RTRD Plan Review

Looking at past plans of asteroid deflection

Introduction

At any given time, 1,400 potentially hazardous asteroids more than 400 feet wide in diameter are within 4.6 million miles of earth, as shown in the figure to the right. Asteroid collision with earth is a constant worry of scientists everywhere, hence there have been many plans in history to prevent the collisions and many futuristic plans for the future. Reviewing these plans helped my group devise a plan so here is a review of some of these plans

MIT Graduate: Sung Wook Paek's Plan

In 2012, an MIT graduate's plan to protect earth from asteroid collision was to cover the asteroid with white paint. He said that two rounds of rockets containing white paint, if timed right, the front and back of the asteroid would be coated in this white paint. The intitial force of the pellets hitting the asteroid would minutely move the asteroid off course, but after, when the white paint is on the asteroid, the albedo of the asteroid would increase. White paint has a albedo measure which means that it reflects most of the radiation and light that hits it. If the asteroid has a high albedo, the sun's radiation would reflect off of it, over time, the sun's photons would push the asteroid off course. Paek estimates that it will take up to 20 years for the solar radiation pressure to push the asteroid off course so this plan is effective for asteroids which are detected far away. He said if the solar radiation fails to deflect the asteroid off course, then at least the asteroid will be easier to detect by telescopes and space agencies would act accordingly.
Deflecting an asteroid, with paintballs

Nuclear weapons!

One of the first things that come to people's mind when getting rid of the threat of an asteroid is a nuclear weapon. Many organizations have devised a plan involving nuclear weapons and here is an overview of 3 kinds of nuclear explosions useful for solving a collision problem: a surface explosion, a subsurface explosion and a standoff explosion. Surface and subsurface explosions are the most effective. The plans involve a nuclear bomb exploding on the surface of the asteroid. This may happen as a result of missiles sent up to the asteroid then exploding on impact, but there is a risk of the asteroid splitting and posing more risk for earth. A standoff explosion is also very useful for deflecting an asteroid. This plan is when a nuclear device is detonated before it impacts the asteroid and the asteroid is pushed away by the shock waves of the nuclear explosion.


A plan devised by the ADCR ( asteroid deflection research center) is in development right now in which they created the hypervelocity asteroid intercept vehicle (HAIV). The HAIV will be instrumental in deflecting NEO's in collision course with earth. The plan uses a hypervelocity kinetic impactor combined with a subsurface nuclear explosion. The proposed HAIV system involves the kinetic impactor colliding with the asteroid to provide enough kinetic energy to create a crater. The following nuclear interceptor will soon after collide with the asteroid in the same crater and detonate a subsurface explosion in order to disrupt the course of the NEO. However, the plan is ineffective at the moment because of the insufficient launch devices. In order for HAIV to work, the impact velocity must be in the range of 10-30 km in respect to the target NEO.

Kinetic Impact

Another plan explored by NASA is kinetic impact. Kinetic impact means basically smashing large objects into the asteroid to nudge it off course. NASA's "kinetic interceptor" will "nudge" the asteroid off course without fracturing it or causing too much damage. Organizations say that a mere 1.6 km/h impact would be sufficient to divert an asteroid 273, 500 kilometers off of its collision course if the impact occurs 20 years before the predicted impact date.

Citations and Further Reading