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Free neutrons do decay pretty fast, but you would need them to be ejected at a pretty low energy.

At any rate, seems impractical. You would need a huge chunk of nuclear fuel for pretty negligible thrust.

Now, if you could work out how to get it to eject neutrons in one direction, you would have an awesome rocket, but I see no way of forcing this.

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Even Musk can only colonize Mars if he finds people willing to buy tickets to colonize Mars. Which is already a stretch. Only millionaires will be able to afford a ticket, and millionaires don't typically become candidates for colonization.

And that is another stretch.

And well, a lunar lander is not the same as a Mars lander.

Why do you assume Musk is not footing the bill for the colonists he chooses from amongst volunteers? Again, at the estimated costs currently posted for the Falcon Heavy, he can personally out of pocket do something like 40-50 launches. That is assuming he doesn't get more money from his other business ventures or that like minded million/billionaires don't join up with the goal of establishing a colony. Musk has pretty repeatedly stated that he views his money as a means to an end, and that not spending it to achieve his goals makes it useless.

It really isn't much of a stretch. You bring up that a lunar lander is not the same as a Mars lander. This is true, but given that from what I've heard about Musks intended Mars lander, it should frankly be easier to land on the moon using the same lander. They intend for the on board rockets to do almost all of the heavy lifting when it comes to slowing down when it hits Mars atmo. Considering the speed the system will have upon engaging in a landing on Mars will be MUCH higher than the speed the same system would have for a Moon landing it seems likely that really the only major change the system would need is a different software profile for a lunar landing. They even lose some carried mass (or at least devote it to more useful means) on the lunar setup, because it won't be carrying the parachutes that the Mars variant is intended to have (which are to only be used in the event of a descent engine failure).

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i think the previous question was answered (sorry if its not!) so im going to ask a question ive got going around in my head.

asumming we got a working albecuire drive that bends space and all, its compressing the space in front/back of it, but then either we're creating more space, or space itself is being stretched from somwhere, presumably ahead of the compressed bit, so wouldnt our ship have to cross the "stretched" space too, basically negating the albecuire drives effect?

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Does rocket exhaust in space jet out?

In a vacuum, exhaust gasses expand more laterally, because there is no air pressure to keep them in a nice pointy shape. So that first picture (as well as KSP) is inaccurate. This is why upper stage nozzles are much longer than first stage ones.

MVac_Dragon_Cargo_640.jpg

Whether the plume is visible or not depends on the gas and the lighting. If light is not reflecting or shining through the particles, then it won't be very visible.

20120314-f1f9.jpg

Edited by Nibb31
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Kerolox stages tend to have much more visible plumes at high altitude than hydrolox ones. Soyuz in particular is infamous for creating 'jellyfish' UFO sightings whenever it has upper stage flight over a populated area.

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  • 3 weeks later...
What would longterm exposure to an RTG do to ones health? Like using it for heat?

Like in The Martian?

If weight isn't an issue, than you can easily shield the generator so that there is no noticable difference to the natural background radiation. At least on earth. The natrual radiation on mars should be more concernable than the RTG.

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Pu238 is mostly an alpha emitter, none of that will get through the RTG shell. There is a little gamma, and the decay products may be more worrying in an older RTG. I'd have to look up the isotopes that occur to be sure.

Also, he is only close to it during sirius 4, 18 sols duration. The rest of the time, it's in its hole, in the hab but presumably.as far from his work area as possible, or in the trailer during the drive to the MAV.

All Mark has to worry about is a slightly higher cancer risk in later life, and the RTG isn't a huge part of that compared to the time on Mars and on the Hermes.

Edited by andrewas
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There was a project of a militarized Soyuz known as Soyuz VI. It carried Pu-powered RTGs instead of solar panels, which saved weight, increased operational capability and reliability, and provided more power for the military equipment.

As you can see on this diagram, the RTGs were on the outside, on extended arms, and angled to minimize radiation on the crew module.

soyvi.jpg

The Soviets obviously thought that the risk of irradiating the crew justified the additional complexity that design, so I don't really think it is that benign.

Edited by Nibb31
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