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The US government is taking a step toward space-based nuclear propulsion

arstechnica.com

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Re: The US government is taking a step toward space-based nuclear propulsion

#41

Post by sircastor »

asu_thomas wrote: post #37
ben_w wrote: post #16

Earlier quoted context omitted.

Depending on the design, failure during launch can be anywhere from "meh" to "basically high-altitude Chernobyl" — random actinide decay products (and plutonium fuel) are bad, unreacted uranium fuel is mostly a heavy metal hazard rather than a radiation hazard. (Could be worse, but the Orion drive is currently illegal by treaty and hopefully nobody is dumb enough to use that in Earth's ionosphere anyway).

What does "meh" mean? Is that english?

"Meh" is a casual response that means "this does not matter much". I don't know that it's proper English by any means, but it is certainly a common colloquialism. A cursory search suggests that it's imported from yiddish.

[1] https://en.wikipedia.org/wiki/Meh

Re: The US government is taking a step toward space-based nuclear propulsion

#42

Post by jamesaurichs »

0xDEF wrote: post #36
jamesaurichs wrote: post #21

Earlier quoted context omitted.

US seems to be in a hardware/science renaissance, now that there is a new Cold War enemy, and manufacturing and research are being brought back to US.

From across the pond it feels like American millennials and Gen-Z have already declared their country to be a failed state. How much can a nation progress if its youth is pessimistic about everything? It doesn't matter whether the pessimism is based on actual problems (healthcare, housing prices etc.) or learned through terminally online reddit/twitter consumption.

If we're talking about the contents on TikTok, there's probably a very good reason why the ultimate owner of TikTok, the Chinese government, wants that kind of content to be the majority sentiment on the platform.

Re: The US government is taking a step toward space-based nuclear propulsion

#43

Post by nukeman »

pdntspa wrote: post #31
somenameforme wrote: post #7

Earlier quoted context omitted.

I think the obvious concern would be failure scenarios. There will always be failures in space technology. As space expands exponentially (as it is likely to do so in the future), failures will become relatively regular. So the obvious question would be what would happen if a nuclear rocket, with reaction in process, crashed to Earth. Or even if it broke up in the atmosphere.

Isn't there a way you can shoot the whole apparatus into the sky while it is inert and then activate in space?

Yes, you can have the reactor offline, with control rods inserted for launch. Then when you reach the requisite altitude, withdraw the control rods and start up the reactor. In the event of a launch accident and potential destruction of the reactor, the enriched uranium fuel would be a chemical hazard (uranium is a heavy metal like lead), but only a mild radiation hazard (since there are no high-gamma fission products, and the uranium has undergone heavy purification prior to fuel fabrication).

Re: The US government is taking a step toward space-based nuclear propulsion

#44

Post by SonicScrub »

0xDEF wrote: post #36
jamesaurichs wrote: post #21

Earlier quoted context omitted.

US seems to be in a hardware/science renaissance, now that there is a new Cold War enemy, and manufacturing and research are being brought back to US.

From across the pond it feels like American millennials and Gen-Z have already declared their country to be a failed state. How much can a nation progress if its youth is pessimistic about everything? It doesn't matter whether the pessimism is based on actual problems (healthcare, housing prices etc.) or learned through terminally online reddit/twitter consumption.

As the folk-wisdom goes "Twitter isn't real life". The ones who have that opinion are the terminally online.

Re: The US government is taking a step toward space-based nuclear propulsion

#45

Post by ethbr1 »

somenameforme wrote: post #7
mdorazio wrote: post #2

Finally! This is one of the few fission uses I'm genuinely excited about. Nuclear-thermal just makes so much sense for in-space propulsion of large vessels compared to chemical rockets.

I think the obvious concern would be failure scenarios. There will always be failures in space technology. As space expands exponentially (as it is likely to do so in the future), failures will become relatively regular. So the obvious question would be what would happen if a nuclear rocket, with reaction in process, crashed to Earth. Or even if it broke up in the atmosphere.

The idea is also to use this for solar system propulsion, rather than Earth to orbit.

Consequently, reactor payloads would be carried on a very small fraction of launches, then used in space for an extended amount of time.

Re: The US government is taking a step toward space-based nuclear propulsion

#47

Post by avar »

somenameforme wrote: post #7
mdorazio wrote: post #2

Finally! This is one of the few fission uses I'm genuinely excited about. Nuclear-thermal just makes so much sense for in-space propulsion of large vessels compared to chemical rockets.

I think the obvious concern would be failure scenarios. There will always be failures in space technology. As space expands exponentially (as it is likely to do so in the future), failures will become relatively regular. So the obvious question would be what would happen if a nuclear rocket, with reaction in process, crashed to Earth. Or even if it broke up in the atmosphere.

    > Or even if it broke up
    > in the atmosphere.
The atmosphere we've already detonated over 500 nuclear weapons in?

Re: The US government is taking a step toward space-based nuclear propulsion

#48

Post by randallsquared »

bigfudge wrote: post #8
honeybadger1 wrote: post #3

The more adoption of nuclear technologies with practical application, the better.

That’s an odd thing to say. Almost as if you’re in favour of nuclear for nuclear’s sake? Plenty of people have reasonable reservations about use of nuclear, not least the social /political ones of where to store waste that are still mostly unsolved. Blasting fission cores into space on rockets with fairly high failure rates in absolute terms seems like a fairly fine balance to strike?

You don't need to store nuclear waste, since you can burn it up in some fuel cycles. Essentially all the problems of nuclear power on the ground are political issues -- entrenched interests, weapons proliferation, and so forth -- not technological ones like safer reactors and nuclear waste.

Re: The US government is taking a step toward space-based nuclear propulsion

#49

Post by asu_thomas »

sircastor wrote: post #41
asu_thomas wrote: post #37

Earlier quoted context omitted.

What does "meh" mean? Is that english?

"Meh" is a casual response that means "this does not matter much". I don't know that it's proper English by any means, but it is certainly a common colloquialism. A cursory search suggests that it's imported from yiddish. [1] https://en.wikipedia.org/wiki/Meh

I have never seen it used outside of Hacker News.

Re: The US government is taking a step toward space-based nuclear propulsion

#50

Post by 7952 »

db48x wrote: post #39
aio2 wrote: post #18

Earlier quoted context omitted.

I remember learning that when they started testing atomic bombs (I think?) the nuclear debris in the air spread basically throughout the whole united states and the government tried to keep quiet about it. Something similar will probably happen here if they mess up with the launch. Btw, the video I saw was on Veritasium.

The thing to remember about that is that we can measure tiny amounts of radiation very cheaply, and tiny amounts are harmless. In fact we are bathed in a constant, but tiny, background level of radiation all the time. Thousands of nuclear weapons were tested all across the world, in the United States, in the Soviet Union, on Pacific Islands, etc, etc. The radiation from that certainly caused a small uptick in the bac…

Background radiation may be unlikely to give an individual cancer whilst still causing cancer across a population. It just isn't possible to attribute the cause. Surely the same is true of fallout from testing and estimates would back that up. It may not be something we worry about as individuals. But it is something that nasa should worry about.
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