NASA's new heavy-lift rocket, designed to fly astronauts to the moon, asteroids and eventually Mars, likely will not have its debut test flight until November 2018, nearly a year later than previous estimates, agency officials said on Wednesday.

NASA is 70 percent confident of making a November 2018 launch date, given the technical, financial and management hurdles the Space Launch System faces on the road to development, NASA associate administrators Robert Lightfoot and Bill Gerstenmaier told reporters in a conference call.

NASA estimates it could spend almost $12 billion developing the first of three variations of the rocket and associated ground systems through the debut flight, and potentially billions more to build and fly heavier-lift next-generation boosters, a July 2014 General Accountability Office report on the program said.