NASA wants to put humans into Mars' orbit by 2033, with the goal of having astronauts return to Earth with a canister of Mars rocks that would have been collected earlier and put into orbit. The goal was unveiled this week by an internal NASA study group working on the agency's Mars program with the goal of finding ways for NASA's human and robotic sides to integrate their work.
Some at NASA are concerned, considering it's more difficult and more expensive to get humans to Mars than robots. On Nature's news blog, Eric Hand writes that "this is the first articulation I’ve seen of a specific, shared date for the key goal of both the human and robotic sides," though the Obama administration has mentioned getting humans near Mars by around that same timeframe. (Read more Mars stories.)