The Indian Space Research Organisation (ISRO) is tracking a large asteroid called Apophis, which is expected to come very close to Earth. The asteroid, named after the Egyptian god of chaos, is speeding towards Earth and will make its closest approach to Earth on April 13, 2029.
A new domain called Planetary Defence has been added to the portfolio of the Indian Space Agency and its job is to protect the Earth from extraterrestrial objects.
ISRO Chairman Dr S Somanath told NDTV, “A major asteroid strike is a real existential threat to humanity. ISRO is very conscious of this threat and our Network for Space Object Tracking and Analysis (NETRA) is tracking Apophis very closely. After all, we have only one Earth to live on. India will cooperate with all countries to avoid this and other future threats.”
Apophis was first discovered in 2004 and its periodicity, in which it comes close to Earth, has been tracked very closely. The next encounter will take place in 2029 and then in 2036. Though there are concerns about it colliding with Earth, some studies suggest that in 2029 it will be a flyby and will not collide with Earth.
How close this encounter will be can be gauged from the fact that India’s geostationary satellites are in an orbit much higher than the possible distance at which Apophis will come close.
At 32,000 kilometres above Earth, no other asteroid of this size has ever come so close to our planet.
“Catastrophe on a continental scale”
The 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 around 340 to 450 metres and any asteroid with a diameter greater than 140 metres that passes near Earth is considered potentially hazardous.
ISRO estimates that any asteroid larger than 300 metres can cause “continental-scale devastation”. In the worst-case scenario, if an asteroid larger than 10 kilometres hits Earth, it can lead to “mass extinction”.
Dr AK Anil Kumar, head of ISRO’s Network for Space Object Tracking and Analysis (NETRA), said a collision with such a large asteroid could cause “global disruption”.
“If it hits Earth it could be devastating. It could cause local extinctions. The dust from the collision could cover the atmosphere, causing global disruption,” he said.
About 500,000 years ago, a meteorite struck India at Lonar in Maharashtra. Today, there is a crater lake at that location that covers an area of more than a square kilometer.
“ISRO will definitely study the Apophis asteroid when it makes its closest approach in 2029. After all, we have a live example of the Lonar crater lake formed by a meteorite strike in Maharashtra,” Dr Somnath said.
NASA plans mission to avert crisis
The world’s leading space agencies are set 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 US spacecraft to return with samples from an asteroid and is now being sent again to meet Apophis. Another mission called the Rapid Apophis Mission for Security and Safety or RAMSES by the European Space Agency may be launched in 2028. Dr Somanath has said that India can join this mission.
This animation shows the distance between the Apophis asteroid and Earth when the asteroid made its closest approach to Earth. The blue dots are the many man-made satellites that orbit our planet, and the pink dot represents the International Space Station pic.twitter.com/WKt8YiBjLh
— Massimo (@Rainmaker1973) 29 April 2019
There are several ways to push an asteroid away from Earth, including striking the asteroid with a spacecraft like NASA’s Double Asteroid Redirection Test (DART), or more benign methods like using a gravity tractor to deflect the asteroid or a high-speed ion beam to change its direction, but the final step could always be to use nuclear explosives to blast the asteroid.
This is not the first asteroid to pose a threat to Earth
The most recent asteroid impact was a 20-meter diameter asteroid that struck Russia’s Oblast on February 5, 2013. About 1,500 people were injured and 7,200 buildings were damaged. In 1908, a 30-meter asteroid struck Tunguska, Russia and is estimated to have destroyed 80 million trees.
The most devastating asteroid collision is estimated to have occurred 650 million years ago, when a 10–15 kilometer diameter asteroid struck Mexico, leading to the extinction of the dinosaurs and about 70% of all species.