Why the MRAP though?
SpaceX successfully launches two humans into orbit
41–50 of 839 posts
Re: SpaceX successfully launches two humans into orbit
#42Same excitement and anticipation, fingers cross this time.
Re: SpaceX successfully launches two humans into orbit
#43Earlier quoted context omitted.
> 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"
I think you can have adequate reliability performance and win on safety with a different choice of propellants.
I also think general history of technology - including space technology - supports this point of view.
Re: SpaceX successfully launches two humans into orbit
#44Earlier 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…
Non-toxic would be better than toxic.
What would be the options? Compressed cold-gas (which don't have much kick, and require compressed gas which carry their own dangers).
You could go with a monoprop Hydrazine which would eliminate half the toxic stuff. There are also some new developments here: hydroxylammonium nitrate (HAN)/water/fuel ? No idea of the trade offs there.
Biprop hydrocarbon/gaseous compressed oxygen? Presumably that'd require an ignition source (and power source). How do you see that trade off?
Do you consider high-test peroxide non-toxic? (It certainly has a different risk profile, but is nasty stuff on contact with about anything that can oxidize). The decomposition would also make storage and rotation a consideration.
Re: SpaceX successfully launches two humans into orbit
#45Re: SpaceX successfully launches two humans into orbit
#46Who else has prepared snacks and beer?
I can feel blood in my ears how excited I am.
Good luck SpaceX & NASA!
Re: SpaceX successfully launches two humans into orbit
#47Earlier quoted context omitted.
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.
Your posts use terms like "inferior" to automatically shift the conversation to the notion that hypergolics are inferior solely because they are dangerous chemicals, and ignore engineering decisions that are made.
Its the same as arguing that RP1 engines are inferior to H2 engines because RP1 is based off fossil fuels. It's not relevant to the point.
Re: SpaceX successfully launches two humans into orbit
#48Anyone 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 disp…
Do they have to stay seated & buckled the whole 19 hours? Dare I ask how they eat or go to the bathroom on the 19 hour trip?
Re: SpaceX successfully launches two humans into orbit
#49Earlier quoted context omitted.
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"
I think you can have adequate reliability performance and win on safety with a different choice of propellants. I also think general history of technology - including space technology - supports this point of view.
You're not arguing anything. You're saying "I think something else can be good too".
Until you literally give an actual engineering (comparison of performance/reliablity/etc) reason that hypergolics are the wrong choice to make, this is effectively saying that "something should be different because I think so"
Re: SpaceX successfully launches two humans into orbit
#50I think Hurley and Behnken wanted to announce a name for their Crew Dragon spacecraft on launch day. Has anyone heard about this?