3 ms·

Just how dangerous is it to travel at 20% the speed of light?

14 points by redman25 10y ago

posterboy 10y ago
> The main problem with running into an atom isn't the physical collision but rather the energy deposited in the spacecraft by the impact Where is the difference? I don't see none except for level of detail.
- noselasd 10y ago
  They mean the physical damage isn't the big issue, but added heat from the collision is - You don't want a spacecraft to accumulate heat - it's hard to get rid of.
scrumper 10y ago
Charlie Stross wrote recently about the threat of beta radiation to these small probes[1]. This isn't discussed at all in this article or the associated paper[2] which focuses on purely mechanical collision effects. Anyone know if this is a separate consideration for another research group? [1] http://www.antipope.org/charlie/blog-static/2016/08/san-trombone-exoplanet-reality.html http://www.antipope.org/charlie/blog-static/2016/08/san-trom... [2] http://arxiv.org/pdf/1608.05284v1.pdf http://arxiv.org/pdf/1608.05284v1.pdf
- T-A 10y ago
  Alpha, not beta (beta radiation is just electrons): > Roughly 1% of the ISM consists of helium atoms, and we have a technical term for an ionized helium nucleus travelling at roughly 2% of the speed of light—6000km/sec—we call it an alpha particle. The article pretty much debunks [1] by concluding that heavier atoms do most damage, but are still manageable.
  - scrumper 10y ago
    Thanks for the correction! Bad memory on my part. So the article refutes [1] because the relatively easy to manage mechanical effects of those alpha particles on the spacecraft exterior mean that it actually functions as an effective, long-term shield against alpha particles?
Koshkin 10y ago
> how dangerous I would think it's just as dangerous as having something traveling at 20% the speed of light relative to you.
TheMagician0 10y ago
Another aspect of the project's challenge is funding. While technically plausible in principle to develop such system, the total funding needed is on the order of $5-10 Billion. There is a relevant discussion about this on [Metaculus](http://www.metaculus.com/questions/208/to-the-stars-1-will-the-private-investment-in-laser-sail-extra-solar-travel-be-matched-by-a-comparable-amount-within-5-years/ http://www.metaculus.com/questions/208/to-the-stars-1-will-t...), for those who are interested.
- TheMagician0 10y ago
  There is actually a "Beam Propulsion Series" on Metaculus(http://www.metaculus.com/questions/#/search/series--beam-propulsion/ http://www.metaculus.com/questions/#/search/series--beam-pro...) addressing relevant questions about the Starshot Project.

14 points by redman25 10y ago

> The main problem with running into an atom isn't the physical collision but rather the energy deposited in the spacecraft by the impact Where is the difference? I don't see none except for level of detail.

noselasd 10y ago
They mean the physical damage isn't the big issue, but added heat from the collision is - You don't want a spacecraft to accumulate heat - it's hard to get rid of.

scrumper 10y ago

Charlie Stross wrote recently about the threat of beta radiation to these small probes[1]. This isn't discussed at all in this article or the associated paper[2] which focuses on purely mechanical collision effects. Anyone know if this is a separate consideration for another research group? [1] http://www.antipope.org/charlie/blog-static/2016/08/san-trombone-exoplanet-reality.html http://www.antipope.org/charlie/blog-static/2016/08/san-trom... [2] http://arxiv.org/pdf/1608.05284v1.pdf http://arxiv.org/pdf/1608.05284v1.pdf

T-A 10y ago
Alpha, not beta (beta radiation is just electrons): > Roughly 1% of the ISM consists of helium atoms, and we have a technical term for an ionized helium nucleus travelling at roughly 2% of the speed of light—6000km/sec—we call it an alpha particle. The article pretty much debunks [1] by concluding that heavier atoms do most damage, but are still manageable.
- scrumper 10y ago
  Thanks for the correction! Bad memory on my part. So the article refutes [1] because the relatively easy to manage mechanical effects of those alpha particles on the spacecraft exterior mean that it actually functions as an effective, long-term shield against alpha particles?

Koshkin 10y ago

> how dangerous I would think it's just as dangerous as having something traveling at 20% the speed of light relative to you.

TheMagician0 10y ago

Another aspect of the project's challenge is funding. While technically plausible in principle to develop such system, the total funding needed is on the order of $5-10 Billion. There is a relevant discussion about this on [Metaculus](http://www.metaculus.com/questions/208/to-the-stars-1-will-the-private-investment-in-laser-sail-extra-solar-travel-be-matched-by-a-comparable-amount-within-5-years/ http://www.metaculus.com/questions/208/to-the-stars-1-will-t...), for those who are interested.

TheMagician0 10y ago
There is actually a "Beam Propulsion Series" on Metaculus(http://www.metaculus.com/questions/#/search/series--beam-propulsion/ http://www.metaculus.com/questions/#/search/series--beam-pro...) addressing relevant questions about the Starshot Project.