Phoenix gets close-up of Martian dust (8/25/2008)

Phoenix testing soil

The microscope station on the Phoenix lander has returned the first image of the dust particles that cloak Mars. The image was taken using the highest resolution microscope operated off Earth and a specially designed substrate to hold the particles in place.

Martian dust plays a large part in colouring the sky pink, forming the dust storms that regularly envelop the planet and producing the distinctive red soil.

The particles were imaged using an atomic force microscope (AFM) produced by a Swiss Consortium led by Urs Staufer. The AFM uses a sharp tip to scan over particles and map out their shape in three dimensions. To hold them in place during the scan a series of pits was etched into a disc of silicon by a team at Imperial College London led by Tom Pike and funded by the Science and Technology Facilities Council (STFC).

The robot-arm scoop of the Phoenix lander collected the soil sample from the surface of the Martian arctic plains and sprinkled it on to the silicon substrates as they protruded from the microscope station. The substrates were then rotated into the field of view of both a conventional optical microscope and the AFM.

The AFM imaged a particle lodged in one of the pits, showing a rounded particle about one micrometer (one millionth of a meter) across. This is the first picture of a clay-sized particle on Mars and the size agrees with predictions from the colours seen in a sunset on the Red Planet.

"I'm delighted that this microscope is producing images that help us understand Mars at the highest detail ever" said Urs Staufer. Tom Pike added "We knew it would be very challenging to image particles this small. After this first success we're now working on building up a portrait gallery of the dust on Mars."

Professor Keith Mason, Chief Executive of the Science and Technology Facilities Council, who support the UK involvement in the mission said, "We are thrilled with the success of the Phoenix mission and the exciting new discoveries and images that are being returned. It's great that some of our UK scientists are making important contributions and enabling us to learn more about this fascinating planet."

Note: This story has been adapted from a news release issued by the Science and Technology Facilities Council

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