LOS ANGELES - NASA's next-generation rover to the surface of Mars, already over budget and behind schedule, may need more money to meet its November launch date, auditors have found.

The grim news was outlined in a report released Wednesday by NASA's inspector general.

Though project managers have solved most of the problems that caused the mission to be delayed by two years, auditors found significant hurdles remained before liftoff.

The mobile Mars Science Laboratory is intended to be the most sophisticated rover sent to the Martian surface. From the outset, the mission managed by the Jet Propulsion Laboratory has been plagued by development woes that have put it behind schedule and driven up costs. The price tag has ballooned to $2.5 billion from $1.6 billion.

NASA's watchdog faulted project managers for routinely underestimating costs and calculated that an extra $44 million may be needed to avoid another delay or cancellation.

The latest price tag "may be insufficient to ensure timely completion of the project in light of the historical pattern of cost increases and the amount of work that remains to be completed," the report said.

The size of a Mini Cooper and nicknamed Curiosity, the rover is a souped-up version of the golf-cart-size twin rovers Spirit and Opportunity. Essentially a science laboratory on wheels, Curiosity carries a suite of tools to analyze Martian rocks and soil to determine whether environmental conditions were ever favorable to support primitive life.

Curiosity was supposed to fly in 2009, but problems during construction forced NASA to push back launch by two years to 2011 when the orbits of Mars and Earth are again closely aligned.

Engineers had to redesign the heat shield after it failed safety tests. There were delays in shipping instruments to NASA. It took longer than expected to build and test the gear boxes that enable the mega-rover to drive and flick its robotic wrist.

Auditors found 1,200 reports of problems and failures that have not been resolved. During testing of the robotic arm, engineers discovered contamination in sample rocks and soil. NASA has since found a solution to minimize contamination, but auditors said they remained concerned that the fix would not be completed until later this month.