Tractor Method of Asteroid Defense

     Inspired by the movie Armageddon, I researched the realistic techniques that Nasa has come up with to defend our planet against asteroids. The method that stood out to me as the most interesting was the Gravity Tractor method. The Gravity Tractor method is based on the most fundamental force in nature, Gravity. 

Image result for moon motion around earth
Orbits of the four inner planets and Jupiter (taken from flickr).

     If you have ever looked at the orbits of the planets around our Sun, or the orbit of the Moon around the Earth, you are looking at gravitation at its finest. Following Newtons 3rd law and basic gravitation equations, two celestial objects exert an identical force of gravity on one another over space that is equal to the product of their masses divided by the square of their distance, all multiplied by the gravitational constant G. The five inner planets all exert the force of gravity on the Sun and the Sun exerts the same force on each planet. The reason why each planet doesn't fall towards the sun is because they are moving at such high speeds that it causes them to fall around the sun. The sun doesn't move towards the planets because of its collosal mass.
     This gravitational force of objects in space is what the Gravity Tractor method is structured around. This is what it looks like in space.
Image result for nasa gravity tractor
NASA
     How it works is that there is a space craft sent to an incoming asteroid which then either orbits or remains stationary over the asteroid. The asteroid and the spacecraft will interact gravitationally and will naturally want to move towards one another. While the planets around the sun move too fast to move towards the sun, the spacecraft does not orbit the asteroid at a speed sufficient enough to not fall towards it. To counteract this, the spacecraft would need to undergo a constant thrust perpendicular to the surface of the asteroid. 

In this video it shows a spacecraft interacting with an asteroid. Notice how the spacecraft is constantly using thrust in order to not fall into the asteroid.

The asteroid is always chasing the spacecraft which in time will change the trajectory of the asteroid and miss the Earth. This method of asteroid defense is mesmerizing because the physics behind it is so simple and beautiful.


Comments

  1. Prof. Chris FragileSeptember 27, 2019 at 6:39 PM

    Cool. One thing to point out, though, would be that methods like this take a lot of time to deflect the orbit of the asteroid by enough to matter, so it is critically important to identify threatening asteroids plenty early.

    ReplyDelete

Post a Comment

Popular posts from this blog

Avengers: Infinity War Movie Analysis

Image
Avengers: Infinity War is another classic superhero movie that involves action scenes made more epic by violating the laws of physics. That being said, it took some time to find scenes that involved spotty physics. Here are a few that caught my eye.  Scene One - Cull Obsidian's Hammer Throw In the battle scene between Black Order and the Avengers in New York City, Cull Obsidian's hammer seems to be resistent to Newtons first law when it is in contact with a concrete wall, but abides by it when interacting with the ground. Newtons first law states that a body will remain at rest or move in a straight line at a constant speed unless acted upon by a net outside force.  1:38-1:42 Notice how the hammer travels straight through the building without slowing down whatsoever. Comparing this to newtons first law, it seems that the hammer is resistent to any outside forces. Now look at this scene where the hammer is slowed down dramatically by the ground. 1:55...
Read more

The Twin Paradox vs. Contact

Image
     The movie Contact makes an effort to display a realistic representation of the Twin Paradox, but the fundamental concept of time dilation was displayed incorrectly. The time dilation in the twin paradox is a result of the point of view of a stationary observer seeing a clock move slower as it moves with a constant velocity past them. This can be portrayed in the diagram below:      Keep in mind that light in a vacuum will always travel at the speed of light [c], which represents the second postulate of special relativity. The second section of the illustration above represents the actual motion of a photon in both a moving inertia frame and a stationary inertia frame. The third section of the illustration represents what a stationary observer would see as the clock moves by them at a constant velocity. Notice how the distance that the photon actually travels (2d) is shorter than the distance that the stationary observer sees. To the stationary obs...
Read more

Sir Martin Rees on Climate Change

Image
Sir Martin Rees, the Astronomer Royal of the United Kingdom, gave a public lecture at the beginning of this month titled "Surviving the Century" in which he offered predictions about the future of humanity and the world changing problems we face. Martin Rees is a world leading cosmologist who gave this lecture not because he is an expert in the field of environmental science, but because he is in a position where he can spread awareness about the critical time we are in.  The topic that he claimed needs the most immediate attention is that of climate change and global warming. He asserted that the population growth in the world has increased 4.2 billion in the last fifty years, which is directly proportional to the worlds fossil fuel use. He stated " If humanity’s collective impact on land use and climate pushes too hard, the resultant ecological shock could irreversibly impoverish our biosphere", which is also causing mass extinction. He followed this statement u...
Read more