The Asteroid Redirect Mission was originally designed to capture a complete asteroid and bring the space rock back into orbit around the moon.

But NASA officials announced a modified version of the plan on March 25, one which involves collecting just a single boulder from the surface of an asteroid, and driving the boulder to an orbit around our own natural satellite.

Asteroid EV5 is the most likely target for the historic mission.

The robotic ARM mission, scheduled for launch in 2020, will take between 215 and 400 days to corral the boulder into orbit around the moon. Five years later, space travelers will launch to the captured space rock aboard a Space Launch System (SLS) booster, housed in an Orion space capsule. Once they arrive at the body, two astronauts will leave the vehicle in a series of spacewalks to collect samples of the boulder.

Asteroid surveys carried out by NASA officials have resulted in a 65 percent increase in the number of near-Earth objects detected over the last three years.

"Asteroids are a hot topic. Not just because they could pose a threat to Earth, but also for their scientific value and NASA's planned mission to one as a stepping stone to Mars," Jim Green, director of NASA Planetary Science, said.

The mission is aimed at testing several technologies needed for future missions, including a journey to Mars. A Solar Electric Propulsion (SEP) drive is one of the new pieces of equipment that will be examined on the mission. This engine collects solar energy through solar cells, and uses that energy to propel charged particles out an exhaust, providing thrust to the spacecraft.

Funding for the mission is currently capped at $1.25 billion, not including launch costs. Those funds are divided among several budget departments in the NASA budget.

"I think there will be some (funding) increase that is specific to the mission. We will take advantage of solar electric propulsion, which is estimated roughly at $300 million, which is already in the runout for space technologies. There's some capture technique mechanisms that were already in parts of the human exploration budget," Lightfoot said.

Asteroid EV5 was discovered in 2008, during observations made as part of of the Catalina Sky Survey, a project to discover comets and asteroids and to search for Near-Earth objects. The object is roughly 1,300 feet in diameter. Observations reveal the presence of large boulders and smaller debris on the surface of the body, and astronomers believe boulders around the desired size of 10 feet are also likely present on the space rock.

Two other asteroids, Itokawa and Bennu, are also being considered as potential targets for the boulder retrieval mission. A final decision on the destination of the spacecraft will not need to be made until the year 2019, one year before launch of the robotic segment of the mission.