Funding for space programs continues its upward trend in the U.S. Air Force’s 2007 budget request, but the service appears to be throttling back a bit on its ambitions in this arena.

The Air Force’s $9.8 billion request for unclassified space activities next year represents a $500 million increase, far less than the $1.8 billion space hike the service asked for — but did not receive — in its 2006 budget. The spending plan also features a more conservative approach to program development and budgeting in what Defense Department officials said is a bid to win support on Capitol Hill for controversial efforts such as the Transformational Satellite (T-Sat) communications system and Space Radar.

Congress has slashed Air Force funding requests for both efforts in recent years, warning that the service was courting trouble by trying to do too much too quickly in space. Virtually all of the Air Force’s major space development efforts in the last decade have experienced technical problems leading to cost growth and delays, and lawmakers fear T-Sat and Space Radar will have similar troubles.

In response, the Air Force has outlined a new strategy that entails higher-fidelity program cost estimates and scaled-back objectives for the initial versions of new satellites, an approach known in Pentagon parlance as spiral development. The idea is to reduce risk by deploying new system capabilities and technologies incrementally rather than all at once.

Spiral development figures prominently in the latest plans for Space Radar and T-Sat, which remain the largest next-generation space development projects on the Air Force wish list, the Pentagon officials said Feb. 6 during a budget briefing.

In the case of T-Sat, the plan represents a new twist on an existing theme. As envisioned, T-Sat would be a constellation of satellites equipped with laser-optical and Internet-router technology that would go a long way toward satisfying the modern military’s insatiable appetite for bandwidth.

Back in 2004, the Air Force proposed a spiral development strategy for T-Sat in which the first satellite would be less widely accessible than subsequent craft. Under the new approach, the first two satellites would be user-limited, and also would have less overall bandwidth than subsequent craft, the officials said.

Lockheed Martin Corp. of Bethesda, Md., and Boeing Co. of Chicago are each leading teams competing to build the T-Sat space segment . The contract award had been slated for late 2006 or early 2007, but has been pushed into 2008 due to Congress’ reduction to the budget request for the program last year, the officials said.

That cut also will delay the launch of the first T-Sat satellite from early 2013 to late 2014, the officials said.

In the case of Space Radar, which would collect high-resolution imagery and detect movements on the ground, the Air Force has scratched plans to launch two quarter-scale demonstration satellites in 2008, the officials said. The Air Force still hopes to begin launching the operational Space Radar satellites in 2015, but will begin with less capable spacecraft and upgrade the technology incrementally , the officials said.

Lockheed Martin and Northrop Grumman Corp. of Los Angeles are leading teams competing for the Space Radar work.

The incremental approach also will be applied to the next-generation GPS satellite navigation system, or GPS 3, the officials said. The GPS 3 budget request also is notable because it projects a first launch in 2013, as was envisioned last year at this time. In recent years, the pattern has been that the initial launch date for GPS 3 would move to a later date with each successive budget request.

Spiral development is not without critics. Chris Hellman, a military policy analyst for the Center for Arms Control and Non-Proliferation, a non profit advocacy group in Washington, said the strategy risks fielding inadequate hardware in the name of meeting notional deployment dates.

A recent example, Hellman said, is the Boeing-built Ground Based Midcourse Defense System, Hellman said. The national missile defense interceptors were deployed at Fort Greely in Alaska and Vandenberg Air Force Base in California over a year ago, but have repeatedly failed in flight tests and have yet to be declared operational, he said.

Also reflected in the 2007 budget request is a new standard for estimating the cost of space programs. The service previously used the so-called 50-50 standard — meaning there was only an even chance that a program would stay within its cost estimate , the officials said.

One official called the 50-50 standard “absurd,” and expressed dismay that the odds of meeting a program’s cost goals were no better than a flip of a coin.

The new approach — recommended by an expert commission led by A. Thomas Young, a former top Lockheed Martin executive — will use a benchmark of 80 percent, meaning the likelihood of a cost overrun is only 20 percent , the officials said.

In spite of the more conservative approach to program funding and execution, the Air Force made room in its 2007 request to start new development efforts. These include a follow on to the Space Based Infrared System (SBIRS) missile warning program, which has been truncated due to technical problems and cost growth.

The service is requesting $103 million in 2007 for the Alternative Infrared Satellite System. The Air Force late last year restructured its SBIRS contract with Lockheed Martin Space Systems of Sunnyvale, Calif., reducing the number of satellites to be purchased from five to no more than three.

The Air Force has begun a dialogue with industry on concepts for the Alternative Infrared Satellite System, which would begin launching sometime next decade, the officials said.

Another new program featured in the 2007 budget request is a hybrid rocket with a reusable first stage and an expendable second stage, the officials said. That rocket, which takes up a significant portion of the $35.6 million requested for Operationally Responsive Space, is envisioned as carrying payloads weighing about 450 kilograms and launching on just two days notice, the officials said.

Meanwhile, the U.S. Navy’s 2007 budget request includes $665.3 million for the Mobile User Objective System communications satellites, an increase of $202.6 million over the current budget for that effort.