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ISS Could Be Fitted With Lasers To Shoot Down Space Junk
An anonymous reader writes Japan's Riken research institute has suggested a new idea for dealing with space junk. They say a fiber optic laser mounted onto the International Space Station could blast debris out of the sky. From the article: "To combat the increasingly dense layer of dead satellites and miscellaneous space debris that are enshrouding our planet, no idea — nets, lassos, even ballistic gas clouds — seems too far-fetched to avoid. Now, an international team of researchers led by Japan's Riken research institute has put forward what may be the most ambitious plan to date. They propose blasting an estimated 3,000 tons of space junk out of orbit with a fiber optic laser mounted on the International Space Station."
Here is the problem. Blowing up or melting items does not work.
But if you heat up one side of an object, that side out-gasses or vaporizes and alters the orbit. Pick the side intelligently and you can slowly nudge stuff into a decaying orbit.
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
there is a better article here: http://www.csmonitor.com/Scien...
you can read the full paper (for free) here: http://www.researchgate.net/pr...
Anons need not reply. Questions end with a question mark.
if you break space junk up it continues on the same orbit.
The force of gravity is proportional to mass, so the acceleration doesn't change if you break an object into parts. However, other effects are not proportional to mass, in particular atmospheric drag and radiative pressure. In low Earth orbit, there is still enough gas around to drag small bodies and dust down over the timescale of months or years.
And radiative momentum transfer can't exceed the momentum of the photons hitting it which won't be a lot or you'd also be pushing on the space station too.
Radiative pressure is all about the ratio of surface area to total mass. Large objects like the space station are pushed on by radiative pressure, but they have relatively small surface area for their mass compared to say dust. Near earth, the pressure from sun light is about 9*10^-6 Pa. If this were applied to a 1 m^2 surface area object that had a mass of only 1 kg (e.g. a solar panel with nothing else attached), its speed would only change by ~1 cm/s after half an hour. For dust a couple microns across and made of metal, that would ~1 m/s delta-v instead. This adds up after many orbits.