NASA's future plans to explore Mars may end up using astronauts as space messengers.
The new idea surfaced as a special team looking for a new Mars robotic exploration plan released a preliminary report Tuesday.
One of the options calls for a Martian robotic rover to collect rocks on the red planet. Later, astronauts in a newly built spaceship would be used to pick them up from a cosmic delivery point somewhere between Earth and Mars and return them home.
The report gives NASA several options with no specific timing for future missions, and no decision is expected until next year. The new plan is needed because budget cuts this year killed two future robotic flights.
The space agency has so far explored Mars with orbiters and robots, like the rover Curiosity that landed last month. The ultimate goal has been to get a robot to collect rocks and Martian soil to send to Earth for more detailed scientific examination.
Separately, NASA is working on new missions for astronauts to explore away from Earth, with an ultimate goal of sending them to Mars sometime in the 2030s. The NASA team proposed combining both dreams, getting astronauts involved in Martian exploration earlier.
That plan takes advantage of the new rocket and spaceship system for astronauts that should be ready in the next decade, said John Grunsfeld, NASA'S associate administrator for sciences.
It also would lessen contamination worries about the Martian rocks. Scientists want to make sure that the Martian samples could not bring alien germs to Earth and that Earth organisms don't contaminate the Martian sample, Grunsfeld said.