Crew Dragon still uses them points more to the tradition than to the nece…
This is such a weird take on things. They don't just choose to use random chemicals for no reason, there are engineering tradeoffs made.
Fuels are extensively well studied and hundreds of thousands of man-hours are spent validating these choices
Re: SpaceX successfully launches two humans into orbit
#33Earlier quoted context omitted.
> Basically all crewed orbital spacecraft have used hypergols in some ways. Right, but Soyuz spacecraft is flying since 1960-s, has a half a year orbital storage time, and yet it has no toxic RCS for the capsule. At least that simplifies handling after landing. And it was long since proven RCS doesn't need to use toxic components. The fact that Crew Dragon still uses them points more to the tradition than to the nece…
Soyuz still uses hypergols on the service module. SpaceX has no separate service module (just the trunk which has no propulsion), which saves money as the whole propulsion system can therefore be reused. If the Soyuz used peroxide for the service module, it’d weigh far more due to lower performance. Peroxide has serious limitations in performance (and, like all strong oxidizers and monopropellants, has serious safety…
Kliper is a relatively modern design, which, while admittedly not produced in metal, used much more benign components for RCS. And Kliper also doesn't have a separate service module.
One can always say "but Klipper is a paper spacecraft". Of course, nothing is perfect. Buran can be brought as an example, and arguments against that could be broght up - "oh, it's too old". The point still stands - it's possible to not use toxic components, it's desirable - and it's not done. In my opinion, performance arguments - for a relatively low delta-V system - aren't convincing. After all, Crew Dragon is much bigger and newer craft that Soyuz.
Re: SpaceX successfully launches two humans into orbit
#34Earlier quoted context omitted.
Do you think NASA considers it an issue? They seem pretty ok with it and have plenty of experience with it. The robustness of the system is hard to give up. And fueling and recovery has always been a large production requiring attention to detail. Has NASA or DARPA put out any requests for a next-gen RCS fuel replacement?
> Do you think NASA considers it an issue? Maybe not, but they'd better do. The experience can be changed - SpaceX, for example, convinced them that loading fuel is better done with crew onboard. The point is, it's better not to have toxic components close to humans, and it also can be done technically. There could be reasons otherwise, but so far I don't see them particularly convincing, robustness and all notwithst…
Reliability and performance is literally the reason that the risk to use hypergolics are made.
"I don't think its a good reason to use a thing if we ignore the reasons to use the thing"
Re: SpaceX successfully launches two humans into orbit
#35Re: SpaceX successfully launches two humans into orbit
#36I'm so hyped for this.
I still remember when I was very little and my dad took me to a launch once.
Hope manned rocket launches will get more regular again and seeing them will inspire a whole new generation.
Re: SpaceX successfully launches two humans into orbit
#37Anyone know how long it will actually take to get to the ISS?
https://www.nasa.gov/specials/dm2/
> Lifting off from Launch Pad 39A atop a specially instrumented Falcon 9 rocket, Crew Dragon will accelerate its two passengers to approximately 17,000 mph and put it on an intercept course with the International Space Station. Once in orbit, the crew and SpaceX mission control will verify the spacecraft is performing as intended by testing the environmental control system, the displays and control system and the maneuvering thrusters, among other things. In about 24 hours, Crew Dragon will be in position to rendezvous and dock with the space station.
Re: SpaceX successfully launches two humans into orbit
#38Earlier quoted context omitted.
> Basically all crewed orbital spacecraft have used hypergols in some ways. Right, but Soyuz spacecraft is flying since 1960-s, has a half a year orbital storage time, and yet it has no toxic RCS for the capsule. At least that simplifies handling after landing. And it was long since proven RCS doesn't need to use toxic components. The fact that Crew Dragon still uses them points more to the tradition than to the nece…
Soyuz still uses hypergols on the service module. SpaceX has no separate service module (just the trunk which has no propulsion), which saves money as the whole propulsion system can therefore be reused. If the Soyuz used peroxide for the service module, it’d weigh far more due to lower performance. Peroxide has serious limitations in performance (and, like all strong oxidizers and monopropellants, has serious safety…
> SpaceX does nothing out of pure tradition
This deserves a separate reply.
SpaceX - correctly - speeds up the process by maximally reusing the known solutions for the problems - this not only makes development faster, but saves a whole lot of money on testing the variants which will be found not working.
I disagree that SpaceX does nothing out of pure tradition. In many areas, where invention is hard, unlikely and expensive, SpaceX instead opts to optimize the known solutions rather than invent new ones. Practically everywhere - landing first stages, full-flow combustion Raptor, reusing Dragon, all of that has good precedents in Delta-Cliper, RD-270, Gemini and VA TKS - SpaceX makes a right commercial decision to use proven technologies, which brings us results and doesn't break the bank. Note that truly innovative things, like spinning detonation wave engines, are still in the research labs, and not - at least in a big way - in the SpaceX factories. That's correct way to go considering that we have and know a lot already which we don't use fully.
> if that hasn’t been made clear by their approach so far.
No it hasn't. They just need to be read differently. The fact that they brought - well-tested and beneficial - traditions from computer industry into rocketry doesn't make them doing everything strictly from the first principles.
Re: SpaceX successfully launches two humans into orbit
#39It's absolutely incredible to see this. So much work to get us here. So much work just to organize this launch event. Seeing astronauts getting dropped off in one of the most technologically advanced automobiles on Earth and walk into the capsule sitting on top of a rocket which is the Pinnacle of humanity's biggest advancements in technology and space is astounding and goosebumps-enducing. What a time to be alive!
Re: SpaceX successfully launches two humans into orbit
#40Earlier quoted context omitted.
> Basically all crewed orbital spacecraft have used hypergols in some ways. Right, but Soyuz spacecraft is flying since 1960-s, has a half a year orbital storage time, and yet it has no toxic RCS for the capsule. At least that simplifies handling after landing. And it was long since proven RCS doesn't need to use toxic components. The fact that Crew Dragon still uses them points more to the tradition than to the nece…
This is such a weird take on things. They don't just choose to use random chemicals for no reason, there are engineering tradeoffs made. Fuels are extensively well studied and hundreds of thousands of man-hours are spent validating these choices
Why weird? Choosing something takes trade-offs - in the case of SpaceX capsules, they chose not to develop non-toxic technoogy, saving some time and money, but making an inferior product. It's not weird, it's their decision - which I'm not sure is good.
Given that we hopefully will soon see Starship flying, that may be rather moot point though.