4660 Nereus

4660 Nereus (pronEng|ˈnɪəriəs "nirr'-ee-əs"; Greek "Νηρέας)" is a small (1 km in diameter) asteroid, discovered by Eleanor F. Helin on February 28, 1982. It is named after Nereus, a Titan in Greek mythology.

Nereus is potentially a very important asteroid. It is an Apollo and Mars-crosser asteroid, with an orbit that frequently comes very close to Earth, and because of this it is exceptionally accessible to spacecraft. Indeed, because of its small size, its delta-V for rendezvous is smaller than the Moon's.

Nereus makes seven approaches to Earth of less than 5 Gm from 1900-2100. The closest will be in February 2060, at 1.2 Gm. The next close approach is in December 2021, when it will be 3.9 Gm away.

Nereus was scheduled for visitation by both the private Near Earth Asteroid Prospector probe, and the Japanese Hayabusa probe. However, the former project is defunct, and Hayabusa's delay in launching caused it to be redirected to 25143 Itokawa. Nonetheless, Nereus may well become a target of future space exploration.

Nereus has been imaged by radar, which reveals a slightly elongated shape.