Laser Orbital Debris Removal

Another week, another scheme to clean up our bourgeoning space debris problem. This one, like many before it, calls for a powerful ground-based laser to remove orbital debris from low earth orbit. Using high-powered laser pulses fired from the ground, the system would create a small plasma jet emanating from the piece of junk itself, essentially turning each piece of debris into its own laser-powered rocket that would remove itself from orbit.

 The system, detailed in a paper released on arXiv last week, would rely on technologies already available or already under development. And unlike other ground-based laser systems proposed in past decades, it would be able to tackle both large and small pieces of space junk. A 33-foot telescope should do the trick, and a powerful enough laser isn’t out of reach, the authors of the paper claim.

Essentially, the heat from the laser--which would have to be targeted very precisely to intercept these extremely small objects whipping around the sky at many thousands of miles per hour--would vaporize a small part of each piece of space junk. The heat would be such that a small plasma jet would form, basically turning that piece of the space junk into fuel for a small jet that would push the debris out of orbit. Small piece of debris would burn up as their orbits decayed. Others would need to be carefully nudged out of orbit such that they end up landing in the Pacific Ocean.

The authors argue that a ground-based laser would obviate the need to launch any space junk-clearing spacecraft into orbit, which would cost hundreds of millions of dollars. Small pieces of junk could be cleared this way for a few thousand dollars. Larger pieces might cost up to $1 million.

Of course, laser-based approaches have been rejected out of hand previously based on the idea that they might also be used to target satellites in space during periods of hostilities. This scheme is likely headed for a similar fate. But at least someone is thinking about the problem, which as you read this is growing unchecked.

 by "environment clean generations"

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Posted in: A Planet Orbiting Two Suns,debris,environment clean generations,I Wanna Make My Own Spacecraft,Laser Orbital Debris Removal,millions of dollars,pacific ocean,space

A Planet Orbiting Two Suns

A mournful French horn blows. An angsty Luke Skywalker stomps out of his aunt and uncle's sand hut and peers up at Tatooine's double sunset, his hair blowing in the breeze. It's a memorable scene from Star Wars—but now, a precedent for such a sky with two suns has been found in our universe.

Using data from the Kepler space observatory, scientists at the Harvard-Smithsonian Center for Astrophysics and SETI have discovered for the first time a planet orbiting a binary star system, passing in front of both its parent stars along its orbit.

The planet, Kepler-16b, resembles Saturn in its mass and gaseous makeup. That mostly rules out the possibility of any living beings being present to enjoy the double sunset view, although chances are good Kepler-16b has an icy, non-gaseous satellite or two, as Saturn does.

The two stars in the system are 20% and 69% as massive as our sun, respectively. The planet orbits at a distance analogous to Venus's orbit in our solar system, which typically would place it within the "habitable zone" of planets that could support life. But since the combined mass of the two stars is still less than our sun, Kepler-16b's Venus-like orbit is most likely a cold one.

An animation of Kepler-16b's orbit:

Binary star systems, first cataloged at length by English astronomer William Herschel in the early 19th century, are key to our understanding of distant stars, since it's easy to derive each star's mass by studying their linked orbit (the two stars in a binary system both orbit around their shared center of mass). But whether or not such systems, which by some estimates account for about half of the stars in the known universe, could form and support orbiting planets has been a contentious topic--making today's finding significant not just for Star Wars fans. 

"It's been pretty much a split vote amongst the theorists," said Alan Boss, a theoretical astrophysicist at the Carnegie Institution for Science, and a co-author of the Kepler 16-b paper. "Some say 'Yeah, we think it's possible to make a Saturn-mass object [in a binary star system].' Other papers say 'Well, no, we don't think it's going to work at all, because those changing gravitational forces from that central binary are going to screw up the process of trying to get little bodies to run into each other and grow bigger and bigger.'"

"One of the exciting things about this is: Kepler, as usual, has answered the question for us," said Boss.

The Kepler observatory's mission is to find and analyze potential Earth-like exoplanets throughout the universe. Today's discovery now significantly expands the working set of stars that could potentially harbor orbiting planets. That means more work for Kepler as it continues what has so far been an extremely successful mission. 

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Posted in: A Planet Orbiting Two Suns,binary system,kepler,orbiting,saturn,space,star wars,sun