This image of the dwarf planet Ceres was acquired on 19 February 2015 by the German-built Framing Camera on board the NASA orbiter Dawn from a distance of just under 46,000 kilometres. There are several unusual bright patches on the surface of Ceres. The brightest of them, situated at the centre of a large impact crater, is clearly visible in this image. Another distinct feature is another, slightly less bright patch within the same impact crater.
Scientists are currently unable to explain the reason for the brighter regions on the surface of the dwarf planet. These images could only provide an image resolution of four kilometres per pixel. This will change from 6 March 2015, when the spacecraft is scheduled to enter orbit around Ceres. It will be able to provide higher-resolution data about the surface from May onwards.
50 years of quarantine for Dawn
Over the course of its mission, Dawn will approach the surface of Ceres until it reaches a distance of approximately 400 kilometres. At the end of the mission – scheduled for next year – the spacecraft is designed to circle the dwarf planet for at least 50 years, following a stable orbit in a form of 'quarantine'. The purpose of this is to prevent any microbes from Earth that may be adhering to the orbiter from contaminating the surface if the craft crashes onto Ceres. If traces of simple forms of life are to be discovered there in future, they should on no account originate from an earthly 'import'.
Ceres is located more than 400 million kilometres from the Sun, and is therefore exposed to far less solar radiation than Earth. The temperatures on Ceres are extremely low, and the dwarf planet's surface consists, to a large extent, of light and volatile elements in a frozen state that barely evaporate. In its outer regions, Ceres is likely to possess a substantial water content of 15 to 25 percent, which is why it is known as a 'wet' asteroid. Planetary researchers predict that there is ice hidden in a 100-kilometre-thick layer in the mantle located beneath the crust. The dwarf planet may also possess a thin atmosphere; some astrobiologists have even speculated that there might be traces of simple life forms on Ceres.
The German camera will create 3D images of Ceres
The German-built Framing Camera on board the Dawn spacecraft will map the surface of Ceres from a variety of directions and under different lighting conditions. First of all, Ceres will be surveyed from a distance of 4500 kilometres – once the spacecraft has reached its initial orbit. Then, towards the end of 2015, the orbit will be lowered to 1500 kilometres, before the altitude of its path around Ceres is reduced to 400 kilometres at the start of 2016. All of the images captured during these orbits will be used as a basis for 3-D models of the dwarf planet. These three-dimensional images will allow researchers to conduct detailed analyses of the geological formations.
The Dawn mission
NASA's Jet Propulsion Laboratory (JPL) in Pasadena manages the Dawn mission; JPL is a division of the California Institute of Technology. The University of California, Los Angeles, is responsible for overall Dawn mission science. The camera system on the spacecraft was developed and built under the leadership of the Max Planck Institute for Solar System Research in Göttingen, Germany, in collaboration with the DLR Institute of Planetary Research in Berlin and the Institute of Computer and Communication Network Engineering in Braunschweig. The Framing Camera project is funded by the Max Planck Society, DLR, and NASA/JPL.