NASA’S Mars Atmosphere and Volatile Evolution (MAVEN) orbiter has taken a deep dive into the Martian atmosphere. The first of a series of five planned deep-dip maneuvers by the unmanned spacecraft, its purpose was to gather information about the lower limits of the upper regions of the Red Planet's atmosphere.
Launched in November 2013 from Cape Canaveral, Florida, MAVEN arrived at Mars on September 21 on a mission to study the Martian atmosphere, its mechanisms, and why the atmosphere is slowly escaping into space. The orbiter's first observations included taking ultraviolet images of the tenuous oxygen, hydrogen, and carbon coronas in the planet's upper atmosphere, and creating a comprehensive map of its ozone layers.
According to NASA, in order to get a comprehensive picture of the atmosphere of Mars, it's necessary for MAVEN to periodically lower itself from its normal orbit of between 150 to 6,200 km (93 to 3,853 mi). For the maneuver carried out from February 10 to 18, mission control ordered MAVEN to drop the lowest point of its orbit to 125 km (78 mi).
The difference in altitude is only 25 km (16 mi), but NASA points out that because the Martian atmosphere is so tenuous, this drop increases the atmospheric pressure by a factor of 10, which is enough to provide scientists with insights into how the atmosphere works and the mechanism by which Mars is losing its atmosphere.
During the February dip, MAVEN spent three days maneuvering into a lower orbit, then spent a further five days skimming through the lower atmosphere through 20 orbits, before firing its engines twice to increase its altitude once more. This return is important because even at a height of 125 km, the Martian atmosphere is thick enough to produce enough drag to induce orbital decay and heat up the spacecraft and damage instruments.
NASA says that over the coming months it will carry out four more such deep dips as scientists study the data sent back from this month's maneuver.