Zapping Rocks with Lasers to Save the World
Posted by Bruce Betts
25-06-2012 17:59 CDT
In the not-so-distant future, if an asteroid is on a collision course with Earth, we might choose the Star Wars solution to that problem: dispatch several spacecraft to swarm around the asteroid and zap it with lasers. In contrast to the Star Wars solution, Red Leader doesn’t need to die at the hands of Darth Asteroid—these spacecraft would be robotic, and they wouldn’t be designed to blow up the asteroid but rather, to vaporize surface rock at just the right location to create jets of rock vapor that would gradually move the asteroid to a safe orbit. World saved, rocks vaporized, and a good time had by all.
Is this scenario realistic? That is what we are trying to find out. The Planetary Society has been sponsoring research at the University of Strathclyde in Scotland to investigate this promising but understudied possible asteroid deflection technique, often called surface ablation. Because it would involve several small spacecraft firing lasers, this project is called Laser Bees. (It used to be called Mirror Bees, but that is so last year. The research originally focused on both lasers and an alternative of using mirrors to reflect sunlight onto a spot to do the vaporizing. The mirror solution turns out to be more complex—for example, in lining up the Sun, the mirror, and the asteroid—and potentially less efficient. All hail Laser Bees, the victor.
The means for potential deflection techniques for asteroids range from nuclear weapons to gravity tugs. Each has advantages and disadvantages. Laser Bees are intriguing because studies indicate they may offer the ability to move asteroids comparatively quickly. Much work must be done to determine if this really pans out, and that is where the Laser Bees project comes in.
The project is a joint venture of the Universities of Strathclyde and of Glasgow and is led by Strathclyde professor Massimiliano Vasile. His graduate student Alison Gibbings visited The Planetary Society earlier this year and presented their results to date. Using support provided by Planetary Society members, the Laser Bees team has created an elaborate laboratory setup that enables them to zap rocks with a high-powered laser, including trials with the rock in a vacuum chamber.
They have done preliminary tests on both solid and porous rocks, collecting ejected material on microscope slides placed at a variety of distances. They have compared these results with models and have made a variety of interesting discoveries, including that the process seems more efficient than predicted.
Now the Laser Bees team is poised to take the next steps. These include attaching force sensors to the rocks to measure the force imparted; testing to see if heating the slides, which represent the optical parts of the spacecraft system, will limit deposition of rock material and thus preserve the efficiency of the system even in a “dirty” environment where rock is being ejected from the asteroid; and, in what should generate great video and great science, using high-speed cameras to record the development of the ejecta plume.
When we discover an asteroid headed for Earth— and it is only a matter of when, not if—we will want a variety of well-studied techniques that can be applied to deflect the asteroid before a regionally destructive catastrophic impact can occur. Thanks to the support of Planetary Society Members and the Laser Bees team, we are moving the process forward to help save the world.
Want more detailed information about Laser Bees:
Alison Gibbings presentation slides from February 2012 (4 MB PDF)
A video of her Alison's entire February 2012 presentation at Planetary Society Headquarters
A Planetary Radio interview with Alison Gibbings from March 2012
Help The Planetary Society support this project: