Bengaluru: The Indian Space Research Organisation (ISRO) is monitoring a large asteroid called Apophis that is expected to come very close to Earth. The asteroid, which is named after the Egyptian God of Chaos, is hurtling towards the earth and will have its closest encounter with Earth on April 13, 2029.
A new domain called planetary defense has been added to the portfolio of the Indian space agency and its job is to protect Earth from extra-terrestrial objects.
"A large asteroid strike is a real existential threat for humanity. ISRO is very alive to that threat and our Network for Space Objects Tracking and Analysis (NETRA) is monitoring Apophis very closely. After all we have only one Earth to live on. India will co-operate with all nations to ward off this and other such future threats," Dr S Somanath, Chairman of ISRO told NDTV.
Apophis was first discovered in 2004 and its periodicity, in which comes close to Earth, has been tracked very closely. The next encounter will be in 2029 and then in 2036. While there are concerns about its impact with Earth, some studies suggest that in 2029 it will be a fly by and may not hit Earth.
How close the encounter will be can be judged by the fact that India's geostationary satellites are in an orbit higher than the distance Apophis is likely to come close to.
At 32,000 kilometers above Earth, no other asteroid of this size has ever come so close to our planet.
"Continental scale devastation"
Asteroid Apophis is larger than India's largest aircraft carrier INS Vikramaditya and the largest cricket stadium, the Narendra Modi Stadium in Ahmedabad.
The asteroid has an estimated diameter of about 340 to 450 meters and any planetary body above a 140 meter diameter, passing close to Earth, is considered potentially hazardous.
ISRO estimates suggest that any asteroid larger than 300 meters can cause "continental scale devastation". In the worst-case scenario, if an asteroid larger than 10 kilometre in diameter hits Earth, it can cause "mass extinction"
Dr A K Anil Kumar, who heads ISRO's Network for Space Objects Tracking and Analysis (NETRA), said a collision with an asteroid that big can cause "global disruption".
"If it collides with Earth it can cause a catastrophe. It can cause local extinction. The dust thrown up by the collision can blanket the atmosphere causing global disruption," he said.
A meteor had hit India some 500,000 years ago at Lonar in Maharashtra. Today, a crater lake which is more than a square kilometer in area marks the site of collision.
"ISRO will surely study the Apophis asteroid on its closest approach in 2029. After all, we have a living example of the Lonar Crater Lake made by a meteor strike in Maharashtra," Dr Somanath said.
NASA plans mission to avert crisis
The world's leading space agencies are likely to launch several missions not only to study the asteroid's trajectory but also to understand its composition.
NASA's OSIRIS-REx was the first American spacecraft to return samples from an asteroid and now it is being retargeted to rendezvous with Apophis. Another mission by the European Space Agency named Rapid Apophis Mission for Security and Safety or RAMSES may be launched in 2028. Dr Somanath has said India may join this mission.
There are ways to nudge the asteroid away from Earth which includes by impacting the asteroid by a space craft like NASA's Double Asteroid Redirection Test (DART), or more benign methods like using a gravity tractor to deflect the asteroid or using a high speed ion beam to change its direction, but the last step could always be using nuclear explosives to detonate on the asteroid.
Not the first asteroid to threaten Earth
Among the most recent asteroid hits was the February 5, 2013 hit at Oblast in Russia by a 20-meter diameter asteroid. About 1,500 people were injured and 7,200 buildings were damaged. In 1908, a 30-meter asteroid hit Tunguska in Russia and it is estimated that 80 million trees were destroyed.
The most devastating asteroid hit is estimated to have taken place 650 million years ago when a 10-15 kilometer diameter asteroid hit Mexico and led to the extinction of dinosaurs and almost 70% of all species.