It’s only a speck, in comparative terms smaller than a dust mote in the vast expanse of sky all around us, but it’s got the scientists worried. The worries grow by the day, as the speck looms larger on their radar.
Astronomers call it 99942 Apophis (the Greek name of the ancient enemy of the Egyptian sun god Ra) or Asteroid 2004 MN4 and it’s hurtling towards planet Earth at some 20,000kph. It could result in the mother of all collisions in 2036.
Seen through a powerful telescope, it’s just a white dot in the night sky, but Apophis is a 20-million-tonne asteroid. That’s a lot of real estate, and if it hits, it’ll make the most powerful nuclear explosion look like a child’s firecrackers.
Apophis’ date with Earth is tentatively estimated at April 13, 2036.The chances of a consummation have been rated at 1 in 45,000, somewhere in the Pacific, off the North American coast. If that happens, the disaster will be planet-wide, dwarfing anything in known history, whether it is the destruction of Krakatoa (1883), the Tunguska explosion (1908) that felled more than 80 million trees in an 830-square-mile region of Siberia, or the much milder 2004 tsunami.
Apophis is one of numerous Armageddon probables that zip through the Milky Way. Sky surveys have identified 127 that pose a threat between 2020 and 2050. Space institutes across the world, including the Indian Space Research Organisation, are tracking more than 100 asteroids apart from Apophis, with 2007 VK184 topping the Earth Impact Table. It is rated one on the Torino Scale of zero to 10 (Torino is to asteroids what Richter is to earthquakes) and is expected to near Earth in 2048.
“It’s no longer science fiction. The world has to be prepared and India is set to work with other leading spacefarers to combat the menace,” says V S Adimoorthy, associate director of the Vikram Sarabhai Space Centre who represents India at the Planetary Defence Forum.
Nations are only too happy to join hands in this effort.
NASA’s Near Earth Object Programme is aimed at providing the United Nations with a plan of action against such threats. One of the staunchest advocates of a UN protocol is Russell Schweickart, Apollo astronaut, who heads the B612 Federation and the Association of Space Explorers.
“The federation believes in anticipatory preparation.
The threat is some quarter of a century away, but scientists feel it needs to be neutralised at least a decade before the year of impact. We must have more than a few opportunities at the target,” Adimoorthy says.
The Schweickart school feels that Apophis can be deflected from Earth’s trajectory with a one-tonne satellite. “Apophis will have a close flyby in 2029, orbiting some 29,470 km from Earth over the mid-Atlantic.
The idea is to position a satellite close to it and use the micro-gravity forces between them to deflect it,” sources say, adding that, “it will appear to the naked eye as a moderately bright point of light moving rapidly across the sky. There is no threat, however, to the geosynchronous satellites. Apophis will pass between the earth and the heavily populated satellite belt.” According to Adimoorthy, a deflection of one cm/second is all that is needed for Earth to be safe.
“We’re meeting next April at the first ever space meet of the International Academy of Astronautics on Planetary Defence. India will present a paper and suggest strategy,” he says.
In fact, the proposed UN protocol for contracting any nation or a group of nations to deal with an alien threat is now being vetted by ISRO.“We will give necessary inputs to make this document a practical action plan,” sources say.
All responses to Apophis pose huge technological challenges. It will be more than a decade before some of them become reality, leaving the world with little time for execution. The Indian plan stresses commonsense allied with current technology rather than spectacular solutions like landing a rover to drill a hole and place a nuclear bomb to blast it to pieces.
“We feel breaking the 20-million-tonne asteroid will only amplify the threat as large chunks will still rain down on earth. The best option is to divert it to another orbit that will take Apophis away forever,” ISRO sources say.
One suggestion is to plant a solar sail on the asteroid when it is some 10 years away,which will push it off its current track. The sail must be large enough to produce enough radiation to move it. “We could also place a huge solar mirror to generate enough pressure to push Apophis away,” says Adimoorthy.
A similar deflection is possible by launching a satellite to meet Apophis when it passes by in 2029. The satellite, or a group of satellites, will shepherd it out of sight.
One last resort, he says, would be to set off a nuclear bomb near the asteroid to create a kinetic impact that would push Apophis out of its present orbit.
A medium-sized nuclear bomb could be sent up in a rocket, or an inter-continental ballistic missile, to be triggered close to the asteroid.
“The blast will take place in deep space and hence poses no radiation threat to earth. But the impact will generate enough kinetic force to scare the huge asteroid out of earth’s mind,” says Adimoorthy.
Apophis, however, is only the most immediate threat. The NASA chart is littered with tongue-twisting code names that indicate possible future threats.
But most of them, unlike Apophis, hover around Torino zero. Till date, no asteroid has climbed above the Torino 2 mark. But that is no reason to lower our guard. There’s no chance of that anyway as the astronomers will be watching day and night, fascinated by this chance visitor, and their gauges will be keeping track of Apophis’ journey while the rest of us go about our business as usual.
(Original headline: Deadly date with a dark god )
