A better way to search for traces of life on Mars — and beyond! (op-ed)

Catching a ride on a drone, OrganiCam could swoop into lava-tube caves on Mars to search for organic molecules marked by the tell-tale signature of life.
Catching a ride on a drone, OrganiCam could swoop into lava-tube caves on Mars to search for organic molecules marked by the tell-tale signature of life. (Image credit: Los Alamos National Laboratory))

Patrick Gasda is a staff scientist in the Space Science and Applications group at Los Alamos National Laboratory. As a member of the OrganiCam team, he works with team leader Roger Wiens to study the geochemistry and astrobiology of Europa. The concept phase of OrganiCam is being funded by the Laboratory Directed Research and Development program. Gasda contributed this article to Space.com's Expert Voices: Op-Ed & Insights.

In the disappointing absence of little green aliens on one of Jupiter's moons or a canal-building civilization on Mars, hunting for life beyond Earth stretches our scientific and technological prowess to the limits. If we do find life out there, it will be tiny, on the molecular scale.

After a successful launch in late July, NASA's Perseverance rover is sailing silently through space on its seven-month journey to Mars, where it will scour Jezero Crater for evidence of habitability and life. In this peaceful interlude before the rover's Red Planet touchdown early next year, we have time to think about future missions seeking life on other planetary bodies across the solar system. 

Related: 6 most likely places for alien life in the solar system

Those missions will hunt for biological organic molecules, the carbon-based building blocks that make up all living things that we know. That's because, if we eventually do find life — or evidence of past life — on Mars or somewhere else, it's not going to be a little green alien. It's going to be a biomolecule or fossilized bacterial life. 

The search focuses on habitable environments on Mars and beyond. Recent missions to the outer planets have observed evidence of water-vapor plumes from Jupiter's moon Europa, which raises the intriguing possibility of organic molecules on its surface, originating from the ocean below. Spacecraft have detected organic molecules within plumes emanating from Saturn's moon Enceladus. Most recently, NASA's Dawn spacecraft flew within 22 miles (35 kilometers) of the surface of Ceres, a dwarf planet in the asteroid belt, and detected brine and a likely vast, deep reservoir of liquid salt water.  

These are all high-priority places to look.

As one of the likeliest places to find life — and certainly the closest — Mars continues to command our attention. Although the cold, dry land, thin atmosphere, and extreme radiation at the surface are hostile to life, NASA's Curiosity rover, which is now exploring Mars, has found organic molecules. But are they biological? It's hard to tell because any molecules on the surface would have been severely damaged by radiation over millions of years.  

Biological organics might be more widespread in the lava-tube caves on Mars. Sheltered deep in the underground, life might once have thrived — or still does? — in salty brines that seeped from now-disappeared surface lakes. Salty water has a lower freezing temperature than plain water, and deep underground heat from Mars' mantle might keep water liquid. 

To find out if life might have formed any of the organic molecules on Mars, we've got to send instruments capable of answering that question, but exploring Mars deep underground is a daunting task. Most known lava tubes on Mars have at least one skylight opening to the surface. While we don't know how deep these caves are, their mouths are 300 feet (91 meters) wide, and some are thought to descend at least a quarter-mile (0.4 km) underground. 

Why not fly in? To do so, our instruments must be simple, rugged, lightweight and compact. The same goes for sending instruments to the rugged, icy, high-radiation environments of Europa, Enceladus or Ceres. To meet these challenging criteria, Los Alamos National Laboratory has leveraged expertise designing and fielding instruments for space exploration to develop a new model, OrganiCam. 

Life on Mars: Exploration and evidence

One precursor instrument developed at Los Alamos, ChemCam, is currently exploring Mars on the Curiosity rover. Sitting high on the rover's mast, ChemCam fires an infrared laser beam at rocks and soils, creating a hot plasma. The instrument then measures the colors of light in the plasma, which provide clues about the rocks' elemental composition. A camera provides highly detailed photographs of the laser targets, which also help scientists determine the surface geology. 

ChemCam's discoveries have deepened our knowledge of Mars as a once warmer and more habitable planet, revolutionized our understanding of the planet's geology, and prompted us to revise upward our estimates of the former abundances of surface water and oxygen in the atmosphere — both conditions for life. 

SuperCam, developed jointly by Los Alamos with the French space agency, is ChemCam on steroids. Now sailing to Mars as part of Perseverance's Mars 2020 mission, SuperCam combines ChemCam's remote chemistry capabilities and imaging with two mineralogy techniques, making it even better at detecting compounds related to the possibility of life. On top of that, it can record sound through a microphone, a first on Mars. 

As the next branch of the family tree, OrganiCam brings further innovations, including unique fast-fluorescence imaging for detecting not just organics, but biomolecules. Here's how it works. When stimulated by the laser, biological organic molecules emit quick bursts of light (about 100 nanoseconds). But other materials, like rock, emit light more slowly (microseconds to milliseconds). OrganiCam uses the same super-fast camera as SuperCam to measure these fast emissions, letting us discriminate biological signals from the background rocks. As a next step in the instrument's analysis, Raman spectroscopy identifies the molecular structure of the biological materials, so we can tell limestone from a volcanic rock. 

OrganiCam also features ultra-radiation-hardened lenses, greater energy efficiency and a lighter and more compact design than its predecessors, so a small drone could carry it to far more places on Mars than it could go by piggybacking on a rover. Even better, a drone could whisk the instrument deep into one of those lava-tube caves. OrganiCam could also easily be adapted to a mission on an icy world. (You can watch a video about OrganiCam here.)

OrganiCam can be pointed at more earthly pursuits as well. It can nondestructively detect biological materials in unique samples without destroying them, such as material returned by missions from the outer planets and asteroids, and it can assess the presence of biological organics in cleanrooms, hospitals or other sterile facilities, to help stem the spread of infections or impurities in industrial processes. 

While these are worthy assignments for this new instrument, for those of us on the Los Alamos team that developed OrganiCam, the lure of finding evidence of life on another planet, a moon, an asteroid or a comet is the overwhelming motivation. A discovery of that magnitude is every scientist's dream. I hope we get the chance. 

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