To find any possible life on Mars, we are embarked on a program to develop non-Earth-centric methods for life detection:   methods that would detect life even if it were made of different things than what our own Earthly life is composed of. The program of research focuses on the physics and chemistry of life, using a variety of imaging methods over many spatial scales, and a variety of chemical methods that measure many different chemical parameters at many spatial scales. Coupled with these methods is the search within the images and within the chemistry for complexity and information. This latter parameter is one that lends itself well to data analysis and data mining approaches, and this constitutes a major part of the growing effort at JPL's Center for Life Detection.

Imaging Approaches

With regard to imaging approaches, we are pushing the development of an X-ray tomographic method that allows us to look inside opaque objects (such as rocks) for biological material hiding within. Such endolithic (inside rock) habitats are commonly found in desert environments on Earth, and the ability to look for potential colonies of living organisms inside the rocks may be a key to identifying samples that are worthy of further analysis. We began this work looking at embryos of dinosaur eggs, have moved to small (mm sized) fossils within rock samples, and now have a high resolution system capable of seeing a single large bacterium in a rock sample. As X-ray sources and computing abilities continue to improve, we expect this instrumentation to become part of the in situ life searching repertoire.

Broad-band Fluorescence

Another approach that is developing very well is that of broad band fluorescence to very deep (short wavelength) ultraviolet (UV) light. The deep UV has the advantage that at such wavelengths there is very little background fluorescence from the rock samples, and it is easy to identify samples containing carbon-based chemistry that could be associated with life. When fluorescence signals are obtained, it is then routine to study these specific sites and ask more detailed chemical questions with more high resolution instruments.

Robotic Life Detection Laboratories

This approach, of building non-invasive, broad spatial searching instruments that find the interesting sites in a rock, is a logical one, but will require the integration of any package in a way such that the spacecraft is " smart " -- capable of making a series of measurements, processing data on its own, and making decisions about which measurements to make next. The interfacing of the instruments with a data acquisition and processing program to identify areas of complexity and further examine them is also a major area of work within the CLD -- work that will lead to autonomous instruments capable of finding life, should it be present.