NASA‘s Curiosity rover has yet to confirm the detection of organic compounds on Mars, however, it has shown that the Mars’ soil contains water and more complex chemicals, as well as signs of an intriguing compound called perchlorate.
According to NBC News, the first soil sample analysis from Curiosity’s Sample Analysis at Mars (SAM) lab was the leading topic today at the American Geophysical Union’s fall meeting in San Francisco.
The findings were much anticipated because of rumors that the Curiosity team was on the verge of announcing major findings. Even though NASA lowered their expectations, the scientists said they were overjoyed with the first round of analysis.
“We really consider this a terrific milestone,” Paul Mahaffy, a NASA researcher who is SAM’s lead scientist, said at the AGU briefing.
Mahaffy said in a statement issued by NASA’s Jet Propulsion Laboratory:
“We have no definitive detection of Martian organics at this point, but we will keep looking in the diverse environments of Gale Crater.”
Curiosity landed on Mars in Gale Crater on Aug. 5, and since then it’s been studying Martian rocks, soil, and atmosphere with the help of ten scientific instruments. Its two-year, $2.5 billion mission is aimed at determining whether conditions in the crater were ever conducive for microbial life.
SAM is a key tool for that mission. It can cook Martian samples in a mini-oven and then analyze the gases that are given off to identify the compounds contained in the sample. Other instruments, including the Chemistry and Mineralogy instrument (CheMin), were also used to study the initial soil samples that were collected over the past several weeks.
These samples were collected from a drift of windblown sand and dust called Rocknest.
NASA said CheMin found that the composition of the Rocknest samples was similar to that of soil analyzed by other Mars rovers such as Pathfinder, Spirit, and Opportunity. The composition consisted of about half common volcanic minerals, and half non-crystalline minerals such as glass.
SAM identified other ingredients in much lower concentrations, which included water molecules that were apparently bound to the grains of sand and dust. Although the water wouldn’t be enough to support any sort of life, the concentration found was higher than expected.
SAM also identified a type of perchlorate, a compound that includes oxygen and chlorine. Perchlorate, which was also found by NASA’s Phoenix Mars Lander in 2008, is considered a toxic substance and is used as an ingredient in rocket fuel on Earth. But scientists say the compound could conceivably serve as an energy source for microbes on Mars.
Mahaffy said the particular type of compound detected by Curiosity appeared to be calcium perchlorate, but “we have to study that further.”
Reactions with other chemicals in SAM’s oven formed chlorinated methane compounds, which geologists consider organic chemicals because they contain carbon and hydrogen.
Mahaffy said it was most likely that the chlorine came from a perchlorate-like compound in the soil. However, he did say that it wasn’t yet clear whether the tiny amount of carbon in the compounds came from the Martian soil or was actually brought to Mars from Earth by Curiosity itself.
Mahaffy told reporters:
“We have to be very careful to make sure both the carbon and the chlorine are coming from Mars.”
Caltech’s John Grotzinger, the project scientist for Curiosity’s mission, agreed with that view. He said:
“We just simply don’t know if they’re indigenous to Mars or not.”
Grotzinger said that the team would first have to confirm that the constituents of the organic compounds seen by SAM truly came from Mars. If the presence of organics is confirmed, then the scientists would have to look into whether they are merely part of the “background fall of cosmic material” onto the planet, or arose through chemical processes on Mars itself.
It would take a step-by-step process to confirm the presence of truly Martian organic compounds, and reconstruct how those compounds were formed.
Grotzinger explains what would happen next:
“Then you have … to decide whether or not those formation pathways are abiotic, or maybe in the end biologic. So you see there’s a complicated decision pathway there, and we have to explore each one systematically.”
Grotzinger cautioned that there would be no “hallelujah moment” in the search for organic chemicals on Mars.