ASTID

Miniature Iron Biomineral Detector for Martian Exobiology (2)

PI: Soon Sam Kim

For the next two decades, NASA’s major theme for space exploration will be focused on finding biosignatures to answer the question whether life ever developed on planets like Mars. It is believed that 4 ~ 3.5 byrs ago, when bacterial life first appeared on Earth, Mars had similar environmental conditions, with liquid water and a planetary magnetic field. Mars also has an abundance of iron minerals on the surface (“red planet”). Thus, it is only
reasonable to assume that life on Mars, if it existed, evolved in a similar fashion to that on Earth. On the surface of Earth, magnetic iron-biominerals are ubiquitous in sediments as fossil remnants from past and present bacterial activity. Such iron biominerals have a much better chance of survival in the Martian surface environment than do more conventional organic fossils. Under PIDDP (2001-2003), using the bacterial magnetic iron oxide minerals as possible biosignatures of life, we have developed in-situ miniature
ferromagnetic resonance (FMR)/electron paramagnetic resonance (EPR) spectrometers for their detection. Our studies on geological samples known to contain bacterial magneto-fossils demonstrate that FMR/EPR techniques can indeed distinguish them from their inorganic counterparts. There are two types of biogenic magnetites; biologically controlled ones for bacterial magnetotacticity, or biologically induced ones for bacterial respiration products. The bacterial iron biominerals produce distinctive FMR/EPR spectral properties which allow them to be recognized easily. Under PIDDP, we have developed a frequency scan (0.5 ~ 8 GHz) zero-field FMR spectrometer (TRL 4). Under ASTID, we will further develop the spectrometer into a flight qualifiable prototype (TRL 6) ready for
flight AO. It will be the most convenient and sensitive technique for the detection of single domain biogenic magnetites and discriminate against irregular shaped, multidomain inorganic counterparts. The FMR will be integrated with frequency scan EPR (3 ~ 5 GHz, @1.3 kGauss) for characterization of biologically induced, superparamagnetic magnetites.
When developed, the miniature FMR/EPR spectrometer (1 kg, <5 W) could conceivably be put on a rover similar to MSL in search for biosignatures.