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

Post by jessaustin » Wed, Mar 01, 2017, 2:51 AM UTC

el_isma wrote: post #403

gravypod wrote: post #133

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Exactly and that's not mentioning the benifit of being able to easily recover a failed prototype or even just analysis of a failed prototype. Imagine trying to diagnose a problem that comes up 10 months into the program after the probe is no longer in a direct visual path or while communications via microwaves start taking 10-20 seconds from point to point. There are too many questions to be answered before we can ju…

I don't understand why the human cost of space travel is always weighted so heavily. All exploration costs lives. How many died conquering America? Exploring the poles? The Everest? To this day people die in the Everest. It's their choice to risk their lives in such a way. Yet I don't hear people saying "don't go there". Space is riskier, but also has more rewards.

Post by sandworm101 » Wed, Mar 01, 2017, 3:50 AM UTC

logfromblammo wrote: post #474

sandworm101 wrote: post #460

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An elected government, at least i theory, is tasked with doing good by its people. That isnt always true, but at least there are elections. An individual person suffers no such limitation. That can act purely in thier own interest without even a tueoretical check. If they want to ride a rocket to the moon, while children on earth starve, there is absoluely nothing we poor can do about it.

There is the possibility that the wealth of an individual was acquired through voluntary trade. In that case, the person has already done so much good for other people that asking them for philanthropy instead of self-indulgence is renegotiating a deal that has already closed. In contrast, most governments have acquired massive wealth through taxation of their subjects. Those subjects are less likely to tolerate the…

Post by bdamm » Wed, Mar 01, 2017, 7:07 AM UTC

gozur88 wrote: post #483

astrodust wrote: post #351

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Being the first to land on the moon was never intended to be cheap. So many things had to be invented simply to get there. Just imagine how economical space flight would be if all of that 1960s technology had been incrementally improved on for efficiency, manufacturing ease, and scale instead of a lot of it being almost literallly mothballed.

There was never any reason to spend that kind of money. It was worth going to the moon once to see what was there, but I have yet to see anybody articulate a reason to go back that doesn't rely on soaring rhetoric and implausible money-making schemes.

Post by palunon » Wed, Mar 01, 2017, 7:48 AM UTC

Symmetry wrote: post #449

palunon wrote: post #377

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Isn't Earth closer to Mars half a (lunar) month ?

No. The Moon is in orbit around the Earth and both the Earth and Mars are in orbit around the sun. The Moon varies between 360,000 and 400,000 km away and the closest Mars gets to us is 54,600,000 kilometers. Those numbers are a bit of an exaggeration because how much fuel you need is just as important as absolute distance/time to travel and for that you need 4 km/s of delta-v to get from Earth orbit to Moon orbit an…

Post by [deleted] » Wed, Mar 01, 2017, 9:27 AM UTC

NickNameNick wrote: post #467

skookumchuck wrote: post #370

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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.

Bearing in mind that the ullage motors need to be of a type that won't suffer from ullage problems. That implies they cant use the main motor fuel. The saturn 5 used small solid rockets as ullage motors. Alternatively you could use externally pressurised bladder tanks for a range of non-cryogenic fuels. Cold gas or possibly h2o2 as a monopropellant come to mind. Either option has a comparatively low specific impulse,…