Global spatial deconvolution of Lunar Prospector Th abundances

Lawrence, D. J.; Puetter, R. C.; Elphic, R. C.; Feldman, W. C.; Hagerty, J. J.; Prettyman, T. H.; Spudis, P. D.

doi:10.1029/2006gl028530

Cited by 68 publications

(70 citation statements)

References 20 publications

(37 reference statements)

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“…As seen in (12), the derivation of gamma-ray flux at the surface is involved in deconvolution problem. There are several ways to solve (12) and to obtain φ(θ 1 , ϕ 1 ) (e.g., Haines et al 1978;Lawrence et al 2007), but the method that is the easiest and the most reliable in obtaining the surface flux is shown here at the expense of spatial resolution. Assuming that φ is almost constant in an area centered at the nadir point, φ is approximated:…”

Section: Transport From the Lunar Surface To The Ge Crystal (Stage 2 mentioning

confidence: 98%

“…The SRF generally plays a significant role in gamma-ray remote sensing, since it is used for the estimation of spatial resolution (e.g., Reedy et al 1973), the smoothing of statistically varied gammaray intensity maps (e.g., Lawrence et al 2003), and the gamma-ray image restoration of spatial deconvolution analysis (e.g., Haines et al 1978;Lawrence et al 2007) as well as the determination of the absolute abundances. However, there is a problem in deriving the SRF of a gamma-ray spectrometer.…”

Section: Introductionmentioning

confidence: 99%

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Determining the Absolute Abundances of Natural Radioactive Elements on the Lunar Surface by the Kaguya Gamma-ray Spectrometer

et al. 2010

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The Kaguya gamma-ray spectrometer (KGRS) has great potential to precisely determine the absolute abundances of natural radioactive elements K, Th and U on the lunar surface because of its excellent spectroscopic performance. In order to achieve the best performance of the KGRS, it is important to know the spatial response function (SRF) that describes the directional sensitivity of the KGRS. The SRF is derived by a series of Monte Carlo simulations of gamma-ray transport in the sensor of the KGRS using the full-fledged simulation model of the KGRS, and is studied in detail. In this paper, the method for deriving absolute abundance of natural radioactive elements based on the SRF is described for the 194 S. Kobayashi et al.analysis of KGRS data, which is also applicable to any gamma-ray remote sensings. In the preliminary analysis of KGRS data, we determined the absolute abundances of K and Th on the lunar surface without using any previous knowledge of chemical information gained from Apollo samples, lunar meteorites and/or previous lunar remote sensings. The results are compared with the previous measurements and the difference and the correspondence are discussed. Future detailed analysis of KGRS data will provide new and more precise maps of K, Th and U on the lunar surface.

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Section: Transport From the Lunar Surface To The Ge Crystal (Stage 2 mentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Determining the Absolute Abundances of Natural Radioactive Elements on the Lunar Surface by the Kaguya Gamma-ray Spectrometer

et al. 2010

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“…This area also has high Th [4,8] and low FeO. Various impacts, volcanic processes, and complex topography in this area imply that the high radioactive elements are not strictly associated with ejecta deposits from Aristarchus crater.…”

Section: Relative Distribution Of Potassiummentioning

confidence: 95%

“…Their distributions on the lunar surface are, therefore, the end products of a series of processes, such as accumulation, collision, and modification. Gamma-ray measurements from Lunar Prospector [3][4][5][6][7][8], Kaguya [9][10][11][12] and CE-1 [13,14] have conclusively demonstrated that the surface occurrences of radioactive elements are mostly confined to the lunar nearside, called Procellarum KREEP Terrane (PKT) [15]. Moderate levels of radioactives are also observed in the South Pole-Aitken basin, on the farside of the Moon.…”

Section: Introductionmentioning

confidence: 97%

Lunar potassium distribution: Results from Chang’E-1 gamma ray spectrometer

Zhu

Chang

et al. 2011

Sci. China Phys. Mech. Astron.

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The global map of potassium is represented in this paper from Chang'E-1 (CE-1) Gamma-ray Spectrometer (CGRS) for its one-year mission. Assuming a linear relationship between net count rate and its abundance, the average potassium abundance of individual landing sites is used as ground-truth for the calibration to derive the global map of absolute concentration. Although CGRS spectra have a lower signal-to-noise ratio, the translated map still keeps relative variations. As calculated from Apollo, Lunar Prospector, and Kaguya, global potassium map from CGRS shows high concentrations on the lunar nearside and secondary concentrations located in the South Pole-Aitken (SPA) basin on the farside. The comparison with Lunar Prospector potassium map shows a good correlation, though abundances on the highlands of the farside are much lower than that of Lunar Prospector. Since the footprint of CGRS measurements is larger than the sampling radius of each landing site, the calibrated map shows a larger variation range of the scale than that of Lunar Prospector, which was derived using theoretical calculation; namely, the calibrated map has higher values in the areas with high concentration while having lower values for the areas with lower concentration. However, the derived potassium map is more consistent with the lunar sample data than that of Lunar Prospector.Chang'E-1, gamma-ray spectrometer, potassium distribution, empirical calibration PACS: 99.55. Ka, 99.55.Pe, 96.20.Br

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“…Characteristic peaks are labeled with element symbols; other unlabeled peaks are spurious signals from elastic and inelastic scattering. tial deconvolution was used to characterize features at higher spatial scales (16,17).…”

Section: Examples Of Cosmochemistry Flight Instrumentsmentioning

confidence: 99%

Spacecraft instrument technology and cosmochemistry

McSween

McNutt

Prettyman

2011

Proc. Natl. Acad. Sci. U.S.A.

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Measurements by instruments on spacecraft have significantly advanced cosmochemistry. Spacecraft missions impose serious limitations on instrument volume, mass, and power, so adaptation of laboratory instruments drives technology. We describe three examples of flight instruments that collected cosmochemical data. Element analyses by Alpha Particle X-ray Spectrometers on the Mars Exploration Rovers have revealed the nature of volcanic rocks and sedimentary deposits on Mars. The Gamma Ray Spectrometer on the Lunar Prospector orbiter provided a global database of element abundances that resulted in a new understanding of the Moon's crust. The Ion and Neutral Mass Spectrometer on Cassini has analyzed the chemical compositions of the atmosphere of Titan and active plumes on Enceladus.A nalyses of extraterrestrial materials performed by instruments on spacecraft have revolutionized our understanding of planets and planetesimals, and have driven significant advances in technology. Here we focus on mobile instruments that have made cosmochemical measurements, in keeping with the theme of this issue.The adaptation of laboratory analytical instruments for flight on spacecraft missions poses many challenges. An obvious limitation for flight instruments is scale-mass and volume. Flight instruments must be crafted from light-weight materials, and miniaturization is required to fit into the confines of the spacecraft. Packing multiple instruments together can cause interferences which must be accommodated. Power limitations are often severe: instruments that use kilowatts in the laboratory might have to operate on watts in space. The storage and transmission capacities for data are limited, and onboard data compression may be required. Flight instruments must be durable to withstand the vibrations and g-forces encountered during launch and orbital insertion or landing. The instruments commonly experience extreme temperatures and irradiation by cosmic rays during long periods of interplanetary cruise. Environmental testing of flight instruments before and after they are integrated into the spacecraft system is expensive and time consuming, adding additional pressure to mission cost and schedule.During the last decade, NASA and its international partners have launched numerous spacecraft, many carrying instruments capable of performing chemical analyses. Here we provide an illustrative sampling of three successful cosmochemistry flight instruments, along with discussions of how the data that they acquired have impacted science and technology. The data from these instruments are archived in NASA's Planetary Data System (PDS, http://pds.nasa.gov/) and are available to any interested investigators. Examples of Cosmochemistry Flight Instruments Alpha Particle X-Ray Spectrometers (APXS). The Mars Exploration Rovers (MER) Spirit and Opportunity landed on Mars in 2004.Each rover carried an APXS (1), and these instruments together have analyzed hundreds of rocks and soils. The sensor head (Fig. 1), mounted on the rover arm, is brought ...

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Global spatial deconvolution of Lunar Prospector Th abundances

Cited by 68 publications

References 20 publications

Determining the Absolute Abundances of Natural Radioactive Elements on the Lunar Surface by the Kaguya Gamma-ray Spectrometer

Determining the Absolute Abundances of Natural Radioactive Elements on the Lunar Surface by the Kaguya Gamma-ray Spectrometer

Lunar potassium distribution: Results from Chang’E-1 gamma ray spectrometer

Spacecraft instrument technology and cosmochemistry

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