From Encyclopedia of Astrobiology
Concept[edit | hide all | hide | edit source]
The ExoLance concept was conceived in 2014 by Steve McDaniel and consists in an impact penetrator that would fly to Mars as a secondary payload on a future Mars lander mission. A Mars lander would carry a set of ExoLance penetrators, each weighing a few kilograms. The penetrators would separate as the lander spacecraft enters the Martian atmosphere, passively falling to the Martian surface. The penetrators would make use of technology originally developed for "bunker buster" munitions, which are designed to burrow under the surface before exploding. In this case, the explosive payload would be replaced by a scientific one, specifically, a metabolic test that would attempt to detect chemical reactions created by any active microorganisms living one to two meters below the surface. The rear end of the penetrator would remain on the surface, connected to the buried probe by a cable, to provide a communications link to orbiting satellites. Having multiple probes allows for individual probe failures without losing the entire mission. The goal is to create something that is both small enough and affordable enough to be able to be put on several planned flights.
Aerojet Rocketdyne is performing computer modeling of the Mars penetrators as a design tool. A company called ExoLife Inc. has patented the improved deep penetrator desiged to carry life-detection equipment and has licensed critical, self-sterilizing coating technology for the penetrators. ExoLife is testing the detection equipment and self-sterilizing surface technology that will be carried as the payloads. Once the concept is sufficiently tested and has been proven, 'Explore Mars' in collaboration with its corporate partners (AeroJet and ExoLife) will approach space agencies and potential commercial providers to carry ExoLance on one or more future Mars missions.
Subsurface habitability[edit | hide | edit source]
Although Mars soils are likely not to be overtly toxic to terrestrial microorganisms, life on the surface of Mars is extremely unlikely because it is bathed in radiation and it is completely frozen. Therefore, the best potential locations for discovering life on Mars may be at subsurface environments that have not been studied yet.
References[edit | hide | edit source]
- Foust, Jeff (5 May 2014). "Mars missions on the cheap". The Space Review. Retrieved 2014-05-06.
- "ExoLance". Explore Mars Inc. 2014. Retrieved 2014-05-06.
- Koebler, Jason (24 April 2014). "Blasting Mars with Missiles Is the Latest Hope for Finding Martian Life". Motherboard. Retrieved 2014-05-06.
- Are you ready to answer the question, are we alone in the universe? ExoLance is Chris Carberry. Indiegogo.
- ExoLance Team Archived 2014-05-06 at the Wayback Machine. (2014).
- Conrad, P. G.; Archer, D.; Coll, P.; De La Torre, M.; Edgett, K.; Eigenbrode, J. L.; Fisk, M.; Freissenet, C.; Franz, H.; et al. (2013). "Habitability Assessment at Gale Crater: Implications from Initial Results". 44th Lunar and Planetary Science Conference. 1719: 2185. Bibcode:2013LPICo1719.2185C.
- Than, Ker (January 29, 2007). "Study: Surface of Mars Devoid of Life". Space.com.
After mapping cosmic radiation levels at various depths on Mars, researchers have concluded that any life within the first several yards of the planet's surface would be killed by lethal doses of cosmic radiation.
- Dartnell, L. R.; Desorgher, L.; Ward, J. M.; Coates, A. J. (2007). "Modelling the surface and subsurface Martian radiation environment: Implications for astrobiology". Geophysical Research Letters. 34 (2): L02207. Bibcode:2007GeoRL..34.2207D. doi:10.1029/2006GL027494.
Bacteria or spores held dormant by freezing conditions cannot metabolise and become inactivated by accumulating radiation damage. We find that at 2 m depth, the reach of the ExoMars drill, a population of radioresistant cells would need to have reanimated within the last 450,000 years to still be viable. Recovery of viable cells cryopreserved within the putative Cerberus pack-ice requires a drill depth of at least 7.5 m.
- Lovet, Richard A. (February 2, 2007). "Mars Life May Be Too Deep to Find, Experts Conclude". National Geographic News. Archived from the original on February 21, 2014.
- Dartnell, L. R.; Desorgher, L.; Ward, J. M.; Coates, A. J. (2007). "Modelling the surface and subsurface Martian radiation environment: Implications for astrobiology". Geophysical Research Letters. 34 (2). Bibcode:2007GeoRL..3402207D. doi:10.1029/2006GL027494.
The damaging effect of ionising radiation on cellular structure is one of the prime limiting factors on the survival of life in potential astrobiological habitats.
- Dartnell, L. R.; Desorgher, L.; Ward, J. M.; Coates, A. J. (2007). "Martian sub-surface ionising radiation: biosignatures and geology". Biogeosciences. 4 (4): 545–558. Bibcode:2007BGeo....4..545D. doi:10.5194/bg-4-545-2007.
This ionising radiation field is deleterious to the survival of dormant cells or spores and the persistence of molecular biomarkers in the subsurface, and so its characterisation. [..] Even at a depth of 2 meters beneath the surface, any microbes would probably be dormant, cryopreserved by the current freezing conditions, and so metabolically inactive and unable to repair cellular degradation as it occurs.
- Dartnell, Lewis R.; Storrie-Lombardi, Michael C.; Muller, Jan-Peter; Griffiths, Andrew. D.; Coates, Andrew J.; Ward, John M. (March 7–11, 2011). "Implications of cosmic radiation on the Martian surface for microbial survival and detection of fluorescent biosignatures" (PDF). 42nd Lunar and Planetary Science Conference. The Woodlands, Texas: Lunar and Planetary Institute.
- Didymus, JohnThomas (January 21, 2013). "Scientists find evidence Mars subsurface could hold life". Digital Journal – Science.
There can be no life on the surface of Mars because it is bathed in radiation and it's completely frozen. However, life in the subsurface would be protected from that. - Prof. Parnell.
- Summons, Roger E.; Amend, Jan P.; Bish, David; Buick, Roger; Cody, George D.; Des Marais, David J.; Dromart, Gilles; Eigenbrode, Jennifer L.; et al. (2011). "Preservation of Martian Organic and Environmental Records: Final Report of the Mars Biosignature Working Group". Astrobiology. 11 (2): 157–81. Bibcode:2011AsBio..11..157S. doi:10.1089/ast.2010.0506. PMID 21417945.
There is general consensus that extant microbial life on Mars would probably exist (if at all) in the subsurface and at low abundance.
- Steigerwald, Bill (January 15, 2009). "Martian Methane Reveals the Red Planet is not a Dead Planet". NASA's Goddard Space Flight Center. NASA. Archived from the original on 2009-01-16.
If microscopic Martian life is producing the methane, it probably resides far below the surface, where it's still warm enough for liquid water to exist
- "Mars Rovers Sharpen Questions About Livable Conditions". NASA. Archived from the original on 2008-02-18.
- "Mars: 'Strongest evidence' planet may have supported life, scientists say". BBC News. January 20, 2013.
- Michalski, Joseph R.; Cuadros, Javier; Niles, Paul B.; Parnell, John; Deanne Rogers, A.; Wright, Shawn P. (2013). "Groundwater activity on Mars and implications for a deep biosphere". Nature Geoscience. 6 (2): 133–8. Bibcode:2013NatGe...6..133M. doi:10.1038/ngeo1706.