NASA Revives Plan to Put Nuclear Reactors on Mars • Hacker News Board

Re: NASA Revives Plan to Put Nuclear Reactors on Mars

#91

Post by wbl » Wed, Jul 05, 2017, 4:00 PM UTC

mathw wrote: post #86

Symmetry wrote: post #38

Earlier quoted context omitted.

Before a rector is turned on the inside of it isn't particularly radioactive. In order to last from the creation of the solar system to the present day uranium had to decay very slowly when not in a critical mass, specifically U235 has a half life of 700 million years. So it's really the radiation of uranium that you have to worry about if you find yourself in a room with a hunk of it but the toxicity. Still, people…

Sure it's not in critical mass or particularly radioactive, but Plutonium is toxic...

So is hydrazine and dinitrogen tetroxide is also all kinds of fun. Heavy metal toxicity is manageable.

Re: NASA Revives Plan to Put Nuclear Reactors on Mars

#92

Post by thehardsphere » Wed, Jul 05, 2017, 4:00 PM UTC

jerrylives wrote: post #83

thehardsphere wrote: post #81

Earlier quoted context omitted.

And a valuable natural resource to make the whole colonization thing worth it.

Well, heh, when you look at the events that unfold afterwards, "worth it" is debatable.

True. I didn't read that series far after the first book, so I will not presume to debate you on that. :)

Re: NASA Revives Plan to Put Nuclear Reactors on Mars

#93

Post by wbl » Wed, Jul 05, 2017, 4:03 PM UTC

baybal2 wrote: post #40

Sharlin wrote: post #33

Earlier quoted context omitted.

Sure they can. That's the whole point! It turns out nuclear reactors scale down surprisingly well.

Relatively speaking. Burnup ratios go up with size. Unless you do blended fuel-moderator designs which as I know, were never built

Triga counts as one of those iiuc.

Re: NASA Revives Plan to Put Nuclear Reactors on Mars

#94

Post by freehunter » Wed, Jul 05, 2017, 4:04 PM UTC

MichaelMoser123 wrote: post #90

sp0ck wrote: post #2

It's about time. Engineering decisions shouldn't be made based of irrational fears of general population. If nuclear power plant is best option for space mission we should use it.

Irrational fears? What are the chances of the rocket launcher blowing up with the reactor? How would we compute the fallout range as a function of altitude of the blast?

Do you know how much nuclear material we've launched into space? Hint: a lot.

Re: NASA Revives Plan to Put Nuclear Reactors on Mars

#95

Post by SEJeff » Wed, Jul 05, 2017, 4:05 PM UTC

Cumulonimbus wrote: post #85

Before we can consider seeding terrestrial stations on Mars, we should consider seeding a communications net around Mars. Once we have a half dozen satellites circling Mars, we can start stable comms from the surface to orbit to Earth. It may take 10-20 minutes (for a signal to be received), but the communication is the essential piece here. I'd also consider putting satellites in Earth and Mars lagrange L3, L4, and…

Pretty sure this reason in specific is why SpaceX accepted the 1 billion USD investment from Google Ventures for their satellite internet constellation project in Seattle. If Musk's endgame plan is a serious Mars colony, there needs to be both location and communication over the entire planet (of mars). There also needs to be bidirectional communication with Earth. An orbiting constellation makes sense to do this.

https://www.nytimes.com/2015/01/21/technology/google-makes-1...

Re: NASA Revives Plan to Put Nuclear Reactors on Mars

#96

Post by hfourm » Wed, Jul 05, 2017, 4:07 PM UTC

simias wrote: post #63

tehwalrus wrote: post #54

Earlier quoted context omitted.

I would say, given the state of politics and the general attitude to the climate and natural resources, our first priority should be colonising another planet. Putting some scientists on Mars for a few years is step 1 in that very important insurance scheme!

I don't know if I agree. Creating a self-sustainable colony on Mars will take a very long time and even if we manage to do it can we really afford to "lose" the earth? Mars is an inhospitable hell for humans and practical terraforming technology is still in the realm of science fiction. Maybe if we manage to destroy earth completely out of selfishness and hate we don't really deserve to spread the virus throughout th…

The universe is full of planet destroying events, why single ourselves out and say we are a virus?

Sure, we need to be better stewards of our environment, but I fail to see how our species is inherently worse then a meteor destroying a planet.

Re: NASA Revives Plan to Put Nuclear Reactors on Mars

#97

Post by DennisP » Wed, Jul 05, 2017, 4:14 PM UTC

mathw wrote: post #86

Symmetry wrote: post #38

Earlier quoted context omitted.

Before a rector is turned on the inside of it isn't particularly radioactive. In order to last from the creation of the solar system to the present day uranium had to decay very slowly when not in a critical mass, specifically U235 has a half life of 700 million years. So it's really the radiation of uranium that you have to worry about if you find yourself in a room with a hunk of it but the toxicity. Still, people…

Sure it's not in critical mass or particularly radioactive, but Plutonium is toxic...

NASA's Kilopower design uses enriched uranium fuel, and with such a small reactor it won't be much uranium.

Re: NASA Revives Plan to Put Nuclear Reactors on Mars

#98

Post by DennisP » Wed, Jul 05, 2017, 4:16 PM UTC

MichaelMoser123 wrote: post #90

sp0ck wrote: post #2

It's about time. Engineering decisions shouldn't be made based of irrational fears of general population. If nuclear power plant is best option for space mission we should use it.

Irrational fears? What are the chances of the rocket launcher blowing up with the reactor? How would we compute the fallout range as a function of altitude of the blast?

Irrational because a uranium fission reactor contains very little radioactivity before you start running it.

Re: NASA Revives Plan to Put Nuclear Reactors on Mars

#99

Post by vkou » Wed, Jul 05, 2017, 4:24 PM UTC

menzoic wrote: post #78

tehwalrus wrote: post #54

Earlier quoted context omitted.

I would say, given the state of politics and the general attitude to the climate and natural resources, our first priority should be colonising another planet. Putting some scientists on Mars for a few years is step 1 in that very important insurance scheme!

If we could terraform a planet as barren as Mars, wouldn't fixing earth be significantly easier?

Yes, it would be.

Re: NASA Revives Plan to Put Nuclear Reactors on Mars

#100

Post by kobeya » Wed, Jul 05, 2017, 4:37 PM UTC

Symmetry wrote: post #38

kobeya wrote: post #21

Earlier quoted context omitted.

The concern was never about a nuclear reactor having a failure mode on Mars. It was about the rocket carrying the nuke having a failure mode and spewing radioactive fuel over central Florida.

Before a rector is turned on the inside of it isn't particularly radioactive. In order to last from the creation of the solar system to the present day uranium had to decay very slowly when not in a critical mass, specifically U235 has a half life of 700 million years. So it's really the radiation of uranium that you have to worry about if you find yourself in a room with a hunk of it but the toxicity. Still, people…

Not saying it was unfounded fear (I'm very pro space nuclear power), just pointing out what the actual contention is. People have an adverse reaction to anything with the word "nuclear" on it, even more so when it is put on top of a half million pounds of propellant and lit with a non-negligible failure rate.

The reality though is that failure of the rocket doesn't mean the reactor or fuel is vaporized and thrown to the wind. It's possible to construct the payload fairing to survive sudden, rapid disassembly and crash land intact off the Florida coast for recovery.