Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

SpaceX to Send Privately Crewed Dragon Spacecraft Beyond the Moon Next Year

spacex.com

Post reply on HN
Print view View original

411–420 of 513 posts

Re: SpaceX to Send Privately Crewed Dragon Spacecraft Beyond the Moon Next Year

#411

Post by SmellyGeekBoy »

clebio wrote: post #223

> ... two private citizens ... have already paid a significant deposit to do a moon mission. Like the Apollo astronauts before them, these individuals will travel into space carrying the hopes and dreams of all humankind ... Except that these two private citizens are presumably absurdly wealthy. Whereas the nationalize space program which brought forth the Apollo mission gave all private citizens, as well as schoolch…

The first cars were only accessible to the "absurdly wealthy". So was air travel. Most things when you think about them, in fact. That doesn't mean the rest of us didn't aspire to have them and eventually have access to them thanks to all that early adopter funded R&D.

Re: SpaceX to Send Privately Crewed Dragon Spacecraft Beyond the Moon Next Year

#412

Post by rimantas »

rwmj wrote: post #392
ctdonath wrote: post #116

Earlier quoted context omitted.

The flight is a necessary step toward viable interplanetary travel. Even NASA slung people around the Moon before later flights landed thereon. Gotta send a rocket up & around & back, with passengers, to make progress toward the "colony on Mars" goal, so may as well do it with someone willing to fund a good chunk of the excursion.

I actually think today we'd be in a better situation if NASA had stopped there and didn't land on the moon (in the 1960s). Here's my reasoning: (1) It's much easier to orbit the moon than to land on it. (2) Both the US and the USSR had the capability to send many people on orbital flights around the moon. (3) With both the US and USSR orbiting the moon, the space race wouldn't have ended (because both had the same ca…

1) It is much easier to stay on Earth than to got into space

2) All the nations have a capability to stay on Earth

…

Re: SpaceX to Send Privately Crewed Dragon Spacecraft Beyond the Moon Next Year

#413

Post by wiredfool »

azernik wrote: post #203
coryfklein wrote: post #114

Earlier quoted context omitted.

Is it? I know very little about rocket fuel, but I always assumed that CO2 is involved. A short bit of Googling "composition of rocket fuel exhaust" wasn't immediately helpful. :/

Other responses go into this in more detail, but basically there are a few very chemically different types of rocket fuel. Usually for main engines these are bipropellants, with a fuel component and an oxidizer component. The expensive, exotic, high-specific-impulse, but low-density and dangerous option is liquid hydrogen + liquid oxygen (hydrolox), which does indeed create water vapor as exhaust. This particular roc…

And then there are the more out-there toxic ones like hydrazine and whatever fuel they use with oxidizers like nitric acid and the chloroflourines.

Re: SpaceX to Send Privately Crewed Dragon Spacecraft Beyond the Moon Next Year

#414

Post by kworker »

mrb wrote: post #349
astrodust wrote: post #346

Earlier quoted context omitted.

Hurray for progress! We're able to repeat what was done in 1972!

Except today it will be done at less than 1/10th the cost. So yeah, progress.

If it will be done. Musk isn't great at the "deliver" part, not to mention how dangerous this mission is.

Re: SpaceX to Send Privately Crewed Dragon Spacecraft Beyond the Moon Next Year

#415

Post by SmellyGeekBoy »

ErikHuisman wrote: post #144
biosoup wrote: post #40

I'm gonna make my tip, given Elon's history: Sergey Brin and Larry Page Two of his freind rich enough, geeky enough, to go first.

I would maybe guess Branson and Bezos as a stunt promoting private space tourism and thereby their space companies :)

Wouldn't that be admitting defeat?

Re: SpaceX to Send Privately Crewed Dragon Spacecraft Beyond the Moon Next Year

#417

Post by rbanffy »

gus_massa wrote: post #310
godelski wrote: post #199

Earlier quoted context omitted.

The thing is that NASA doesn't want to put anyone on something has the chance of doing that. The emergency system is for emergencies. Ideally it should NEVER be used. Vetting for manned missions is a lot different than cargo. That's all I'm getting at here. When rockets have recently exploded NASA gets pretty worried about putting humans on it.

For comparison, the Space Shuttle has NO emergency system and approximately a 2% catastrophic failure rate ...

It had a couple abort options if one or more SMEs failed. Unfortunately, none of the catastrophic failures were predicted.

Nature has a way to do things we don't expect it to do.

Re: SpaceX to Send Privately Crewed Dragon Spacecraft Beyond the Moon Next Year

#419

Post by baq »

skookumchuck wrote: post #370
NickNameNick wrote: post #366

Earlier quoted context omitted.

Liquid fuel rockets use Surface tension against the slosh baffles to hold fuel in partially full fuel tanks in place. Ullage motors are used to settle the fuel at the bottom of the tanks, so the main motor pumps can get to it. Once the main motor starts providing acceleration, the ullage motors are no longer required. For cross tanking, keeping the ullage motors running for long enough to transfer all the fuel, witho…

I didn't know about ullage motors, thanks for the link. The link also says that only very tiny accelerations are needed - so this shouldn't be a big problem for a tanker. Like I hypothesized, the problem has been solved.

it's only been solved if it's demonstrated, which it wasn't.

Re: SpaceX to Send Privately Crewed Dragon Spacecraft Beyond the Moon Next Year

#420

Post by mathw »

TheArcane wrote: post #401
prewett wrote: post #329

Earlier quoted context omitted.

Depending on how you count, it does. The 747-8 freighter can carry 240k L of fuel [1], and 308k lbs of cargo [2], so 1.3 L/lb. The Falcon Heavy can launch 120k lbs of cargo into low-Earth orbit [3], and according to the grandparent, is carrying 1250k L of fuel (including oxygen, which is an essential component of "fuel" in this case), so 10.4 L/lb. Still, that's better than I expected. And if you want to go to Mars,…

Would it be erreneous to say that no matter how 'green' our industries and power consumption on ground becomes, aviation and space flight would always require carbon based fuel?

We may be able to develop better electricity storage to allow electric planes to be more practical than they currently are.

However, there's also a lot of interest in using biofuels for aviation, so you may see that in the mid-term future we're using carbon-based fuels but they're largely carbon-neutral.

Post reply on HN