Twenty-year anniversary of the Mars Express: Planetary researchers at Freie Universität Berlin publish color mosaic of Mars with never before seen detailsTwenty years ago to the day, the European space probe Mars Express began its journey to Earth’s "red" neighbor. Since then, it has been collecting images and data on Mars that can be used to draw important conclusions about the planet’s composition and the history of its climate. Mars Express is considered one of the most successful missions ever sent to Earth’s neighboring planet. Among the instruments on board the probe is a High Resolution Stereo Camera (HRSC), developed by the German Institute of Planetary Research (DLR). To celebrate the twenty-year anniversary of the space probe’s launch, researchers at Freie Universität Berlin and DLR have published a new mosaic image of the surface of Mars, featuring details that have never been seen before.
The special camera used on Mars Express was developed in Germany and provides insight into the complex composition of the materials that make up the surface of what was always considered to be our "red" neighboring planet. According to researchers from the Planetary Sciences and Remote Sensing group at Freie Universität Berlin’s Institute of Geological Sciences, the color information that these images provide is unparalleled. Based at Freie Universität Berlin, the research project was made possible thanks to the support of the DLR as part of the funding program 50 OO 2204, carried out on behalf of the German Federal Ministry for Economic Affairs and Climate Action.
Since its launch on June 2, 2003, Mars Express has provided a consistent supply of images of Mars. The data that the HRSC has delivered has led to several new findings over the past years. The team behind the camera’s development was led by physicist Professor Gerhard Neukum, who sadly passed away in 2014. The idea behind the project was to carry out a global mapping of Mars in color and stereo and with a high resolution of 12 m per pixel. The HRSC was first installed on the Russian probe Mars 96, which failed to orbit and burned up on reentry to the Earth’s atmosphere. This unfortunate event did not deter Professor Neukum. As director of the DLR’s Institute of Planetary Research in Adlershof, Berlin, he was one of the key players behind the European Space Agency’s (ESA) decision to send its first research probe to another planet. Professor Neukum moved to Freie Universität Berlin in 2002, where he established the university’s planetary sciences and remote sensing disciplines.
Mars in Color and Like You Have Never Seen It BeforeWhen taking pictures of the planet’s surface, the HRSC normally photographs Mars from an altitude of 300 km - the closest the spacecraft gets to Mars in its elliptical orbit. The resulting images have a spatial resolution of up to 12.5 m per pixel and cover areas approximately 50 km wide. Thanks to its four color channels (red, green, blue, infrared) and five panchromatic channels (one nadir channel, two stereo channels, and two photometric channels), the HRSC is capable of depicting Mars not only in three dimensions, but also in color.
To create the mosaic, scientists used ninety individual images taken from even higher altitudes (between 4,000 and 10,000 km) above the surface of Mars, meaning they were able to capture areas approximately 2,500 km across with a lower spatial resolution (between 200 and 800 m per pixel).
This resulted in the image seen below; with a spatial resolution of two kilometers per pixel, the image shows a never before seen diversity and level of detail regarding the colors on Mars’ surface. At the same time, the image provides a great deal of information about the composition of the planet’s surface.
Mars is famous for its reddish color, caused by high levels of oxidized iron in the dust that covers the planet’s surface and is responsible for its nickname of the Red Planet. However, it is clear to anyone viewing the new images and the resulting mosaic that a considerable part of Mars now appears darker with blueish tones. These dark areas consist of grayish-black basaltic sands, volcanic in origin, that form far-reaching, dark layers of sand across the planet’s surface. These are blown around by the wind, creating imposing sand dunes and dune fields within impact craters. These sands are comprised of dark, basaltic minerals, just like volcanic lava on Earth.