Curiosity’s robotic arm-mounted Mars Hand Lens Imager (MAHLI): Characterization and calibration status Kenneth S. Edgett, Michael A. Caplinger, Justin N. Maki, Michael A. Ravine, F. Tony Ghaemi, Sean McNair, Kenneth E. Herkenhoff, Brian M. Duston, Reg G. Willson, R. Aileen Yingst, Megan R. Kennedy, Michelle E. Minitti, Aaron J. Sengstacken, Kimberley D. Supulver, Leslie J. Lipkaman, Gillian M. Krezoski, Marie J. McBride, Tessa L. Jones, Brian E. Nixon, Jason K. Van Beek, Daniel J. Krysak, and Randolph L. Kirk MSL MAHLI Technical Report 0001, version 2 version 1: 19 June 2015; version 2: 05 October 2015 Citation: Edgett, K. S., M. A. Caplinger, J. N. Maki, M. A. Ravine, F. T. Ghaemi, S. McNair, K. E. Herkenhoff, B. M. Duston, R. G. Willson, R. A. Yingst, M. R. Kennedy, M. E. Minitti, A. J. Sengstacken, K. D. Supulver, L. J. Lipkaman, G. M. Krezoski, M. J. McBride, T. L. Jones, B. E. Nixon, J. K. Van Beek, D. J. Krysak, and R. L. Kirk (2015) Curiosity’s robotic arm-mounted Mars Hand Lens Imager (MAHLI): Characterization and calibration status, MSL MAHLI Technical Report 0001 (version 1: 19 June 2015; version 2: 05 October 2015). doi:10.13140/RG.2.1.3798.5447 – MSL MAHLI Tech. Rept. 0001 – Mars Science Laboratory (MSL) Mars Hand Lens Imager (MAHLI) Technical Report 0001 Cover photo Mars Science Laboratory (MSL) rover Curiosity’s Mars Hand Lens Imager (MAHLI; center) and Dust Removal Tool (DRT; right), as observed by the Mastcam-34 camera on Sol 30 (06 September 2012) in northern Gale crater, Mars. This is a portion of Mastcam image 0030ML0000400000100851E01. Author affiliations Michael A. Caplinger, Brian M. Duston, Kenneth S. Edgett, Tessa L. Jones1, Megan R. Kennedy, Gillian M. Krezoski, Daniel J. Krysak, Leslie J. Lipkaman, Marie J. McBride, Sean McNair, Brian E. Nixon, Michael A. Ravine, Kimberley D. Supulver, Jason K. Van Beek Malin Space Science Systems, San Diego, California, USA Justin N. Maki, Aaron J. Sengstacken2, Reg G. Willson Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA F. Tony Ghaemi Ghaemi Optical Engineering, San Diego, California, USA Kenneth E. Herkenhoff, Randolph L. Kirk U.S. Geological Survey, Astrogeology Science Center, Flagstaff, Arizona, USA Michelle E. Minitti, R. Aileen Yingst Planetary Science Institute, Tucson, Arizona, USA 1now at: Cymer, San Diego, California, USA 2now at: Garmin International, Olathe, Kansas, USA Change Log • Version 2, 05 October 2015 – Equation 2 was incorrect; changed 3.4201 to 3.5201. – 2 – – MSL MAHLI Tech. Rept. 0001 – Table of Contents Abstract .......................................................................................................................... 6 1 Introduction .............................................................................................................. 7 2 Mission and MAHLI overview ................................................................................. 7 2.1 MSL mission ................................................................................................................... 7 2.2 MAHLI instrument and investigation ............................................................................ 8 3 Approach and timeline ............................................................................................ 9 3.1 Data availability .............................................................................................................. 9 3.2 Conventions and definitions ....................................................................................... 10 3.2.1 Time .......................................................................................................................... 10 3.2.2 MSL science and engineering tools and instruments ............................................... 10 3.2.3 Distance and range .................................................................................................. 10 3.2.4 Terms relating to grain size ...................................................................................... 11 3.2.5 Image identification ................................................................................................... 11 3.2.6 Parent and child images ........................................................................................... 11 3.2.7 Color interpolation .................................................................................................... 12 3.2.8 Compand and decompand ....................................................................................... 12 3.3 Instrument characterization and calibration approach ............................................. 12 3.4 Timeline ......................................................................................................................... 14 3.5 Impact of dust coatings ............................................................................................... 17 3.5.1 MAHLI dust cover ..................................................................................................... 17 3.5.2 MAHLI calibration target ........................................................................................... 17 4 Image range and scale characterization .............................................................. 19 4.1 Optomechanical system characteristics .................................................................... 21 4.1.1 Stepper motor actions and motor count ................................................................... 21 4.1.2 Stepper motor count reportage ................................................................................. 21 4.1.3 Dust cover motion ..................................................................................................... 22 4.1.4 Lens focus ................................................................................................................ 22 4.1.5 Stepper motor and focus repeatability ...................................................................... 23 4.2 Relation between focus, motor count, working distance and image scale ............ 23 4.2.1 Pixel scale and image scale ..................................................................................... 23 4.2.2 Minimum working distance ....................................................................................... 24 4.2.3 Dust cover open, infinity focus position .................................................................... 25 4.2.4 Dust cover open, motor count relation to working distance ...................................... 27 4.2.5 Dust cover closed, motor count relation to working distance ................................... 29 4.3 Image resolution and contrast .................................................................................... 31 4.3.1 Lens MTF ................................................................................................................. 31 4.3.2 System MTF ............................................................................................................. 31 4.3.3 Assessment of resolution from Mars data ................................................................ 33 4.4 Depth of field ................................................................................................................. 36 4.5 Scale of features observed in MAHLI images ............................................................ 37 4.5.1 Scale from objects of known size or features at known distance ............................. 37 4.5.2 Range and scale from motor count and nested imaging .......................................... 38 5 Camera head positioning and stability characterization ................................... 40 5.1 Pre-launch tests regarding camera motion during image acquisition .................... 40 5.2 Motion damping before image acquisition ................................................................ 41 – 3 – – MSL MAHLI Tech. Rept. 0001 – 5.2.1 Duration determined before launch and best practice for Mars operation ................ 41 5.2.2 Duration determined on Mars for wheel inspection imaging ..................................... 41 5.3 Camera motion during image acquisition as observed on Mars ............................. 42 5.4 Camera head positioning and repeatability ............................................................... 43 5.5 Imaging with incremental turret rotation .................................................................... 44 6 Onboard image products characterization .......................................................... 46 6.1 Data compression and color interpolation ................................................................ 46 6.2 Product type identification, creation, and receipt on Earth ..................................... 47 6.3 Onboard focus merge product creation and assessment ........................................ 47 6.3.1 Capability and options .............................................................................................. 47 6.3.2 Focus stack acquisition and reporting ...................................................................... 48 6.3.3 Focus merge product reportage and traceability ...................................................... 50 6.3.4 Range information in range map products ............................................................... 51 6.3.5 Merge options characterization ................................................................................ 52 6.3.6 Individual focus stack images received on Earth .....................................................