John Michael Keller

Recipes for Spatial Statistics with Global Datasets: A Martian Case Study

The Mars Odyssey Gamma Ray Spectrometer has yielded planetary data of global extent. Such remote-sensing missions usually assign the value of a continuous-valued geospatial attribute to a uniform latitude-longitude grid of bins. Typical attributes include elemental-mass fraction, areal fraction of a mineral type, areal fraction of rocks, thermal inertia, etc. The fineness of the grid is chosen according to the spatial resolution of the orbiter and concomitant data processing. We describe methods to maximize the information extracted from both bin and regional data. Rigorous use of statistical parameters and related methods for inter- and intra- regional comparisons are also discussed. While we discuss results from the Mars Odyssey mission, the techniques we describe are applicable whenever continuous-valued attributes of a planet’s surface are characterized with bins and regions. Our goal is to distill the simplest statistical methods for regional comparisons that would be intuitively accessible to planetary scientists.

RESULTS FROM THE 2014 NOVEMBER 15TH MULTI-CHORD STELLAR OCCULTATION BY THE TNO (229762) 2007 UK126

We present results derived from the first multi-chord stellar occultation by the trans-Neptunian object (229762) 2007 UK

THE RESEARCH AND EDUCATION COLLABORATIVE OCCULTATION NETWORK: A SYSTEM FOR COORDINATED TNO OCCULTATION OBSERVATIONS

_{126}

Concentration of H, Si, Cl, K, Fe, and Th in the low‐ and mid‐latitude regions of Mars

, observed on 2014 November 15. The event was observed by the Research and Education Collaborative Occultation Network (RECON) project and International Occultation Timing Association (IOTA) collaborators throughout the United States. Use of two different data analysis methods obtain a satisfactory fit to seven chords, yelding an elliptical fit to the chords with an equatorial radius of

Bulk composition and early differentiation of Mars

R=338_{-10} ^{+15}

Equatorial and midlatitude distribution of chlorine measured by Mars Odyssey GRS

km and equivalent radius of

Variations in K/Th on Mars

R_{eq}=319_{-7} ^{+14}

GRS evidence and the possibility of paleooceans on Mars

km. A circular fit also gives a radius of

Recent geological and hydrological activity on Mars: The Tharsis/Elysium corridor

R=324_{-23} ^{+30}

Possible ancient giant basin and related water enrichment in the Arabia Terra province, Mars

km. Assuming that the object is a Maclaurin spheroid with indeterminate aspect angle, and using two published absolute magnitudes for the body, we derive possible ranges for geometric albedo between