 |
| Near Earth asteroid are potential threat to Earth (Image Credit: NASA/JHUAPL) |
A Near-Earth asteroid having 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 width of 1.3 Km is
just a collection of rubble which include 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
hour 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 materials and helps in holing molecules together. For example
the ability of Geckos to stick to 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 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 potential threat to collide with Earth.
The direct interaction may cause the cohesive force to destabilise and may
result in 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.