This is the story of two spacecraft, three comets and four rendezvous. So, keep your eye on the moving targets at all times.
Comet 81P Wild 2 (c#1) was visited (r#1) by the Stardust mission (s#1) in 2004 (it was launched in 1999), and sent its sample canister containing the comet bits back to Earth in 2006. The mission returned samples of the comet’s tail.
Comet 9P Tempel 1 (c#2) was impacted (r#2) on 4 July 2005 by NASA’s Deep Impact mission (s#2). Deep Impact was re-purposed for the 103P Hartley 2 (c#3) rendezvous (r#3), which took place on 4 November 2010.
And that is how you do cometary science on the cheap and with low risk.
In 2005, Tempel 1 made its closest approach to the sun. This likely changed the surface of the comet. Now, scientists will get a chance to re-image the surface of the comet with Stardust and compare the images with those taken by Deep Impact five years ago.