Comets are leftovers of stars and planets that used to exist somewhere around 4.6 billion years prior. Asteroids are easier to track and detect over comets. Comets lurk in dark depths of the solar system before reaching the neighbouring areas in the solar system.
If a big comet manages to hit Earth, which is highly unlikely, it would cause chaos and devastation. It would lead to huge tidal waves, fires, release amount of dust and soot in the air, blocking of sunlight, the death of animals and plants etc. However, only small comets hit the Earth and the last big one to hit Earth was 65 million years ago (the one responsible for wiping out dinosaurs from the face of Earth).
65 million years ago, the comet hit Yucatan peninsula, Mexico and killed many species of animals along with dinosaurs. However, this isn’t just some once in a lifetime occurrence. According to the fossil records, in every 130 million years, there is a sudden massive wipeout of the majority of the species on the Earth. Scientists believe it to be the effect of comets and asteroids.
NASA believes that another comet will collide with Earth’s surface to create chaos. For detecting that, the Government is launching two spacecraft- one by European Space Agency, 2020 and another by NASA in 2021. The main aim of the spacecraft is to detect the comet and try to change the direction of flying.
HOW TO DETECT OR STOP IT?
The upside of this is that with scientific tools and devices, it is possible to detect a meteor or comet months in advance. NASA uses Sentry (collision monitoring system) which scans for asteroids and comets along with their impact over the span of 100 years. JPL Small-Body Database Browser catalogues these entries.
Various space missions are employed for monitoring asteroids and comets. For stopping the comets, the comet-specific approach is needed. Nukes launched by spacecraft can deal with big space objects but the production of such a spacecraft would require millions of dollars.
Powerful laser blasts can also be used for vaporizing comet’s surface and making its return back to its original trajectory. A large laser can deflect any comet and de-orbit it back to space. There are various methods for deflection of a comet back to the orbit including solar radiation and nuclear weapons.