THE MARS SCIENCE LABORATORY MARS HAND LENS IMAGER (MSL MAHLI)

The Mars Science Laboratory (MSL) rover mission, slated to begin Martian surface operations in 2010, seeks to explore the past and present habitability of a yet-to-be-selected site on Mars. Armed with a suite of instruments capable of spectral, chemical, mineralogical, organic and isotopic analyses, MSL will comprehensively study the Martian atmosphere and rocks and soils on the Martian surface. The Mars Hand Lens Imager (MAHLI), the “geologist's handlens” for MSL, supports habitability studies through aiding the selection of samples for in-depth analysis and placing such samples in a geologic and geomorphic context. More broadly, the goal of MAHLI is to examine the texture, morphology, structure, mineralogy, and stratigraphy of rocks, soils, frost and ice at the microscale. MAHLI will achieve this objective using capabilities new to Martian cameras including a CCD with a Bayer Pattern Filter coupled with a focusable lens. The Bayer Pattern Filter produces RGB color images akin to those taken by the standard commercial digital camera. Placement of MAHLI by the MSL Robotic Arm (RA) at a particular distance from the sample of interest and MAHLI's internal focus mechanism combine to achieve a desired image resolution. At its closest placement (22.5 mm), MAHLI has 9 µm/pixel resolution. In practice, RA placement may be sufficiently uncertain that 9 µm/pixel will not be achieved regularly; however, resolutions in the 12–15 µm/pixel range are expected for typical high resolution images. Depending on the target distance and its surface relief, the target may not be in focus over the entire image. For those cases, MAHLI acquires a series of images taken at a range of focus positions that bracket the location of best focus. MAHLI's onboard software is capable of merging this stack of images, into a single best-focus image. MAHLI can image in natural illumination but it also possesses four, white light emitting diodes (LED) for illumination of samples in shadow or at night and two, longwave ultraviolet (365 nm) LED's for exploratory purposes. Through these innovative capabilities, MAHLI results will improve upon the revolutionary results of the two Mars Exploration Rover Microscopic Imagers (MI) and extend our understanding of the Martian surface at the microscale.