29 September 2008

Phoenix Sees Snow and Carbonates on Mars!

Posted by Ryan Anderson

Big news from the Phoenix lander! A new JPL press release just came out, announcing the detection of snow and carbonates on Mars! From the press release:

A laser instrument designed to gather knowledge of how the atmosphere and surface interact on
Mars has detected snow from clouds about 4 kilometers (2.5 miles) above the spacecraft’s landing
site. Data show the snow vaporizing before reaching the ground.

“Nothing like this view has ever been seen on Mars,” said Jim Whiteway, of York University,
Toronto, lead scientist for the Canadian-supplied Meteorological Station on Phoenix. “We’ll be
looking for signs that the snow may even reach the ground.”

The evidence for calcium carbonate in soil samples from trenches dug by the Phoenix robotic arm
comes from two laboratory instruments called the Thermal and Evolved Gas Analyzer, or TEGA,
and the wet chemistry laboratory of the Microscopy, Electrochemistry and Conductivity Analyzer, or

“We have found carbonate,” said William Boynton of the University of Arizona, lead scientist for
the TEGA. “This points toward episodes of interaction with water in the past.”

The TEGA evidence for calcium carbonate came from a high-temperature release of carbon dioxide
from soil samples. The temperature of the release matches a temperature known to decompose
calcium carbonate and release carbon dioxide gas, which was identified by the instrument’s mass

The MECA evidence came from a buffering effect characteristic of calcium carbonate assessed in
wet chemistry analysis of the soil. The measured concentration of calcium was exactly what would
be expected for a solution buffered by calcium carbonate.

Both TEGA, and the microscopy part of MECA, have turned up hints of a clay-like substance. “We
are seeing smooth-surfaced, platy particles with the atomic-force microscope, not inconsistent with
the appearance of clay particles,” said Michael Hecht, MECA lead scientist at NASA’s Jet
Propulsion Laboratory in Pasadena, Calif.

I’ll keep you updated as I learn more!

Update: Emily has a very detailed update, with lots of other cool news as well!