As NASA scientists prepare to give a faulty instrument on the Mars Lander another try, they've also been using an electric fork and an atomic force microscope to get more clues about the makeup of Martian soil.

"It all relates to putting the whole story together," said Ray Arvidson, a co-investigator for the Mars Lander's robotic arm team and a professor at Washington University in St. Louis. "We're trying to understand the overall evolution of the planet and the soil covering it."

The Mars Lander, which is on the northern pole of the red planet, has been using the fork-like probe for weeks now. The Lander's robotic arm has been sticking the fork in the air to gage the humidity. Late last week, the robotic arm stuck the fork in the ground for the first time and gave it a good zap.

The fork, which has four 1.5-centimeter prongs, sends out both heat and electrical pulses to check the soil's thermal and water conductivity, according to Arvidson.

The Lander's Swiss-made atomic microscope was used late last week to study images of individual particles in the soil. Arvidson explained that the microscope uses a fine needle made of silicon that is scraped across crystals and soil particles to get highly detailed information. "The needle helps you make a topographical map," he added. "It'll show us the crystal shapes and if they've been damaged by salt deposits or if they've been corroded by water."

The atomic force microscope can provide details of soil-particle shapes as small as 100 nanometers, which is less than one-hundredth the width of a human hair, reported NASA. That is about 20 times smaller than what can be resolved with Phoenix's optical microscope, which has provided much higher-magnification of particles previously imaged on Mars.

All of this work comes while NASA runs a week of tests after a short circuit temporarily derailed one of the Lander's test ovens.

The Lander's eight analysis ovens, which have been dubbed TEGA, heat Martian soil so that any gases emitted can be analyzed. On its first test, in mid-June, one of the ovens short circuited. NASA scientists stalled any further TEGA analysis while they were studying the problem. The repaired oven will first be used to test Martian ice, according to Arvidson.

"Because of the possibility, even the remote possibility, that TEGA might go belly-up in the next sample, we wanted to go straight to ice," said Arvidson in a previous interview. "We cleared the pathway to get the next sample from the ice. The prudent choice is to go off and get the most important sample."

The Mars Lander, which is on a one-way mission to Mars, is expected to gather and analyze samples from the northern pole of the planet for a total of three months. Scientists are looking for the elements that could support life, and determining whether there is water on Mars has been one of the mission's key goals.