In this computer graphic, NASA's proposed ARM -- Asteroid Redirect Mission -- spacecraft settles to the surface of an asteroid and locks onto a boulder targeted for return to the vicinity of the moon for hands-on analysis by spacewalking astronauts. NASA

After an extended review, NASA has opted to forego capturing a small asteroid as an interim step on the road to sending astronauts to Mars. Instead, the agency will focus on robotically plucking a sizable boulder from the surface of an asteroid and returning it to the vicinity of the moon for analysis by spacewalking astronauts in the mid 2020s, officials said Wednesday.

Agency managers said the mission will serve as a testbed for technologies needed for eventual deep space missions, give NASA astronauts experience interacting with another body, provide new insights into the birth and evolution of the solar system and shed light on what might be needed to someday divert an asteroid on a collision course with Earth.

"When you think about what we're trying to do with this Asteroid Redirect Mission, it's bringing together the best of NASA's human exploration, its science portfolio, technology portfolio and really gives us an opportunity to demonstrate capabilities we're going to need for future human missions beyond low-Earth orbit and then ultimately, to Mars," said Robert Lightfoot, the NASA manager overseeing the project.

The Asteroid Redirect Mission, or ARM, is the centerpiece of the Obama administration's post-shuttle, post-space station plan to send astronauts beyond low-Earth orbit, bypassing the moon in favor of one or more piloted flights to get hands-on experience with a nearby asteroid in the mid 2020s. NASA's long-range goal is a flight to orbit or land on Mars in the 2030s.

The ARM project has drawn fire from many space advocates and scientists who argue it is not necessary and that NASA's time and money would be better spent on a return to the moon to perfect the technologies needed for eventual Mars missions.

In any case, NASA managers and engineers have been studying two basic ARM options. In one, an entire asteroid would be captured and hauled back to the vicinity of the moon for detailed study by astronauts using NASA's new Orion crew capsule. The other option calls for collecting a large boulder as a more manageable, representative sample.

NASA managers met Tuesday and selected Option B, deciding it offered the best chance for success and a better fit with the agency's long-range plans.

"At the end of the day, we selected the option (where) we're going to go to an asteroid and take a boulder off of it," Lightfoot told reporters during an afternoon teleconference. "Let's get on with it, so we can get this next key step in our journey to Mars moving on."

Read the original post:

NASA opts to grab a boulder, not the whole asteroid