NASA has authorized a second extension of the Dawn mission, which has so far explored the asteroid Vesta and, for the last two years, has been orbiting the dwarf planet Ceres. The spacecraft will continue to orbit Ceres until its fuel runs out.
But more exciting science will happen before then. The team is currently looking into maneuvering the spacecraft into a new orbit that will take Dawn as low as 200 kilometers (125 miles), which is almost twice as close as the space probe has ever been to the dwarf planet. The previous record is 385 kilometers (240 miles) of altitude.
This flyover will allow Dawn to take some close-up views of the dwarf planet's surface, as well as study its mineralogy using an infrared instrument. It will also collect more data with its gamma-ray and neutron spectrometer, which will allow researchers to understand what the uppermost layer of Ceres is actually made of.
An important date for Ceres will be April 2018, when the dwarf planet reaches its perihelion – its closest approach to the Sun. Scientists expect that more ice will melt on its surface when it gets closer to the Sun and that the water vapor could form a very weak and temporary atmosphere around Ceres. The European Space Telescope’s Herschel did spot such a feature before Dawn arrived two and half years ago.
The team expects that Dawn will continue operating until the second half of 2018. It will carry out as much science as possible, before being put on a stable orbit. Unlike Rosetta or Cassini, the mission will not end with a bang. The scientists aim to protect Ceres from Earthly contamination. Dawn will become a permanent satellite of the dwarf planet.
The Dawn mission is the first human mission to orbit two different solar system bodies. The spacecraft studied asteroid Vesta for 14 months between 2011 and 2012 and then moved onto Ceres, which it reached in March 2015.
The Dawn spacecraft has helped astronomers understand some of the mysteries of Ceres, such as its bright spot, which is a salt deposit from some form of geological eruption, possibly related to an impact.