UBC professor to help analyse images of Mercury

Latest pictures from NASA probe show volcanic activity, deep crevices

WASHINGTON—A NASA probe with a B.C. connection shot past Mercury this month, finding evidence of past volcanic activity on the planet as well as a puzzling geological feature scientists have named “The Spider.”

On Wednesday, the U.S. space agency released some of the first photos and data collected by its car-sized Messenger spacecraft, which flew past Mercury on Jan. 14.

Messenger is an acronym for Mercury Surface, Space Environment, Geochemistry and Ranging.

Some of that data will later be analysed by Catherine Johnson, a professor of earth and ocean sciences at the University of B.C. who is one of about 20 scientists worldwide chosen by NASA to be involved in the project.

Surdas Mohit, a post-doctoral researcher who works with Johnson, said Wednesday that Johnson will be using data from Messenger to help learn about Mercury’s magnetic field.

While Mercury looks superficially like Earth’s moon with a cratered, rocky surface, scientists said Wednesday that Messenger is showing them something quite different.

“We were continually surprised. It was not the planet we expected. It was not the moon,” said Sean Solomon of Carnegie Institution of Washington, the mission’s lead investigator.

“It’s a very dynamic planet with an awful lot going on.”

Mercury is a mystery in many ways and its proximity to the sun has made it difficult to observe from Earth.

Mercury has been visited by a spacecraft only twice before, in 1974 and 1975 when NASA’s Mariner 10 flew past it three times and mapped about 45 per cent of its surface.

The latest fly-by covered another 30 per cent of the surface, showing a side of the planet never seen before.

The probe is due to fly by again in October of this year and in September 2009 before beginning a year-long orbit of the planet in 2011.

“The Spider” was the most striking feature described by the scientists Wednesday.

It is made up of more than 100 narrow, flat-floored troughs radiating from a central point, much as petals from a daisy or the legs of a spider.

“The Spider” has a crater 40 km wide near its centre, but it is unclear whether this is related to the feature’s original formation and scientists aren’t sure what to make of it.

“It’s a real mystery,” said Louise Prockter of Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, who works on the mission.

“The Spider” is in the middle of Mercury’s Caloris basin, one of the solar system’s biggest impact craters, formed more than 3.8 billion years ago when a large space rock hit.

Based on the new observations, the diameter of the Caloris basin is now thought to be 1,550 km, larger than a previous estimate based on Mariner 10’s data.

The basin’s interior looks like it was volcanically resurfaced by magma from deep within Mercury’s crust or mantle.

Prockter said Mariner 10 data provided some evidence of past volcanic activity on the planet, but Messenger leaves “very little doubt … that there has been widespread volcanism on Mercury’s surface.”

It was launched in 2004 and flew past Venus twice and Earth once en route to Mercury.

With Pluto now classified as a dwarf planet, Mercury is the solar system’s smallest full planet, with a diameter of 4,880 km, only a bit larger than Earth’s moon.

It orbits the sun every 88 days.