Engineering topics
Publications and source records attributed to Cohen, Barbara.
Geochronology: More than just rock ages. What are the constraints on the time evolution ofthe dynamic solar system? When did the outerplanets migrate and the asteroid belt lose mass? How did it affect other bodies at that time?
Water is a human-exploitable resource. Lunar Flashlight is a Cubesat mission to detect and map lunar surface ice in permanently-shadowed regions of the lunar south pole. EM-1 will carry 13 Cubesat-class missions to further smallsat science and exploration capabilities; much room to infuse LEO cubesat methodology, models, and technology. Exploring the value of concurrent measurements to measure dynamical processes of water sources and sinks.
Legacy of the Apollo samples is the link forged between radiometric ages of rocks and relative ages according to stratigraphic relationships and impact crater size frequency distributions.
Planetary science cubesats are being built. Insight (2018) will carry 2 cubesats to provide communication links to Mars. EM-1 (2019) will carry 13 cubesat-class missions to further smallsat science and exploration capabilities. Planetary science cubesats have more in common with large planetary science missions than LEO cubesats- need to work closely with people who have deep-space mission experience
Invest this decade in in situ instruments(including sample selection and handling can we choose using VR?) to TRL 6; put them on flight missions in the 2020s and 2030s to relevant destinations where in situ precision can provide meaningful constraints on geologic history.
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The Dhofar 961 lunar meteorite was found in 2003 in Oman. It is texturally paired with Dhofar 925 and Dhofar 960 (though Dhofar 961 is more mafic and richer in incompatible elements). Several lines of reasoning point to the South Pole-Aitken Basin (SPA) basin as a plausible source (Figure 2): Mafic character of the melt-breccia lithic clasts consistent the interior of SPA, rules out feldspathic highlands. Compositional differences from Apollo impact-melt groups point to a provenance that is separated and perhaps far distant from the Procellarum KREEP Terrane SPA "hot spots" where Th concentrations reach 5 ppm and it has a broad "background" of about 2 ppm, similar to lithic clasts in Dhofar 961 subsamples If true, impact-melt lithologies in this meteorite may be unaffected by the Imbrium-forming event that is pervasively found in our Apollo sample collection, and instead record the early impact history of the Moon.
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Since these techniques are very new and as they have never been used or this purpose. they will need to be replicated by several independent studies. These techniques may be very important if the optical imaging encounters difficulties, for example, if a sample is made of very dark or monochromatic material and in the case of very deep pits (>500 microns) Based on the preliminary results, the LIBS continuum technique is more appropriate to the large pits produced by long ablations The relationship may work best homogeneous samples, but the continuum is collected with every LIBS analysis so does not require any addition to the experimental suite of techniques. The integration of a QCMB in the ablation chamber may be a very interesting solution to determine the ablated mass. Even if it only measures a fraction of the total mass, its sensitivity should be able to weigh hundreds of nanograms accumulated on the crystal during ablation and relate it to the actual ablated mass. In the future. these options may help in situ K-Ar dating to give the age of the rock with the best accuracy and precision.
Noble-gas isotopes are a well-established technique for providing detailed temperature-time histories of rocks and meteorites. We have established the MSFC Noble Gas Research Laboratory (MNGRL) at Marshall Space Flight Center to serve as a NASA investigator facility in the wake of the closure of the JSC laboratory formerly run by Don Bogard. The MNGRL lab was constructed to be able to measure all the noble gases, particularly Ar-Ar and I-Xe radioactive dating to find the formation age of rocks and meteorites, and Ar/Kr/Ne cosmic-ray exposure ages to understand when the meteorites were launched from their parent planets.
The Potassium (K) - Argon (Ar) Laser Experiment (KArLE) will make in situ noble-gas geochronology measurements aboard planetary robotic landers and roverss. Laser-Induced Breakdown Spectroscopy (LIBS) is used to measure the K abun-dance in a sample and to release its noble gases; the evolved Ar is measured by mass spectrometry (MS); and rela-tive K content is related to absolute Ar abundance by sample mass, determined by optical measurement of the ablated volume. KArLE measures a whole-rock K-Ar age to 10% or better for rocks 2 Ga or older, sufficient to resolve the absolute age of many planetary samples. The LIBS-MS approach is attractive because the analytical components have been flight proven, do not require further technical development, and provide complementary measurements as well as in situ geochronology.
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