In 1981, a proposal for an asteroid mission was submitted to the European Space Agency (ESA).
Named the Asteroidal Gravity Optical and Radar Analysis (AGORA), this spacecraft was to launch some time in 1990–1994 and perform two flybys of large asteroids.
The preferred target for this mission was Vesta.
AGORA would reach the asteroid belt either by a gravitational slingshot trajectory past Mars or by means of a small ion engine.
However, the proposal was refused by the ESA.
A joint NASA–ESA asteroid mission was then drawn up for a Multiple Asteroid Orbiter with Solar Electric Propulsion (MAOSEP), with one of the mission profiles including an orbit of Vesta.
NASA indicated they were not interested in an asteroid mission.
Instead, the ESA set up a technological study of a spacecraft with an ion drive.
Other missions to the asteroid belt were proposed in the 1980s by France, Germany, Italy and the United States, but none were approved.
Exploration of Vesta by fly-by and impacting penetrator was the second main target of the first plan of the multi-aimed Soviet Vesta mission, developed in cooperation with European countries for realisation in 1991–1994 but canceled due to the Soviet Union disbanding.

In the early 1990s, NASA initiated the Discovery Program, which was intended to be a series of low-cost scientific missions.
In 1996, the program's study team recommended a mission to explore the asteroid belt using a spacecraft with an ion engine as a high priority.
Funding for this program remained problematic for several years, but by 2004 the Dawn vehicle had passed its critical design review and construction proceeded.

It launched on 27 September 2007 as the first space mission to Vesta.
On 3 May 2011, Dawn acquired its first targeting image 1.2 million kilometers from Vesta.
On 16 July 2011, NASA confirmed that it received telemetry from Dawn indicating that the spacecraft successfully entered Vesta's orbit.
It was scheduled to orbit Vesta for one year, until July 2012.
Dawn's arrival coincided with late summer in the southern hemisphere of Vesta, with the large crater at Vesta's south pole (Rheasilvia) in sunlight.
Because a season on Vesta lasts eleven months, the northern hemisphere, including anticipated compression fractures opposite the crater, would become visible to Dawn's cameras before it left orbit.
Dawn left orbit around Vesta on 4 September 2012 11:26 p.m. PDT to travel to Ceres.

NASA/DLR released imagery and summary information from a survey orbit, two high-altitude orbits (60–70 m/pixel) and a low-altitude mapping orbit (20 m/pixel), including digital terrain models, videos and atlases.
Scientists also used Dawn to calculate Vesta's precise mass and gravity field.
The subsequent determination of the J₂ component yielded a core diameter estimate of about 220 km assuming a crustal density similar to that of the HED.

Dawn data can be accessed by the public at the UCLA website.
In 1981, a proposal for an asteroid mission was submitted to the European Space Agency (ESA). Named the Asteroidal Gravity Optical and Radar Analysis (AGORA), this spacecraft was to launch some time in 1990–1994 and perform two flybys of large asteroids. The preferred target for this mission was Vesta. AGORA would reach the asteroid belt either by a gravitational slingshot trajectory past Mars or by means of a small ion engine. However, the proposal was refused by the ESA. A joint NASA–ESA asteroid mission was then drawn up for a Multiple Asteroid Orbiter with Solar Electric Propulsion (MAOSEP), with one of the mission profiles including an orbit of Vesta. NASA indicated they were not interested in an asteroid mission. Instead, the ESA set up a technological study of a spacecraft with an ion drive. Other missions to the asteroid belt were proposed in the 1980s by France, Germany, Italy and the United States, but none were approved. Exploration of Vesta by fly-by and impacting penetrator was the second main target of the first plan of the multi-aimed Soviet Vesta mission, developed in cooperation with European countries for realisation in 1991–1994 but canceled due to the Soviet Union disbanding.
In the early 1990s, NASA initiated the Discovery Program, which was intended to be a series of low-cost scientific missions. In 1996, the program's study team recommended a mission to explore the asteroid belt using a spacecraft with an ion engine as a high priority. Funding for this program remained problematic for several years, but by 2004 the Dawn vehicle had passed its critical design review and construction proceeded.
It launched on 27 September 2007 as the first space mission to Vesta. On 3 May 2011, Dawn acquired its first targeting image 1.2 million kilometers from Vesta. On 16 July 2011, NASA confirmed that it received telemetry from Dawn indicating that the spacecraft successfully entered Vesta's orbit. It was scheduled to orbit Vesta for one year, until July 2012. Dawn's arrival coincided with late summer in the southern hemisphere of Vesta, with the large crater at Vesta's south pole (Rheasilvia) in sunlight. Because a season on Vesta lasts eleven months, the northern hemisphere, including anticipated compression fractures opposite the crater, would become visible to Dawn's cameras before it left orbit. Dawn left orbit around Vesta on 4 September 2012 11:26 p.m. PDT to travel to Ceres.
NASA/DLR released imagery and summary information from a survey orbit, two high-altitude orbits (60–70 m/pixel) and a low-altitude mapping orbit (20 m/pixel), including digital terrain models, videos and atlases. Scientists also used Dawn to calculate Vesta's precise mass and gravity field. The subsequent determination of the J₂ component yielded a core diameter estimate of about 220 km assuming a crustal density similar to that of the HED.
Dawn data can be accessed by the public at the UCLA website.
4 Vesta