Life in Lava Tubes
ROBOTIC EXPLORATION OF LAVA TUBES ON THE MOON AND MARS PRIOR TO
Mars colony, colonize Mars, human colonization of Mars, human exploration of Mars, AUTONOMOUS ROVERS, LASERS, STUDENTS AT HARVEY MUDD COLLEGE USE LASE TO SEARCH FOR LIFE IN LAVA TUBES
The increasing privatization of space exploration now includes proposals for the colonization of Mars. SpaceX, founded by Elon Musk,, and Mars One, founded by Bas Lansdorp, have announced plans to have permanent residents on the Red Planet within the next 15 years.
If life is to survive on any planet it must be protected from ionizing radiation. On Earth our atmosphere and magnetic field provide a protective shield. But the surfaces of our own moon, Mars, or the ice moons of the outer planets are not so hospitable. In those environments life, whether human or microbial, must find protection many meters beneath the surface, or die quickly from heavy particle bombardment. Lava tubes have been imaged on the moon and on Mars that might provide just such a protected habitat for both microbial and human life.
Multple lava pit craters have been found on Earth's moon. This Mare Tranquillitatis pit crater contains boulders on an otherwise smooth floor. For scale the image is 400 meters wide. The pit depth is about 100 meters and width estimates range from 100 to 115 meters.
Image Credit: NASA/GSFC/Arizona State University
This Mare Ingenii pit is 70 meters deep and about 120 meters in diameter. Each image is 150 meters wide.
Image Credit: NASA/GSFC/Arizona State University.
These three images of the Maurius Hills pit were taken at different times. The variations in lighting help define the structure of the pit crater. Each panel is 300 meters wide. The pit is about 34 meters deep and 65 by 90 meters wide.
Image Credit: NASA/GSFC/Arizona State University
For further information on Lunar pits see Lunar Reconnaisance Orbiter.
Multiple lava tube skylights have also been detected on Mars. In 2007, seven dark holes on the north slope of Arsia Mons volcano (9 degrees south latitude, 239 degrees east longitude) were imaged in visible and infrared wavelength light by the Thermal Emission Imaging System (THEMIS) camera on NASA's Mars Odyssey orbiter. Ranging in diameter from about 100 to 225 meters, the holes were proposed as tube skylights based on THEMIS infrared data documenting day-night temperature patterns characteristic of an underground cave environment.
Image credit: NASA/JPL-Caltech/ASU/USGS
For more information see Mars Odessy Finds Cave Skylights.
In 2010, students at Evergreen Middle School in Cottonwood, California, found a lava tube with what appears to be a skylight entrance to an underground cave. The students used the cameras aboard the Mars Odyssey as part of the Mars Student Imaging Program offered by NASA and Arizona State University. The skylight is on the slope of an equatorial volcano, Pavonis Mons. For more information see Seventh Graders Find a Cave on Mars.
Image credit: NASA/JPL-Caltech/ASU
405 nm laser excitation of epilithic community on a lab optical bench
Autonomous Robotic Exploration of Lava Tubes
While exploring lava tubes on the Moon or Mars, a rover would be shielded from contact with Mission Control. Students at Harvey Mudd College (HMC) have begun exploring the possibility that autonomous rovers could obtain optical biosignatures of microbial life in lava tubes. Using compact lasers, cameras, spectrometers and intelligent pattern recognition, the students are training rovers to explore and map lava tubes. The imaging and spectral data generated are obtained without touching or destroying samples. The data sets will ultimately include fluorescence emission, Rayleigh and Raman scattering, and homochirality. The optical and rover system constraints are being investigated in a collaborative effort with Professor Greg Lyzenga (Physics) and Professor Chris Clark (Engineering) at HMC.
The first image depicts the investigation of a sample at a distance of two meters using a prototype laboratory system in the summer of 2011. Here a 405 nm violet laser illuminates a cyanobacteria colony living on a rock - an "epilithic" (living on a rock) photosynthetic community. The laser is particularly chosen because it searches quite efficiently for the porphyrin rings found in all known microbial, plant, and animal life on Earth.
Porphyrin rings are the central core of photosynthetic molecules such as chlorophyll, metabolic molecules such as the cytochromes, and even the molecule that carries oxygen in human red blood cells, hemoglobin. Interestingly, the same technology developed to identify life in the rocks of a Mars lava tube could be used to evaluate the health of forests and crops, monitor skin cancers, or survey crime scenes for forensic evidence here on Earth.
The next image depicts the 2013 field version of the optical science instrumentation riding aboard a Jaguar autonomous rover.
405 nm laser spectrometer riding on autonomous rover in the Mojave Desert near Mars analog lava tubes.
The science package is designed to capture RGB color images, reflectance spectra, and laser induced fluorescence emission (L.I.F.E.) images and spectra. The rover is designed to autonomously navigate and map a lava tube. It can earmark a site for future scientific investigation, and return to that exact site after completing more pressing mission goals.
Field Sites: Lava Tubes in the Mojave Desert
Two hours east of HMC, the Mojave Desert provides a series of lunar and Mars analog lava tube test sites. HMC summer students in physics and engineering have embarked on a project to integrate geobiological scientific investigation with autonomous robotic mapping techniques. The test sites are lava tubes embedded in the flank of Pisgah Crater. Students are building rover-mounted cameras and spectrometers capable of identifying targets on lava tube walls that are geological or biological artifacts of interest. These autonomous, intelligent rovers use the information provided by the science instruments to modify mission goals and priorities.
A Jaguar Rover at Pisgah Crater moves across a landscape that markedly resembles the surface of Mars.
Skylights provide access to almost 200 lava tubes.
Lichen communities are found at the enhance to many of the lava tubes.
A Jaguar rover with 405 nm laser and white LED headlights enters a lava tube.
A thermal image of the rover deep in the lava tube.
(Photograph by K. Yang, camera curtesy of C. Brinkworth, Spizer Space Science Center)
Autonomous acquisition of a L.I.F.E. image and spectra with 405 nm excitation. The normally pitch-dark tunnel has been illuminated with a DSLR flash. The violet (405 nm) laser light scatters off the basalt wall with frequency unaltered. The central carbonate target fluorescence is captured in blue, green and red bands of the DSLR giving the artifact a white L.I.F.E. signature.
(Photograph by S. Messenger)
An RGB reflectace and a L.I.F.E. image of a carbonate target in a Pisgah Crater lava tube following 405 nm excitation from a distance of one meter.
More information on HMC engineering and physics student participation in this project can be found in two videos
Storrie-Lombardi, M.C., Hall, A.P., Hang, S., Lyzenga, G.A., Clark, C.M., Sattler, B.I., Bej, A.K. and Hoover, R.B. (2011) Spectral Profiling & Imaging (SPI): Extending L.I.F.E. technology for the remote exploration of life in ice Caves (R.E.L.I.C.) on Earth and Mars. Instruments, Methods, and Missions for Astrobiology XIV 8152 (17), 1-12. An abstract can be found below.
Ruiz, A., Messenger, S., Yang, J., Yim, S.; Paudel , S., Huerta, L., Villegas, J., Zúñiga, W., Lyzenga, G., Clark, C., Storrie-Lombardi, M. (2014) Rovers and Lasers: The Autonomous, Non-Destructive Search for Life in Lava Tubes [#1478], Eighth International Conference on Mars, Pasadena, CA, Pasadena, CA; p 2.
For more information of L.I.F.E. signals from microbes living within ice see Life in Ice.