Blasting Space Debris With Lasers

[Buffy]

Okay this is kind of interesting:

 

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.

Source: Scientists want to blast space debris with frickin' lasers, Andrew Tarantola, engadget.com 4/17/2015

 

I've been watching this issue with some trepidation for quite a while because the problem of space debris has the potential to even completely cut us off from space if we let it get out of hand.

 

Do you think this will work? Do you have a better idea?

 

 

Every solution to every problem is simple. It's the distance between the two where the mystery lies, :phones:

Buffy

 

[Titan]

My question is should we for any reason be concerned at all about where this stuff will go?

 

Also, would it be a better idea to somehow destroy them into smaller pieces or "vaporize" them on their way out of orbit or just shoot them away in their current size. 

 

I guess im over-thinking this since throwing of a satellite into the vastness of space would be like asking if 

we should worry about flicking a spec of dust into a lake.

[CraigD]

I've been watching this issue with some trepidation for quite a while because the problem of space debris has the potential to even completely cut us off from space if we let it get out of hand.

The nightmare scenario for this is not a slow accumulation of Earth-orbiting space debris, but the Kessler syndrome, a runaway cascade of collisions producing more debris that collides with more large bodies to make more debris, and so on.

 

The 2003-2004 anime series Planetes, that followed the adventures of cure young astronauts in the business of removing space debris, was praised for its scientific and technical accuracy. If you can tolerate slow-paced hard SF anime, you’d likely enjoy Planetes.

 

Science Fiction like Planetes may be overly optimistic. If a Kessler syndrome occurs, it might happen suddenly, triggered by the destruction of a single large spacecraft, and suddenly making near-Earth space travel so difficult that debris-removal schemes like its are rendered impossible.

 

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.

Source: Scientists want to blast space debris with frickin' lasers, Andrew Tarantola, engadget.com 4/17/2015

 

I couldn’t find a free pre/reprint of Ebisuzaki et al’s paper, but this recent news release confirmed my guess about the basics of their scheme

The new method combining these two instruments will be capable of tracking down and deorbiting the most dangerous space debris, around the size of one centimeter. The intense laser beam focused on the debris will produce high-velocity plasma ablation, and the reaction force will reduce its orbital velocity, leading to its reentry into the earth's atmosphere.

To put in another way, the scheme uses a powerful laser to make tiny impromptu rocket motors on small space debris, using their own vaporized material as reaction mass. Zap the debris in the right place in its orbit, and you can put it in a more elliptical orbit that enters the upper atmosphere, and let aerobraking do the rest to deorbit it.

 

My question is should we for any reason be concerned at all about where this stuff will go?

Since the stuff Ebisuzaki’s scheme targets is small, no. Like the roughly 15000000 kg of naturally occurring small material that enters the Earth’s atmosphere from space each year, these small objects should ablate during reentry into harmless dust and gas.

 

Deorbiting larger bodies, like intact spacecraft, would, I think, require different schemes, like those depicted in fiction like the Planetes.

 

Also, would it be a better idea to somehow destroy them into smaller pieces or "vaporize" them on their way out of orbit or just shoot them away in their current size.

At low-Earth altitudes like the ISS’s, it takes a much greater change in velocity, and thus for a laser propulsion scheme, much more energy and targeting, to give a body an Earth escape orbit than to make it dip into the atmosphere. For example, to transfer from a circular orbit about as high as the ISS, 400 km above ground level, to one that drops into the thicker part of the atmosphere, about 75 km AGL, takes a delta-V of about 3 m/s (compared to its orbital speed of about 7772 m/s). To give it escape takes a delta-V of about 3219 m/s.

 

This changes as altitude increases. A circular geostationary orbit, 35786 km AGL, takes a delta-V of about 1476 m/s to deorbit, 1273 to escape. There’s less concern about space debris in higher orbits, though there is a lot of it in GEO.

 

I don’t think vaporizing space debris with a laser is a very good idea. The resulting gas might be as or more dangerous than the body. It would also take much more energy, and as the pieces became smaller and smaller, it would be harder to detect and target them.