NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft arrived at the Red Planet back in September. Its mission is to analyze the martian atmosphere in hopes of learning more about what had happened to it, and why Mars is no longer able to sustain liquid water on the surface. Part of this year-long mission will include five low dips toward the planet’s surface in order to study the lower aspects of the upper atmosphere. The first of these five dips has recently been carried out, NASA’s Goddard Space Flight Center has announced.
"During normal science mapping, we make measurements between an altitude of about 150 km and 6,200 km (93 miles and 3,853 miles) above the surface," MAVEN PI Bruce Jakosky said in a press release. "During the deep-dip campaigns, we lower the lowest altitude in the orbit, known as periapsis, to about 125 km (78 miles) which allows us to take measurements throughout the entire upper atmosphere.”
The altitude dip might not seem very significant considering the vast range of altitude it orbits under normal conditions, but this positions the spacecraft in a location to analyze a layer of the atmosphere it would not normally be able to access. The density of the upper atmosphere changes considerably, with the bottom end being up to 10 times more dense than the top. These deep dips will allow scientists to understand the density at the bottom, and see how it changes throughout.
"We are interested in the connections that run from the lower atmosphere to the upper atmosphere and then to escape to space," Jakosky explained. "We are measuring all of the relevant regions and the connections between them.”
Part of what makes the deep dip so daring is how the spacecraft will respond when flying through the thicker air. This extra drag creates significant heat through friction, which could potentially be problematic to the instruments that were meant to be operated at much lower temperatures.
"Although we changed the altitude of the spacecraft, we actually aimed at a certain atmospheric density,” Jakosky continued. "We wanted to go as deep as we can without putting the spacecraft or instruments at risk.”
After MAVEN was returned within the range of its normal cruising altitude, scientists began sifting through the incredible amount of data that was returned. It is hoped that this data set, as well as the four to come, will help astronomers understand how the atmosphere of Mars depleted over time.