NASA’s Dawn mission became the first spacecraft to visit a dwarf planet when it entered orbit around Ceres on Friday.
NASA’s Dawn mission made history as the first spacecraft to visit a dwarf planet when it entered orbit around Ceres at 7:39 a.m. EST on Friday, March 6. The spacecraft made its orbital insertion when it was approximately 38,000 miles away from the dwarf planet.
“Since its discovery in 1801, Ceres was known as a planet, then an asteroid and later a dwarf planet,” Dawn’s chief engineer and mission director Marc Rayman said in a statement. “Now, after a journey of 3.1 billion miles (4.9 billion kilometers) and 7.5 years, Dawn calls Ceres, home.”
In addition to becoming as the first spacecraft to visit a dwarf planet, Dawn also became the only spacecraft in history to orbit two celestial bodies in the solar system beyond the Earth-moon system. Dawn was the first spacecraft to visit an object in the main asteroid belt when it entered orbit around protoplanet Vesta in 2011.
Dawn was launched in 2007 on a mission to study Ceres and Vesta, the largest known bodies in the main asteroid belt, in order to better understand the role size and water play in determining the evolution of planets. Both Ceres and Vesta were baby planets whose growth was interrupted by the pull of Jupiter’s immense gravity. They are fossils, remnants from the dawn of the solar system, which may offer clues as to how planets are formed.
Ceres, the largest of the two at 590 miles in diameter, is very wet and primitive, while Vesta, measuring 326 miles wide, is dry and evolved. The contrast between the two will provide valuable insights into the evolution and formation of planets.
Orbiting two previously unexplored worlds in the solar system was made possible by Dawn’s ion propulsion system. Previous missions with multiple targets using conventional propulsion systems were limited to flybys. Dawn is only the second NASA spacecraft to utilize ion propulsion. NASA’s Deep Space 1 mission launched in 1998 to test the technology. However, this is the first time the technology has been used for a purely exploratory mission.
“We would not be able to orbit and explore these two worlds without ion propulsion,” Robert Mase, project manager for the Dawn mission said in a statement. “Dawn capitalizes on this innovative technology to deliver big science on a small budget.”
The Dawn spacecraft only narrowly beat out NASA’s New Horizons probe in becoming the first spacecraft to visit a dwarf planet. NASA’s New Horizons probe is scheduled to conduct a highly anticipated flyby Pluto on July 14, 2015. Pluto was demoted from planetary status in 2006 after the International Astronomical Union created the new classification of celestial bodies.
Dawn will continue to study Ceres from orbit until the mission ends in June 2016.
The Slooh Community Observatory will be providing a live stream of this historic event starting at 1 p.m. EST on Friday, March 6.