February 10, 2015 – The MAVEN spacecraft has started the first “deep-dip” campaign of the mission. The MAVEN navigation team has given the green light for today’s initial “walk down,” which will lower the periapsis of the spacecraft by about 20 km and begin a transition into an area of Mars’ upper atmosphere known as the “homopause.” This region of Mars’ atmosphere, at the boundary between Mars’ upper and lower atmospheres, is about 30 times more dense than the area explored by MAVEN during its primary science mapping operations.
The first maneuver of this initial Deep Dip campaign will be carried out this afternoon and will lower the periapsis altitude to about 133 km. It is the first of three maneuvers that will “walk” the MAVEN spacecraft into the deep-dip density corridor.
Last week, mission operators successfully ran the full sequences for a “deep-dip demo,” which included everything except having the lower periapsis. The instruments were in their deep-dip modes and the spacecraft was in its deep-dip orientation for the test.
This week’s deep-dip campaign will begin with a two-day “walk-down” into the target density corridor, which will be followed by five days with a periapsis in this corridor of about 125 km (77 miles) above the surface of the planet, and then another two days of periapsis raising maneuvers to bring the spacecraft back into its nominal science mapping orbit.
MAVEN will execute five deep-dip campaigns, each lasting 20 orbits (approximately five days.) Through these campaigns, along with its normal orbital operations, MAVEN is able to make measurements throughout the entire upper atmosphere, from its base to its upper boundary where it interacts with solar wind.
MAVEN’s orbit is elliptical and in its nominal science mapping ornament, it is roughly 150 km (93 miles) above the surface of Mars at its closest point. At its highest point, it is more than 6000 km (3728 miles) above the surface.
Many of the design features, algorithms, processes, and lessons-learned from previous Mars missions support deep-dip operations. MAVEN’s gull-wing solar panel design is one of those features. The spacecraft’s solar panels are bent at a 20-degree angle.
As MAVEN travels through the upper atmosphere, the air pressure will increase to a point that could disrupt flight dynamics if the solar panels were flat. MAVEN’s bent solar panels shift the center of air pressure away from the spacecraft’s center of gravity, providing a self-stabilizing configuration for atmospheric flight. The effect is similar to the self-stabilization provided by feathers on a badminton shuttlecock.
MAVEN’s measurements will allow scientists to characterize the current state of the upper atmosphere and ionosphere, determine the rates of loss of gas to space today, and extrapolate backward in time in order to determine the total loss to space through time.
MAVEN is led by its Principal Investigator Bruce Jakosky, from the University of Colorado at Boulder. The university built two of the eight science instruments and is conducting the mission’s science operations. Lockheed Martin of Littleton, Colorado, built the spacecraft and is performing mission operations. MAVEN was launched on November 18, 2013 atop a United Launch Alliance Atlas V rocket.
For more information about MAVEN’s science mapping orbit, visit: