Visiting Comets and Asteroids: Small Bodies Up Close

Giotto was launched in 1985 and flew within a few hundred kilometers of Halley Comet in March 1986, returning the first close images ever taken of a comet nucleus. Dust impacts damaged some instruments, yet it was redirected to Comet Grigg-Skjellerup in 1992, the first spacecraft to visit two comets.

Launched in 1996, NEAR Shoemaker entered orbit around the asteroid Eros in February 2000, the first spacecraft to orbit an asteroid. On February 12, 2001 it touched down on the surface, the first landing on an asteroid, with operations ending about two weeks later.

Deep Space 1 was launched in October 1998 as a technology demonstration under the New Millennium Program, not mainly for science. It still flew past the asteroid Braille and then Comet Borrelly, returning images and data from both encounters between 1998 and 2001.

Stardust, launched in 1999, flew through the coma of Comet Wild 2 in January 2004 and caught dust in aerogel. Its capsule parachuted into the Utah desert in January 2006, making it the first mission to return comet samples.

Japan launched Hayabusa in 2003 to Itokawa. Despite damage to its ion engines and a loss of attitude control, it briefly touched down in 2005 and sent grains home in June 2010, the first asteroid sample return.

Deep Impact released an impactor that struck Comet Tempel 1 on July 4, 2005, while the main craft watched the debris. The first look beneath a comet crust showed it to be more porous and fragile than expected, and the extended EPOXI mission later reached Comet Hartley 2 in 2010.

Lucy launched on October 16, 2021 on a twelve year journey, the first spacecraft sent to the Jupiter Trojan asteroids. It is planned to fly past a main belt asteroid and several Trojans, which are thought to be remnants from the formation of the solar system.

Psyche launched on October 13, 2023 toward 16 Psyche, a large metallic asteroid that scientists believe may be the exposed core of an early planetesimal. It carries imaging instruments, a magnetometer and a gamma ray and neutron spectrometer, and is expected to arrive later in the decade after a Mars gravity assist.