It is very easy for us to forget that since 2012, mankind has been driving around a nuclear-powered vehicle about the size of an ordinary SUV on Mars.
This amazing feat of engineering is known as NASA’s Mars rover Curiosity, and has completely revolutionized our knowledge about the red planet. And because of the intrepid rover, we also know that ancient Mars contained some carbon-based compounds we know as organic molecules—which are the key raw materials needed for life.
A brand new study that was recently published in Science offered the very first evidence that large organic molecules exist on Mars’ surface, which was an objective that started with the Viking landers that NASA launched during the 1970s. Previous tests only hinted at the presence of these organics, there was because chlorine that existed within Martian dirt confounded the interpretations at the time.
“When you work with something as crazy as a rover on Mars, with the most complex instrument ever sent to space, it seems like we’re doing what may have been perceived earlier as impossible,” stated study author Jennifer Eigenbrode, who is presently a biogeochemist for NASA at Goddard. “I work with an amazing group of people on Mars, and we have discovered so much.”
Life Substances in a Lake Crater
Curiosity’s most recent data has revealed that a lake that previously filled the Gale Crater on the surface of Mars consisted of some very complex organic molecules that existed around 3.5 billion years ago. Hints of these molecules are yet preserved within some sulfur-spiked rocks collected from the lake sediments. Sulfur could have helped to protect these organics even after the rocks began to be exposed to radiation as well as a bleach-like substance known as perchlorates.
Alone, this new data isn’t enough evidence for the existence of ancient life on Mars because even non-living processes has the potential to yield molecules like these. At a very minimum, the study indicates how traces of past Martians might have survived for ages—if they even existed—and it also hints at the places that rovers in the future could look for them.
“This is an important finding,” said Samuel Kounaves, who is a chemist from Tufts University and also a former lead scientist for the Phoenix Mars lander for NASA. “There are locations, especially subsurface, where organic molecules are well-preserved.”
Periods of Methane
In addition to the ancient carbons, Curiosity has discovered potential organics that actually exist on Mars currently. The rover sniffs the atmosphere of Mars periodically even since it landed there, and in 2014, scientists who had been monitoring this data discovered that methane—one of the simplest of organic molecules—currently exists within Mars’s atmosphere.
The presence of methane on Mars is actually baffling, since it only survives a few hundred years at any one time, which has to mean that something keeps replenishing the source. “It’s a gas in the atmosphere of Mars that really shouldn’t be there,” claims scientist Chris Webster from NASA’s Jet Propulsion Lab.
Also, the behavior of the methane on Mars is quite bizarre. In 2009, scientists observed inexplicable Martian plumes were belching out tons of methane randomly.
Webster’s most recent study that was also published in Science, revealed that Mars “breathes” methane on a seasonal basis. Every Martian summer, the methane concentration in its atmosphere increase to around 0.6 parts per billion. However, during the winter, it drops to around 0.2 parts per billion.
“We don’t have seasonal variations in many molecules in Earth’s atmosphere, so to have a planet have seasonal variations in chemistry is very otherworldly,” noted Eigenbrode. “It’s an astounding observation.”
Webster and his team believe that this phantom methane is coming from the deep underground, and when temperature fluctuates on the surface of Mars, it creates an upward flow. During the winter time, the gases are possibly trapped underground within ice crystals known as clathrates, which then melt away during the summer, thereby freeing the gas.
But as what is actually creating this methane? It is anybody’s guess.
“We really can’t tell if this methane we see today is a current product of serpentinization [a chemical reaction between iron-bearing rocks and liquid water] or microbial activity at some depth,” claims Michael Mumma, who is the NASA scientist from Goddard who originally discovered the methane plumes on Mars methane plumes. “Or is it something that is stored from an ancient time that’s being slowly released?”