NASA, which was expected to announce its finalized plans for bringing an asteroid -- or at least a small part of one -- into an orbit around the moon for closer study says it will need more time to select final mission parameters.
NASA says it is considering two mission options, A and B. In Option A, a probe would be sent out to capture a small asteroid then tow it back to the lunar orbit. In Option B, a smaller probe would land on the surface of a larger asteroid, collect a boulder or rock off the surface, and return with it.
Either option would place its asteroid prize in a lunar orbit that would make it easy for astronauts to visit it for study.
Astronauts launching in an Orion capsule using NASA's Space Launch System, both currently in development, would intercept the orbiting meteorite to retrieve samples and return them to Earth.
NASA had been expected to announce its choice of option for its effort, dubbed the Asteroid Redirect Mission, after a meeting Tuesday but said more study would be needed before a choice could be made.
The final plan for mission, which would launch no earlier than 2019, could be decided on in early 2015, said NASA Associate Administrator Robert Lightfoot.
Option B, the "boulder grab," would allow the space agency to test more of the technologies that could be a part of future missions to Mars, Lightfoot said, but would make the asteroid mission more complex and more costly -- to the tune of around $100 million more on top of the mission's estimated $1.25 billion overall cost.
"The challenge we're having is, while it [Option B] is more complex, it also demonstrates a lot more of the technologies we need," Lightfoot said. "We're going to have to test these eventually. We're going to have to check them out eventually, so that's kind of an interesting trade we have to make."
NASA scientists say they've selected six space rocks -- three for each of the mission options -- as candidates.
Asteroids dubbed 2009 BD, 2011 MD and 2013 EC20 would be appropriate targets for Option A, they say, while asteroids known as Itokawa, Bennu and 2008 EV5 could be suitable for Option B.
Despite the delay in making a final mission decision, Lightfoot had nothing but praise for the NASA scientists and engineers involved in the mission's planning.
"I was so impressed with our teams and what they did," he said. "They're all focused on getting these technologies ready to go so that we can start this pioneering piece and get humans beyond low-Earth orbit."
