14 Jul 2011 - NASA Spacecraft to Enter Asteroid's Orbit on July 15

[NASA]

http://solarsystem.nasa.gov/multimedia/gallery/VESTA_160X120(4).jpg (http://solarsystem.nasa.gov/news/display.cfm?News_ID=37903)14 Jul 2011 - NASA Spacecraft to Enter Asteroid's Orbit on July 15
On 15 July, NASA's Dawn spacecraft will begin a prolonged encounter with the asteroid Vesta, making the mission the first to enter orbit around a main-belt asteroid.


More... (http://solarsystem.nasa.gov/news/display.cfm?News_ID=37903)

[steveofengland]

This is very interesting, scientists are guessing at its size and mass so the DAWN craft can enter its orbit. I wonder how large a mass has to be before it generates its own gravity? They seem keen to gather information before december 2012 lol!

Comets are not the same as asteroids. Hence why comets apparently cant create gravitational pull.
You learn something new everyday.