"Long before it's in the papers"
June 04, 2013

RETURN TO THE WORLD SCIENCE HOME PAGE


Martian salts not bad for life: scientists

Aug. 6, 2008
Courtesy NASA
and World Science staff

Sci­en­tists with NASA’s Phoe­nix Mars mis­si­on spoke Tues­day about an on­go­ing in­ves­ti­ga­tion of per­chlo­rate salts de­tected in soil by the Phoe­nix Lan­der.

The find­ing “is nei­ther good nor bad for life, but it does make us re­as­sess how we think about life on Mars,” said Mi­chael Hecht of NASA’s Je­t Pro­pul­si­on Lab­o­r­a­to­ry in Pas­a­de­na, Calif.

The Phoenix land­ing site on north­ern Mars as pho­to­graphed from the lan­der. (Im­age cre­dit: NA­SA/JPL-Cal­tech/U. of Ari­zona/Tex­as A&M U.)


Re­search­ers spoke in re­sponse to news re­ports claim­ing the dis­cov­ery had dam­aged the pros­pects for life on Mars. The mis­si­on team had wanted to per­form furth­er checks on the find­ing be­fore re­port­ing it, but said the news re­ports prompted them to speak out now. 

Hecht is lead sci­ent­ist for the Mi­cros­co­py, Elec­tro­chem­istry and Con­duc­ti­vity An­a­lyz­er or MECA, the in­stru­ment that in­cludes Phoe­nix’s wet chem­is­try lab­o­r­a­to­ry.

If con­firmed, the re­sult is ex­cit­ing, Hecht said, “be­cause dif­fer­ent types of per­chlo­rate salts have in­ter­est­ing prop­er­ties that may bear on the way things work on Mars if—and that’s a big ‘if ’—the re­sults from our two tea­spoons of soil are rep­re­sent­a­tive of all of Mars,” or at least much of it.

“The Phoe­nix proj­ect has de­cid­ed to take an un­usu­al step” in talk­ing about the re­search when its sci­ent­ists are only about half-way through the da­ta col­lec­ti­on, said Phoe­nix prin­ci­pal in­ves­ti­ga­tor Pe­ter Smith of the Uni­ver­s­ity of Ar­i­zo­na, Tuc­son.

“We de­cid­ed to show the pub­lic sci­ence in ac­ti­on be­cause of the ex­treme in­ter­est in the Phoe­nix mis­si­on, which is search­ing for a hab­it­a­ble en­vi­ron­ment on the north­ern plains of Mars,” Smith added. “Right now, we don’t know wheth­er find­ing per­chlo­rate is good news or bad news for pos­si­ble life on Mars.” 

Per­chlo­rate is an ion, or charged par­t­i­cle, that con­sists of an at­om of chlo­rine sur­rounded by four ox­y­gen at­oms. It is an ox­i­dant, that is, it can re­lease ox­y­gen, but it is not a pow­er­ful one. Per­chlo­rates are found nat­u­rally on Earth at such places as Chile’s hyper-arid At­a­cama Des­ert. The com­pounds are quite sta­ble and do not de­stroy or­gan­ic ma­te­ri­al un­der nor­mal cir­cum­stances, re­search­ers said. Some mi­croor­gan­isms on Earth are fu­eled by pro­cesses that in­volve per­chlo­rates, and some plants con­cen­trate the sub­stance. Per­chlo­rates are al­so used in rock­et fu­el and fire­works.

Per­chlo­rate was dis­cov­ered with a mul­ti­-use sen­sor that de­tects per­chlo­rate, ni­trate and oth­er ions. The MECA team saw the per­chlo­rate sig­nal in a sam­ple tak­en from the Dodo-Goldilocks trench on June 25, or Sol 30, or the 30th Mar­tian day of the mis­si­on af­ter land­ing, and again in anoth­er sam­ple tak­en from the Snow White trench on July 6, or Sol 41.

The ad­di­ti­on­al checks were be­ing done with anoth­er lan­der in­stru­ment, the Ther­mal and Evolved Gas An­a­lyz­er or TEGA, which heats soil and an­a­lyzes gas­es driv­en off. When that in­stru­ment heat­ed a sam­ple of soil dug from the Dodo-Goldilocks trench on Sol 25 to high tem­per­a­ture, it de­tected an ox­y­gen re­lease, said TEGA lead sci­ent­ist Wil­liam Boyn­ton of the Uni­ver­s­ity of Ar­i­zo­na.

Per­chlo­rate could be one of sev­er­al pos­si­ble sources of this ox­y­gen, he said. Late last week, when TEGA an­a­lyzed anoth­er sam­ple, this one from the Snow White trench, the TEGA team looked for chlo­rine gas. The in­stru­ment de­tected none. “Had we seen it, the iden­ti­fica­tion of per­chlo­rate would be ab­so­lutely clear, but in this run we did not see any chlo­rine gas. We may have been an­a­lyz­ing a per­chlo­rate salt that does­n’t re­lease chlo­rine gas up­on heat­ing,” Boyn­ton said.


* * *

Send us a comment on this story, or send it to a friend

 

Sign up for
e-newsletter
   
 
subscribe
 
cancel

On Home Page         

LATEST

  • Meet­ing on­line may lead to hap­pier mar­riages

  • Pov­erty re­duction, environ­mental safe­guards go hand in hand: UN re­port

EXCLUSIVES

  • Was black­mail essen­tial for marr­iage to evolve?

  • Plu­to has even cold­er “twin” of sim­ilar size, studies find

  • Could simple an­ger have taught people to coop­erate?

  • Diff­erent cul­tures’ mu­sic matches their spe­ech styles, study finds

MORE NEWS

  • F­rog said to de­scribe its home through song

  • Even r­ats will lend a help­ing paw: study

  • D­rug may undo aging-assoc­iated brain changes in ani­mals

Scientists with NASA’s Phoenix Mars mission spoke Tuesday about an ongoing investigation of perchlorate salts detected in soil analyzed by the Phoenix Lander. “Finding perchlorates is neither good nor bad for life, but it does make us reassess how we think about life on Mars,” said Michael Hecht of NASA’s Jet Propulsion Laboratory, Pasadena, Calif.. Researchers said they spoke out in response to recent news reports claiming the discovery had damaged the prospect for life on Mars. The mission team had wanted to perform additional checks on the finding before reporting on it, but said the news reports prompted them to speak out now. Hecht is lead scientist for the Microscopy, Electrochemistry and Conductivity Analyzer or MECA, the instrument that includes Phoenix’s wet chemistry laboratory. If confirmed, the result is exciting, Hecht said, “because different types of perchlorate salts have interesting properties that may bear on the way things work on Mars if—and that’s a big ‘if ‘—the results from our two teaspoons of soil are representative of all of Mars, or at least a significant portion of the planet.” “The Phoenix project has decided to take an unusual step” in talking about the research when its scientists are only about half-way through the data collection, said Phoenix principal investigator Peter Smith of the University of Arizona, Tucson. “We decided to show the public science in action because of the extreme interest in the Phoenix mission, which is searching for a habitable environment on the northern plains of Mars,” Smith added. “Right now, we don’t know whether finding perchlorate is good news or bad news for possible life on Mars.” Perchlorate is an ion, or charged particle, that consists of an atom of chlorine surrounded by four oxygen atoms. It is an oxidant, that is, it can release oxygen, but it is not a powerful one. Perchlorates are found naturally on Earth at such places as Chile’s hyper-arid Atacama Desert. The compounds are quite stable and do not destroy organic material under normal circumstances, researchers said. Some microorganisms on Earth are fueled by processes that involve perchlorates, and some plants concentrate the substance. Perchlorates are also used in rocket fuel and fireworks. Perchlorate was discovered with a multi-use sensor that detects perchlorate, nitrate and other ions. The MECA team saw the perchlorate signal in a sample taken from the Dodo-Goldilocks trench on June 25, or Sol 30, or the 30th Martian day of the mission after landing, and again in another sample taken from the Snow White trench on July 6, or Sol 41. The additional checks were being done with another lander instrument, the Thermal and Evolved Gas Analyzer or TEGA, which heats soil and analyzes gases driven off When TEGA heated a sample of soil dug from the Dodo-Goldilocks trench on Sol 25 to high temperature, it detected an oxygen release, said TEGA lead scientist William Boynton of the University of Arizona. Perchlorate could be one of several possible sources of this oxygen, he said. Late last week, when TEGA analyzed another sample, this one from the Snow White trench, the TEGA team looked for chlorine gas. The instrument detected none. “Had we seen it, the identification of perchlorate would be absolutely clear, but in this run we did not see any chlorine gas. We may have been analyzing a perchlorate salt that doesn’t release chlorine gas upon heating,” Boynton said. “There’s nothing in the TEGA data that contradicts MECA’s finding of perchlorates.” As the Phoenix team continues its investigation of the artic soil, the TEGA instrument will attempt to validate the perchlorate discovery and determine its concentration and properties.