Asteroid mission alert: Tackle threat as one
On September 24, excitement peaked in the astronomer and astrobiologist communities when a capsule carrying 250 grams of rubble from Bennu, a carbon-rich asteroid, landed in a remote part of the Utah desert in the US. It was from NASA’s OSIRIS-REx (stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) mission launched in 2016, which collected samples from Bennu in 2020, flew by Earth at a distance of 1 lakh km last week, and jettisoned the sample-laden capsule which parachuted down in the desert.
NASA is expected to carry out analyses of the sample and announce the results on October 11, which explains the excitement among scientists.
About 4.5 billion years ago, before the planets formed, the infant Sun was surrounded by a disk of dust and gas called the protoplanetary disk. While most of this disk divided and collapsed to form the planets, the leftovers ended up as the asteroid belt between the orbits of Mars and Jupiter. The largest known asteroid, Ceres, measures 900 km in diameter and the smallest, 2015 TC25, is just two meters.
These are among an estimated 17 lakh asteroids in the belt. Asteroids evoke curiosity because of their scientific value as much as for the threat they may pose to Earth. This is why missions exploring and intercepting asteroids excite scientists. Asteroids are believed to carry a variety of metals including cobalt, nickel, gold, platinum, and rhodium— one estimate puts the value of the entire asteroid belt at $700 quintillion (a quintillion is a billion billion). They are also considered to be time capsules that hold secrets to the formation of the solar system and the building blocks of life on Earth.
On the threat front, the entire dinosaur population was wiped out about 65 million years ago when a 10-km-wide asteroid struck Earth off Mexico’s Yucatán Peninsula, resulting in the 180-km-wide Chicxulub crater. It is said to have caused a decades-long winter, with the impact-induced dust plume covering the globe and shutting out sunlight and heat. A recurrence of an asteroid strike of that magnitude remains a possibility.
There are much larger asteroids in the belt that can come loose and head towards our Earth. Asteroids signify the good and the very bad—they can tell us about our future and past, and they can wipe us out. They need to be tackled by humanity as one.