The Search for Life on Mars Must Start Now

Cite as: Špaček, J. (2021) “The Search for Life on Mars Must Start Now”. Primordial Scoop, 2021, e0211. https://doi.org/10.52400/HYAD5567

The Space Race is on again, and short of a global apocalypse, we can expect humans walking on Mars within the next 20 years. If NASA is serious about the planetary protection we either need to ban interplanetary human travel or determine if life is present on Mars within the next decade or two.

A global ban on human interplanetary travel would be impossible to enforce once the interplanetary transportation technology is available. The plan to do manned missions after we find or disprove life on Mars does not apply to the current situation, where several independent entities want to reach Mars. Soon to be developed affordable space travel pushes us to flip the script and do a large-scale life screening before humans land. Those concerned about planetary protection have only one option: Work must begin today on affordable robotic large-scale screening for present-day Martian life.

The risks posed by manned missions to Mars and Earth environments have been listed by NASA (Fig. 1) and the Committee on Space Research (COSPAR):

1. Mars explorers bring back Martian life that will harm humanity (backward contamination). Protection from this thread is the highest priority.
2. Explorers deliver Terran microorganisms to the Martian surface (forward contamination), which damages the Martian biome before humanity has a chance to study it, a tragic loss to science. Extermination of a planetary biosphere is (still perceived as) an ethical issue. Hence, protection of extraterrestrial life is the second most important priority of planetary protection.
3. As “it will not be possible for all human-associated processes and mission operations to be conducted within entirely closed systems”, Earth-originated biomolecules and organisms will likely hinder any search for native Martian life by creating false positive signals (Rummel and Conley, 2018).

In my opinion, the first two cases are highly unlikely, but we should be cautious of them due to the severity of their potential consequences. The third one is a very likely scenario. All of these could be avoided by preventing everyone from ever reaching Mars (undesirable outcome), or by sending life finder to Mars as soon as possible, which might lead to these good outcomes:

1. A mission funded by NASA (or someone else) finds unambiguous evidence of life on the surface of Mars before the first humans get there. NASA (or someone else) will be in a position to coordinate future exploration of Mars, and NASA (or someone else) will be recognized for having made a civilization-defining discovery.
2. A mission funded by NASA (or someone else) will with reasonable probability disprove the existence of life on or near the Martian surface. The world will be disappointed by this result, but this finding will at least allow to declare Mars to be “free real estate”. NASA (or someone else) will get to decide future policy based on scientific knowledge, not speculation.  

 What must be done?

We must prove the existence of extant (still surviving) life on Mars or, with a high level of certainty, disprove its existence, before the first human Mars landing.

How to do it?

At the 2019 astrobiological conference in Carlsbad, New Mexico, astrobiologists reached a consensus that extant life is likely present on Mars. The group identified four possible habitats where current Martian life could reside: caves, deep subsurface, ice, and salts. They did not attempt to prioritize between these environments. 

I will prioritize the ice. Specifically mid-latitude underground layered “lasagna” ice has the highest priority, and here is why:

The deep subsurface environments and closed cave systems not communicating with the Martian atmosphere are the lowest priority because they cannot endanger the soon arriving explorers. Further, short of extensive terraforming of Mars, we cannot affect it. Therefore, we can safely postpone analyses of deep lithotrophic communities and closed cave systems. The same applies to the search for past Martian life.

This leaves us with environments which communicate with the Martian surface, at least sporadically. These can be sources of backward contamination, or be destroyed by forward contamination.

As shown in my previous post, most of the Martian surface undergoes cyclic mixing (dust storms, and the summer/winter, and glacial/interglacial water cycles) which keeps the mid-latitude ice geologically young. Thus, all of this ice contains samples from all of the Martian surface. This includes all “Martian Special Regions“, places where Martian life may proliferate. As on Earth, Martian microscopic life is likely transported through the atmosphere and trapped in this ice. Earth-analog microorganisms can survive for millions of years in viable form, trapped in an ancient ice. That is time enough for several ice age cycles on Mars. Martian life may be sparse in mid-latitude ice, if only a few sites on Mars host it, but it will be represented. 

Because all of the Martian accessible habitats are represented in the mid latitude “lasagna” ice, this ice is the only place we need to analyze to find Martian life.

Instruments in design can find alien genetic molecules, which are charged polymers – universal biosignatures. The same instruments would put an upper limit on the density of Martian microbes on the surface if no biosignature molecules are observed. The larger the sample of ice examined, the lower the limit would be. 

Easy and affordable

Most astrobiologists dare not to ask for samples of Martian water larger than a few milliliters. This is insufficient. An effective search for potentially sparse life (using the method we propose here) would need samples of fresh Martian mid-latitude ice over a millions times larger– several swimming pools worth. 

Easy, right?

Actually, it is.

Human return Mars missions require rockets to be refueled on the Martian surface. Since we don’t expect Martian life to be advanced enough to sell us gas, we must manufacture the propellant on site. As Robert Zubrin described in his Mars Direct plan, the best way is to send the automated infrastructure to produce the propellant on site before humans begin their voyage. SpaceX is following this plan, albeit on a much larger scale.

The [Star]ship will deploy an automated propellant plant, mining Martian ice and atmospheric carbon dioxide to make sure that the first crewed mission has a return vehicle ready and fueled, before they even leave the Earth. Hundreds of tons of Martian ice will need to be mined, distilled, electrolyzed, and combined with CO₂ to produce the propellant – methane and oxygen. This will require several football fields of solar panels to produce enough energy. Human mission to Mars, as envisioned by SpaceX, will be supported by a huge automated on-site industrial endeavor, possible only with a fleet of fully reusable SpaceX Starship rockets.

But if planning is done correctly, the mined ice has value more than as a fuel feedstock: It is a huge sample for astrobiology. I suggest that the mined water be scanned for alien genetic molecules before it is used for fuel manufacturing. Adding an instrument to detect universal biosignatures after the ice is mined and before it is consumed would be barely noticeable compared to the overall financial, energetical, and technological costs of the Starship return mission. 

Further, we can be sure that humans will not land on the Martian surface until in situ refueling is perfected and functioning. Hence, if the life searching mission is tied to in situ propellant generation, we can be sure that humans will not land on Mars before we know if there is life on Mars.

Finally, we can exploit the fact that both life and SpaceX Starships need water to function to our universal advantage: On every extraterrestrial body where a Starship refueling station is built, the automatic life detection architecture can also be run nearly for free – “just in case”.

Author’s note: At the time of writing I was not aware of the frequent exchange of the material between Earth and Mars. Impact ejecta is constantly exchanged in both directions. Mars is not biologically isolated from Earth and vice versa. Planetary protection seems to disregard this this fact.