Traffic Maneuver Problems of Older Drivers: Final Technical Report

DTFH61-90-C-00008This project includes a literature review and accident analysis that supported the hypothesis that age differences in motion perception capabilities represent a likely source of difficulty for specific traffic maneuver problems experienced by older drivers. A feasibility study was performed to evaluate the most appropriate apparatus for use in later driving simulation tests planned in this research. Two sets of experiments were subsequently conducted. In the first experiment, drivers in three age groups--18-55, 56-74, and 75+ years of age--estimated the time-to-collision (TTC) of an approaching vehicle, from both stationary and moving perspectives. The conflict vehicle approached at varying speeds, and was removed from the view of the test subject at varying times/distances relative to the subject. In the second experiment, drivers viewed a dynamic roadway scene containing an approaching conflict vehicle. The subject's task was to judge the "last safe moment to proceed" with a particular traffic maneuver in relation to the conflict vehicle, to determine a gap judgment measure. Both the TTC and the gap judgment measures were obtained under laboratory conditions using multiple stimulus presentation methodologies in a driving simulator. Limited controlled field validation data were also obtained for both types of dependent measures, using the same test sample. Recommendations for countermeasures to accommodate older driver difficulties with turning maneuvers at intersections were developed consistent with the results of these studies

Planning considerations related to the organic contamination of martian samples and implications for the Mars 2020 rover

© Copyright 2014, Mary Ann Liebert, Inc. Data gathered during recent NASA missions to Mars, particularly by the Rovers Spirit, Opportunity, and Curiosity, have provided important insights into the past history and habitability of the Red Planet. The Mars science community, via input through the National Research Council (NRC) Planetary Science Decadal Survey Committee, also identified the prime importance of a Mars sample return (MSR) mission to further exploration of the Red Planet. In response, the Mars 2020 Mission (Mars 2020) Science Definition Team (SDT) (Mustard et al., 2013) was chartered by the NASA Mars Exploration Program to formulate a new rover mission that would take concrete steps toward an eventual sample return. The SDT recommended that the 2020 rover should select and cache scientifically compelling samples for possible return to Earth. They also noted that organic contamination of the samples was a significant and complex issue that should be independently investigated by a future committee. Accordingly, NASA chartered the Mars 2020 Organic Contamination Panel (OCP). The OCP was charged with evaluating and recommending sample contamination requirements for the proposed Mars 2020. A further task was to assess implementation approaches in support of the investigation of broad scientific questions concerning the history and habitability of Mars. Central to these objectives would be the ability to reliably differentiate indigenous martian organic molecules from terrestrial contamination in any future samples returned from Mars. Early on during its deliberations, the OCP recognized that the scientific and planetary protection (PP) objectives of MSR are intimately linked, in that both rely heavily on measurements of organic molecules in the returned samples. In each case, a key aspect of the problem is being able to recognize and interpret organic molecules as indigenous to Mars against a potential background of Earthsourced contamination. It was within this context that the OCP committee considered the structure for a set of measurement goals related to organic molecules in the returned samples that would be of common interest to science and PP. The following is a summary of the most significant findings of the OCP regarding organic geochemical measurements that would be shared for both science and PP in relation to potential future MSR