The launch of the first in a series of small satellites that can be controlled directly by military commanders in the field will take place no earlier than December due to issues with the launch vehicle, according to military and industry officials.

The first flight of that launcher, the Falcon 1 rocket built by Space Exploration Technologies (SpaceX) of El Segundo, Calif., ended in failure shortly after liftoff.

In the meantime, SpaceX , has added a previously unannounced launch to its manifest. The new launch will take place in late September or sometime in October, according to Elon Musk, SpaceX’s founder and president.

Musk said in a May 23 e-mail that the Defense Advanced Research Projects Agency is the customer for the October launch, but declined to identify the payload. However, he said the focus on the mission is not the payload, but demonstrating the launch vehicle, as was the case with the initial Falcon 1 launch March 24.

Industry and Pentagon sources said that the October launch will likely feature either no payload or a dummy as the military seeks to restore its confidence in the Falcon 1. The military is reluctant to launch another satellite aboard the Falcon 1 until it watches how the rocket performs with launches scheduled in late 2006 and early 2007, a Pentagon source said.

The deal with the Defense Advanced Research Projects Agency for the fall flight will bring SpaceX’s total number of launch contracts to 10, Musk said.

The Pentagon plans on using Operationally Responsive Space (ORS) assets like the TacSats for a variety of purposes including augmenting existing satellites, replenishing satellite constellations that have been attacked by enemies, and denying enemies the use of space, according to briefing charts used at the 4th Responsive Space Conference in Los Angeles in late April by Air Force Maj. Gen. Mark Shackleford, director of plans and requirements at Air Force Space Command.

The TacSat-1 spacecraft, which includes low-power visible and infrared sensors, was initially scheduled to launch in January 2004 on what would have been the first flight of the Falcon rocket. The TacSat-1 effort is funded by the Pentagon’s Office of Force Transformation, with the Naval Research Laboratory managing the program.

However, a series of technical issues with the rocket delayed the launch, and the military elected to first use the Falcon 1 to launch a $700,000 payload built by students at the Air Force Academy. The Falcon 1’s first stage failed, and an investigation into the mishap is under way.

The launches of the Defense Department satellites planned to follow TacSat-1 have been pushed out by issues including the delays on the Falcon 1 as well.

The second TacSat mission was originally expected to take place in late 2004. Pentagon officials had initially expected to use the SpaceX Falcon 1 rocket to launch TacSat-2, but on May 22 announced that Orbital Sciences Corp.’s Minotaur will carry that satellite, as well as TacSat-3.

TacSat-2 will feature an imaging sensor capable of taking pictures with 1-meter resolution, as well as several scientific payloads, according to a paper written by military officials running the ORS effort that was distributed at the Responsive Space Conference in April.

The paper was written by Air Force Col. Tom Doyne, a strategist in the Pentagon’s Office of Force Transformation; Peter Wegner of the Air Force Research Laboratory’s space vehicles directorate; Air Force Lt. Col. Randy Riddle of the Air Force Space and Missile Systems Center’s Detachment 12; and Mike Hurley, Mark Johnson and Ken Weldy of the Naval Research Laboratory.

The spacecraft, which is sponsored primarily by the Air Force Research Laboratory, was expected to launch in 2007 prior to the award of the contract to Orbital Sciences, but now it may launch before TacSat-1, according to the Pentagon source. A Minotaur rocket was already built for the launch of the Missile Defense Agency’s Near Field Infrared Experiment, which has been delayed until April 2007, creating an opportunity to launch TacSat-2 in November, the source said.

TacSat-3, which is expected to follow in late 2007, will feature a hyperspectral imager as well as a communications relay payload, according to the paper, which is titled “A TacSat and ORS Update.” The Air Force Research Laboratory is leading the work on the project.

TacSat-4 will follow in 2008, and is expected to be launched aboard Orbital’s Minotaur 4 rocket, according to the paper. The payload on TacSat-4 will be capable of allowing troops to communicate while on the move, as well as relay information from Navy buoys and blue force tracking devices carried by troops, according to the paper.

To avoid friendly fire accidents, the Pentagon uses a variety of what are known as blue force tracking devices developed by the military and commercial companies to track the position of troops in the field with GPS navigation equipment.

The Navy is leading the work on TacSat-4, which will be placed into a highly elliptical orbit intended to maximize its dwell time over a given area , according to the paper. Reaching the geostationary orbital arc that is typically used for communications satellites would entail expensive launch, aperture and power requirements well beyond the ORS goals, according to the paper.

Some highly elliptical orbits could offer periods of three to four hours of coverage over particular areas, enabling continuous coverage with a small constellation of satellites, according to the paper. Those orbits also may offer better coverage in certain areas including mountainous or otherwise obstructed terrain than geostationary positions, according to the report.