Advanced solar electric propulsion technologies will be an essential part of any future missions into deep space with larger payloads, such as the Asteroid Capture Initiative.
This artist's concept illustration shows an SEP-based spacecraft during NASA's mission to find, rendezvous with, capture and relocate an asteroid to a stable point near the moon. Using a robotic craft like this before sending humans to an asteroid offers more mission flexibility than would be possible if a crewed mission went directly to the asteroid.
NASA's interest in asteroids isn't new. Multiple probes have completed flybys of asteroids on their way to other planets. Two missions have also launched specifically to study asteroids, the Near-Shoemaker mission to the asteroid Eros and the Dawn spacecraft when it reached the asteroid Vesta in July 2011. The Dawn craft is now on its way to our solar system's largest asteroid, Ceres.