The Atmospheric Structure Investigation Accelerometers measured the density of atmospheric gases at different altitudes during the spacecraft's repeated flights in and out of the Martian atmosphere. The measurements provided new understanding of seasonal wind variations, the effects of dust storms, and the structure of the atmosphere.
During the aerobraking phase of the mission, data from the engineering accelerometer was used to determine the atmospheric density at the altitude of the spacecraft.
This information in turn provided information about coupling between the lower and upper atmosphere of Mars and about variations in seasonal winds and the effects of dust storms on atmospheric density.
The Principal Investigator (lead scientist) is Gerry Keating from George Washington University and the co-Investigator is Steve Bougher from the University of Michigan.