Mar. 7, 2016

A year ago, NASA's Dawn probe entered the orbit of Ceres, after orbiting around the Vesta asteroid. The Jet Propulsion Laboratory has released new pictures of the dwarf planet closest to us, including the mysterious Ahuna Mons mountain

NASA's Dawn probe can celebrate a new milestone: a year of work around Ceres, the most ancient celestial body in the asteroid belt.
On 6 March 2015 Dawn entered the orbit of the dwarf planet located in the region between Mars and Jupiter, after seven and a half years of travelling and almost 5 billion km covered.
Discovered in 1801 by Italian astronomer Giuseppe Piazzi, Ceres's history has been tormented: initially thought to be a star, it was then considered a planet, later an asteroid, and only more recently identified as a dwarf planet.

Two centuries after its discovery, NASA initiated its Dawn mission, selected in 2001 within the Discovery programme. First goal: asteroid Vesta, whose orbit was reached by the probe in 2011. Dawn then turned towards the dwarf planet Ceres, which it reached in March last year.
Italy was one of the key players in Dawn's trip, with its image spectrometer VIR-MS (Visible and Infra-red Mapping Spectrometer) supplied by ASI and manufactured by Finmeccanica-Selex ES, under the scientific guidance of INAF-IAPS.

Now NASA's Jet Propulsion Laboratory (JPL) responsible for the Dawn mission celebrates the anniversary of its probe around Ceres by releasing a series of new images that show the fascinating face of this dwarf planet.
The photographs were taken between December 2015 and January 2016, when Dawn reached its lowest height: it got to only385 km away from Ceres and was therefore able to study its surface with an unprecedented level of detail.

Its “eye” thus captured a series of craters, hills and fractures whose observation gave astronomers crucial information on the history and composition of the dwarf planet.
Some of the most spectacular photographs are those that show the series of craters called Gerber Catena: valleys and fractures probably caused by movements of Ceres's crust, similar to those recently studied on Mars.
But the latest images released by JPL are even more interesting. They show craters that have not yet been classified and whose observation may reveal new information on the jagged surface of the dwarf planet closest to the Earth.

But there's more to it. In addition to these new photographs, NASA has also released the first close-up pictures of yet another of Dawn's surprises: the Ahuna Mons mountain. This mountainous structure had been observed in February 2015 from a distance of about 46,000 km, but the images came into focus for the first time only when the probe entered the orbit of the dwarf planet. This made it possible for researchers to measure the height of Ahuna Mons, approximately 4 km with peaks of 5 km.
“No one had expected to find a mountain on Ceres”, comments Chris Russell from the University of California, a member of the Dawn mission, “in particular one such as Ahuna Mons. We still don't have a satisfactory model that explains how it was formed”

Investigating this mountain on Ceres will be one of the Dawn team's main goals in the upcoming months.
“Ceres has challenged our expectations”, declares Carol Raymond of the Jet Propulsion Laboratory. “It has already surprised us in countless ways, thanks to the large amount of data Dawn has collected in one year. We're still working on the mysteries that the probe has revealed to us.”

Image:
(B) A non-classified crater with a complex of central peaks on Ceres. Bundles of almost parallel fractures can be observed in the lighter areas of the crater's floor. The image corresponds to approximately 45 degrees north and 50 degrees east. Photograph taken on 24 January 2016 from a distance of 385 km. Resolution: 35 metres per pixel.
(C) A non-classified crater. The structures on the edge of the main fracture show a lighter, less deep surface in the bottom half of the image. Photograph taken on 24 January 2016 from a distance of 385 km. Resolution: 35 metres per pixel.

(D) Craters in the shade, in Ceres's northernmost latitudes. Photograph taken on 25 January 2016 from a distance of 385 km. Resolution: 35 metres per pixel.
(E) The mysterious Ahuna Mons mountain on Ceres, in a mosaic of images collected by the Dawn probe in December 2015, from a distance of 385 km. Resolution: 35 metres per pixel.