A close encounter of the asteroid kind

Tomorrow Asteroid 2012 DA14, which orbits the sun similar to the orbit of Earth, will make a flyby of our planet

Tomorrow Asteroid 2012 DA14, which orbits the sun similar to the orbit of Earth, will make a flyby of our planet just a cat’s leap away, relatively speaking. At its closest point above the eastern Indian Ocean off Sumatra, it will be just 27,700 kilometres above the Earth’s surface.

What makes this event so unique is that the asteroid’s flyby is the closest ever-predicted Earth approach of an object this size.

The asteroid is a chunk of rock about 45 metres in diameter with an estimated mass of some 130,000 metric tons. Normally it swings by Earth relatively close twice per orbit but this time it is passing by so close that it will slice between the outer constellation of satellites (those used for communications, weather forecasting, defense and intelligence) in geosynchronous (24-hour) orbit and the closer constellation of satellites orbiting Earth and which include the International Space Station just 386 kilometres up.

There are almost no satellites orbiting at the distance at which the asteroid will pass. How fortuitous is that?

The asteroid was discovered just a year ago by the La Sagra Sky Survey in Mallorca, Spain.  It was 4.3 million kilometres away then. That tells you how far and how fast it has come in just 12 months. When it gets here it will be in the Earth/Moon system for about 33 hours and zipping by us at 28,100 kilometres an hour.

This is all great stuff for astronomers and scientists. Seeing asteroids this close provides some amazing studies on the run. NASA already has plans to launch a spacecraft in 2016 to study another asteroid and potentially bring back samples for study. But in their sights are manned missions to asteroids and “potentially resource mining operations” according to NASA’s website.

NASA’s Near Earth Object Observation Program finds and tracks asteroids and comets close to Earth. The obvious objective of “Spaceguard” is to find what objects are potentially hazardous to Earth and figure out what to do about them.

This is a global cooperative. All observatories worldwide send their observations to the NASA funded Minor Planet Center operated by the Smithsonian Astrophysical Observatory. Here, a huge database is maintained documenting all known asteroids and comets in the solar system. Research is ongoing as to how to deflect problematic rocks in space and the level of space technology needed to carry out such missions.

It’s kind of sobering to know that NASA estimates there are about 500,000 near-Earth asteroids the size of 2012 DA14 but less than one per cent have actually been discovered. Some of them do make it through on a collision course with Earth. In 1908 an asteroid slightly smaller than DA14 hit Earth in Tuguska, Siberia. It hit with enough force to flatten 1,200 square km of forest in what is now Krasnoyarsk, Russia. NASA scientists have calculated that a DA14 size asteroid flies very close to Earth every 40 years and that one impacts roughly once every 1,200 years.

For this flyby event, the asteroid will be best viewed from Europe, Africa and Asia. By the time Earth has rotated enough for North Americans to see it, the asteroid with have receded and faded in magnitude. But powerful telescopes everywhere will be all over it. The asteroid’s next notable visit will be February 15th 2046 but at a tame one million kilometres from Earth’s surface.

When the asteroid flashes past tomorrow, its distance from us will be just 1/13th the distance from the Earth to the Moon.

Now that’s what I call a close encounter.