Commentary | Searching for Subsurface Life on Mars
It has been two years since the Curiosity rover successfully landed on Mars and it has been a remarkable success. However, the most exciting phase of its mission is about to start. When it arrives at Mount Sharp, it will view spectacular vistas unlike anything we have seen on Mars. Huge formations of stratified rock will be visible. Not only will the layers in these rocks show us the geological past of Mars more clearly than ever before, but they could very well shed light on whether Mars ever sustained life.
Of course, Curiosity is not able to confirm current life, and neither will the 2020 rover. This is unfortunate. Since there is general agreement that the search for life on Mars is one of the top goals of the Mars program, we should be more aggressive in the search.
But there is hope. The radiation environment on the surface of Mars is deadly for organic material, including any sort of macrobiotic life. But only meters beneath the surface, where previous martian probes have already detected water ice, there may exist a protected layer where life once thrived, or perhaps even still exists.
One option for searching for this martian life was recently announced at American University. On July 31, Explore Mars officially unveiled its ExoLance project, which aims to deliver a life detection experiment 1-3 meters below the martian surface using deep earth penetrators. Explore Mars announced that it will be funding the first phase of ExoLance through an Indiegogo crowdfunding campaign from August through September (see www.indiegogo.com/projects/exolance). The goal is to build and initially test the delivery system within 12 months.will provide in-kind expertise including computer modeling of the impact. Other organizations supporting ExoLance include Uwingu, the Planetary Society and the National Institute of Aerospace.
In the first 12-month phase of ExoLance, Explore Mars will develop and test the penetrator delivery system to verify whether this concept is feasible. If the concept proves viable and demonstrates an effective, low-cost and robust method of getting below the martian surface, then the next step will be to try it — and why wouldn’t we?
Explore Mars is currently reviewing various options for delivery to Mars, but would prefer to send ExoLance on a currently planned mission. This creates substantial challenges. Payloads for these landing missions have already been selected and mission planners would be hesitant to add mass and risk to these missions.
There is a delivery option that the ExoLance team will investigate that would not add any substantial mass to the mission — ballast. Some Mars landers (such as Curiosity) bring along ballast that is ejected at various points of entry, descent and landing. Since this weight has to be brought and ejected, why not replace the ballast with ExoLance arrows? While it is probably more easily said than done, one of the goals of Phase 1 of ExoLance will be to see if this option is technically feasible and if it would add additional risk to the primary mission.
The ExoLance team will also look at other penetrator concepts — such as NASA’s Deep Space 2 probe — to see what elements of those concepts may be helpful to ensure success for ExoLance. In particular, it will identify risk reduction ideas to help guarantee a higher probability of success.
If it is determined that the penetrators work as proposed, the ExoLance science team is looking at science payload options. One such option is a process in chemistry called chirality. Many chemicals, nutrients included, come in two forms that are identical down to the atom but have different construction. They differ like a person’s hands — mirror images, identical in composition, but not superposable. ExoLance’s science experiment involves a metabolic test that clearly distinguishes nonliving chemistry from the chemistry produced from metabolism of living microorganisms.
What makes this experiment even more intriguing is that if it detects life, it will also be able to determine whether that life is related to life on Earth or is a new strain of life — a separate “genesis.”
In addition, Explore Mars proposes that multiple penetrators be released during entry, descent and landing to impact over a wide area to provide a greater chance of detection in different terrains.
If the ultimate goal is to search for life on Mars, then we should be searching for life. With government funding for space exploration becoming more and more difficult to obtain, new ideas for exploration must be examined. Explore Mars, its partners and supporters are stepping up to try to answer one of the most fundamental questions of life — are we alone in the universe?
Chris Carberry is executive director of Explore Mars, and Blake Ortner is the group’s director of D.C. Ops.