Dawn: Mission Vesta-Ceres Mission - Orbiter Space Flight Simulator 2010

• Report rights infringement
• published: 01 Mar 2015
• views: 9762

Facebook. Advances, pictures, details, comments: http://www.facebook.com/orbiterfilmmaker Dawn is a space probe launched by NASA in September 27, 2007 to study the two most-massive protoplanets of the asteroid belt: Vesta and the dwarf planet Ceres. Dawn began long-term cruise ion engine propulsion on December 17, 2007. On October 31, 2008, Dawn completed its first thrusting phase to send it on to Mars for a gravity assist flyby in February 2009. During this first interplanetary cruise phase, Dawn spent 270 days, or 85% of this phase, using its thrusters. It expended less than 72 kilograms of xenon propellant for a total change in velocity of 1.81 kilometers per second. Dawn made its closest approach (549 km) to Mars on February 17, 2009 during a successful gravity assist. On May 3, 2011, Dawn acquired its first targeting image, 1,200,000 km from Vesta, and began its approach phase to the asteroid. On June 12, Dawn's speed relative to Vesta was slowed in preparation for its orbital insertion 34 days later. Dawn was scheduled to be inserted into orbit at 05:00 UTC on July 16 after a period of thrusting with its ion engines. Because its antenna was pointed away from the Earth during thrusting, scientists were not able to immediately confirm whether or not Dawn successfully made the maneuver. The spacecraft would then reorient itself, and was scheduled to check in at 06:30 UTC on July 17. NASA later confirmed that it received telemetry from Dawn indicating that the spacecraft successfully entered orbit around Vesta. The exact time of insertion could not be confirmed, since it depended on Vesta's mass distribution, which was not precisely known and at that time had only been estimated. During its time in orbit around Vesta the probe experienced failures of reaction wheels. Investigators will modify their activities upon arrival at Ceres for close range geographical survey mapping. The Dawn team will orient the probe by what they have stated is a "hybrid" mode. This mode will utilize both reaction wheels and ion thrusters. Engineers have determined that the hybrid mode will conserve fuel. On November 13, 2013, during the transit, in a test preparation, Dawn engineers completed a 27-hour-long series of exercises of said hybrid mode. Dawn was originally scheduled to depart Vesta and begin its two and a half year journey to Ceres on August 26, 2012. However, a problem with one of the spacecraft's reaction wheels forced Dawn to delay its departure from Vesta's gravity until September 5, 2012. Dawn began photographing an extended disk of Ceres on December 1, 2014, with images of partial rotations on January 13 and 25, 2015 released as animations. Images taken from Dawn of Ceres after January 26 will exceed the resolution of the Hubble Space Telescope, while images taken of Pluto by New Horizons will exceed the resolution of the Hubble telescope by approximately May 5, 2015. Because of the failure of two reaction wheels, Dawn will make fewer camera observations of Ceres during its approach phase than it did during its Vesta approach. Camera observations require turning the spacecraft, which consumes precious hydrazine fuel. Seven optical navigation photo sessions (OpNav 1–7, on January 13 and 25, February 3 and 25, March 1, and April 10 and 15) and two full rotation observation sessions (RC1–2, on February 12 and 19) are planned before full observation begins with orbital capture. The gap in March and early April is when Ceres appears too close to the sun from Dawn?'?s vantage point to take pictures safely. Dawn arrive at Ceres on March 6, 2015. It was initially hoped that, after the primary mission, a flyby of Pallas might be possible when the asteroid crosses the ecliptic in December 2018. (Because of the high inclination of the Palladian orbit, only a quick flyby would have been possible.) However, with two of Dawn's reaction wheels out of commission, the remainder of Dawn's hydrazine fuel will need to be expended to augment the remaining wheels to orientate the craft in low Cererian orbit. There will be nothing left for a Palladian flyby. It is predicted that Dawn will become a perpetual satellite of Ceres when the mission is over, due to its highly stable projected orbit.