NASA just successfully launched  a solar-sail pico-satellite from an experimental micro-satellite. That's the first time NASA has launched one satellite from another, and it also hints at a positive future for space debris clean-up.
The Fast, Affordable Science and Technology (FASTSAT) satellite launched on November 19 with a clutch of scientific experiments aboard. One of these was the NanoSail-D spacecraft--a tiny cube about the size of a loaf of bread. This was lodged in something called a P-Pod (Poly Pico-Satellite Orbital Deployer) which is more usually mounted on the final stage of a launch rocket. By installing NanoSail-D in another satellite instead, NASA has done something new.
After sailing free, NanoSail-D began a three-day countdown. When it reaches zero, on Thursday, it will deploy a gossamer-thin solar sail that stretches out to 100 square feet. This is designed to test solar propulsion, similar to the Japanese  effort earlier this year. It'll use that weak push from the sun's light to bring about an early demise, burning up in the atmosphere long before it would otherwise have done.
That may sound morbid, but NanoSail-D is actually proving it can be part of a major clean-up operation. By removing itself from the pool of space debris , it is demonstrating a tech that some have suggested  should be included on all satellites so that they can be swiftly brought back to Earth--and not spend decades floating uselessly in orbit, potentially smashing into other satellites.
The launch of FASTSAT was a joint effort between NASA and the Department of Defense Space Test Program. That means the Pentagon will be watching the results with interest. A satellite that can unleash a smaller one could have all sorts of defensive, offensive and surveillance uses.
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