Thursday, January 17, 2008

Mercury's Hawaiian connection, and is it volcanic?

We'll soon know lots more about Mercury than we once did, thanks to a voyaging spacecraft called MESSENGER.

(Photo: An image from the MESSENGER spacecraft during a flyby Jan. 14, 2008, showing Mercury at the edge of night and day. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.)

We already know that Mercury is hot, except where it's not. On the sunny side, it can reach 800 degrees

Fahrenheit, while on the night side, that can drop more than a thousand degrees.

That it's a small planet, just a third wider in diameter than our Moon.

That it spins very slowly compared to Earth. From one Mercury noon to the next takes half an Earth year.

And that, like the Moon, it gets pounded by space rocks. Since it has no atmosphere, meteorites blast to the surface without burning up as many do in Earth's atmosphere. Images of the planet make it look remarkably battered and Moon-like.

But Mercury, the planet closest to the sun, is so close to Old Sol that's it's difficult to study thoroughly without being blinded by the brightness alongside. The last time researchers had a good look was during the Mariner 10 spacecraft mission in 1991. The new mission is the Mercury surface, space environment, geochemistry and ranging effort, whose first and sometimes second letters have been cobbled together into the word messenger.

University of Hawai'i researcher Jeffrey Gillis-Davis, with the Hawai'i Institute of Geophysics and Planetology, is a member of the MESSENGER team.

“If Mercury were a puzzle, we would only have half the pieces, which makes it difficult to put geologic processes into a global perspective. MESSENGER will fill in a lot of those missing puzzle pieces this month,” Gillis-Davis said.

His role is to use an array of sensors on the craft to study the planet's origin and its geologic evolution, to determine whether volcanic activity has played a role and to compare its geology to that of the other rocky planets, like Earth.

After the first flyby this week, the spacecraft will swing past the planet again in October 2008 and September 2009, and will enter orbit in March 2011.

Learn more on the web at

© 2007 Jan W. TenBruggencate