NASA’s MAVEN spacecraft, in orbit at Mars since Sept. 21, 2014, has completed the fourth deep-dip campaign of its primary science mission. The series of five-day campaigns are designed to lower the periapsis (lowest altitude) of the spacecraft above #Mars in order to achieve a targeted atmospheric density corridor and to sample the lower, well-mixed portion of the Martian upper atmosphere. The density at 125 km (78 mi) can be 30 times that encountered during the nominal science orbits, where the periapsis is approximately 150 km (93 mi).
The latest deep-dip campaign concluded in the early hours of Sept. 10th with the second of two “walk-out” maneuvers, designed to raise the periapsis of MAVEN back to near 150 km. The minimum periapsis altitude achieved during the campaign was 121 km (75 mi) above the #Martiansurface. The maximum atmospheric density encountered was 3.0 kg/km³.
The two “walk-out” maneuvers (executed on Sept. 9 & 10) had ∆V (delta-V) magnitudes of 3.3 m/sec and 0.6 m/sec, and raised the periapsis by 20 km (12 mi) and 4 km (2.5 mi) respectively. These maneuvers returned MAVEN to a nominal periapsis altitude of 145 km (90 mi) and achieved an estimated density of 0.11 kg/km³.