Near Earth asteroid held together by weak cohesive force

Near Earth Asteroid
Near-Earth asteroids are potential threat to Earth (Image Credit: NASA/JHUAPL)

A Near-Earth asteroid having a potential threat to Earth does not have enough gravity to hold it together with its very high spinning speed. The spinning speed is high enough to break it apart into pieces then how is this asteroid held together?

The researchers from the University of Tennessee, led by Benjamin Rozitis, have solved the mystery by discovering a force responsible for holding rubble-pile asteroid together. The force is known as van der Waal force which has not found in any other asteroid.

The near- Earth asteroid 1950 DA having the width of 1.3 Km is just a collection of rubble which includes many big and small stones with lots of space between them. The rotation speed of asteroid is very high which is very surprising for a rubble-pile asteroid.

The asteroids are not found to spin faster than once in 2.2 hours but this asteroid has crossed the limit by rotating once in 2.12 hours. The density of asteroid should be very high about 3.5 times the density of water to provide enough gravity to hold the rubble-pile together.

The thermal image and size observations have suggested that the density of asteroid should be 1.7 times of water. The density of asteroid is very less to provide gravity to hold it together. The gravity is found to be negative near the equator of the asteroid which implies that if an astronaut stands there he or she would just fly apart. This suggests that something more than the gravity and the friction is required to hold it together.

The researchers have found that the force responsible for holding it together in van der Waal force of attraction. This force is also found in most of the materials and helps in holding molecules together. For example, the ability of Geckos to stick to the glass surface with one toe is only due to van der Waal force.

The presence of such a cohesive force makes the asteroid more fragile and dangerous because it may breaks into pieces during the collision with Earth and can cause more destruction. The near-Earth asteroid that crashed in Russia in 2013 was proved to be very hazardous because of breaking into pieces.

The discovery of this force in the asteroid may be helpful in treating the asteroids which have the potential threat to collide with Earth. The direct interaction may cause the cohesive force to destabilise and may result in the disintegration of the asteroid.

The safer procedure can be used to deflect the asteroid from its path towards the Earth. “Gravity tractor” is a technique in which a heavy spacecraft may be used to pull the asteroid off the path with the help of gravity.

The discovery of this force will be definitely helpful for the companies who want to perform exploration mission for mining the asteroid. Asteroid 1950 DA is surely not a good candidate for such an exploration because it will not be possible to land on it.

Reference:

Near-Earth asteroid held together by weak force

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