NASA's grand Asteroid Initiative (pictures)

Last week, it was announced that $78 million has officially been set aside in the fiscal year 2014 budget for NASA to start development on an asteroid capture plan in which a spacecraft will rendezvous with a "small asteroid".
The program, titled the Asteroid Retrieval and Utilization Mission, sounds like something out of a science-fiction movie.
This illustration from NASA shows what capturing an asteroid might look like. During the first phases of the project, NASA will enhance detection and characterization capabilities, accelerate the building of solar electric propulsion technologies, and begin design and development of the mission.
After capturing the asteroid, the plan is to then move it into a stable orbit near the moon where astronauts can then set foot on the rock to scoop up samples for study back on Earth.

The first step in the asteroid capture process is choosing the right target. To help with this, NASA is building a space-based telescope that will use an infrared sensor to improve detection and tracking capabilities.
Asteroids reflect visible light, which is how we find them. Odd and irregular shapes create varying degrees of reflectivity. A small, light-colored space rock might be very reflective, and thus can look the same as a big, dark one. As a result, data collected with optical telescopes using visible light can be deceiving.
An infrared sensor, called the NEOCam chip (right), is the critical piece of technology for the new Near Earth Object Camera. The NEOCam will be used to support future missions designed to protect Earth from potentially hazardous asteroids lurking in the Near-Earth sphere -- within 28 million miles of Earth's path around the sun.

The Near Earth Object Camera will use a new sensor, called the NEOCam chip, that has more pixels and better sensitivity than previous generations of infrared sensors.
Made of mercury, cadmium, and tellurium, the new chip is about the size of a postage stamp and is optimized for detecting the faint heat emitted by asteroids circling the Sun. The NEOCam chip is the first megapixel sensor capable of detecting infrared wavelengths at temperatures achievable in deep space without refrigerators or cryogens.

This illustration shows a notional spacecraft with an asteroid capture mechanism.

This illustration shows a spacecraft with its asteroid capture mechanism deployed.

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.