The LCROSS Cratering Experiment

Abstract

As its detached upper-stage launch vehicle collided with the surface, instruments on the trailing Lunar Crater Observation and Sensing Satellite (LCROSS) Shepherding Spacecraft monitored the impact and ejecta. The faint impact flash in visible wavelengths and thermal signature imaged in the mid-infrared together indicate a low-density surface layer. The evolving spectra reveal not only OH within sunlit ejecta but also other volatile species. As the Shepherding Spacecraft approached the surface, it imaged a 25- to-30-meter-diameter crater and evidence of a high-angle ballistic ejecta plume still in the process of returning to the surface--an evolution attributed to the nature of the impactor.

Characterization of the LCROSS impact plume from a ground-based imaging detection

“…Most early predictions for the LCROSS mission that were based on computational models and crater scaling relations 15 included a single plume component 16,17 . However, impact experiments conducted at the NASA Ames Vertical Range Gun in support of the LCROSS mission that used hollow projectiles demonstrated a bimodal ejecta plume structure consistent with the LCROSS SSc observations 4,18 . In these laboratory experiments, solid projectiles produced the standard, single-component plume (dubbed the 'low-angle' plume), whereas hollow projectiles produced a two-component plume (a 'low-angle' plus a 'high-angle' plume), with the low-angle plume excavating material from greater depths than the high-angle plume 18 .…”

“…The second stage of the rocket that launched LCROSS and the Lunar Reconnaissance Orbiter (LRO) was impacted into Cabeus crater on 09 October 2009 at 11:31:19.5 UTC to launch material (termed 'ejecta') from the subsurface and loft it into sunlight. An instrumented Shepherding Spacecraft (SSc) followed the impactor to obtain images and spectra of the debris plume from a nadir perspective before itself impacting into the Moon B4 min later 3,4 . Although measurements from the SSc and LRO did successfully detect water lofted from the LCROSS impact [2][3][4][5][6] , the SSc provided the only visible images of the debris plume.…”

“…An instrumented Shepherding Spacecraft (SSc) followed the impactor to obtain images and spectra of the debris plume from a nadir perspective before itself impacting into the Moon B4 min later 3,4 . Although measurements from the SSc and LRO did successfully detect water lofted from the LCROSS impact [2][3][4][5][6] , the SSc provided the only visible images of the debris plume. Without an independent observation of the visible debris plume from a more oblique view, models of the morphology and dynamics of the ejecta from this unique cratering experiment are poorly constrained.…”

Surface Composition of Vesta: Issues and Integrated Approach

“…Mars and the meteorite spectra show OH absorptions near 3 µm. The Vesta spectrum exhibits strong ferrous bands near 1 and 2 µm, but has only weak or no OH absorption per stage rocket into a shadowed part of a lunar polar crater in October 2009, and evidence of water ice and other volatile materials were reported in the resulting excavated plume (Colaprete et al 2010a(Colaprete et al , 2010bSchultz et al 2010).…”

Development of the LunaH-Map miniature neutron spectrometer

“…The Lunar CRater and Observation Sensing Satellite (LCROSS) observed larger concentrations of water after impacts from the Centaur booster and Shepherding Spacecraft at the lunar southern pole [4,5]. Data from the Lunar Reconnaissance Orbiter's (LRO) Lunar Epithermal Neutron Detector (LEND) and Lunar Prospector Neutron Spectrometer (LPNS) indicate a heterogeneous distribution of water on scales less than 10 km [6][7][8][9][10].…”