Earlier this week, the NASA probe Maven entered orbit around Mars, a key step in its mission to solve one of the solar system’s most puzzling mysteries—what happened to the Red Planet’s atmosphere?
The journey took 10 months, covered 442 million miles, and ended in a blaze of rocket fire as the craft’s engines fired for more than 30 minutes to ease it into the desired orbit. Over the next month and a half, mission control will wake the probe’s various systems and run checks to make sure they’re working properly. Flight controllers will also bring the spacecraft closer to Mars in preparation for its science mission. At some points, Maven will be cruising just 77 miles above the surface of the planet, far closer than the 260 miles the International Space Station is above Earth.
Such intimacy with Mars will help Maven with it’s primary mission. By dipping into the Red Planet’s thin atmosphere, it can measure the rate at which gases are being lost. Knowing that, scientists can then extrapolate backwards to determine when, exactly, Mars had a thicker atmosphere that might have supported life.
There are two leading hypotheses on the fate of Mars’s atmosphere. The first says that the planet’s geology absorbed much of it in the form of carbonate rocks. (The same process happens on Earth, but plate tectonics and other activities keep the crust in check.) The other hypothesis says the gases were lost to space as solar winds slowly blew them away over billions of years. Mars lacks a strong magnetic field to protect it against the Sun’s continuous assault of charged particles, unlike Earth.
Maven carries a complement of eight sensors for various purposes. Here’s Jonathan Amos, reporting for BBC News:
Some of Maven’s instruments will concentrate on the Sun’s influence, looking at how much energy it puts into the planet and its atmosphere.
Others instruments will investigate the composition and behaviour of the atmosphere itself, and this will involve some “deep dip” manoeuvres that take Maven closer to Mars’ surface so it can sample air molecules directly.
In addition to sampling Martian gases, Maven will observe how debris from the close pass of Comet Siding Spring reacts with the planet’s outer atmosphere. The craft will also team up with NASA’s Curiosity and Opportunity rovers, serving as a backup communications relay, and India’s Mars Orbiter Mission, which will be observing other aspects of the Red Planet’s atmosphere and surface.