NASA's MAVEN (Mars Atmosphere and Volatile EvolutioN) mission has captured stunning views of Mars in two ultraviolet images taken at different points along our neighbouring planet's orbit around the Sun.

By imaging the planet at ultraviolet wavelengths, scientists can gain insight into the Martian atmosphere and see surface features in remarkable ways.
MAVEN's Imaging Ultraviolet Spectrograph (IUVS) instrument acquired these spherical images of Mars in 2022 and 2023, when the planet was near opposite ends of its elliptical orbit.

The IUVS instrument measures wavelengths between 110 and 340 nanometres, which are outside the visible spectrum. To make these wavelengths visible to the human eye and to facilitate interpretation, the images are composed with varying brightness levels of the three ultraviolet wavelength ranges represented as red, green and blue. In this colour scheme, atmospheric ozone appears purple, while clouds and haze appear white or blue. The surface may appear tan or green, depending on how the images are optimised to increase contrast and show detail.

The first image was taken in July 2022 during the southern hemisphere summer season, which occurs when Mars passes close to the Sun. The summer season is due to the tilt of the planet's rotation axis, similar to the seasons on Earth. The Argyre Basin, one of the deepest craters on Mars, is seen in the lower left, filled with atmospheric haze (depicted here in pale pink). The deep canyons of Valles Marineris appear cloud-filled at top left (flesh-coloured in this image). The southern polar ice cap is seen in white at the bottom and is shrinking due to the relative warmth of summer. The southern summer warming and dust storms push water vapour to very high altitudes, explaining MAVEN's discovery of increased hydrogen loss from Mars at this time of year.

The second image is of Mars' northern hemisphere and was taken in January 2023, after Mars had passed the furthest point from the Sun in its orbit. In the north polar region, the rapidly changing seasons cause abundant white clouds. The deep canyons of Valles Marineris, with its many craters, can be seen in bronze in the lower left. The ozone, which appears magenta in this UV image, accumulated during the cold polar nights of the northern winter. It is then destroyed in the northern spring by chemical reactions with water vapour, which at this time of year is confined to the low altitudes of the atmosphere.

MAVEN was launched in November 2013 and entered Mars' orbit in September 2014. The mission's goal is to explore the planet's upper atmosphere, ionosphere and interactions with the Sun and solar wind to investigate the loss of the Martian atmosphere to space. Understanding the loss of atmosphere will give scientists insight into the history of Mars' atmosphere and climate, liquid water and the habitability of the planet. The MAVEN team is preparing to celebrate the spacecraft's 10th anniversary on Mars in September 2024.

Source: nasa.gov/