24/7 monitoring of Ceres kicks off

On 6 March, NASA’s Dawn space probe will be captured by the gravitational field of the dwarf planet

March 04, 2015

Is the dwarf planet Ceres, whose diameter of around 950 kilometres makes it the largest inhabitant of the asteroid belt, an unchanging, dead chunk of rock? Or are there signs of geological activity on its surface? NASA’s Dawn space probe is to look into these questions over the next few months. This Friday, the gravitational field of the celestial body will capture the space probe and will steer it into an orbit in the weeks to come. This is the starting signal for 24/7 monitoring which will last at least until mid-2016. Photos from the last approach phase already show a large variety of structures on the surface of the spherical body, bright spots, for example, which possibly consist of ice or salts. The images were produced with the onboard camera system that was developed under the direction of the Max Planck Institute for Solar System Research.

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These images of the dwarf planet Ceres were taken on 25 February 2015 from a distance of 40000 kilometres. The resolution of the camera data is 3.7 kilometres per pixel.
These images of the dwarf planet Ceres were taken on 25 February 2015 from a distance of 40000 kilometres. The resolution of the camera data is 3.7 kilometres per pixel.

After a flight through the asteroid belt taking two and a half years, the US space probe Dawn reaches its destination next Friday: the dwarf planet Ceres, which orbits the Sun between the orbits of Mars and Jupiter. This is the second research visit to the asteroid belt for Dawn. The vehicle already headed for the Vesta asteroid back in 2011 and accompanied it for more than a year. Dawn is thus the first space probe in history to orbit two bodies, one after the other.

The two research objects could not be more different. Vesta turned out to be rocky and dry and resembles the inner planets Mercury, Venus, Earth and Mars. Ceres, in contrast, consists of around 25 percent water according to the researchers’ estimates. Dawn will look not least into the question of how two bodies that are so close in cosmic terms could develop so differently.

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Many craters of different sizes and forms cover the surface of the dwarf planet Ceres. This mosaic was generated from images taken by the onboard camera system on 19 February 2015 from a distance of 46000 kilometres.

 

Many craters of different sizes and forms cover the surface of the dwarf planet Ceres. This mosaic was generated from images taken by the onboard camera system on 19 February 2015 from a distance of 46000 kilometres.

 

“To investigate Ceres in detail is to do a kind of historical research in space,” says Jim Green, director of the Planetary Science Division of the American space agency NASA. “Data that Dawn transmits to Earth can help us understand how the solar system was formed.”

Both Vesta and Ceres were well on their way, 4.5 billion years ago, to developing into fully-grown planets. They found themselves in competition with the giant planet Jupiter, which was forming at the same time, however. Its enormous gravitational force attracted all the material in its vicinity and has been causing chaos in the asteroid belt ever since; Vesta and Ceres were no longer able to grow. “Both bodies are therefore fossils from the dawn of the solar system and shed light on its formation,” says the Deputy Principle Investigator Carol Raymond from the Jet Propulsion Laboratory (JPL) at NASA.

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Arriving at its destination: This drawing shows how the Dawn space probe reaches the dwarf planet Ceres.
Arriving at its destination: This drawing shows how the Dawn space probe reaches the dwarf planet Ceres.

Since January of this year, Dawn has been providing images of the dwarf planet which surpass all images to date in terms of their resolution. The space probe is equipped with a scientific camera system that was developed under the direction of the Max Planck Institute for Solar System Research in Göttingen, from where it is now operated.

In addition to craters, a conspicuous number of which have an imposing mountain at their centre, Ceres’ surface is littered with bright spots. “We are not familiar with structures of this type from any other body in the asteroid belt,” says Andreas Nathues from the Max Planck Institute, scientific head of the camera team. Since these regions reflect more than 40 percent of the incident light, the researchers presume that they contain frozen water or salts.

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Dawn uses a so-called ion propulsion system to travel through the asteroid belt. Xenon ions are emitted and thus provide the thrust for the space probe.
Dawn uses a so-called ion propulsion system to travel through the asteroid belt. Xenon ions are emitted and thus provide the thrust for the space probe.

At the beginning of last year, the Herschel space telescope actually discovered water vapour in the vicinity of Ceres. Some scientists therefore believe that the dwarf planet emits water into space from its interior. Over the coming weeks, the Max Planck researchers want to observe the spots in detail and check whether they possibly change over time. This could be an indication of activity.

BK / HOR

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The Dawn Mission is headed by the Jet Propulsion Laboratory (JPL) of the American space agency NASA. JPL is a department of the California Institute of Technology in Pasadena. The University of California in Los Angeles is responsible for the scientific part of the mission. The camera system aboard the spacecraft was developed and built under the direction of the Max Planck Institute for Solar System Research in Göttingen in collaboration with the Institute of Planetary Research of the German Space Center (DLR) in Berlin, and the Institute of Computer and Network Engineering in Braunschweig. The camera project is supported financially by the Max Planck Society, the DLR and NASA/JPL.

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