NASA’s unmanned Dawn spacecraft, having completed its high-altitude mapping of the asteroid Vesta, drops to a lower altitude for more detailed mapping of Vesta’s surface. On average, its new orbit will allow Dawn to circle Vesta at an altitude of 130 miles, down from its previous 430-mile-high altitude. Dawn is imaging Vesta stereographically, allowing for precise measurements of surface features and the asteroid’s overall shape. In 2012, Dawn is scheduled to fire its ion thruster again, breaking orbit and leaving Vesta for a three-year cruise to the largest body in the asteroid belt, Ceres, arriving in 2015.
NASA’s Dawn unmanned space probe fires up its ion propulsion system, breaking its orbit around the large asteroid Vesta. Having orbited and mapped Vesta since 2011, Dawn must now survive a nearly-three-year trip through the main asteroid belt to reach the largest body in that region, Ceres. Successful arrival at Ceres, planned for 2015, would make Dawn the first unmanned spacecraft to have orbited two bodies in the solar system.
Originally launched by China to orbit the moon in 2010, and later parked at a LaGrange point beyond the moon’s orbit, the unmanned Chang’e 2 space probe flies by asteroid 4179 Toutatis at a distance of under two miles, capturing the first close-up images of the asteroid as it passes Earth almost half a million miles away. Though 4179 Toutatis has been imaged by ground-based radar on several occasions during its semi-frequent visits to the inner solar system, this is the first space probe to visit it at close range. As of this encounter, Chang’e 2 is the most distant Chinese spacecraft from Earth.
One of the closest asteroid encounters since the beginning of intensive asteroid tracking, asteroid 2012 DA14 swings past Earth at a distance of only 17,200 miles – putting it closer to Earth than most weather and communcations satellites in geosynchronous orbit. Despite this, the asteroid is well outside the orbit of such low-Earth-orbit structures as the International Space Station. Discovered in February 2012, 2012 DA14 has a diameter of approximately 150 feet and is moving at a speed of over 17,000 miles per hour. 2012 DA14’s next closest approach will take place in 2046, but it will not make another passage this close until 2110. The asteroid is unrelated to a meteor airburst event earlier the same day over Russia.
The Japanese Aerospace Exploration Agency (JAXA) launches the Hayabusa-2 unmanned space probe, intended to study and sample asteroid 162173 Ryugu in 2018. Mission plans call for the ion-engine-powered Hayabusa-2 to remain at Ryugu for a year before returning to Earth with its sample. Hayabusa-2 also carries a European-built lander and an explosive penetrator to expose the asteroid’s subsurface material (using the same principle as the Deep Impact mission to Comet Tempel 1 in 2005.
The unmanned NASA spacecraft Dawn transmits a series of pictures of Ceres, the minor planet which is the largest known object in the main asteroid belt between Mars and Jupiter, back to Earth, representing the best view yet of an object which had been seen as little more than a point of light since its discovery in 1801. From a distance of only 147,000 miles, Dawn is able to see more detail on Ceres than the best Hubble Space Telescope images of the same body. Dawn will arrive at Ceres and use its ion propulsion system to enter its orbit in March 2015.
The unmanned NASA/JPL space probe Dawn arrives at its second and final destination, the dwarf planet Ceres, a body which dominates the asteroid belt between Mars and Jupiter. Beginning to bring itself into a closer mapping orbit around Ceres, Dawn has already spotted unusually bright surface features, drawing early speculation from scientists that the highly reflective points on Ceres may be indicative of ice formations or cryovolcanism. Though its main engine is powered by charged ions, Dawn is scheduled to remain at Ceres for as long as its chemical propellant supply holds, powering smaller traditional rockets needed for attitude control.
NASA launches the unmanned OSIRIS-REx (Origins Spectral Interpretation Resource Identification Security Regolith Explorer) spacecraft, bound for the asteroid Bennu, a target it won’t reach for two years. Once at Bennu, OSIRIS-REx is intended to orbit the asteroid and then drop down close enough to gather surface samples for return to Earth in a small sample container capable of surviving re-entry through the atmosphere. The samples from Bennu, an asteroid considered a hazard for Earth in the future, will not arrive until September 2023.
NASA’s New Horizons space probe, operated by Johns Hopkins University’s Applied Physics Lab, passes within 2,200 miles of the mysterious Kuiper Belt object 2014 MU69, a tiny fragment of leftover material from the birth of the solar system. Previously seen only as a tiny pixel even by the powerful lens of the Hubble Space Telescope, nothing was known of 2014 MU69 prior to the flyby, which revealed it as a contact binary: two bodies which had become gravitationally fused together. As 2014 MU69 (informally nicknamed Ultima Thule in a public poll conducted by the New Horizons public outreach team) is a billion miles further away than Pluto, and with New Horizons continuing outward at 30,000 miles per hour, signals between Earth and New Horizons take at least six hours to reach their destination, so the downlink of data from the flyby would take until 2020 to complete.