3357

**3357**

3357 is a small, main-belt asteroid located within the asteroid belt between Mars and Jupiter. Discovered on October 10, 1981, by Eleanor Helin at the Palomar Observatory, it was initially designated as 1981 ET2. The asteroid has since been named **Nereus**, after the mythological sea god Nereus, who was known for his many forms and fluid nature. This naming was proposed by astronomer Brian Marsden in 1982.

Nereus is classified as a S-type asteroid, meaning it is composed primarily of silicate minerals. Its diameter is estimated to be around 30 kilometers, making it relatively small compared to other well-known asteroids. The asteroid has an elongated, irregular shape and a rotation period of approximately 5.6 hours. Its surface appears relatively dark, reflecting only about 5 percent of the sunlight that strikes it.

Nereus is notable for its relatively low orbital inclination, which places it close to the ecliptic plane. Its orbit is also slightly eccentric, meaning its distance from the Sun varies between approximately 2.0 and 2.7 astronomical units (AU). This proximity to Earth makes it a target of interest for future space missions, particularly due to its potential as a resource-rich asteroid. In 2019, NASA selected Nereus for a mission concept study as part of its New Frontiers program, aiming to send a spacecraft to explore it in the 2020s.

As of recent observations, Nereus does not pose a threat to Earth, and its trajectory remains stable. It is currently the only known asteroid with a defined mission profile for human or robotic exploration in the near future.