Dawn launched in 2007 on a journey that put about 4.3 billion miles (6.9 billion kilometers) on its odometer. Propelled by ion engines, the spacecraft achieved many firsts until its extended mission concluded on Oct. 31, 2018.
In 2011, when Dawn arrived at Vesta, the second-largest world in the main asteroid belt, the spacecraft became the first to orbit a body in the region between Mars and Jupiter.
In 2015, when Dawn went into orbit around Ceres, a dwarf planet that is also the largest world in the asteroid belt, the mission became the first to visit a dwarf planet and go into orbit around two destinations beyond Earth.
Among its accomplishments, Dawn showed how important location was to the way objects in the early solar system formed and evolved.
Dawn also reinforced the idea that dwarf planets could have hosted oceans over a significant part of their history – and potentially still do.
The data Dawn beamed back to Earth from its four science experiments enabled scientists to compare two planet-like worlds that evolved very differently.
10 Need-to-Know Things About Dawn
1
Two-for-One First
Dawn was the first spacecraft to orbit two extraterrestrial destinations (Vesta and Ceres).
2
And ... First Orbit
When Dawn arrived at Vesta, it became the first spacecraft to orbit an object in the main asteroid belt.
3
And ... First Look
When Dawn arrived at Ceres, it was the first spacecraft to visit a dwarf planet.
Full View of Vesta
4
Location, Location, Location
Dawn showed us that location was key to how the early system organized and evolved.
5
Ocean Worlds
Dawn reinforced that dwarf planets, not just icy moons, could have hosted oceans during a large part of their history—and potentially still do.
6
Building Blocks of Life
Dawn found organics at Ceres and left us wanting to know more.
7
Science Fiction to Fact
Star Wars’ far-ranging “TIE” fighters stand for “twin ion engine.” Thanks to its own ion engines, Dawn broke several exploration records.
8
More than a Space Rock
Dawn found Vesta was a more varied world than scientists expected.
9
Bright Spots
Dawn revealed that Ceres is geologically active—or was very recently.
Last Look at Ceres
10
Science to the End
Dawn gathered science data at Ceres and returned it to Earth right up to the point the spacecraft ran out of fuel.
Major Engineering Achievements
- First space mission to orbit two destinations
- Record-breaking use of solar-electric propulsion: 25,700 mph, 2.7x any prior spacecraft, and nearly equal to the velocity provided by Dawn’s Delta launch vehicle
- Active powered flight: 5.9 years (54% of the time in space as of Sep. 7, 2018)
Key Mission Findings
Dawn orbited Vesta for more than a year, from July 2011 to September 2012. Its investigation confirmed that Vesta is the parent of the HED (howardites, eucrites, and diogenites) meteorites, which Dawn connected to Vesta’s large south polar basin, a priceless cosmic connection between samples in hand and a singular event on a small planet.
Vesta is small enough (about the same size as Saturn's moon Enceladus) to have been deeply scarred by the Rheasilvia impact that launched the HEDs, but large enough to have differentiated into an iron core, silicate mantle, and igneous crust. Dawn also found hydrated and carbon-rich material on its surface supplied by impactors, a result that was unexpected based on pre-Dawn telescopic observations.
After its escape from Vesta and its journey onward, Dawn entered orbit around Ceres in March 2015. Dawn discovered that the inner solar system’s only dwarf planet was an ocean world where water and ammonia reacted with silicate rocks. As the ocean froze, salts and other telltale minerals concentrated into deposits that are now exposed in many locations across the surface. Dawn also found organics in several locations on Ceres’ surface.
Key Mission Events
2007 — Launch (September)
2009 — Mars Gravity Assist (February)
2011 — Vesta Arrival (July)
2012 — Vesta Departure (September)
2015 — Ceres Arrival (March)
2016 — End of prime mission (June)
2016 — Start of first extension (July)
2017 — Start of second extension (November)
2018 — End of mission (October)
Notable ExplorersNotable Explorers
Vishnu Reddy
Scientist
"Don't let anyone tell you that you can't do something. I tell students if someone like me with filmmaking background can do science, anyone can. "
Quick Facts
Type: Orbiter
Status: Successful
Launch Date: Sept. 27, 2007 | 11:34 UTC
Launch Location: Cape Canaveral Air Force Station, Florida
Destinations: Vesta and Ceres
Dawn By the Numbers
Key statistics from the end of mission:
51,385 hours of ion engine thrusting.
172 GB of science data collected.
3,052 orbits around Vesta and Ceres.
100,000 images taken.
4.3+ billion miles (6.9+ billion kilometers) traveled since launch.
367+ million miles (591+ million kilometers): Farthest distance from Earth.
More Resources
