Three Russian satellites have failed to enter orbit after they were launched on a rocket from the Baikonur cosmodrome in Kazakhstan.
Russian aerospace experts said the Glonass spacecraft and the upper-stage booster carrying them probably fell into the Pacific Ocean near Hawaii.
The satellites were to be part of a navigation system meant to rival GPS.
Russia has already successfully launched a number of the Glonass satellites this year.
Officials had hoped to have the navigation system fully in place in 2011.