Apollo 15 Geochemical X-Ray Fluorescence Experiment: Preliminary Report

Approximately 180 glasses in each of three Apollo 15 soils have been analyzed for nine elements. Cluster analysis techniques allow the recognition of preferred glass compositions that are equated with parent rock compositions Green glass rich in Fe and Mg, poor in Al and Ti may be derived from deep seated pyroxenitic material now present at the Apennine Front. Fra Mauro basalt (KREEP) is most abundant in the LM soil and is tentatively identified as ray material from the Aristillus‐Autolycus area. Highland basalt (anorthositic gabbro), believed to be derived from the lunar highlands, has the same composition as at other landing sites, but is less abundant. The Apennine Front is probably not true highland material but may contain a substantial amount of material with the composition of Fra Mauro basalt, but lacking the high‐K content. Glasses with mare basalt compositions are present in the soils and four subgroups are recognized, one of which is compositionally equivalent to the large Apollo 15 basalt samples

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“…The Al/Si ratio of low-K Fra Mauro basalt is identical with Adler et al's (1972) measurements for the Apennine Mountains.…”

Section: The Apennine Front and Fra Mauro Basaltssupporting

confidence: 54%

Major Element Composition of Glasses in Three Apollo 15 Soils

Reid¹,

Warner²,

Ridley

et al. 1972

Meteoritics

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“…The X-ray Fluorescence Spectrometer (1->3 keV), carried in the Scientific Instrument Module of the Command and Service Module on the Apollo 15 mission, was mainly used for orbital mapping of the lunar surface composition (see, e.g., Adler et al 1972aAdler et al ,b, 1975. Galactic X-ray observations were made during the trans-Earth coast for several periods of about an hour (e.g., Adler et al 1972b).…”

Section: A1 Apollo 15 Observationsmentioning

confidence: 99%

Restless quiescence: thermonuclear flashes between transient X-ray outbursts

Kuulkers¹,

Zand

Lasota

2009

A&A

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For thermonuclear flashes to occur on neutron-star surfaces, fuel must have been accreted from a donor star. However, sometimes flashes are seen from transient binary systems when they are thought to be in their quiescent phase, during which no accretion, or relatively little, is expected to occur. We investigate the accretion luminosity during several such flashes, including the first-ever and brightest detected flash from Cen X-4 in 1969. We infer from observations and theory that immediately prior to these flashes the accretion rate must have been between about 0.001 and 0.01 times the equivalent of the Eddington limit, which is roughly 2 orders of magnitude less than the peak accretion rates seen in these transients during an X-ray outburst and 3-4 orders of magnitude more than the lowest measured values in quiescence. Furthermore, three such flashes, including the one from Cen X-4, occurred within 2 to 7 days followed by an X-ray outburst. A long-term episode of enhanced, but low-level, accretion is predicted near the end of the quiescent phase by the disk-instability model, and may thus have provided the right conditions for these flashes to occur. We discuss the possibility of whether these flashes acted as triggers of the outbursts, signifying a dramatic increase in the accretion rate. Although it is difficult to rule out, we find it unlikely that the irradiance by these flashes is sufficient to change the state of the accretion disk in such a dramatic way.

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“…Since the days of the Apollo 15 and 16 missions, where the first XRFS data from another planetary body were obtained (Adler et al 1972), the spatial and spectral resolution, and the overall sensitivity available for remote-sensing X-ray instruments, have improved substantially. After the Apollo era, XRFSs have been included in several orbiting planetary spacecraft payloads, including NEAR Shoemaker (Goldsten et al 1997), SMART-1 (Grande et al 2003), Hayabusa (Okada et al 2006), and Kaguya (formerly Selene) .…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Laboratory studies into the effect of regolith on planetary X-ray fluorescence spectroscopy

Näränen

Parviainen²,

Muinonen³

et al. 2008

Icarus

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Laboratory studies into the effect of regolith on planetary X-ray fluorescence spectroscopy. Icarus, Elsevier, 2008, 198 (2) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTLaboratory studies into the effect of regolith on planetary X-ray fluorescence spectroscopy A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT AbstractIn the analysis of X-ray fluorescence spectra from planetary surfaces, it is traditionally assumed that the observed surface is a plane-parallel, smooth, and homogeneous medium. The spectral and spatial resolutions of the instruments that have been used to measure X-ray emission from planetary surfaces to date have been such that this has been a reasonable assumption, but a new generation of X-ray spectrometers will provide enhanced spectral and spatial resolutions when compared with previous instrumentation. In light of these improvements in performance, it is important to assess how the requirements on the methodology of analysis of spectra may change when the surface is considered as a regolith. At other wavelengths, varying physical properties of planetary regoliths, such as the packing density, are known to have an effect on the observed signal as a function of viewing geometry. In this paper, the results from laboratory X-ray fluorescence measurements of regolith analogue materials at different viewing geometries are presented. Characteristic properties of the regolith such as particle sizes and packing density are found to affect the measured elemental line ratios. A semiempirical function is introduced as a tool for fitting fluorescent line intensity dependences as a function of viewing geometry. The importance of the results is discussed and recommendations are made for the future analysis of planetary X-ray fluorescence data.

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Apollo 15 Geochemical X-Ray Fluorescence Experiment: Preliminary Report

Cited by 89 publications

References 5 publications

Major Element Composition of Glasses in Three Apollo 15 Soils

Major Element Composition of Glasses in Three Apollo 15 Soils

Restless quiescence: thermonuclear flashes between transient X-ray outbursts

Laboratory studies into the effect of regolith on planetary X-ray fluorescence spectroscopy

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