PARIS: On 15 February 2013, asteroid 2012 DA14 will pass Earth at just 24,000km – closer than many commercial satellites.
An amateur team discovered the unusual asteroid on 22 February 2012. Its small size and orbit meant that it was spotted only after it had flown past Earth at about seven times the distance of the Moon.
While an impact with Earth has been ruled out on the asteroid’s next visit, astronomers will use its close approach for more studies and to calculate the Earth and the Moon’s gravitational effects on it.
“This is a safe distance, but it is still close enough to make the asteroid visible in normal binoculars,” said Detlef Koschny, responsible for near-Earth objects in European Space Agency’s (ESA) Space Situational Awareness (SSA) office in Spain. ”We will be keen to see the asteroid’s resulting orbit after the next close approach in order to compute any future risk of impact.”
Astronomers spot ‘slippery target’
The asteroid was discovered by the La Sagra Sky Survey observatory in Spain at an altitude of 1700m, one of the darkest, least light-polluted locations on the European mainland.
“Considering its path in the morning sky, its rather fast angular motion, the quite faint and fading brightness and its orbit high above the plane of Earth’s orbit, it was a slippery target – and easily could have escaped undetected during this Earth visit,” said Jaime Nomen, one of the discoverers.
The team use several automated telescopes to scan the sky, and the discovery came somewhat serendipitously after they decided to search areas of the sky where asteroids are not usually seen. “A preliminary orbit calculation shows that 2012 DA14 has a very Earth-like orbit with a period of 366.24 days – just one more day than our terrestrial year – and it ‘jumps’ inside and outside of the path of Earth two times per year,” said Nomen.
Half a million undiscovered objects
Together with information on space weather and debris, data from the La Sagra Sky Survey will help scientists to understand and assess hazards, particularly if an Earth-threatening asteroid is ever found.
The discovery of 2012 DA14 is particularly significant, because it is typical of the estimated half a million undiscovered near-Earth objects up to 30m across. “We are developing a system of automated optical telescopes that can detect asteroids just like this one, with the goal of being able spot them at least three weeks before closest approach to Earth,” said Detlef.
European Space Agency – Space Situational Awareness