Publications

BOARD THE NASA LRO A. Sanin, I. Mitrofanov, W. Boynton, G. Chin, N. Demidov1, J. Garvin3, D. Golovin1, L. Evans4, K. Harshman2, A. Kozyrev1, M. Litvak1, A. Malakhov1, T. McClanahan3, G. Milikh5, M. Mokrousov1, G. Nandikotkur5, I. Nuzhdin1, R. Sagdeev5, V. Shevchenko7, V. Shvetsov8, R. Starr6, V. Tretyakov1, J. Trombka5, D. Usikov5, A. Varennikov1 and A. Vostrukhin1, 1Space Research Institute, RAS, Moscow, 117997, Russia, sanin@mx.iki.rssi.ru, University of Arizona, Tucson, AZ USA , 3NASA Goddard Space Flight Center, Greenbelt, MD USA, 4Computer Science Corporation, Greenbelt, MD USA, 5University of Maryland, College Park, MD USA, 6Catholic University, Washington DC, USA, 7Sternberg Astronomical Institute of Moscow State University, Moscow, Russia, 8Joint Institute of Nuclear Energy, Dubna, Russia

We have monitored a newly erupted volcanic island in the Kingdom of Tonga, unofficially known as Hunga Tonga Hunga Ha'apai, by means of relatively frequent high spatial resolution (~50 cm) satellite observations. The new ~1.8 km2 island formed as a tuff cone over the course of a month-long hydromagmatic eruption in early 2015 in the Tonga-Kermadec volcanic arc. Such ash-dominated eruptions usually produce fragile subaerial landscapes that wash away rapidly due to marine erosion, as occurred nearby in 2009. Our measured rates of erosion are ~0.00256 km3/year from derived digital topographic models. Preliminary measurements of the topographic expression of the primary tuff cone over ~30 months suggest a lifetime of ~19 years (and potentially up to 42 years). The ability to measure details of a young island's landscape evolution using satellite remote sensing has not previously been possible at these spatial and temporal resolutions.

The data from the collimated sensors of the LEND instrument are shown to be of exceptionally high quality. Counting uncertainties are about 0.3% relative and are shown to be the only significant source of random error, thus conclusions based on small differences in count rates are valid. By comparison with the topography of Shoemaker crater, the spatial resolution of the instrument is shown to be consistent with the design value of 5 km for the radius of the circle over which half the counts from the lunar surface would be determined. The observed epithermal‐neutron suppression factor due to the hydrogen deposit in Shoemaker crater of 0.25 ± 0.04 cps is consistent with the collimated field‐of‐view rate of 1.7 cps estimated by Mitrofanov et al. (2010a). The statistical significance of the neutron suppressed regions (NSRs) relative to the larger surrounding polar region is demonstrated, and it is shown that they are not closely related to the permanently shadowed regions. There is a significant increase in H content in the polar regions independent of the H content of the NSRs. The non‐NSR H content increases directly with latitude, and the rate of increase is virtually identical at both poles. There is little or no increase with latitude outside the polar region. Various mechanisms to explain this steep increase in the non‐NSR polar H with latitude are investigated, and it is suggested that thermal volatilization is responsible for the increase because it is minimized at the low surface temperatures close to the poles.

The MGS Orbiter is carrying the high-precision Mars Orbiter Laser Altimeter (MOLA) which, when combined with precision reconstructed orbital data and telemetered attitude data, provides a tie between inertial space and Mars-fixed coordinates to an accuracy of 100 m in latitude / longitude and 10 m in radius (1 sigma), orders of magnitude more accurate than previous global geodetic/ cartographic control data. Over the 2 year MGS mission lifetime, it is expected that over 30,000 MOLA Global Cartographic Control Points will be produced to form the basis for new and re-derived map and geodetic products, key to the analysis of existing and evolving MGS data as well as future Mars exploration. Additional information is contained in the original extended abstract.