The Deep Impact craft flew within 435 miles of comet Hartley 2 on Thursday, snapping pictures during the rendezvous.
The images at the NASA Jet Propulsion Laboratory in California reveal a peanut-shaped comet. It's the fifth time that a comet's core has been viewed up close.
Thursday's mission is not the first for Deep Impact. In 2005, it dazzled the world when it fired a copper probe into another comet, Tempel 1, giving scientists their first look at the interior.
Scientists are interested in comets because they're icy leftovers from the formation of the solar system. Studying them could provide clues to how Earth and the planets formed 4.5 billion years ago.