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NASA: snow found in Martian skies

Sept. 29, 2008
Courtesy NASA
and World Science staff

NASA’s Phoe­nix Mars Lan­der has de­tected snow fall­ing from Mar­tian clouds, sci­en­tists say, and space­craft soil tests have given ev­i­dence of past in­ter­ac­tion be­tween min­er­als and liq­uid wa­ter, pro­cesses seen on Earth. 

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, the re­search­ers re­ported. Da­ta show the snow va­por­iz­ing be­fore reach­ing the ground. 

Athin lay­er of wa­ter frost is vis­i­ble on the ground around NA­SA's Phoe­nix Mars Lan­der in this im­age tak­en by the machine's Sur­face Stereo Im­ag­er the morn­ing of Aug. 14, re­search­ers say. The frost be­gins to dis­ap­pear short­ly af­ter 6 a.m. as the sun rises on the Phoe­nix land­ing site. The im­age is col­or-enhanced to re­veal col­or vari­a­tions. (Cred­it: NA­SA/JPL-Caltech/U. of Ari­zon­a/Texas A&M U.)
“Noth­ing like this” has been found be­fore 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.” No pho­to­graphs were tak­en of the pur­ported snow.

Phoe­nix ex­pe­ri­ments al­so yielded clues point­ing to cal­ci­um car­bon­ate, the main com­po­nent of chalk, and par­t­i­cles that could be clay, agen­cy sci­en­tists said. Most car­bon­ates and clays on Earth form only in the pres­ence of liq­uid wa­ter. 

“We are still col­lect­ing da­ta and have lots of anal­y­sis ahead, but we are mak­ing good prog­ress on the big ques­tions we set out for our­selves,” said Phoe­nix Prin­ci­pal In­ves­ti­ga­tor Pe­ter Smith of the Uni­ver­s­ity of Ar­i­zo­na, Tuc­son. 

Since land­ing on May 25, Phoe­nix has con­firmed that a hard subsur­face lay­er at its far-northern site con­tains wa­ter-ice, ac­cord­ing to re­search­ers. De­ter­min­ing wheth­er that ice ev­er thaws would help an­swer wheth­er the en­vi­ron­ment there has been fa­vor­a­ble for life, a key aim of the mis­sion. 

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 MECA. 

“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 Phoe­nix mis­sion, orig­i­nally planned for three months on Mars, now is in its fifth month. But it faces a de­cline in so­lar en­er­gy that is ex­pected to cur­tail and then end the lan­der’s ac­ti­vi­ties be­fore the end of the year. Be­fore pow­er ceases, the Phoe­nix team plans to try to ac­tivate a mi­cro­phone on the lan­der to pos­sibly cap­ture sounds on Mars. 

“For nearly three months af­ter land­ing, the sun nev­er went be­low the ho­ri­zon at our land­ing site,” said Bar­ry Gold­stein, Phoe­nix proj­ect man­ag­er at NASA’s Je­t Pro­pul­sion Lab­o­r­a­to­ry in Pas­a­de­na, Ca­lif. “Now it is gone for more than four hours each night, and the out­put from our so­lar pan­els is drop­ping each week. Be­fore the end of Oc­to­ber, there won’t be enough en­er­gy to keep us­ing the robotic ar­m.”

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NASA’s Phoenix Mars Lander has detected snow falling from Martian clouds, scientists say. Spacecraft soil experiments also have provided evidence of past interaction between minerals and liquid water, processes that occur on Earth. 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, the researchers reported. Data show the snow vaporizing before reaching the ground. “Nothing like this” has been found before 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.” No photographs were taken of the purported snow. Phoenix experiments also yielded clues pointing to calcium carbonate, the main component of chalk, and particles that could be clay, agency scientists said. Most carbonates and clays on Earth form only in the presence of liquid water. “We are still collecting data and have lots of analysis ahead, but we are making good progress on the big questions we set out for ourselves,” said Phoenix Principal Investigator Peter Smith of the University of Arizona, Tucson. Since landing on May 25, Phoenix already has confirmed that a hard subsurface layer at its far-northern site contains water-ice, according to researchers. Determining whether that ice ever thaws would help answer whether the environment there has been favorable for life, a key aim of the mission. 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 MECA. “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 Phoenix mission, originally planned for three months on Mars, now is in its fifth month. But it faces a decline in solar energy that is expected to curtail and then end the lander’s activities before the end of the year. Before power ceases, the Phoenix team plans to try to activate a microphone on the lander to possibly capture sounds on Mars. “For nearly three months after landing, the sun never went below the horizon at our landing site,” said Barry Goldstein, Phoenix project manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Now it is gone for more than four hours each night, and the output from our solar panels is dropping each week. Before the end of October, there won’t be enough energy to keep using the robotic arm.”