Asteroid Impact Prevention
Past plans, current plans, future plans to prevent impact.
Previous Plans
Plans that have already been planned, developed and carried out by Nasa and other astronomy organizations.
Current Plans
Plans that are currently in development or are being launched in outer space for testing, not guaranteed to succeed.
Futuristic Plans
Plans that are theoretically possible, although may require future technology, nothing more than drawings on the board, however have the potential to be carried out, especially on larger threats to Earth.
Past Plans
Some plans that have already been put to action to handle meteorites and asteroids include:
The Asteroid Impactor
As its name implies, the Impactor is launched to collide with potentially harmful objects and deflect them by altering the asteroid's course away from Earth. The impactor has to travel at a fast enough speed and must have a high mass in proportional enough to budge the asteroid upon impact. There are risks to the plan since, it is probable that collisions will miss the rapid and rough-shaped space rocks.
Nuclear Actions
Nuclear bombs are the most powerful form of explosion known to man. There are enough bombs on Earth for humans to wipe themselves from existence. In space however, the force is minimized, and the bombs are used to alter the course of asteroids, rather than completely destroying them. When deflecting, explosions in the subsurface may fragment the asteroid, making it more risky, so the most successful action would be to produce impact on the surface.
Rock Impact
Similar to the Impactor, this plan has a higher chance of success, but takes longer to execute and is more costly. Thrusters or spaceships push more, smaller space rocks to collide with the larger asteroid to alter its course. The calculations are more quantitative in this process and is more of the essence. Just like the Asteroid Impactors, success is not guaranteed, and a bit risky to carry out perfectly.
Present Plans
Plans being considered by astronomers now to prevent asteroid (or at least meteorite) impact with Earth include:
Solar Sail
The solar sail is a device that would be attached to a space rock and apply constant pressure of sunlight over certain areas. The pressure of the sunlight on the rock would cause the rock to radiate energy from one of its sides, therefore slowly and steadily changing its original course. However this plan is only effective on smaller rocks during for shorter given periods of time. For this plan to be effective on something larger would require action, many years in advance.
Painted Surface
As strange as it may sound, there are plans of painting the surface of asteroids and meteorites to alter their course. According to the "Yarkovski effect", the more heated surface of an asteroid will emit more thermal radiation, therefore, controlling the heated areas using paint may help control radiating areas and ultimately alter the rock's course slightly. However, just as the solar sail, this plan requires years in advance notice to be effective on larger rocks.
Future Plan
A plan probably not in consideration right now, but may be considered in the future, with possible advances in technology, currently no more than a theory...
This plan is by far no more than a rough sketch and a theory, however may have some sort of potential in the future. The main concern is that a large asteroid may one day appear and wipe out the human race, even using regular tactics may not be enough. Which is where the Caterpillar Initiative comes in. The idea is that a caterpillar-like laser drill, digs into dense surfaces of huge asteroids easily by heating the surface first. It would burrow down in several layers around the huge space rock and place nuclear warheads (30 000 kilotons of nuclear energy each) that it carries in its attached pods. The highest concentration of energy would be in the center, to fragment the rock into smaller pieces, while the lowest would be on the surface, to be used solely as to separate clusters of debris. Advantages to this is that the pods can be attached and disattached so they can be flown up separately and attached in the target's orbit, Making the trip faster and safer.
Inspiration for the Caterpillar
Originally the plan was supposed to drill into asteroids, extract resources , while decreasing mass, while another ship is on standby with nuclear bombs. The problem was, that it might not be enough to properly separate debris and because of gravity, blowing the asteroid up would be useless. So the plan was actually further inspired by a movie called The Core.
The Core Trailer