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Glass in Martian crater could trap bits of past life, study says

June 8, 2015
Courtesy of Brown University
and World Science staff

Left­o­ver traces of past Mar­tian life could be trapped in pieces of glass on the Red Plan­et, sci­en­tists say in a new stu­dy.

The idea is that me­te­or strikes on a plan­et of­ten form glass in the sear­ing heat of the im­pact. Or­gan­ic mo­le­cules and even bits of plant mat­ter might stay per­ma­nently sealed in this glass. This hap­pens on Earth, ac­cord­ing to one stu­dy. 

A rocky peak in the middle of the Alga Crater on Mars, color-coded to show where glass may lie (green). Blue and red represent other substances (pyroxene and olivine).


Thus re­search­ers hope that even if noth­ing lives on Mars now, its glass could pre­serve traces of life from a past, more hab­it­a­ble phase of the plan­et’s his­to­ry. In the new work, sci­en­tists from Brown Uni­vers­ity in Rho­de Is­land used sat­el­lite da­ta to de­tect glass in Mar­tian craters left be­hind from an­cient im­pacts.

“No one had been able to de­fin­i­tively de­tect [glass] on the sur­face” of Mars be­fore this stu­dy, said Kev­in Can­non, a Ph.D. stu­dent at Brown and the lead au­thor of a re­port on the work. 

Now sev­er­al craters turn out to have glass, ac­cord­ing to the re­port—and one of these is at­tract­ing par­tic­u­lar in­ter­est, partly be­cause it may have formed in a wet ar­ea.

The re­search is pub­lished on­line in the jour­nal Ge­ol­o­gy.

De­tect­ing glassy de­posits with­out phys­ic­ally go­ing to Mars was­n’t easy, the in­ves­ti­ga­tors said, but glass does leave very faint traces in the sun­light that re­flects off Mars be­fore reach­ing Earth.

“Sig­na­tures from the glass tend to be over­whelmed by the chunks of rock mixed in with it,” Mus­tard ex­plained. “But Kev­in found a way to tease that sig­nal out.” Can­non mixed to­geth­er pow­ders with a si­m­i­lar make­up to Mar­tian rocks and fired them in an ov­en to make glass. He then meas­ured the pre­cise spec­trum, or set of col­ors, com­ing from that glass.

The re­search­ers then looked for si­m­i­lar sig­nals in da­ta from an in­stru­ment aboard NASA’s Mars Re­con­nais­sance Or­biter, called the Com­pact Re­con­nais­sance Im­ag­ing Spec­trom­e­ter for Mars. Mus­tard is the dep­u­ty prin­ci­pal in­ves­ti­ga­tor for the in­stru­ment.

That glass turned up in the mid­dle of craters made sense and re­as­sured the in­ves­ti­ga­tors that their meth­od was on track, they said.

One of the ap­par­ently glassy craters is called Har­graves, and it lies near the Nili Fos­sae trough, a 400-mile-long de­pres­sion. The re­gion is one of the lead­ing land­ing site con­tenders for the Mars 2020 rov­er, a mis­sion that aims to cache ground sam­ples for pos­si­ble fu­ture re­turn to Earth.

The trough is al­ready of sci­en­tif­ic in­ter­est be­cause the crust in the re­gion is thought to date from when Mars was a much wet­ter place. The re­gion is al­so rife with what ap­pear to be an­cient hy­dro­ther­mal frac­tures, warm vents that could have pro­vid­ed en­er­gy for life to thrive just be­neath the sur­face.

“If you had an im­pact that dug in and sam­pled that subsur­face en­vi­ron­ment, it’s pos­si­ble that some of it might be pre­served in a glassy com­po­nen­t,” Mus­tard said. “That makes this a pret­ty com­pel­ling place to go look around, and pos­sibly re­turn a sam­ple.”


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Leftover traces of past Martian life could be trapped in pieces of glass on the Red Planet, scientists say in a new study. The idea is that meteor strikes on a planet often form glass in the searing heat of the impact. Organic molecules and even bits of plant matter might stay permanently sealed in this glass. This happens on Earth, according to one study. Thus researchers hope that even if nothing lives on Mars now, its glass could preserve traces of life from a past, more habitable phase of the planet’s history. In the new work, scientists from Brown University in Rhode Island used satellite data to detect glass in Martian craters left behind from ancient impacts. “No one had been able to definitively detect [glass] on the surface” of Mars before this study, said Kevin Cannon, a Ph.D. student at Brown and the lead author of a report on the work. Now several craters turn out to have glass, according to the report—and one of these is attracting particular interest, partly because it may have formed in a wet area. The research is published online in the journal Geology. Detecting glassy deposits without physically going to Mars wasn’t easy, the investigators said, but glass does leave very faint traces in the sunlight that reflects off Mars before reaching Earth. “Signatures from the glass tend to be overwhelmed by the chunks of rock mixed in with it,” Mustard explained. “But Kevin found a way to tease that signal out.” Cannon mixed together powders with a similar makeup to Martian rocks and fired them in an oven to make glass. He then measured the precise spectrum, or set of colors, coming from that glass. The researchers then looked for similar signals in data from an instrument aboard NASA’s Mars Reconnaissance Orbiter, called the Compact Reconnaissance Imaging Spectrometer for Mars. Mustard is the deputy principal investigator for the instrument. That glass turned up in the middle of craters made sense and reassured the investigators that their method was on track, they said. One of the apparently glassy craters is called Hargraves, and it lies near the Nili Fossae trough, a 400-mile-long depression. The region is one of the leading landing site contenders for the Mars 2020 rover, a mission that aims to cache soil and rock samples for possible future return to Earth. The trough is already of scientific interest because the crust in the region is thought to date from when Mars was a much wetter place. The region is also rife with what appear to be ancient hydrothermal fractures, warm vents that could have provided energy for life to thrive just beneath the surface. “If you had an impact that dug in and sampled that subsurface environment, it’s possible that some of it might be preserved in a glassy component,” Mustard said. “That makes this a pretty compelling place to go look around, and possibly return a sample.”