Dawn spacecraft fires up for a fresh view of Ceres
NASA's Dawn spacecraft is set to maneuver into a higher orbit around the dwarf planet Ceres. After operating in a low altitude orbit at a height of around 240 km (149 miles) for the last eight months, the move is designed to get a new perspective of the dwarf planet and prolong the already successful mission.
Dawn's supply of hydrazine fuel is waning fast. Once the fuel is gone, the spacecraftwill be unable to face Ceres, or to orientate its antennato Earth to receive commands and transmit data. The probe will alsobe incapable of turning its solar panels to face the Sun, resulting in an inevitable loss of power.
The move to a higher orbit will allowDawn's mission team to think up new ways to maximize the probe's scientific output in the time it has left. The transition will also help to prolong the operational life of the spacecraft, because in ahigher orbit it will not need to expend as much hydrazine in orderto counter the effects of Ceres gravitational pull.
Starting on September 2, Dawn will begin raising its orbit to a height of 910 miles(1,460 km) above Ceres, a process that will take around five weeks. The spacecraft was at a similar height earlier in its mission, but this time it will be in a different plane, meaning a different views of the dwarf planet's barren surface can be captured.
"Most spacecraft wouldn't be ableto change their orbital altitude so easily" comments Marc Rayman,chief engineer and mission director for Dawn at NASA's Jet PropulsionLaboratory, Pasadena, California. "But thanks to Dawn's uniquelycapable ion propulsion system, we can maneuver the ship to get thegreatest scientific return from the mission."
Dawn has already far outstripped thescientific goals of its primary mission, which drew to a close on June 30. Dawn's handlers are expected to submita full extended mission itinerary next month.