The Pentagon is likely to come close to meeting its cost target for building and launching the first in a series of small spacecraft intended for use by tactical forces, but the price tag of those that follow now is expected to be at least twice what the military had hoped to spend, according to a draft audit report and Pentagon officials.

Costs associated with launching the small spacecraft known as TacSats could rise as well because the insurance premiums for one rocket the U.S. Air Force plans to use could go up by a factor of 10 or more than the previous quote, according to the report.

The Government Accountability Office (GAO) audit, “[Defense Department] Needs a Department Wide Strategy for Pursuing Low-Cost Tactical Space Capabilities,” was requested by U.S. Rep. Terry Everett (R-Ala.), chairman of the House Armed Services strategic forces subcommittee. The report is circulating inside the Pentagon to give the military a chance to comment on its findings, and is expected to be made public in March.

The TacSats were envisioned as costing about $15 million each, including launch costs, when the late Arthur Cebrowski, a retired U.S. Navy vice admiral who headed the Pentagon’s Office of Force Transformation, began promoting the concept in 2003.

Cebrowski’s vision entailed building inexpensive spacecraft that could be directly tasked by commanders in the field who typically do not have access to many satellite capabilities. The Pentagon would keep a batch of TacSats on the ground that could be launched on short notice by new responsive rockets.

TacSat-1, which features a low-power imaging sensor, will likely cost $9.3 million, according to the GAO report, which was based on interviews with Pentagon officials.

That satellite, which was initially scheduled to launch in January 2004, now is expected to launch in mid-2006, according to Lt. Col. Gus Hernandez, chief of space vehicle requirements for Operationally Responsive Space at Air Force Space Command.

The Air Force plans to follow with TacSat-2 in May 2007, TacSat-3 in July 2007, and TacSat-4 in late 2008, Hernandez said in a Feb. 6 interview with Space News. Those satellites still are considered small but are significantly heavier and more sophisticated than TacSat-1, he said.

TacSat-1 is roughly 110 kilograms, while TacSat-2 is about 300 kilograms, and TacSat-4 is expected to be about 400 kilograms, Hernandez said.

Along with a rise in capability and weight is a rise in price. The GAO report estimates TacSat-2 will cost $37 million, TacSat-3 $35 million, and TacSat-4 $41 million. Those prices do not include launch costs.

Pentagon sources said that they still consider the TacSats a bargain in comparison to the cost of other military satellites. The Air Force has a stronger appetite for more capable satellites than the Office of Force Transformation, which was responsible for TacSat-1 and sought to keep the spacecraft as simple and affordable as possible, the sources said.

One source noted that the TacSats are prototypes intended for demonstrations with some operational capability, and that it is difficult to determine the typical cost of buying operational satellites based on the estimates of the first four spacecraft.

The Pentagon could find that operational satellites require more robust hardware that is even more expensive than the estimates for TacSat-2 through TacSat-4, or find significant cost savings through purchasing a large number of TacSats at once, the source said.

However, the GAO report noted that projected economies of scale with small satellites have failed to materialize in at least one instance in the recent past. The Pentagon had expected the high launch rates would keep down the cost of rides aboard the Pegasus, Taurus and Minotaur launchers sold by Orbital Sciences Corp. of Dulles, Va. Orbital builds the Pegasus and Taurus and modifies the Minotaur launchers, which are decommissioned ICBMs.

However, the launch rates have been far lower than projected. The report notes that the Taurus has launched only seven times since 1994, and the Pegasus only 36 times since 1990. This experience might serve as a cautionary tale as the Pentagon develops its own small launcher under the Falcon program, according to the report.

The Pentagon is weighing the possibility of refurbishing other ICBMs for use in launching TacSats, but those rockets would likely cost $18 million to $23 million, according to the GAO report.

TacSat-1 is slated to launch aboard the Falcon 1 rocket built by Space Exploration Technologies (SpaceX) of El Segundo, Calif. SpaceX currently offers Falcon 1 launches for $6.7 million including range expenses, but that figure could rise as the company’s insurance costs for launches from Vandenberg Air Force Base in California go up. According to the GAO report, the insurance on Falcon rockets could rise from $40,000 to as much as $500,000.

SpaceX President Elon Musk said he had been notified that his premiums would go up after the Air Force commissioned Lockheed Martin Corp. of Bethesda, Md., to build a launch pad at Vandenberg for its Atlas 5 rockets, but said that he hoped that the cost would be lower than the numbers contained in the GAO report.

The company will likely have a clearer sense of its regular Vandenberg insurance premiums and their effect on the launch price tag after conducting missions from that range, Musk said.

The Air Force has requested $35 million in 2007 for responsive space work that includes the TacSat program, and plans to spend a total of $347 million through 2011 on that work. While the budget for responsive space is dwarfed by many other programs in the Air Force budget request, senior service officials say that the work is still a high priority.

Ronald Sega, the undersecretary of the Air Force, said during a Feb. 22 conference call with reporters that a variety of other programs outside the Air Force budget benefit responsive space as well, though he declined to provide a estimate for the value of that work.