NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) mission has marked one Martian year (roughly two Earth years) orbiting the red planet.
The spacecraft was launched to observe the Martian upper atmosphere and its interactions with the sun and solar wind, the continuous stream of charged particles that stream from the sun and permeates the solar system.
How the atmosphere eroded over time could also help uncover how the early Martian climate, once warm and wet, became cold and dry as we know it today.
MAVEN has had its mission extended into a second Mars year, or until the end of 2018. But it’s already made a number of discoveries during its year abroad. Here are just a few.
Here MAVEN is poised to launch aboard a United Launch Alliance Atlas V rocket. It successfully hurled off Earth on 18 November 2013. After a 10-month, 711 million kilometre journey, it slotted into Martian orbit on 21 September 2014.
In October 2014, comet C/2013 A1 (Siding Spring) came within 230,000 kilometres of Mars. With MAVEN a new arrival, it provided an unprecedented view of the effect the comet had on the Martian environment.
In order to protect sensitive equipment from potential harm, some of MAVEN’s instruments were turned off during the flyby, but its magnetometer – which measures the solar wind – remained on.
Comet Siding Spring’s coma – the sheath of gas flowing from the comet’s nucleus – acted much like the solar wind barrelling into Mars’ thin atmosphere.
In the days leading to Christmas 2014, MAVEN’s instruments detected a bright, ultraviolet glow spanning Mars’ northern hemisphere.
The phenomenon is similar to Earth’s northern or southern lights, which are caused by energetic particles hurtling into the atmosphere.
Because Mars lacks the magnetic field of Earth, these particles can easily hit the Martian atmosphere.
This image is a map of Mars’ surface, overlaid with MAVEN’s Imaging Ultraviolet Spectrograph detections of the “Christmas lights”.
Early results from the MAVEN spacecraft helped researchers create this computer simulation of the interaction between the solar wind and electrically charged particles in Mars’ upper atmosphere.
Atoms in the upper atmosphere of Mars are charged following interaction with solar and space radiation. This, in turn, allows them to interact with the magnetic and electric forces of the solar wind, which has thinned Mars’ atmosphere over time.
The lines here represent ions’ path and the colours, their energy. This simulation shows that the polar plume, in red, contains the most energised ions.
MAVEN’s instruments measured that the solar wind strips away gas particles in the Martian atmosphere at rate of about 100 grams each second.
This rate of atmospheric erosion is increased during the sun’s outbursts called solar storms.
Investigators at the University of Colorado in the US suggested that this rate was likely much higher billions of years ago when the sun was younger and more active – potentially a major contributor to Mars’ dramatic climate change.
This image is an artists’ rendering of a solar storm hitting Mars and ions stripped from the upper atmosphere.
This high-resolution image was captured on 13 July 2016 from MAVEN’s Imaging Ultraviolet Spectrograph. It has been rendered with false colour to approximate what we would see if our eyes were sensitive to ultraviolet light.
The view shows us a 3,200-kilometre canyon system named the Valles Marineris appearing as a blue-green gash.
Also shown are three Tharsis volcanoes on the images top left, and the pink region at the bottom shows where ozone at Mars’ south pole is absorbing ultraviolet light.