How likely is it for a spaceship going at very high speeds to impact a small piece of asteroid or particle that's just moving around in space?Isn't this a major hazard that for some reason people are overlooking?
>>17025728Space is basically empty, the chance is non zero but low.
>>17025728>How likely is it for a spaceship going at very high speeds to impact a small piece of asteroid or particle that's just moving around in space?[math]p = \int_{m=m_{min}}^{m_{max}} \int_{r=r_i}^{r_f}\;n(m,r)\; \sigma \;ds(r)[/math]Where σ is the cross section of the spacecraft with incoming particles, n is the number density of particles of various mass as one moves away from the Sun, and s is the spacecraft's path.If you take n to be approximately constant for some given particle size, and assume the probability of impact goes to 1 at some mean free path |s| = λ, then[math]\lambda = \frac{1}{n \sigma}[/math]Density of μm-sized interplanetary dust particles is about 1e-6 particles per cubic meter. So for a spacecraft with a circular cross section with a 2.5 m radius (ex. Orion capsule), λ ~ 5.1e3 m. Which means a spacecraft traveling at Earth escape velocity (11.2 km/s) would be hitting about 2 micron-sized dust particles every second. By comparison, density of cm-sized particles is about 1e-17 per cubic meter, or λ ~ 5.1e15 m. So your spacecraft might hit one once every 14.4K years.Many spacecraft have some rudimentary protection from smaller impacts, like the Whipple shields on the ISS, which do take some hits, mostly from sub-millimeter particles, but collisions with nano and microparticles happen regularly enough that they're considered normal wear and tear (a panel near one of the ISS airlocks was replaced and was observed to have evidence of about five dozen impact marks from impactors in the micron to hundred micron range after about eight years of service). Collisions with particles large enough to actually cause catastrophic damage are so unlikely to happen on accident that they're basically not considered. When NASA sends missions through the asteroid belt, for example, they don't even bother planning out trajectories of known bodies because the odds of an accidental intercept are effectively zero.
>>17025728>going at very high speeds to impact a small piece of asteroid or particlestars are spraying out particles all the time, so at very high speeds is it not like you are the target in a particel accelrator?
>>17025772>assume the probability of impact goes to 1 at some mean free path |s| = λSo fresh
>>17026015You have a better approach?
The problem is actually thermodynamic and it makes going much faster than the parker space probe over interstellar distances impossible due to the relativistic heating effect of the interstellar dust and gas vs a blackbody radiator. This sets an upper speed limit far below 1% of c because any ship would melt.
>>17026408At higher fractions of c (10-20%) interstellar atoms and dust act like a particle accelerator, turning impacts into bursts of plasma or X-ray radiation. To survive this, proposed designs use sacrificial forward shields (like a thin sheet of beryllium, ice, or graphite pushed far ahead of the main craft) or magnetic/laser deflection systems to vaporize and push aside dust before it hits the hull.
>>17026414Doesnt matter, the problem is thermodynamic, an ideal black body radiator vs the effect of heat on the shield Even using a magnetic shield, the ship will melt.
