DAWN: Into the Asteroid Belt

LATEST!
DAWN was captured by Ceres' gravity at about 4:39 a.m. PST (7:39 a.m. EST) Friday, March 6th 2015 and is now orbiting dwarf planet Ceres! The DAWN spacecraft completed its primary mission on June 30th, 2016 with 2,450 orbits around Vesta and Ceres and returning about 69,000 images of both bodies. DAWN completed its prime mission on June 30, 2016 having surpassed all of its scientific objectives at Vesta and at Ceres and NASA extended the mission to perform new studies of Ceres. NASA has authorized, as of October 2017, a second extension of the DAWN mission at Ceres, will bring the spacecraft to lower altitudes than ever before. In early June 2018, DAWN will reach its lowest-ever orbit for a close-up examination of Ceres. That will also its final orbit around the minor planet and engineers turned DAWN's ion engines off for the last time by late June 2018. That orbit will be less than 30 miles (50 kilometers) above the surface. The mission will keep then in a stable orbit indefinitely after its hydrazine fuel runs out
. check to a description of DAWN capture into Vesta orbit
last updated: June 1st, 2018

DAWN's science at Vesta and Ceres

Mission

A mission launched by September 2007, DAWN is a NASA mission to two minor planets, Vesta, and Ceres, which are celestial bodies orbiting in the asteroid belt, a area located between Mars and Jupiter. As these planets are leftovers of the solar system's formation and may have endure somehow some phases of the planetary formation process, the mission will yield data allowing to understand the early stages of the solar system as well as basic planetary processes, like differentiation. DAWN is a ion thruster propulsed spacecraft following a characteritic spiral orbit, getting gently and progressively further from Sun as such a engine does not allow for large thrusts. The craft alternated propulsion, coast phases, and gravity-assisted flybys by some planet. During its journey to Vesta, Dawn accomplished the largest propulsive acceleration of any spacecraft, with a change in velocity of more than 4.2 miles per second (6.7 kilometers per second), due to its ion engines. The probe will stay about one year in orbit around each of both minor planets. The mission will carry a silicon chip containing the names of asteroid, space enthusiasts from around the world. DAWN will have been traveling nearly four years and 1.7 billion miles (2.7 billion kilometers) before reaching its first target Vesta. 2015 is the date scheduled for the approach to Ceres. DAWN is equiped with three instruments, mostly a camera system (navigation and images), a spectrometer working in the visible and the infrared and gamma rays neutron detector

Asteroids of the asteroid belt are termed either 'minor planet' or 'asteroid' as a new usage among professional astronomers is to name them both by their number and name bringing, for example, to '1 Ceres', instead of 'Ceres' only. Vesta has a diameter of 330 miles (530 km) as it is thought to be the source of a large number of meteorites that fall to Earth. During the initial reconnaissance orbit, at approximately 1,700 miles (2,700 km), the spacecraft will get a broad overview of Vesta with color pictures and data in different wavelengths of reflected light. The spacecraft will then move into a high-altitude mapping orbit, about 420 miles (680 km) above the surface to systematically map the parts of Vesta's surface illuminated by the Sun, collect topographic stereo image, acquire higher-resolution data to map rock types at the surface and learn more about Vesta's thermal properties. The craft after that then will move even closer, to a low-altitude mapping orbit approximately 120 miles (200 kilometers) above the surface. The primary science goals will turn to detect the byproducts of cosmic rays hitting the surface, help scientists determine the many kinds of atoms there, and probe that 'protoplanet's' internal structure. DAWN will then spiral away from Vesta as pausing again at the high-altitude mapping orbit, with the Sun's angle having progressed and scientists able to see previoulsy hidden terrain. When DAWN arrives at Vesta in July 2011, the south pole will be in full sunlight, giving scientists a clear view of a huge crater at that pole. That crater may reveal the layer cake of materials inside Vesta that will tell us how the body evolved after formation. The orbit design allows DAWN to map new terrain as the seasons progress over its 12-month visit. The spacecraft will also measure the tug of Vesta's gravity to learn more yet about its internal structure. The tools of DAWN are like follows: the gamma ray and neutron detector using 21 sensors with a very wide field of view to measure the energy of subatomic particles emitted by the elements in the upper yard (meter) of the asteroid's surface; the visible and infrared mapping spectrometer (VIR) measuring the surface mineralogy of both Vesta and Ceres. The spectrometer is a modification of a similar one flying on the European Space Agency's Rosetta and Venus Express missions. Dawn also will make another set of scientific measurements at Vesta and Ceres using the spacecraft's radio transmitter broadcasting to Earth. DAWN's framing camera complement the VIR spectral data to produce geologic and compositional maps

Ceres was the first asteroid discovered, by 1801, by astronomer Giuseppe Piazzi. Ceres is about 590 mi wide (960 km), by far the largest and most massive body in the asteroid belt, and representing almost one third of the total mass of it. One day on Ceres lasts 9 hours as the asteroid is nearly round is shape. The interior of Ceres might have been differentiated -layered- like those of terrestrial planets. It might feature a rocky inner core, a icy mantle, and a thin, dusty outer crust. Ceres is featuring too a bright spot, brighter than its surroundings yet still very dark, and with a feeble albedo. That spot is remaining a mystery

DAWN is a mission managed by JPL for NASA's Science Mission Directorate in Washington. UCLA is responsible for overall DAWN mission science. Orbital Sciences Corp. of Dulles, Va., designed and built the DAWN spacecraft with special contributions in terms of a instrument with the Max Planck Institute for Solar System Research in Katlenburg-Lindau in Germany, the German Aerospace Center (DLR) Institute of Planetary Research in Berlin, and the Institute of Computer and Communication Network Engineering in Braunschweig