Salt might have thwarted Martian life
Feb 22,2008 00:00 by Bend_Weekly_News_Sources

Sci­en­tists have dreamed of find­ing ev­i­dence for past life on Mars, where they be­lieve there was once plen­ty of liq­uid wa­ter. But now they’re say­ing it might have been too salty.

“Not all wa­ter is fit to drink,” said An­drew Knoll, a Har­vard Uni­ver­s­ity bi­olo­g­ist who is on the sci­ence team for the NASA Mars rov­er Op­por­tun­ity. 

High con­centra­t­ions of dis­solved min­er­als as well as ac­ids may have thwar­t­ed mi­crobes from de­vel­op­ing on the red plan­et, he added.

Mars as seen by the Hub­ble Space Tel­e­scope (cred­it: Li­sa Frat­tare/STScI)

Op­por­tun­ity and its twin, Spir­it, be­gan their fifth year on Mars last month af­ter prov­ing about 16 times longer-lasting than ex­pected, ac­cord­ing to sci­en­tists. 

At a meet­ing of the Amer­i­can As­so­cia­t­ion for the Ad­vance­ment of Sci­ence in Bos­ton on Feb. 15, re­search­ers dis­cussed the rov­ers’ re­cent dis­cov­er­ies.

Op­por­tun­ity spent re­cent months ex­am­in­ing a bright band of rocks around the in­ner wall of a crat­er in the pla­net’s Ter­ra Merid­i­ani re­gion. The cra­ter turned out to lie atop an un­der­ground wa­ter ta­ble, ac­cord­ing to sci­en­tists. Knoll said the rov­er—which serves as a robotic ge­ol­o­gist—found that the wa­ter, which once cov­ered the ar­ea, left be­hind ev­i­dence of its high ac­id­ity and salin­ity.

“This tight­ens the noose on the pos­si­bil­ity of life,” con­si­der­ing salt is a pre­ser­va­tive, he added. Con­di­tions may have been more hospita­ble ear­li­er, with wa­ter less briny, Knoll said. But “life at the Mar­tian sur­face would have been very chal­leng­ing for the last 4 bil­lion years. The best hopes for a sto­ry of life on Mars are at en­vi­ron­ments we haven’t stud­ied yet—older ones, subsur­face ones.”

Courtesy Jet Propulsion Laboratory and World Science staff