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 began on Sept. 2nd with two “walk-in” maneuvers that lowered the periapsis of the spacecraft to 121 km (75 mi) above the Martian surface. These maneuvers had ∆V (delta-V or a change in velocity) magnitudes of 2.7 m/sec and 0.6 m/sec. The 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 maximum atmospheric density encountered during the deep-dip was 3.0 kg/km³.
The two “walk-out” maneuvers (executed on Sept. 9 & 10) had ∆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.
