James Dean, FLORIDA TODAY

The launch for Orbcomm Inc. was postponed from May by a rocket issue.

The reason for the latest slip was not immediately available.

SpaceX briefly test-fired a Falcon 9 rocket's engines today, but it's unknown when a full-duration firing will occur to launch a group of six commercial satellites from Cape Canaveral Air Force Station.

A planned launch Sunday evening was delayed to allow time for more tests on one of Orbcomm Inc. satellites, which had experienced an issue described as minor earlier in the week.

"In an effort to be as cautious as possible, it was decided to perform further analysis to verify that the issue observed on one satellite during final integration has been fully addressed," Orbcomm said in a statement Friday. "We are working with SpaceX to identify the next available launch opportunity, and we will update the schedule shortly."

The mission won't be ready by Monday, which was the backup launch date.

After that, the Air Force's Eastern Range was scheduled to begin a two-week maintenance period, and it was not immediately clear if a launch could be attempted during that time.

The Air Force's 45th Space Wing did not respond to a question today about the range's availability.

The Orbcomm mission has been delayed multiple times.

The Air Force's loss of a tracking radar earlier in the year, which shut the range down for two weeks, had a ripple effect that pushed the launch from April into May.

Then a Falcon 9 rocket problem postponed an attempt a month ago. This week, the satellite issue moved the launch from Thursday to Sunday, and now to a date to be determined.

The mission is the first of two SpaceX plans this year to deploy a new constellation of 17 small satellites in low Earth orbit for Orbcomm, a provider of machine-to-machine communications.

Contact Dean at 321-242-3668 or jdean@floridatoday.com.