Martian Soil Similar To Earth Soil, Scientists Say
Martian Soil Similar to That of Earth, Scientists Say; Results From First Wet Chemistry Analysis Performed On Another Planet
Washington -- Soil just under the surface at one spot on the arctic plains of Mars is similar to soil found in the dry valleys of Antarctica and in other places on Earth, said scientists describing results from the first wet chemistry analysis performed on another planet.
The microscopy, electrochemistry and conductivity analyzer (MECA) instrument on NASA's Phoenix Mars lander performed the experiment June 25, revealing that soil in the spacecraft's immediate area is alkaline rather than acidic.
"The amazing thing about Mars is not that it's an alien world," Phoenix co-investigator Sam Kounaves of Tufts University, science lead for the wet chemistry investigation, said during a June 26 briefing, "but that it's very Earth-like in a lot of aspects. Chemistry and mineralogy is the same on Mars as it is on Earth."
The Martian soil is "the type of soil you'd probably have in your backyard -- alkaline," he added. "You might be able to grow asparagus in it really well [but not] strawberries."
About 80 percent of Phoenix's first, two-day wet chemistry experiment is complete. The spacecraft has three more wet chemistry cells for use later in the mission.
Analysis of about a cubic centimeter of soil for inorganic elements also produced a variety of components of salts, including magnesium, sodium, potassium and chloride.
"We basically have found what appear to be the nutrients [needed] to support life," including microbes, Kounaves said, "whether past, present or future."
Three-legged Phoenix touched down on the Red Planet May 25, after a 679-million-kilometer journey from Earth, in a region called Vastitas Borealis at 68 degrees north latitude, 234 degrees east longitude. It has been sending data about the Martian soil and atmosphere back to scientists ever since. Phoenix is about a third of the way through its scheduled 90-day mission. (See "Perfect Landing Marks Start of New Mission on Mars.")
Peter Smith, Phoenix principal investigator at the University of Arizona-Tucson, leads the mission, with project management at NASA's Jet Propulsion Laboratory and development partnership at Lockheed Martin in Denver.
International contributions come from the Canadian Space Agency, the University of Neuchatel in Switzerland, the universities of Copenhagen and Aarhus in Denmark, the Max Planck Institute in Germany and the Finnish Meteorological Institute.
Doing chemical analysis by sending signals millions of kilometers across space to a robot is "an extraordinarily difficult thing to do and one we've been working on developing for about 10 years," said MECA lead scientist Michael Hecht of NASA's Jet Propulsion Laboratory.
First steps in the analysis are for the robot to take water from Earth that has been frozen solid in a block, melt it, pour it into a container and add a cup of liquid that scientists call a calibration solution. Then Martian soil collected from the surface is added to the container and stirred into mud while scientists monitor data-collecting sensors.
The results from Phoenix, Hecht said, gave scientists the kind of information someone would need to build an autonomous remote greenhouse on Mars.
"We could begin to tell [a biologist] what aspects of the soil on Mars could support the growth of the plants, what nutrients were in the soil, what critical parameters like pH are that would allow the plants to grow, and what [extra nutrients would be needed] to allow that greenhouse to work on Mars. So it's a huge step forward."
The measure pH, which stands for potential hydrogen, indicates whether a substance is acidic or alkaline.
Another analytical Phoenix instrument, the thermal and evolved-gas analyzer (TEGA), which heats samples and identifies vapors from them, has baked its first soil sample to 1,000 degrees Celsius.
TEGA scientists are analyzing the gases released at a range of temperatures to identify the chemical makeup of soil and ice. Analysis is a complicated, weekslong process. (See "Two Phoenix Lander Instruments Begin Examining Martian Dirt.")
Leslie Tamppari, the Phoenix project scientist from JPL, tallied what Phoenix has accomplished during the first 30 Martian days of its mission and outlined future plans.
The stereo surface imager has completed about 55 percent of its three-color, 360-degree panorama of the Phoenix landing site, Tamppari said. Phoenix has analyzed two samples in its optical microscope and first samples in TEGA and the wet chemistry laboratory.
Phoenix has collected information daily on clouds, dust, winds, temperatures and pressures in the atmosphere, and has taken the first nighttime atmospheric measurements. Lander cameras have confirmed that white chunks exposed during the digging of a trench were frozen water ice because they vaporized over a few days.
On July 8, Phoenix touched Martian soil with a fork-like probe for the first time and began using a microscope that examines the shapes of tiny particles by touching them.
The robotic arm pushed the probe's four spikes into undisturbed soil to test the procedure. The prongs of the thermal and electrical conductivity probe are 1.5 centimeters long. The science team will use the probe tool to assess how easily heat and electricity move through the soil from one spike to another to learn about frozen or unfrozen water in the soil.
Meanwhile, the Phoenix team is determining the best way to use TEGA to gather a sample of Martian ice. Researchers are using Phoenix's robotic arm to clear off a patch of hard material uncovered in a shallow trench informally called "Snow White."
In coming days, they will begin using a motorized rasp on the back of the arm's scoop to loosen bits of the hard material that is expected to be rich in frozen water.