NASA says that Dawn was around 38,000 miles from Ceres when it was caught by the gravitational field of the dwarf planet. Shortly after, scientists received a signal that Dawn had entered orbit as planned, writes Jenny Winder for The Christian Science Monitor.
Dawn: making history
Radio signals take 55 minutes to get from Earth to Dawn and back, given that the spacecraft is now located some 310 million miles from Earth. Dawn was launched from Earth back in 2007 with the aim of investigating two massive bodies in the main asteroid belt. It is thought that these baby protoplanets had their growth disrupted by the formation of Jupiter and its gravitational pull.
Dawn is now the only spacecraft to have orbited two celestial objects, having previously gathered data on the giant asteroid known as Vesta over the course of 14 months between 2011 and 2012.
Since its discovery in 1801, Ceres has been designated as a planet, then an asteroid, before scientists decided it was a dwarf planet in 2006. Other dwarf planets include Pluto, Haumea, Makemake and Eris. Until the arrival of Dawn, Ceres was the largest object between the Sun and Pluto that had not been visited by a spacecraft.
The images recently released by Dawn were taken from the dark side of Ceres, so the dwarf planet appears as a crescent. Dawn’s trajectory will take it to the other side of Ceres around mid-April, from where it will be able to take better quality pictures. The spacecraft will also begin to take various other measurements as it enters a closer orbit over the course of the year.
“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,” said Chris Russell, principal investigator of the Dawn mission at the University of California, Los Angeles (UCLA).
The team are hoping to better understand the formation of space objects such as Ceres during the early history of our Solar System. Their second objective is to study the composition of the building blocks of terrestrial planets, as well as comparing the evolutionary history of Vesta and Ceres.
NASA says that Dawn will spend the rest of its operational life orbiting Ceres.