Astrobiologists got excited with evidence for early water on Mars, but other discoveries are putting the quash on hopes it has or had life.
We can only observe Mars in the present. Current evidence might suggest past realities, but can only infer probabilities for the past, based on one’s assumptions. What we know today from the Mars rover Curiosity and other sources is that: (1) some Martian minerals contain water; (2) Curiosity has failed to detect methane, a potential biomarker; and (3) perchlorate in the soil would be toxic to life.
Perchlorates (compounds containing chlorine and oxygen) were first detected near the Martian north pole by the Mars Polar Lander Phoenix (Wikipedia). Now, perchlorates have been found by Curiosity in Gale Crater, reported Science Daily, PhysOrg and Astrobiology Magazine; “This finding at Curiosity’s equatorial site suggests more global distribution” of perchlorates, according to a JPL Mars Science Laboratory press release. These “troublesome chemicals” can interfere with the SAM (Sample Analysis on Mars) instrument’s search for organic molecules, because they give off oxygen that rapidly destroys evidence of their existence. As a result, “The quest for evidence of life on Mars could be more difficult than scientists previously thought.”
Some water: Evidence for water-containing minerals, therefore (as reported by Science Daily), is little consolation in the face of the bad news. Soil minerals dug up from the Curiosity rover’s arm were found to contain several percent water by weight. Even though described as a “Wow moment” for the mission team, the finding of toxic chlorinating chemicals in the same environment is not conducive to life now or in the past. This puts a wet blanket on recent suggestions that Earth life might have come from Mars (see 9/07/13).
Still, if water could be mined right out of the soil, it might be handy for future manned missions to Mars – but then there are the damned perchlorates. “If the water was the good news for the astronauts,” the BBC News remarked, “this is the bad news.” Ingesting some of the fine-grained soil could “interfere with thyroid function,” the article explained.
No methane: Years ago, hints of methane in the Martian atmosphere temporarily aroused excitement it might be a whiff from life. Unfortunately, the Mars Science Laboratory (MSL) rover Curiosity has failed to detect methane, a JPL press release announced. “It reduces the probability of current methane-producing Martian microbes, but this addresses only one type of microbial metabolism,” an MSL scientist cautioned. It would have been “exciting to find” methane, but “We measured repeatedly from Martian spring to late summer, but with no detection of methane.”
Veteran atmospheric scientist Sushil Atreya said if it was there, it should have been detectable, because it would take centuries for the methane to deplete. He was insistent about it: “Without a way to take it out of the atmosphere quicker, our measurements indicate there cannot be much methane being put into the atmosphere by any mechanism, whether biology, geology, or by ultraviolet degradation of organics delivered by the fall of meteorites or interplanetary dust particles.”
Researchers have hung on to the hope that the molecule’s signature at Mars might also indicate a life presence.
The inability of Curiosity’s sophisticated instrumentation to make this detection is likely now to dent this optimism. (BBC News)
In its coverage, Science Magazine rather indelicately quipped, “Mars Rover Finds No Evidence of Burps or Farts.” The editor must gotten some Bronx cheers for that one. The headline now reads, “Not a Whiff of Life on Mars” – leaving unanswered the burning question of whether emission of methane by a microbe qualifies as a fart.
How’s that for a gift of a segue? Astrobiological speculation about the origin and evolution of life is about as useful and desirable, scientifically speaking, as a – shall we say – sudden eruption of particulate-laden vaporous emissions from the lower end of a GI tract. Eat Darwin-brand philosophy with your science, and a certain venting of fogma is predictable. Scientific observations constitute the nutritious part. They are absorbed to become the meat, bone and sinew of scientific understanding. The evolutionary junk food, though, based on hopes, assumptions and improbable expectations – like cotton candy, lacking substance – breaks down into its constituent volatiles. When not quickly belched out to the press, the vapor gets refined on its journey, mixed with the methane of storytelling and the hydrogen sulfide of relativism, till it reaches the back orifice, where hordes of journal editors and science reporters await the product. It wrecked ‘em. They thought it would give them a “high” of understanding. Instead, it contributed less to knowledge than to angry partisanship, a kind of global warming. Maybe the planet would benefit from some climate change – in the other direction. Cool it, Charlie. Kick the DIDO habit. Go on a health food diet.