Chennai: Even as scientists are studying whether the object that killed one person when it fell from the sky into an engineering college compound in Vellore is a meteorite, a former senior official of an Indian space agency said tracking meteorites is very difficult because of their small size.
A meteorite is a portion of an asteroid or a comet that survives the Earth's atmospheric heat and impacts the earth's surface.
The portion or debris of an asteroid or comet before it hits the Earth's surface is called a meteoroid.
"Once a meteoroid escapes the Earth's atmosphere then it falls towards the Earth at a speed of 2-4 km per second. Normally meteoroids turn into ashes when they enter the Earth's atmosphere due to friction," MYS Prasad, former director of Satish Dhawan Space Centre of the Indian Space Research Organisation (ISRO), told IANS.
But if the meteoroid is large and travels down slowly, then some portion of that can survive the atmospheric heat.
"No country in the world now has the capability to track meteoroid that escapes the atmosphere," he added.
According to the US's National Aeronautical and Space Administration (NASA) website: "Asteroids are typically composed of rock-forming minerals, most commonly olivine and pyroxene. However, they often contain metal (iron and nickel), sulfides (chemical mixtures of metals and sulfur), clays, and organic compounds. The structure and composition of asteroids vary from object to object."
Prasad said most asteroids in our solar system are in the region between Mars and Jupiter known as asteroid belt.
Kamaraj, employed as a driver with Bharathidasan Engineering College in Natrampalli in Vellore district, around 170 km from Chennai, was killed and three others were injured in an explosion after a burning object fell from the sky on 6 February.
Police said Kamaraj and others were hit by splinters from the impact of the unknown object which also created a three-foot wide crater on the ground.
According to police, the fragments of material embedded in Kamaraj's body have been sent for forensic analysis and the post-mortem examination report would be finalised only after the analysis report is received.
On Sunday, Tamil Nadu Chief Minister J Jayalalithaa announced Rs 1 lakh for Kamaraj's family and compensation of Rs 25,000 each to the three injured, saying the death and injury happened due to meteorite hit.
Meanwhile, scientists from the Indian Institute of Astrophysics, Bengaluru, have been deputed to study the issue.
According to Prasad, when large meteorites hit the earth, they can shatter glass due to pressure waves.
Asteroids and meteors can be observed from the Earth only by telescopes and also by launching space telescopes.
It is said the chances of a meteorite hitting the Earth surface during the day or night are equal, Prasad said.
However, many meteorite hits on the Earth are recorded after spring and before summer and the reason for this is not known, he added.
The size of meteorites that hits the Earth will be in the range of one millimetre to 10 metres.
Prasad said a study done by a team of International Academy for Astronautics has identified around 1,100 objects — asteroids and comets — over one kilometre diameter in size and has catalogued around 700 of them.
He said the US government has tasked NASA to track and catalogue near-Earth objects measuring 140 metres and more by 2020.
Prasad said most of the meteorites have iron and nickel and may stick to a magnet.
Interestingly a police official in Vellore told IANS that the space object recovered from the engineering college campus sticks to magnet.