By T. Duxbury, George Mason University, Fairfax, VA, USA W

Home , Airy (Martian crater)

NEW SPIN AXIS, SPIN RATE AND PRIME MERIDIAN EXPRESSIONS FOR PRECISION MARS CARTOGRAPHY by T. Duxbury, George Mason University, Fairfax, VA, USA W. Folkner and T. Parker, Jet Propulsion Laboratory, Pasadena, CA, USA R. Kirk and B. Archinal, US Geological Survey, Flagstaff, AZ, USA J. Oberst, German Space Center DLR and Technical University Berlin, Berlin, Germany

presented at the

ISPRS Working Group IV/8 Planetary Mapping and Spatial Data Bases Berlin, September 24/25, 2015

Oral Session 4 (24 September 16:00 - 17:30) Chairperson: Randy Kirk Mars

9/24/15 Mars Inertial Orientation 1 HISTORY

THE CURRENT EXPRESSIONS FOR THE MARS INERTIAL ORIENTATION ARE BASED UPON REGISTERING AIRY 0 TO MOLA (Duxbury, Caplinger, Neumann, 1999) AND THE SPIN POLE / SPIN RATE DETERMINED FROM RADIOMETRIC TRACKING OF THE VIKING AND MPF LANDERS (Konopliv, et al., 1999).

Airy 0

Caplinger MSSS Neumann GSFC Duxbury GMU Folkner JPL MOLA DIM and VO-1 Imaging MOLA ground track and a MOC Image THESE EXPRESSIONS ARE DOCUMENTED IN THE MGCWG REPORT BY Duxbury, et al., 2002 FOR MORE HISTORY SEE Archinal and Caplinger, 2002 9/24/15 Mars Inertial Orientation 2

AN UPDATE TO THE MARS INERTIAL ORIENTATION IS NEEDED THE MARS SPIN POLE AND SPIN RATE HAVE VARIATIONS DUE TO THE SEASONAL MASS MOVEMENT BETWEEN THE POLES (Konopliv, et al., 2011) THE ABSOLUTE LOCATION OF AIRY 0 RELATIVE TO THE MOLA GLOBAL DTM IS UNCERTAIN AT THE 50 m 1-σ LEVEL (Duxbury, et al., 2014)

Airy 0 > Airy 0

FULL STEREO PHOTOGRAMMTRIC REDUCTION OF THEMIS IR TIED TO MOLA MOC IMAGE WITH MOLA GROUND TRCK

Duxbury et al GMU Folkner JPL

9/24/15 Mars Inertial Orientation 3 AN UPDATE TO THE MARS INERTIAL ORIENTATION IS NEEDED (CONT.) THE ABSOLUTE LOCATIONS OF VL-1, VL-2, MPF, MER-A, MER-B AND MSL RELATIVE TO THE MOLA GLOBAL DTM HAVE UNCERTAINIES AT THE 50 m 1-σ LEVEL

Kirk USGS

9/24/15 Mars Inertial Orientation 4 AN UPDATE TO THE MARS INERTIAL ORIENTATION IS NEEDED (CONT.) THE ABSOLUTE LOCATIONS OF VL-1, VL-2, MPF, MER-A, MER-B AND MSL RELATIVE TO THE MOLA GLOBAL DTM HAVE UNCERTAINIES AT THE 50 m 1-σ LEVEL (CONT.) HiRISE image PSP_001719_2025

VL-1 LANDING SITE

Parker JPL 9/24/15 Mars Inertial Orientation 5 THE POSITION ADOPTED BY THE MGCWG

• THE ORIENTATION OF THE MARS SURFACE IN INERTIAL SPACE IS TIED TO THE LOCATION OF CRATER AIRY 0. THE MOLA GROUND TRACKS HAVE ALTIMETRY EVERY 300 m IN LATITUDE BUT HAVE GAPS OF 2 – 3 km IN LONGITUDE AT THE EQUATOR (Smith, et al., 2001 and Neumann, et al., 2001). THEREFORE THE ABSOLUTE LOCATION OF AIRY-0 IN INERTIAL SPACE / RELATIVE TO THE MOLA GLOBAL DTM CAN ONLY BE DETERMINED TO AN ACCURACY OF 10’S OF METERS USING ANY IMAGING DATASET TIED TO MOLA.

• THE LANDER LOCATIONS CAN BE DETERMINED TO THE METER LEVEL OF ACCURACY FROM THE EARTH-BASED RADIOMETRIC TRACKING.

• THE LANDERS ARE VISIBLE IN ORBITER IMAGES.

THEREFORE

• DETERMINE THE “MOST ACCURATE” MARS-FIXED LOCATION OF VL-1 IN IMAGES TIED TO THE MOLA GLOBAL DTM / CURRENT BEST GUESS AS TO THE AIRY 0 LOCATION – THIS IS KNOWN TO HAVE AN UNCERTAINTY OF 50 m 1-σ

• HOLD CONSTANT THIS MARS-FIXED LOCATION OF VL-1 AND REDUCE ALL RADIOMETRIC TRACKING DATA OF ALL LANDERS TO DETERMINE THE LOCATION OF ALL OTHER LANDERS RELATIVE TO VL-1 WHEN SOLVING FOR THE SPIN AXIS DIRECTION AND SPIN RATE. THE PRIME MERIDIAN EPOCH VALUE IS NOW FIXED AND TIED TO THE LOCATION OF VL-1

• ANY FUTURE CHANGES TO THE PRIME MERIDIAN EPHEMERIS POSITION AT J2000.0 CAN BE TIED TO CHANGES IN LANDER LOCATIONS, EXPECTED TO BE AT THE METER LEVEL, AND NOT TO ANY NEW OBSERVED LOCATION OF AIRY 0 THAT IS EXPECTED TO BE ACCURATE TO ONLY 50 m 1-σ.

9/24/15 Mars Inertial Orientation 6 THE UPDATED MARS INERTIAL ORIENTATION EXPRESSIONS (Kuchynka, et al., 2014)

Mars Spin Axis Right Ascension in J2000.0

Mars Spin Axis Declination in J2000.0

Mars Prime Meridian in J2000.0

NOTE: The current expressions only have epoch value and secular rate terms (1st two terms)

9/24/15 Mars Inertial Orientation 7 THE CHANGE TO THE COMPUTED MARS INERTIAL ORIENTATION

1 X 10-3 deg = 60 meters 9/24/15 Mars Inertial Orientation 8 THE STATUS OF THE UPDATED MARS INERTIAL ORIENTATION EXPRESSIONS • THE NEW EXPRESSIONS WERE REVIEWED AND APPROVED BY THE NASA MARS EXPLORATION PROGRAM OFFICE GEODESY AND CARTOGRAPHY WORKING GROUP (MGCWG). • AN ALPHA TEST NAIF SPICE PLANETARY CONSTANTS KERNEL (PCK) IS AVAILABLE • THE MGCWG RECOMMENDED THE NEW STANDARD TO THE IAU WORKING GROUP FOR CARTOGRAPHIC COORDINATES AND ROTATIONAL ELEMENTS (WGCCRE) FOR ADOPTION. • THE IAU WGCCRE (B. Archinal Chairman) IS INCLUDING THE NEW STANDARD IN ITS PUBLICATION TO BE RELEASED IN 2016.

Giovanni Schiaparelli

9/24/15 Mars Inertial Orientation 9 REFERENCES

• Archinal, B. A., and M. Caplinger (2002), Mars, the meridian, and Mert: The quest for Martian longitude, Eos Trans. AGU, 83(47), Fall Meet. Suppl., Abstract P22D-06. [Available at http://abstractsearch.agu.org/meetings/2002/FM/sections/P/sessions/P22D/ abstracts/P22D-06.html.]

• Christensen, P. R., et al. (2004), The Thermal Emission Imaging System (THEMIS) for the Mars 2001 Odyssey mission, Space Sci. Rev., 110, 85–130.

• Duxbury, T. C., R. L. Kirk, B. A. Archinal, and G. A. Neumann (2002). “Mars Geodesy/Cartography Working Group Recommendations on Mars Cartographic Constants and Coordinate Systems,” ISPRS, v. 34, part 4, “Geospatial Theory, Processing and Applications,” Ottawa. See http://astrogeology.usgs.gov/search/details/Research/ISPRS/Duxbury/pdf. Also available at http://www.isprs.org/proceedings/XXXIV/part4/.

• Kuchynka, P., W. M. Folkner, A. S. Konopliv, T. Parker, S. Ryan, S. Park, S. Le Maistre, and V. Dehant (2014), New constraints on Mars rotation determined from radiometric tracking of the Opportunity Mars Exploration Rover, Icarus, 229, 340–347,doi:10.1016/j.icarus.2013.11.015

• Konopliv, A. S., S. W. Asmar, W. M. Folkner, O. Karatekin, D. C. Nunes, S. E. Smrekar, C. F. Yoder, and M. T. Zuber (2011), Mars high resolution gravity fields from MRO, Mars seasonal gravity, and other dynamical parameters, Icarus, 211, 401–428.

• Malin, M. C., G. E. Danielson, A. P. Ingersoll, H. Masursky, J. Veverka, M. A. Ravine, and T. A. Soulanille (1992), The Mars observer camera, J. Geophys. Res., 97(E5), 7699–7718, doi:10.1029/92JE00340.

• Neumann, G., F. Lemoine, D. Rowlands, D. E. Smith, and M. T. Zuber (2001), Crossover analysis in MOLA data processing, J. Geophys. Res.,106(E10), 23,753–23,768.

• Smith, D. E., et al. (2001), Mars Orbiter Laser Altimeter: Experiment summary after the first year of global mapping of Mars, J. Geophys. Res., 106(El0), 23,689–23,722

NASA MGS MOC IMAGES, M. MALIN PI, MSSS NASA MRO HiRISE IMAGE, A. McEWEN PI, U of AZ NASA ODY THEMIS IR IMAGES, P. CHRISTENSEN PI, ASU NASA MGS MOLA DTM, D. SMITH PI, MIT

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