Mission controllers at the NASA Jet Propulsion Laboratory (JPL) in Pasadena, California, say that the Dawn spacecraft is currently undergoing final preparations, before finally departing the largest asteroid in the solar system, Vesta. Its next target is the dwarf planet Ceres.
Both objects are located in the Inner Asteroid Belt (IAB), between the orbits of Mars and Jupiter. If successful, the space probe will become the first orbiter to enter orbit around two celestial bodies, and conduct scientific investigations on both of them.
According to JPL scientists, Dawn is scheduled to depart Vesta's orbit on September 5 (September 4 PDT). It will take about 30 months for the spacecraft to reach its destination, which it's scheduled to reach around February 2015.
The spacecraft was launched aboard a Delta II delivery system on September 27, 2007, from Space Launch Complex 17B (SLC-17B), at the Cape Canaveral Air Force Station (CCAFS), in Florida.
After completing a flyby of the Red Planet, on February 4, 2009, the orbiter finally entered orbit around Vesta on July 16, 2011. Since then, it occupied four different orbits around the solar system's largest asteroid, conducting a host of scientific studies of the protoplanet.
The reason why Vesta and Ceres were selected as targets for Dawn is because they have the potential to clear up many uncertainties related to the early history of the solar system, and also to provide experts with more data on how planets and asteroids form around a young star.
In less than a week, the orbiter will activate its hyper-efficient ion propulsion system, and gently spiral away from Vesta on the same route it came. Its engines use an electrical current to ionize xenon, a process that generates thrust.
“Thrust is engaged and we now are climbing away from Vesta atop a blue-green pillar of xenon ions. We are feeling somewhat wistful about concluding a fantastically productive and exciting exploration of Vesta, but now we have our sights set on dwarf planet Ceres,” Marc Rayman explains.
The JPL expert holds an appointment as the chief engineer and mission director for the Dawn mission.
“We went to Vesta to fill in the blanks of our knowledge about the early history of our solar system. Dawn has filled in those pages and more, revealing to us how special Vesta is as a survivor from the earliest days of the solar system,” adds Christopher Russell.
“We now can say with certainty that Vesta resembles a small planet more closely than a typical asteroid,” concludes the University of California in Los Angeles (UCLA) professor, who is Dawn's principal investigator.