What "weed need" is a space mission!

[chalsall]

Originally Posted by Dubslow

Now, the partial agreement with this proposal is that it would be possible to make an infrastructure investment to have an active cooling and storage system in the proposed garage, however it would be significantly more expensive and difficult than [the author of the article, not Musk] seems to think.

Agreed. However, it is worth noting that there is a great deal of energy, and thermal differences, available in space which could be used for cooling. Heck, just launch a tanker full of liquid nitrogen every so often and let it boil off in the vacuum behind a sun-shade to sub-cool down the LOX and liquid methane.

Originally Posted by Dubslow

The third point by the second article is also quite a problem IMO. I remember when Musk was asked about radiation for the trip and he kind of waved it away, that was one of the few moments when I thought to myself "Uh... okay then Mr Musk, but that's actually a serious problem".

So always orient the ship with it's back end pointed towards the sun (the largest source of dangerous radiation). All those engines, the tank of liquid methane, the tank LOX, the tank(s) of water, and the cargo would probably help quite a bit.

Originally Posted by Dubslow

So although it may not necessarily look like the presentation Musk made (in physical look or in the architecture of the missions), I am still quite confident that SpaceX will achieve what they set out to do in one form or another.

Or, at the very least, they will push the state of the art forward. As Musk himself said, they're likely to fail. But at least they're working the problems.

And, without question, the plan will evolve over time. Slowly spinning the ship, for example, makes a lot of sense.

[retina]

Originally Posted by chalsall

Slowly spinning the ship, for example, makes a lot of sense.

How slow? Trying for one G requires a lot of structural support apparently so is infeasible at this time due to weight considerations. Even one atm is hard enough, we still don't do that on commercial aircraft.

[chalsall]

Originally Posted by retina

How slow? Trying for one G requires a lot of structural support apparently so is infeasible at this time due to weight considerations. Even one atm is hard enough, we still don't do that on commercial aircraft.

Why would you try to achieve 1G when your destination is only 0.38? Not to mention the Coriolis effect in a small radius.

Similarly, while one ATM is maintained on the ISS, there is no need to do so during interplanetary (or even innerplanetary) travel.

[xilman]

Originally Posted by retina

How slow? Trying for one G requires a lot of structural support apparently so is infeasible at this time due to weight considerations. Even one atm is hard enough, we still don't do that on commercial aircraft.

Only a small fraction of the ship needs to be at high gravity. The connection between those points and the core structure will be in tension, which is much easier to arrange with a low mass budget than are compression or sheer. Nonetheless it's an interesting engineering problem.

[chalsall]

Originally Posted by xilman

Nonetheless it's an interesting engineering problem.

It's a ferris wheel. A rotating frame of reference.

Been there; done that.

Hope to go again....

[xilman]

Originally Posted by chalsall

It's a ferris wheel. A rotating frame of reference.

Been there; done that.

Hope to go again....

Indeed, but with differences. A Ferris wheel doesn't have such a tight mass budget as the spacecraft equivalent. It has to withstand a slightly varying g-force which averages 1 g in one constant direction whereas the spacecraft should produce a uniform acceleration acting purely radially.

[chalsall]

Originally Posted by xilman

A Ferris wheel doesn't have such a tight mass budget as the spacecraft equivalent. It has to withstand a slightly varying g-force which averages 1 g in one constant direction whereas the spacecraft should produce a uniform acceleration acting purely radially.

Agreed. A Ferris wheel doesn't have /as much/ of tight mass budget, but it does have one. And I was reflecting on your point that it would be a tension structure; just like a bicycle or some car wheels.

My fundamental point was that rotating tension structures are well studied and widely used. And since the spaceship is going to need gyros anyway, why not use some of them to provide "artificial gravity" to the passengers?

[chalsall]

So, an internet meme has manifested about the possibility that a rifle took out SpaceX's rocket carrying a satellite owned by an Israeli company while it was fuelling on the pad.

I have no idea how this is going to play out, but I suspect SpaceX are going to have a *whole* lot more high-speed and high resolution cameras and microphones recording at all times.

They might want to talk with NewTek. Their NDI solution domain is pretty cool.

[Dubslow]

I've heard rumors that they didn't have much in the way of audio recordings, though they certainly will moving forward.

It certainly didn't help that they requested access to the roof of a ULA building on the basis of some white blobs and shadows from far off video. (ULA eventually allowed Air Force investigators to investigate; they found nothing.) Not exactly the best PR to let out.

[chalsall]

Originally Posted by Dubslow

I've heard rumors that they didn't have much in the way of audio recordings, though they certainly will moving forward.

Indeed. Multiple widely distributed microphones each tied with a GPS receiver for extremely accurate time stamping could have been very useful for triangulation in this investigation.

Such GPS time coordination is widely used in the communications, electrical power distribution and financial trading industries, to give only a few examples.

SpaceX rarely makes the same mistake twice.

[Dubslow]

Originally Posted by chalsall

SpaceX rarely makes the same mistake twice.

http://thecodelesscode.com/case/100