Statistics
Scientific paper
Dec 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008agufm.u21a0028e&link_type=abstract
American Geophysical Union, Fall Meeting 2008, abstract #U21A-0028
Statistics
5410 Composition (1060, 3672), 5464 Remote Sensing, 5470 Surface Materials And Properties
Scientific paper
Determining the surface composition of Mercury is important for an understanding the origin and evolution of the planet. A Gamma-ray Spectrometer (GRS) with a high-purity germanium detector is part of the scientific payload on the MESSENGER spacecraft used to measure the elemental composition of the Mercury's surface. The MESSENGER spacecraft flew by Mercury for the first time on 14 January 2008 and will fly by again on 6 October 2008. During the first flyby the GRS was powered on starting about 35 hours prior to closest approach. Gamma-ray spectrometry is typically is photon limited, as the fluxes from a planet are relatively low. Simulations, nonetheless, indicated that some of the strongest peaks from Mercury might be measurable during the flyby. Spectra of the planet were taken while the spacecraft was within 2500 km range (for period of 22 minutes). Gamma-ray peaks from K, Si, Al, and Fe were identified and analyzed. All of these peaks were also measured during the longer period prior to closest approach. To be significant, any net signal from Mercury must be resolvable above this background level. Estimates based on the decay of 40K, indicated that abundances of K greater than 1% by weight on Mercury would be detectable, even for this short accumulation time. The first flyby measurement gave only an upper limit for K of 0.5% for the equatorial region viewed during closest approach. This result adds a new constraint on the abundance of K- rich minerals, at least for this region on the planet. The only peak that was statistically significant above background was the Si inelastic scatter gamma ray at 1779 keV. The second fly-by will allow further measurements of these elements for a different area on Mercury. These measurements will also be combined with those from the first flyby to improve the statistics for estimating the average elemental abundances in the equatorial regions of Mercury.
Boynton Willam V.
Evans Larry G.
Goldsten John O.
McCoy Timothy James
Nittler Larry R.
No associations
LandOfFree
Gamma-Ray Spectrometer Measurements at Mercury during MESSENGER's First Two Flybys does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Gamma-Ray Spectrometer Measurements at Mercury during MESSENGER's First Two Flybys, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gamma-Ray Spectrometer Measurements at Mercury during MESSENGER's First Two Flybys will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1240888