22nd September 2014
NASA's MAVEN probe arrives in orbit around Mars
The latest mission to Mars will attempt to uncover new clues about why the planet lost its atmosphere and surface water billions of years ago.
Another entry on our timeline is becoming a reality, as the Mars Atmosphere and Volatile EvolutioN (MAVEN) probe has successfully entered Mars' orbit. Launched by an Atlas V rocket in November 2013, the spacecraft travelled 442 million miles (711 million km) to reach its destination. As it approached the Martian north pole last night, MAVEN performed a 33-minute burn to reduce its speed, a manoeuvre that consumed over half its fuel. This allowed it to be captured by the planet's gravity and inserted into an elliptical orbit, with arrival confirmed shortly before 0230 GMT (2230 EDT Sunday; 0330 BST).
Using a total of eight instruments, MAVEN will now begin studying the Red Planet’s upper atmosphere and its interactions with the solar wind. There is strong evidence that Mars once possessed a denser atmosphere and higher temperatures, allowing vast amounts of liquid water on the surface – possibly including a large ocean that covered one-third of the planet. These conditions may even have been suitable for life to emerge. At some point in the distant past, however, Mars lost 99% of its atmosphere to space. It is theorised that over millions of years, the planet's core began to cool and its magnetic field decayed, allowing the solar wind to sweep away most of the water and volatile compounds that the atmosphere once contained.
The goal of MAVEN is to determine the history of the Martian atmosphere and its climate evolution. By measuring the rate at which gases are currently escaping to space and gathering knowledge about the relevant processes, researchers will be able to infer how the atmosphere changed over time. During the next twelve months, a series of "deep dips" will occur at 77 miles (125 km) minimum altitude to sample the upper atmosphere. This data will provide information down to where the upper and lower atmospheres meet, giving scientists a full profile of the upper tier.
MAVEN is the first probe to study the tenuous upper atmosphere of Mars in such detail. It will also examine the Sun's influence, looking at how much energy it puts into the planet and its climate. By chance, a comet will pass extremely close to Mars next month, offering a rare opportunity to see how incoming water and other molecules affect the physical processes. You can follow the mission progress at nasa.gov/maven and Twitter/MAVEN2Mars.