US Space Agency NASA have confirmed that their Dawn probe has gone into orbit around Ceres, the largest object in the Solar System that lies between Mars and Jupiter. The satellite sent a signal confirming its status at 13:36 GMT.
Ceres is the first dwarf planet in the Solar System to be visited by a satellite and scientists are hoping to gain lots of information from the mission including about the beginning of the Solar System itself, some four and a half billion years ago.
Journey
Dawn has taken seven and a half years to reach Ceres and its arrival has instantly seen it pass to the ‘dark side’ of the dwarf planet. The next month will see controllers re-shape its orbit so that it will be ready to start its main mission late in April.
As time goes on, the idea is to progressively lower the orbit of the probe until it is only a few kilometres above the surface, allowing it to take very high resolution pictures.
Chris Russell, the mission’s principal investigator from the University of California, Los Angeles (UCLA) said that the team were ‘exhilarated’ but that there was much to do over the next year and a half. He added that they had a robust plan in place to achieve the scientific aims of the mission.
Practised
In fact, the satellite itself has experience in its mission as it visited the asteroid Vesta as it travelled to its current location. Vesta is also found in the rocky debris ring that circles around the Sun beyond Mars. Vesta is smaller than Ceres at 525km to the dwarf planet’s 950km diameter but, according to r Carol Raymond, the mission’s deputy principal investigator at the NASA Jet Propulsion Laboratory, both objects should tell a similar story.
Both Ceres and Vesta are thought to be proto-planets. This means they were on course to form larger planets and were the type of objects that went on to form planets such as our own. But somewhere they stopped their evolution and are now effective ‘time capsules’ that show the beginning of the Solar System.
Proving Ideas
Researchers believe that the interior of Ceres is dominated by a rocky core, topped by ice that is insulated by deposits of rocky lag on the surface. What is unknown is if there is a liquid ocean of water at any depth, with models suggesting it is possible. Evidence will likely come from the craters on Ceres that have a muted look to them. This soft interior has the effect of relaxing the craters original hard outline.
Another interesting point was noted on the satellite’s approach to the dwarf planet – two very bright spots seen inside a crater in the Northern hemisphere that stretches for 92km. Some believe that the spots were caused by something striking the surface and exposing the buried ice below. The ice will have then been vaporised but highly reflective salt would be left behind.
The mission is expected to study Ceres for at least the next 14 months.
