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The structure of the upper atmosphere of Mars (above ∼100 km) has been probed in situ mainly using spacecraft accelerometers during the aerobraking phases of 3 Mars or-biters. In a similar manner, the Mars Atmosphere and Volatile Evolution (MAVEN) Ac-celerometer Experiment (ACC) will also use atmospheric drag accelerations sensed by iner-tial measurement(More)
The Mars Atmosphere and Volatile Evolution (MAVEN) mission, during the second of its Deep Dip campaigns, made comprehensive measurements of martian thermosphere and ionosphere composition, structure, and variability at altitudes down to ~130 kilometers in the subsolar region. This altitude range contains the diffusively separated upper atmosphere just above(More)
Coupling between the lower and upper atmosphere, combined with loss of gas from the upper atmosphere to space, likely contributed to the thin, cold, dry atmosphere of modern Mars. To help understand ongoing ion loss to space, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made comprehensive measurements of the Mars upper atmosphere,(More)
Data collection during the aerobraking period. The atmospheric density of Mars at the aerobraking altitude showed significant variation over time as well as large orbit-toorbit differences. On each orbit the density must be predicted to determine the appropriate and safe depth within the atmosphere for the aerobraking passage sufficiently in advance to(More)
Since its founding, NASA has been dedicated to the advancement of aeronautics and space science. The NASA Scientific and Technical Information (STI) Program Office plays a key part in helping NASA maintain this important role. The NASA STI Program Office is operated by Langley Research Center, the lead center for NASAÕs scientific and technical information.(More)
During the last 2 weeks of February 1977, an intensive scientific investigation of the martian satellite Phobos was conducted by the Viking Orbiter-1 (VO-1) spacecraft. More than 125 television pictures were obtained during this period and infrared observations were made. About 80 percent of the illuminated hemisphere was imaged at a resolution of about 30(More)
Atmospheric drag measurements obtained from the study of the orbital decay of Pioneer Venus 1 indicate that atomic oxygen predominates in the Venus atmosphere above 160 kilometers. Drag measurements give evidence that conditions characteristic of a planetary thermosphere disappear near sundown, with inferred exospheric temperatures sharply dropping from(More)
† ‡ A trade study was conducted that compared various entry, descent, and landing technologies and concepts for placing an 1,800 kg payload on the surface of Mars. The purpose of this trade study was to provide data, and make recommendations, that could be used in making decisions regarding which new technologies and concepts should be pursued. Five(More)
In NASA's past, targeting to a Mars landing site has required iteration between the Entry, Descent and Landing (EDL) analysts at NASA Langley Research Center and the interplanetary navigators at the Jet Propulsion Laboratory (JPL). JPL would develop thousands of arrival states at Mars based on an assumed, constant entry flight path angle and down range(More)