1. Determining Favorable Environments for Endolithic Growth From Physics Considerations
Doug Archer, Dr. David Allred
Dept. of Physics and Astronomy
Brigham Young University

2. What’s an Extremophile?
Extremophile’s are organisms that can live in extreme environments
Examples are Halophiles, Thermophiles, and Endoliths

3. Limits on Life Lack of Liquid Water Temperature extremes
Ultraviolet Radiation
Soil toxicity
Sparse Energy Resources

4. Mars Had Water in the Past and Still Has Water Today

5. Temperature Concerns Mars’ Temperature range -123C to 20C
Once thought a major concern, the discovery of Extremophiles metabolically active from -15C to 120C has changed our thinking.
Active->Dormant cycle

6. Ultraviolet Radiation
UVA = nm
UVB = nm
UVC = nm
Below ~290nm, UV energy is very damaging to most biological systems.
It affects proteins, lipids, and most importantly, DNA.

7. UV Flux, Earth vs. Mars UVC and B (W/m^2) UVA DNA effective irradiance
Present Day Earth
1.86
52.81 .1
Present Day Mars
13.2
41.5
116.4
Early Earth
5.2
34.1 41
Early Mars
4.8
22.3
33.8

8. The Role of Ozone
The Chapman Reaction describes ozone creation/reaction.
Ozone absorbs between nm
Mars’ ozone layer is <1% of earths at maximum

9. UV Damage

10. Surviving UV There are three primary methods:
Avoidance: chemoautotrophs
Repair: photolyase cuts thymine dimers. Present in modern branches of ancient archaebacteria.
Protection: Matting, Substrate Production, Physical Environment Sheltering.

11. Why Endoliths?
Endolithic communities, also known as cryptoendoliths, could provide protection from numerous life limiting conditions.
We have ready access to endoliths in the Southern Utah Desert.

12. Physics Concerns Which compounds found in common minerals block UV?
This is a function of band gap
Is UV light preferentially absorbed or scattered out of certain materials? Rayleigh vs. Mie scattering
Particle size (<1/10 wavelength=Ray.)
Wavelength Dependence (λ^4 vs λ)
How fast does the intensity drop as a function of depth and wavelength
To what extent is color important and how is it produced?

13. Martian Minerology
Sample
Na2O
MgO
Al2O3
SiO2
SiO3
K2O
CaO
TiO2
Fe2O3
Near Yogi
3.7
8.1
8.9
46.8
6.3
0.2
5.5
1.4
15.6
Scooby Doo
1.9
6.9
50.3
5.2
0.5
7.1
1.1
14.5
Rocky Flates:crust
 --
7.4
7.2
44.1 10
0.9
5.9
0.6
18.3

14. Absorption Example

15. Correlate and Compare Minerals with Fe203:
Hematite, Maghemite
Compare to Martian minerals using spectography and terrestrial analogues.
USGS Imaging Spectroscopy
Have found abundant Olivene (Mg1.6Fe2+0.4(SiO4))

16. Remaining Questions
Can microporosity and capillary action act to prevent or lessen dessication of the cryptoendoliths?
How can we robotically detect the presence of Endoliths?

17. Conclusions
Given what we know about the early history of Earth and Mars, it is not a stretch to theorize that life appeared simultaneously. Earth provided a more successful habitat, but conditions on Mars do not preclude the continued presence of life.
Endolithic habitats provide a refuge from many of the limiting factors on life as we know it.