NASA’s Dawn spacecraft has become the first mission to achieve orbit around a dwarf planet. The spacecraft was approximately 38,000 miles (61,000 kilometres) from Ceres when it was captured by the dwarf planet’s gravity at about 4:39 am PST (12:39 pm GMT) Friday.
Mission controllers at NASA’s Jet Propulsion Laboratory in Pasadena, California received a signal from the spacecraft at 5:36 am PST (1:36 pm GMT) that Dawn was healthy and thrusting with its ion engine, the indicator Dawn had entered orbit as planned.
“Since its discovery in 1801, Ceres was known as a planet, then an asteroid and later a dwarf planet,” said Marc Rayman, Dawn chief engineer and mission director at JPL. “Now, after a journey of 3.1 billion miles (4.9 billion kilometres) and 7.5 years, Dawn calls Ceres, home.”
In addition to being the first spacecraft to visit a dwarf planet, Dawn also has the distinction of being the first mission to orbit two extraterrestrial targets. From 2011 to 2012, the spacecraft explored the giant asteroid Vesta, delivering new insights and thousands of images from that distant world. Ceres and Vesta are the two most massive residents of our solar system’s main asteroid belt between Mars and Jupiter.
The most recent images received from the spacecraft, taken on March 1st, show Ceres as a crescent, mostly in shadow because the spacecraft’s trajectory put it on a side of Ceres that faces away from the Sun until mid-April. When Dawn emerges from Ceres’ dark side, it will deliver ever-sharper images as it spirals to lower orbits around the planet.
“We feel exhilarated,” said Chris Russell, principal investigator of the Dawn mission at the University of California, Los Angeles (UCLA). “We have much to do over the next year and a half, but we are now on station with ample reserves, and a robust plan to obtain our science objectives.”
This background video to the Dawn mission from 2007, prior to the spacecraft’s launch later that year, was narrated by the late Leonard Nimoy — the photographer, director and actor immortalised in the rôle of Star Trek‘s Mr. Spock, who died last week.
Inside the magazine
In the March issue of Astronomy Now, we preview the arrival of the Dawn spacecraft at Ceres, speak to the mission’s principal investigator and highlight the discoveries that could be made on this strange new world.
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