Eros

Eros was the first near-Earth asteroid ever discovered, and a century later it became the first asteroid to be orbited by a spacecraft and the first to have one land on it.^[1]

Found by accident

Gustav Witt, director of the Urania Observatory in Berlin, discovered Eros on 13 August 1898; Auguste Charlois found it independently the same day at Nice, in France.^[1] Witt had been taking a two-hour photographic exposure of a different asteroid, and Eros appeared on the plate as a short trail.^[1] Within two weeks its orbit had been shown to pass well inside the orbit of Mars.^[1] Before radar existed, astronomers used Eros to help measure the mass of the Earth-Moon system and the length of the astronomical unit.^[1]

What it is

Eros is an elongated asteroid about 34 km long, about one and a half times the length of Manhattan.^[2] It is an S-type, or stony, asteroid, the most common type in the inner asteroid belt.^[1] Its orbit crosses that of Mars but does not quite reach Earth's, and a close approach in 1975 brought it within about 22 million km of Earth.^[1]

Orbited, then landed on

NASA's Near Earth Asteroid Rendezvous spacecraft, the first mission of the agency's low-cost Discovery program, flew past Eros on 23 December 1998 and found two medium-sized craters, a long surface ridge and a density similar to that of Earth's crust.^[2] It went into orbit on 14 February 2000 and, renamed NEAR Shoemaker in honor of the geologist Eugene Shoemaker, studied Eros from orbit for nearly a year.^[2][1]

On 12 February 2001, with the mission ending, controllers brought the spacecraft down in a slow, controlled descent, taking 69 high-resolution photos on the way.^[2] It touched down at about 6.4 km per hour, walking pace, although it had never been designed to land.^[2] It survived and kept returning data for about two weeks, until last contact on 28 February 2001.^[2] For later missions that brought pieces of asteroids back to Earth, see Itokawa and Bennu.