The Mars Atmosphere And Volatile EvolutioN (MAVEN) spacecraft is being developed by a government, academic, and commercial aerospace team to determine the role that loss of atmospheric gas to space played in changing the Martian climate. The spacecraft is scheduled to launch between November 18 and December 7, 2013 and will be the first mission devoted to understanding the Martian upper atmosphere.
MAVEN will determine how much of the Martian atmosphere has been lost over time by measuring the current rate of escape to space and gathering enough information about the relevant processes to allow extrapolation backward in time, giving insight into the history of Mars atmosphere and climate, liquid water, and planetary habitability.
According to NASA, flows of ions from Mars' upper atmosphere have been seen by both NASA's Mars Global Surveyor and the European Space Agency's Mars Express spacecraft.
As the martian atmosphere thinned, the planet got drier because water vapor in the atmosphere was also lost to space, and because any remaining water froze out as the temperatures dropped when the atmosphere disappeared. MAVEN will discover how much water has been lost to space by measuring hydrogen isotope ratios.
On Mars, hydrogen escapes faster because it is lighter than deuterium. Since the lighter version escapes more often, over time, the martian atmosphere has less and less hydrogen compared to the amount of deuterium remaining. The martian atmosphere therefore has become richer and richer in deuterium.
Comparing the present and original H/D ratios will allow the team to calculate how much hydrogen, and therefore water, has been lost over Mars' lifetime. As NASA explains it, if the team discovers the martian atmosphere is ten times richer in deuterium today, the planet's original quantity of water must have been at least ten times greater than that seen today.
Goddard Space Flight Center is managing the project and will also build some of the instruments for the mission, specifically, a magnetometer and a neutral gas and ion mass spectrometer (NGIMS). The NGIMS will be provided by the Planetary Environments Laboraotry and it will measure the composition and isotopes of neutral ions.
Lockheed Martin recently completed building the MAVEN's primary structure at its Space Systems Company facility near Denver.
“It’s always a significant milestone when the project moves from a paper design to real hardware and software,” said Guy Beutelschies, MAVEN Program Manager at Lockheed Martin. “Seeing the core structure reinforces the fact that MAVEN is no longer just a set of ideas that scientists and engineers have come up with, it is starting to become a spacecraft.”
The primary structure is cube shaped at 7.5 x 7.5 x 6.5 ft. Built out of composite panels comprised of aluminum honeycomb sandwiched between graphite composite face sheets, the entire structure only weighs 275 lb. At the center of the structure is the 4.25 ft diameter core cylinder that encloses the hydrazine propellant tank and serves as the primary vertical load-bearing structure. The tank will hold approximately 3615 lb of fuel.
In mid October, the structure was scheduled to be moved to Lockheed Martin’s Structures Test Lab and undergo static load testing, which includes simulating the dynamic loads the spacecraft will experience during launch.
The structure has been designed to support the entire spacecraft mass during the launch, which applies an equivalent axial force at the launch vehicle interface of approximately 61,000 lb when including accelerations up to 6 g. After completion of the static tests, the structure will be moved into a clean room to start propulsion subsystem integration. The Assembly, Test and Launch Operations (ATLO) phase begins July 2012.
“There’s still a lot of work to go before we have the complete spacecraft, but this is a major step in getting us to the launch pad in two years,” said Bruce Jakosky, MAVEN Principal Investigator from the Laboratory for Atmospheric and Space Physics at the University of Colorado (CU/LASP).