This is a Press Release from NASA
NASA 2036 forecast: Asteroid crash
Foreign delegates at the space expo at the 58th international astronautical congress in Hyderabad. (AFP)
New Delhi, Sept. 25: An asteroid three football fields wide might crash into Earth in 2036 seven years after whizzing past the planet closer than some satellites in orbit, a US space scientist said today.
If the asteroid named Apophis passes a specific, small region of space during its close fly-by in 2029, it will return to impact Earth in 2036, said William Ailor, director of the Centre for Orbital and Re-entry Studies with the Aerospace Corporation.
In this small region of space that scientists compare to a “keyhole”, Earth’s gravity will perturb the asteroid’s trajectory such that the subsequent encounter in 2036 would lead to an impact.
The chance of such an impact is currently predicted to be 1 in 45,000, Ailor said in a talk on Earth-threatening asteroids at the International Astronautical Congress, 2007, in Hyderabad.
“It’s not a civilisation-ender, but if it does strike, it’ll cause significant damage. People alive today — young people in schools and colleges — are going to see it go by or will have to deal with it,” Ailor told The Telegraph in an interview.
Further observations of Apophis in 2012 and 2013 will allow scientists to recalculate the chance of an impact.
“The probability of impact could go up or come down,” Ailor said.
In 2029, Apophis will get closer than some geostationary satellites parked about 37,000km above Earth. A realisation at that time that it will impact in seven years would give scientists too little time to prepare, Ailor said.
Space scientists have pencilled Armageddon-style missions to protect Earth from an incoming asteroid. But unlike in the 1998 film starring Bruce Willis and Liv Tyler, the options involve deflecting the asteroid rather than blowing it to smithereens.
A high-speed spacecraft may be crashed into the asteroid or a heavy spacecraft may be parked close to it so that it acts like a gravity tractor.
“Something to pull the asteroid away from Earth,” Ailor said.
Another option is to explode a nuclear device tens of metres above the asteroid so that the explosion boils away its surface and makes it change trajectory, he said.
But Ailor cautioned that it was still not clear how exactly asteroids would respond to such attempts at deflection because the composition of many asteroids is unknown and small asteroids tend to have irregular shapes.
The last major asteroid impact had occurred in 1908 over Tunguska in Siberia when a 50-metre-wide space rock levelled more than 2,000 square kilometres of a forest, an area larger than Washington DC.
Over the past eight years, a concerted search has helped find 90 per cent of the asteroids 1km and larger — the civilisation-killers. “But we have yet to find some 20,000 objects between 300 metres and 140 metres,” Ailor said.
“It’s not a case for panic, but we need preparations to nudge objects out of the way (should the need arise),” said Richard Kline, president of Klintech, a technical consulting company that organised Ailor’s talk at the 58th astronautical conference.
Ailor said the effort to push an asteroid out of a collision course would increase sharply with the passage of time. A longer wait would mean the need for a larger explosion or heavier or more spacecraft to deflect an incoming asteroid.
The reason is that the closer an asteroid gets to Earth, the bigger the momentum one would need to nudge it off the planet’s path.
