NASA says a future mission to Mars should include collecting rocks and bringing them back to Earth so scientists can study them. The next rover to Mars should search for signs of past microbial life and collect a cache of rocks that a later mission could bring back to Earth, a NASA-appointed panel said Tuesday. The recommended science goals are the most ambitious yet for any Mars mission. Scientists have long wanted to examine Martian rocks and dirt under a microscope on Earth, but spacecraft sent to the surface so far don't have the capability to store samples. Though the 2020 rover should be designed to collect rocks, the panel said NASA isn't obligated to bring them back. NASA has the final say on what the future rover will accomplish. The space agency said last year said it planned to launch another spacecraft to the red planet in 2020 following the success of Curiosity, which touched down in Gale Crater to much fanfare. To keep costs down, engineers will recycle spare parts where possible and use the same landing technology that delivered the car-size Curiosity to the surface. Curiosity recently departed on a month-long trek toward a mountain rising from the middle of the crater.