4 ms·

Personally I am excited to see this, but I wonder if the optics will kill it? People get upset enough about reactors that don’t move and live inside huge struc

Personally I am excited to see this, but I wonder if the optics will kill it? People get upset enough about reactors that don’t move and live inside huge structures of reinforced concrete. Can we convince this segment of the population that launching a small device (with necessarily less shielding) is safe? Even the most reliable launch vehicles (Falcon 9, Atlas V) are probably not more than ~99% likely to succeed. Can the payload be made safe in the event that it fails to make orbit?

nradov 4y ago
NASA has already used multiple radioisotope thermoelectric generators in space probes without many people getting upset. An RTG recently went to Mars. So this new engine doesn't seem like much of a stretch from a political and public relations standpoint. https://inl.gov/mars-2020/ https://inl.gov/mars-2020/
- idlewords 4y ago
  This reply deserves more upvotes; NASA routinely launches big hunks of plutonium, and a nuclear thermal reactor at launch (before it's been turned on) is far less radioactive.
  - ETH_start 4y ago
    The key point that needs to be related to the public is that the reactor is turned off while in Earth's atmosphere, and a reactor poses very little danger when it's turned off.
nordsieck 4y ago
> Even the most reliable launch vehicles (Falcon 9, Atlas V) are probably not more than ~99% likely to succeed. Falcon 9 is it at this point. All of the remaining stock of Atlas Vs and Ariane 5s have been sold. Of course Vulcan and Ariane 6 will come online soon; buy they don't have anywhere close to the safety record that Falcon 9 does. I'm not a statistician, but I wouldn't be surprised if Falcon 9 had better than 99% chance of success. It has more than a 150 long success streak. And no rockets in the current configuration have ever failed. > Can we convince this segment of the population that launching a small device (with necessarily less shielding) is safe? This isn't obviously no to me. NASA has launched a bunch of RTGs in the past. Those have the same sort of safety concerns in the event of a failed launch. Probably less material, though.
- lisper 4y ago
  Those were launched in a different era with a very different political climate.
  - Ankaios 4y ago
    The RTGs weren't launched in a different era. The most recent RTG went up less than three years ago. (On Perseverance.)
    - lisper 4y ago
      I stand corrected. I thought all the rovers were solar powered. My mistake.
      - Ankaios 4y ago
        Most of them have been, but Perseverance and Curiosity were exceptions. I believe the original motivation was for Curiosity to be able to land at higher latitudes.
        lisper 4y ago
        Yeah, I actually knew that. Just had a brain wedgie/senior moment. (Seems to be happening more and more as time goes by. Funny how that happens.)
- xyzzyz 4y ago
  If p is the probability of success, then probability of 1500 successes in 150 independent trials is p^150. With p = 0.99, the chance you see 150 successes in a row is 0.22. If we take significance level to be the standard 0.05, then we cannot reject the hypothesis that the chance of success of Falcon 9 is less than 99%. We can, however, reject the hypothesis that it's less than 98%: if it was 98%, then in 150 trials, probability of all successes is 0.048, which is smaller than 0.05.
TobTobXX 4y ago
If the flight plan is layed out intelligently, I suppose less people would experience radiation than in the cold war days with the many above-ground detonations.
perihelions 4y ago
It doesn't matter at all: they'd only be lifting unused nuclear fuel, which isn't a hazardous material. This isn't comparable to the 238Pu radioisotope generators; it's much safer.
- epgui 4y ago
  I don't think the general public cares much for the actual safety. All they care about is how they perceive safety on the basis of their emotions.
  - CommitSyn 4y ago
    NASA understands this well and if they feel they need to (considering the current political climate, it's likely) then they will likely start a years-long PR campaign soon to get ahead of it. I'm sure someone's crunching the numbers on this and other articles shared across social media.
  - Grimburger 4y ago
    Representative democracies need to stop caring about what the most outrageous media-baiting people in a society can say about safe practices and just do it.
    - epgui 4y ago
      That's called technocracy, and I'm all for it.
    - vermilingua 4y ago
      They can’t, they’re representative democracies, caring about the vocal minority (or being perceived to) is the key function needed for incumbents to stay alive.
lowbloodsugar 4y ago
SpaceX is eating Big Rocket’s lunch, so the politicians need a new way to funnel billions of our tax dollars to them. This seems ideal!
- deleted 4y ago
  [deleted]
godelski 4y ago
> I wonder if the optics will kill it? There's been a clear shift in nuclear power through the last decade. I've seen people that previously protested for the closure of plants turn their tune. Really all this is because we've learned that the fact that it produces zero carbon during operation and has a lot of other environmental advantages (like a low footprint), that many are considering the benefits vs the costs. Previously people only cared about the costs but now we see the picture is more complicated. So not only do I have hope for this project, but I also have hope for nuclear power in general. (remember, the argument isn't "nuclear vs renewables" it is "nuclear + renewables vs fossil fuels" vs "renewables vs fossil fuels". Anyone making another argument is not coming from the scientific community). Also, an interesting aspect of nuclear engines is that astronauts will likely receive lower dosages of radiation as opposed to using traditional engine designs. This is because even with increased radiation from the engine (which can be shielded, but that's more weight) the reduced travel time means that the astronauts are exposed to lower amounts of solar (directional) and cosmic (omnidirectional) radiation. The NASA article mentions reduced weight of supplies but shielding also matters and is quite heavy.

nradov 4y ago

NASA has already used multiple radioisotope thermoelectric generators in space probes without many people getting upset. An RTG recently went to Mars. So this new engine doesn't seem like much of a stretch from a political and public relations standpoint. https://inl.gov/mars-2020/ https://inl.gov/mars-2020/

idlewords 4y ago
This reply deserves more upvotes; NASA routinely launches big hunks of plutonium, and a nuclear thermal reactor at launch (before it's been turned on) is far less radioactive.
- ETH_start 4y ago
  The key point that needs to be related to the public is that the reactor is turned off while in Earth's atmosphere, and a reactor poses very little danger when it's turned off.

nordsieck 4y ago

> Even the most reliable launch vehicles (Falcon 9, Atlas V) are probably not more than ~99% likely to succeed. Falcon 9 is it at this point. All of the remaining stock of Atlas Vs and Ariane 5s have been sold. Of course Vulcan and Ariane 6 will come online soon; buy they don't have anywhere close to the safety record that Falcon 9 does. I'm not a statistician, but I wouldn't be surprised if Falcon 9 had better than 99% chance of success. It has more than a 150 long success streak. And no rockets in the current configuration have ever failed. > Can we convince this segment of the population that launching a small device (with necessarily less shielding) is safe? This isn't obviously no to me. NASA has launched a bunch of RTGs in the past. Those have the same sort of safety concerns in the event of a failed launch. Probably less material, though.

lisper 4y ago
Those were launched in a different era with a very different political climate.
- Ankaios 4y ago
  The RTGs weren't launched in a different era. The most recent RTG went up less than three years ago. (On Perseverance.)
  - lisper 4y ago
    I stand corrected. I thought all the rovers were solar powered. My mistake.
    - Ankaios 4y ago
      Most of them have been, but Perseverance and Curiosity were exceptions. I believe the original motivation was for Curiosity to be able to land at higher latitudes.
      - lisper 4y ago
        Yeah, I actually knew that. Just had a brain wedgie/senior moment. (Seems to be happening more and more as time goes by. Funny how that happens.)
xyzzyz 4y ago
If p is the probability of success, then probability of 1500 successes in 150 independent trials is p^150. With p = 0.99, the chance you see 150 successes in a row is 0.22. If we take significance level to be the standard 0.05, then we cannot reject the hypothesis that the chance of success of Falcon 9 is less than 99%. We can, however, reject the hypothesis that it's less than 98%: if it was 98%, then in 150 trials, probability of all successes is 0.048, which is smaller than 0.05.

TobTobXX 4y ago

If the flight plan is layed out intelligently, I suppose less people would experience radiation than in the cold war days with the many above-ground detonations.

perihelions 4y ago

It doesn't matter at all: they'd only be lifting unused nuclear fuel, which isn't a hazardous material. This isn't comparable to the 238Pu radioisotope generators; it's much safer.

epgui 4y ago
I don't think the general public cares much for the actual safety. All they care about is how they perceive safety on the basis of their emotions.
- CommitSyn 4y ago
  NASA understands this well and if they feel they need to (considering the current political climate, it's likely) then they will likely start a years-long PR campaign soon to get ahead of it. I'm sure someone's crunching the numbers on this and other articles shared across social media.
- Grimburger 4y ago
  Representative democracies need to stop caring about what the most outrageous media-baiting people in a society can say about safe practices and just do it.
  - epgui 4y ago
    That's called technocracy, and I'm all for it.
  - vermilingua 4y ago
    They can’t, they’re representative democracies, caring about the vocal minority (or being perceived to) is the key function needed for incumbents to stay alive.

lowbloodsugar 4y ago

SpaceX is eating Big Rocket’s lunch, so the politicians need a new way to funnel billions of our tax dollars to them. This seems ideal!

deleted 4y ago
[deleted]

godelski 4y ago

> I wonder if the optics will kill it? There's been a clear shift in nuclear power through the last decade. I've seen people that previously protested for the closure of plants turn their tune. Really all this is because we've learned that the fact that it produces zero carbon during operation and has a lot of other environmental advantages (like a low footprint), that many are considering the benefits vs the costs. Previously people only cared about the costs but now we see the picture is more complicated. So not only do I have hope for this project, but I also have hope for nuclear power in general. (remember, the argument isn't "nuclear vs renewables" it is "nuclear + renewables vs fossil fuels" vs "renewables vs fossil fuels". Anyone making another argument is not coming from the scientific community). Also, an interesting aspect of nuclear engines is that astronauts will likely receive lower dosages of radiation as opposed to using traditional engine designs. This is because even with increased radiation from the engine (which can be shielded, but that's more weight) the reduced travel time means that the astronauts are exposed to lower amounts of solar (directional) and cosmic (omnidirectional) radiation. The NASA article mentions reduced weight of supplies but shielding also matters and is quite heavy.