A lot will have to go right for SpaceX to meet its ambitious moon-mission timetable, experts say.

On Monday (Feb. 27), SpaceX founder and CEO Elon Musk announced that the company plans to launch two paying customers on a weeklong trip around the moon before the end of 2018.

Astronauts first saw the moon's far side way back in 1968, but the antiquity of that achievement shouldn't fool anyone into thinking that SpaceX's proposed mission will be easy, said Wayne Hale, a former manager of NASA's space shuttle program. [SpaceX to the Moon - 2018 a Lofty Goal? (Video)]

"Even with today's technology, it's still an extraordinarily difficult, extraordinarily dangerous task to undertake, period — I don't care who you are," said Hale, who retired from NASA in 2010 and now serves as director of human spaceflight at the Colorado-based engineering company Special Aerospace Services.

SpaceX could pull off a crewed lunar loop eventually, Hale said, but he's skeptical that the mission will happen next year.

"I think their schedule is so aggressive as to not be believable," he told Space.com.

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