Rosetta homes in on target asteroid

 

A European spaceprobe is on final approach to fly past the biggest asteroid ever visited. The billion-euro unmanned Rosetta will make its closest approach to a giant space rock called Lutetia on Saturday.

Impression of Rosetta flying past Steins

Impression of Rosetta flying past Steins (ESA)

It will spend two hours taking close-up photos and other measurements as it zooms by at 34,000mph (54,000kph).

Rosetta, launched in 2004, will come within 2,000 miles of the asteroid at a distance of 282 million miles from the Earth as it orbits between the planets Mars and Jupiter. The asteroid has never been seen close-up before but is thought to be about 83 miles long and 60 miles wide.

Rosetta has already flown past another asteroid called Steins in September 2008. The spaceprobe has made a number of swings past the Earth and Mars in a kind of interplanetary snooker to gain speed. Its mission is designed finally to land on a comet called Comet Churyumov-Gerasimenko in 2014. One flypast of the Earth proved embarrassing when scientists mistook Rosetta itself for an incoming asteroid.

Planetary scientists are keen to learn more about asteroids like Lutetia because they believe they are chunks of rock which failed to collect together to form a planet and so are unchanged from the early days of the solar system. Understanding their make-up will also help with plans in how to deal with any deadly asteroids found on course for an Armageddon-style impact with the Earth.

Lutetia might also be a chunk of a larger asteroid that broke up, a possibility suggested by observations that hint that there may be metals on its surface. One day asteroids could be a target for mining companies wanting to exploit their rich mineral content.

Update: See the stunning images from Rosetta’s Lutetia flyby on the ESA wesbite.

Meanwhile, a cannister that made a spectacular return to Earth from an asteroid last month has been opened to reveal – just a few particles of dust. Space scientists were hoping that their unmanned $200 million Hayabusa probe had brought back fragments of a giant cosmic rock called Itokawa.

Its seven-year trip ended when Hayabusa re-entered the Earth’s atmosphere as a brilliant fireball over Australia. But it ejected the tea-caddy sized cannister which parachuted to a safe landing in the Outback.

Japanese scientists knew that Hayabusa – meaning Falcon – had failed to collect any large pieces of the 590-yard (540-meter) long asteroid. But they hoped that a brief landing on Itokawa had thrown up some fragments that the cannister had then collected.

Japan’s space agency JAXA now say they found minute particles inside the cannister after it was opened in a sterile laboratory. They hope the dust will prove to be from the asteroid rather than contamination back on Earth.

If so, the samples will be priceless for scientists because they will be pristine material from the birth of the planets more than 4 billion years ago which will help them learn how the solar system evolved.

• Discover space for yourself and do fun science with a telescope. Here is Skymania’s advice onhow to choose a telescope. We also have a guide to the different types of telescope available. Check out our monthly sky guide too!

©PAUL SUTHERLAND, Skymania.com

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