Kelsey Young

Refining lunar impact chronology through high spatial resolution 40Ar/39Ar dating of impact melts

Laser Ar-Ar dating of lunar melts improves chronology. Quantitative constraints on the ages of melt-forming impact events on the Moon are based primarily on isotope geochronology of returned samples. However, interpreting the results of such studies can often be difficult because the provenance region of any sample returned from the lunar surface may have experienced multiple impact events over the course of billions of years of bombardment. We illustrate this problem with new laser microprobe 40Ar/39Ar data for two Apollo 17 impact melt breccias. Whereas one sample yields a straightforward result, indicating a single melt-forming event at ca. 3.83 Ga, data from the other sample document multiple impact melt–forming events between ca. 3.81 Ga and at least as young as ca. 3.27 Ga. Notably, published zircon U/Pb data indicate the existence of even older melt products in the same sample. The revelation of multiple impact events through 40Ar/39Ar geochronology is likely not to have been possible using standard incremental heating methods alone, demonstrating the complementarity of the laser microprobe technique. Evidence for 3.83 Ga to 3.81 Ga melt components in these samples reinforces emerging interpretations that Apollo 17 impact breccia samples include a significant component of ejecta from the Imbrium basin impact. Collectively, our results underscore the need to quantitatively resolve the ages of different melt generations from multiple samples to improve our current understanding of the lunar impact record, and to establish the absolute ages of important impact structures encountered during future exploration missions in the inner Solar System.

Results from Desert FLEAS III: Field Tests of EVA/Robotic Collaboration for Planetary Exploration

Through the Lunar Advanced Science and Exploration Research (LASER) program, NASA has supported an ongoing research program at the University of Maryland and Arizona State University on collaboration between humans in extravehicular activity (EVA) and robotic systems performing scientific exploration of planetary surfaces. These field tests have been named, with a nod to NASA’s longstanding series of Desert Research and Technology Studies (RATS) tests, the Desert Field Lessons in Engineering And Science, or Desert FLEAS. This paper presents the results of the third set of field tests in this program, which consisted of a full week of field trials at SP Crater near Flagstaff, Arizona in June, 2012. Trained field geologists from Arizona State University served as test subjects for series of field exploration sorties. Each subject performed three similar sorties: one in shirtsleeves as a control; one in the MX-B pressure suit simulator to replicate the restrictions of an actual EVA; and one in MX-B directly assisted by RAVEN, including providing a ride for the suited test subjects to and from the science sites. Continual full-body biomechanics data was collected by a conformal body suit worn under the liquid cooling garment, which incorporated 18 inertial measurement units which document the motions of all major body joints throughout the sortie. Post-test subjective evaluations were collected based on the NASA task load index (TLX) protocol and Cooper-Harper ratings, along with an evaluation of the scientific exploration performance (in terms of noted observations, collected sample number and quality, and correct interpretation of data in real time) of the subject in each of the operating modes. These tests were performed both in daylight and in darkness, using lighting provided by the suits and the rover. The 2012 Desert FLEAS tests sought to provide rigorous quantitative data on the benefits and limitations of robotic augmentation of EVA for geological science data collection, including a statistically significant number of trained geologist test subjects. Following the presentation of these results, the paper briefly outlines the plans for the last two years of Desert FLEAS testing, which will focus on more extreme terrains, more advanced robotic systems, and multi-person, multi-robot exploration teams.

Connecting the Next Generation of Science Journalists with Scientists in Action

As scientific advances and controversies flood the media, journalists with strong scientific backgrounds must ensure that complex science is portrayed accurately (Mooney, 2004). Science journalists see evidence-based reporting with scientific explanation and argumentation as essential tenets of their work (Secko and Fleury, 2014). NASA’s Remote, In Situ, and Synchrotron Studies for Science and Exploration (RIS4E; pronounced “rise”) team recognizes this need, and in collaboration with the Stony Brook University School of Journalism and the Alan Alda Center for Communicating Science, created the RIS4E Science Journalism Program. This innovative program uses RIS4E research to help journalism students strengthen their understanding of the practice of science and learn to report more effectively and accurately on scientific research. RIS4E begins with a semesterlong science journalism practicum and culminates with a field experience in which students report on active NASA planetary science field research. This is the first program to engage undergraduate and graduate journalism students as a team in a deep, extended investigation of a NASA research effort.