Winged Messenger buzzes Mercury

A robotic spaceprobe became the first craft to visit the planet Mercury in almost 33 years yesterday. Nasa’s Messenger probe flew 124 miles above the closest planet to the Sun, taking close-up pictures of its Moon-like mountains and craters.

Photos due to be radioed back to Earth were expected to reveal terrain not seen by the last US visitor to Mercury, Mariner 10 in 1975.

Messenger, which was launched in August 2004, will eventually go into orbit around Mercury in 2011. But oddly, last night’s visit was the first of three flybys that it will make as it loops across the inner solar system.

It means that the probe is only half way through a 4.9 billion mile journey that it must make before it eventually goes into orbit around Mercury.

Messenger has already flown past the Earth once and Venus twice, using their gravity to propel it like a slingshot on its way. It will again skim the surface of Mercury in October this year and September 2009 .

Pictures sent back last night were expected to include an 800-mile wide impact crater called the Caloris basin which is one of the biggest in the solar system.

Mission scientist Louise Prockter said: “Caloris is huge, about a quarter of the diameter of Mercury, with rings of mountains within it that are up to two miles high. Mariner 10 saw a little less than half of the basin. During this first flyby, we will image the other side.”

Since Mariner’s visit, planetary scientists have learned that Mercury has a liquid core. British engineers are about to sign a contract to build a European probe, BepiColombo, that will be sent to Mercury in 2013.

Picture: An artist’s impression of the flyby. (NASA/Johns Hopkins Applied Physics Laboratory/Carnegie Institution of Washington).

Paul Sutherland

Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.
Paul Sutherland

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Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.

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