Phoenix struggles with sample

2008-06-09 10:15

Washington - A soil sample from the Martian arctic dug up by the Phoenix probe appears to be too firmly clumped to deliver any particles into the spacecraft's main test instrument, mission experts said.

Apparently no testable bits from the 200ml of Martian permafrost which researchers hope will provide clues to whether the planet was once habitable for microbial life passed through a screen into Phoenix's thermal and evolved gas analyser (TEGA), Phoenix team experts at the University of Arizona said on Saturday.

That deduction came after TEGA failed to signal it had received any material from the sample, following its retrieval from the Mars polar surface by Phoenix's articulated robot arm.

"I think it's the cloddiness of the soil and not having enough fine granular material," Ray Arvidson, one of the mission's lead scientists, said in a statement.

"In the future, we may prepare the soil by pushing down on the surface with the arm before scooping up the material to break it up, then sprinkle a smaller amount over the door," he said.

Phoenix relayed images on Friday that showed the clump resting on a screen over the TEGA sample port.

The screen is designed to allow through it particles measuring one millimetre or less. Inside the port there is an infrared beam, which is to determine if particles enter the machine.

Phoenix, which landed on the stark terrain of Mars' north pole region on May 25, collected the sample on Thursday.

The clump of ground was topped by a white crust that set Nasa scientists debating whether it is ice or salt deposits from evaporated water.

Phoenix mission chief scientist Peter Smith called it a good sample on Friday.

"This is really an important occasion for us, to be poised to make a measurement for the first time of the polar soil that will tell us how much water is in the soil, and secondly what the minerals are that make up the soil," said Smith.

It is the first sample take in the three month project to inspect Mars' soil for the right combination of water in its ice form and minerals that would demonstrate the planet could or can support basic microbial life.

Once it gets a sample, the TEGA instrument spends several days analysing its content, first testing for the level of water content, and then heating it gradually to 1 000 degrees Celsius to better assess the mineral composition.

- AFP