[ml/nj]

If you expel a particle mass that weighs one microgram at the speed of light (no mean feat) its momentum would be 3x10⁸ x 10^-6 or 300 gr m/sec. A single pilot alone weighs about 75,000 grams so if he got all of the momentum to balance the expulsion his speed would increase less than half a millimeter per second. What am I missing?

ML/NJ

[LibWhacker]

This article is about future unmanned spacecraft that are, literally, the size of a sewing needle, having a mass that is probably only a small fraction of gram.

[headsonpikes]

I think that should read 3x10 to the 12th power, not 8th.

[LibWhacker]

If you expel a particle mass that weighs one microgram at the speed of light (no mean feat)...

BTW, you caught me in a mistake here and I should admit it; huge particle accelerators (like the 17-mile ring of the LHC) can accelerate protons up to nearly lightspeed, but nowhere does the article claim that our little needleships will be able to do so and I shouldn't have said it. Instead, they will accelerate protons away at some relatively high speed (but in all likelihood, not anywhere close to lightspeed) for some extended period of time and the cumulative effect of that will eventually bring the speed of our needleship up to near light speed. Thanks!

[wastedyears]

I don’t know if you’re missing anything, but I’m missing everything.