Space Exploration Technologies' Falcon 1 automatically aborted the launch from Kwajalein Atoll with about 1.5 minutes left in the countdown, said launch commentator Gwynn Shotwell.

The abort may have occurred when communication with the vehicle was switched from a landline to a radio frequency and the signal was not picked up, Shotwell said.

It was possible the launch would be rescheduled for Tuesday.

The El Segundo, Calif., company known as SpaceX has yet to successfully launch a Falcon 1, the first of what is planned to be a family of low-cost rockets. It is designed to carry up to 1,254 pounds to low orbit for $6.7 million.

A March 24, 2006, launch from Omelek island in the Kwajalein Atoll failed when leaking fuel caught fire seconds into liftoff. An Air Force Academy satellite was lost in the accident, which an investigation linked to corrosion of an aluminum nut due to prolonged exposure on the launch pad.

The new mission, Demo-2, is primarily to gather flight data. It also carries two experiments, the autonomous flight safety system and the low cost tracking and data relay satellite system transmitter.

Falcon 1 is a 70-foot-long, two-stage rocket powered by liquid oxygen and kerosene. Its first stage is designed to parachute into the ocean to be recovered and used again.