By Dr Ajey Lele
On 30 June 30, 1908, an explosion tore through the air above a distant forest in Siberia, near the Podkamennaya Tunguska River. It is believed that the fireball was around 50-100m wide and exhausted 2,000 sq. km of the forest in the area. The impact is known to have flattened about 80 million trees. The impact of the so-called blast was so huge that the earth around this region was totally shaken. Some residents from the nearby town which was 60 km away were blown off their feet.
Exact reasons for this event are still not known. There are various theories offered to explain the reason for the Tunguska event. Was that owing to the impact of a meteor or comet? Some believe that it is even possible that it could have happened due to intense cosmic disruption. Also, the possibility of the asteroid impact could not be ruled out. Whatever may the reason be, but the event ended up producing about 185 times more energy than the Hiroshima atomic bomb.
The United Nations celebrates June 30, as Asteroid Day (also known as International Asteroid Day) every year with an aim to raise public awareness of the risks of asteroid impacts. During the last decade, two to three major incidents have happened when asteroids have passed from a very close distance (few lakhs of km) from the earth. Based on various geological evidences and studies of fossils, various scientific studies have reached the conclusion that around 66 million years back asteroids have hit the earth resulting in wiping out around 75% of all species including the dinosaurs.
Asteroid Day is not only for raising the awareness about asteroids but also is a day, when humans need to take a pause and think about what can be done to protect the Earth from any possible asteroid strike. The challenge is huge, that few feel that nothing can be done about this, however good amount of research has been happening on this subject for many years. Asteroids are rocky remnants left over from the early formation of our solar system about 4.6 billion years ago. NASA estimates that there are 1,097,148 asteroids. These bodies, which are sometimes referred to as small planets, are mostly irregular in shape, though a few are nearly spherical. They revolve around the Sun in elliptical orbits and also rotate, sometimes quite erratically. Interestingly, about 150 are known to have their known moons (some have two moons).
Asteroids are found orbiting the Sun between Mars and Jupiter, which could be viewed as the main asteroid belt. The biggest asteroid called Vesta has a diameter of 530 km. The orbits of asteroids can be changed by Jupiter’s massive gravity and at times is responsible for changing the orbits of asteroids. This on occasion leads to asteroids leaving the main belt. Such asteroids could go all over in space across the orbits of other planets. Lost asteroids and asteroid fragments have banged into Earth and the other planets in the past and this could happen in the future too.
The US government on June 20, 2018 published a report titled the “National Near-Earth Object Preparedness Strategy and Action Plan.” This report outlines the steps that NASA and the Federal Emergency Management Agency (FEMA) will take over the next 10 years to both prevent dangerous asteroids from striking Earth and prepare the country for the potential consequences of such an event. NASA has evolved a concept called the Planetary defence, which is about developing capabilities to detect the possibility and warn of potential asteroid or comet impacts with Earth, and then either prevent them or mitigate their possible effects. Luckily, at present scientists do not predict any major asteroid to cause serious damage to Earth in the foreseeable future. However, scientists are working to devise a mechanism to avoid any such possible impact.
Presently, human interest is increasing for the purposes of mining minerals over asteroids. We have almost exhausted all-natural resources from the earth’s crust. It is expected that possible asteroid mining could potentially revolutionize space exploration. Already few ‘space rocks’ have been catalogued as best targets for mining. They mostly have nickel, cobalt, iron & magnesium silicate, platinum and gold in their crust. Japan has already undertaken asteroid sample return research missions and few other states are working in that direction. Indian Space Research Organisation (ISRO) too has plans for visiting asteroids, but it may take many some years for this to happen. Asteroid Day offers an opportunity to debate on this important and interesting, but less discussed subject of space sciences.
(The author is Senior Fellow, MP-IDSA, New Delhi. Views expressed are personal and do not reflect the official position or policy of Financial Express Online. He can be reached at: [email protected])