When, in 1801, Giuseppe Piazzi first spotted a dim light in the space sky, he mistook it for a planet but after many other similar discoveries, all with no planetary disks, Sir William Herschel coined the term ‘asteroid’ to the celestial object, meaning ‘star-like’ in Greek. With scores of them turning up, today the ones bigger than 100 meters alone count up to 150 million and there are even more in number once you scale down. These usually shapeless rocks are just out there; adrift in the vacuum, circummambulating the Sun but every now and then, one starts to move closer into the planets’ orbit posing a potential threat of colliding with Earth in forthcoming years.
The first asteroid discovered, Ceres, today seen thorough better telescopes. Photo Credits: - NASA
In truth, about 100 tons of asteroids are entering into Earth’s atmosphere every day but they don’t ever make it to the surface thanks to atmospheric drag or friction. Most of these are the size of a grain of sand and are space dust but still, no matter how improbable it is, the threat of bigger asteroid impacts remains, for example in 2013, in Chelyabinsk, Russia, a 20 meter wide asteroid made it to the surface at a speed of 11 miles per second, hitting the earth with the power of 500 kilotons of TNT. It killed 1,500 people and heavily damaged buildings.
In 2014, NASA registered about 10,000 Near-Earth asteroids out of which 861 were over 1 kilometer in diameter and 1,409 were dubbed potentially dangerous. Only in tens or hundreds of millions of years later is such an asteroid going to hit Earth like the one which triggered the dinosaurs’ extinction 65 million years ago. Despite this, we should be ready for any unforeseen event and turn it to our advantage rather than allow it to be the cause of our destruction.
See, asteroids are much more than what meets the eye. They are full of minerals which astronomers detect, by bouncing off lights of different wavelengths from it, as different minerals reflect different wavelengths. Almost 80% of the asteroids in the Asteroid Belt between Mars and Jupiter contain C-type asteroids or carbonaceous asteroids. The 20% left contains the more valuable S-type or siliceous asteroids containing silicon, iron and nickel and the M-type or metallic asteroids shelters precious gold and platinum deposits aside the common metals.
A recently discovered asteroid in 2011, UW 158, was found to contain 90 million tons of platinum. That is a massive amount considering that Earth has about 192 million tons of platinum! The total worth of the asteroid would range around 5 trillion dollars! 3554 AMUN is another one that we can hope to contain and make use of, as it will be 10 Gm close to Venus in 2034 and 2103. This one is considered as an M-type asteroid and after observing its mineral composition it was valued at 20 trillion dollars! The possibilities of what fruit it could bear humanity are unfathomable.
A concept of the 'asteroid-capturing spacecraft’, NASA has planned to launch by 2025
To harness such resources, NASA has devised a plan that they hope to execute by 2025. The idea is to design a solar powered spacecraft that has a space bag in front of it. After calculating trajectories and moving the vehicle close to the asteroid, they will carefully en-wrap the asteroid in the bag and using ion engines return to the Moon from where a ground team on Earth can pick the asteroid for mining. Other ideas like firing the asteroid with lasers and stuff will only make it harder to bag the smithereens of the asteroid. Many asteroids even contain water and these are larger than the usual ones. Perhaps in the future, asteroids could serve as a recharge station for spacecraft, where they could use the hydrogen from the water as fuel. Again, the possibilities are endless.