Benton C. Clark, Author at Elements Magazine

Flyby Missions to Comets and Return Sample Analysis

Comets, Thematic Articles / Donald E. Brownlee

Images from flyby missions show comets to be geomorphically diverse bodies that spew jets of gas, dust, and rocks into space. Comet surfaces differ from other small bodies because of their ejection of mass into space. Comet solids >2 µm are similar to primitive meteorite ingredients and include the highest temperature materials made in the early solar system. The presence of these materials in ice-rich comets is strong evidence for large-scale migration of solid grains in the early solar system. Cometary silicates appear to have formed in numerous hot solar system regions. Preserved interstellar grains are rare, unless they have eluded identification by having solar isotopic compositions

This content is for Registered members only. To subscribe, please
join one of our participating societies or contact the Editorial Team.

Flyby Missions to Comets and Return Sample Analysis Read More »

In Situ Compositional Measurements of Rocks and Soils with the Alpha Particle X-ray Spectrometer on NASA’s Mars Rovers

Mineralogy of Mars, Thematic Articles / Ralf Gellert

The Alpha Particle X-ray Spectrometer (APXS) is a soda can–sized, arm-mounted instrument that measures the chemical composition of rocks and soils using X-ray spectroscopy. It has been part of the science payload of the four rovers that NASA has landed on Mars. It uses 244Cm sources for a combination of PIXE and XRF to quantify 16 elements. So far, about 700 Martian samples from about 50 km of combined traverses at the four landing sites have been documented. The compositions encountered range from unaltered basaltic rocks and extensive salty sandstones to nearly pure hydrated ferric sulfates and silica-rich subsurface soils. The APXS is used for geochemical reconnaissance, identification of rock and soil types, and sample triage. It provides crucial constraints for use with the mineralogical instruments. The APXS data set allows the four landing sites to be compared with each other and with Martian meteorites, and it provides ground truth measurements for comparison with orbital observations.

This content is for Registered members only. To subscribe, please
join one of our participating societies or contact the Editorial Team.

In Situ Compositional Measurements of Rocks and Soils with the Alpha Particle X-ray Spectrometer on NASA’s Mars Rovers Read More »

Author name: Donald E. Brownlee

Flyby Missions to Comets and Return Sample Analysis

In Situ Compositional Measurements of Rocks and Soils with the Alpha Particle X-ray Spectrometer on NASA’s Mars Rovers