Field measurements differ fundamentally from laboratory, airborne, and satellite spectrometer measurements. Laboratory measurements alone are not sufficient to understand all the spectral effects present in field data.
We use spectrometers (hyperspectral) to research effects from:
The current Mars exploration strategy calls for the identification from orbit of minerals that form in environments conducive to life or that preserve biomarkers, using infrared remote sensing. The results would then be used to select landing sites. Predictions of the instrumentation needed were based on laboratory measurements of pure minerals, or airborne measurements made by multi-channel radiometers (e.g. TIMS) combined with ground truth.
Our research shows that rough and weathered materials are substantially more difficult to detect and identify than predictions that used lab data or ground truth predicted. However, our data sets show that these materials can be identified by a sensitive instrument that measures with high information content.
This may explain why there has been no clear identification of materials such as carbonates and chert on Mars, including by the Global Surveyor Thermal Emission Spectrometer (TES). The results indicate that 2001 Mars Odyssey multi-channel radiometer THEMIS probably lacks the information content to identify most rough and weathered minerals.
Our study combines laboratory spectra (2.5 - 200 �m); unique, high quality airborne spectrometer data (Spatially Enhanced Broadband Array Spectrograph System, SEBASS); and high quality field spectrometer data (2.5-5 and 7-13 �m). The Lunar and Planetary Institute, Houston, TX, and The Aerospace Corporation, El Segundo, CA sponsor this work.
Additional information, including SEBASS
How to set detection limits for unknown targets, (published in Applied Optics)
Implications for the Mars astrobiology program (published in SPIE Proceeding 4495)
Results from our terrestrial work, (published in Remote Sensing of Environment)