June 10, 2016 – The Space Sciences Laboratory at the University of California, Berkeley, reports that the MAVEN spacecraft is in the midst of its latest deep-dip campaign. This is the final deep-dip campaign of five planned for the mission.
Three maneuvers were successfully carried out to lower the periapsis (or lowest) altitude of the spacecraft by approximately 29 km, placing MAVEN into the targeted density corridor, where the average density of Mars’ atmosphere is 3.0 kg/km³.
During normal science mapping, MAVEN makes measurements between an altitude of 150 km and 6,200 km above the surface. During deep dip campaigns, the spacecraft’s lowest altitude in orbit (periapsis) is lowered to provide additional data. At 119 km, MAVEN reaches the Martian homopause, which is the lower, well-mixed region of Mars’ upper atmosphere, where the density is about thirty times greater than at periapsis during a typical science orbit.
The fifth deep dip for MAVEN is uniquely located over the solar terminator (the boundary between dayside and nightside), close to the ecliptic plane, and at a Martian latitude of 35ºN.
The three maneuvers—carried out on June 7 and 8 required a total ∆V of 4.6 m/s and resulted in a periapsis altitude of ~119 km (74 miles).
Each of the five deep-dip campaigns lasts five days. The first three days of the campaign are used to lower the periapsis, by gently firing the rocket motors to “walk” the spacecraft to its lower orbit. The remaining two days allow the spacecraft to collect data for roughly 20 orbits. Since the planet rotates under the spacecraft, the 20 orbits allow sampling of different longitudes spaced around the planet, providing close to global coverage. At the end of the campaign, two maneuvers are conducted to return MAVEN to normal science operation altitudes.
One of the major goals of the MAVEN mission is to understand how gas from the atmosphere escapes into space, and how this has affected the planet’s climate history through time. In being lost to space, gas is removed from the top of the upper atmosphere, but the thicker lower atmosphere controls the climate. The science team can combine the data from the deep dip campaigns with the results seen during its regular mapping to get a better picture of the entire atmosphere and of the processes affecting it.
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 the first mission dedicated to studying the upper atmosphere of Mars. The spacecraft launched atop a United Launch Alliance Atlas V rocket on November 18, 2013, from Cape Canaveral Air Force Station in Florida. MAVEN successfully entered Mars’ orbit on September 21, 2014.
MAVEN is led by 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.
NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN project and provided two science instruments for the mission. The University of California at Berkeley’s Space Sciences Laboratory also provided four science instruments for the mission. NASA’s Jet Propulsion Laboratory in Pasadena, California provides navigation and Deep Space Network support, as well as the Electra telecommunications relay hardware and operations.