WASHINGTON – The Pentagon’s interest in inexpensive small satellites that can be made available quickly has prompted the U.S. Air Force to make plans for a partially reusable rocket that would cut launch costs by two-thirds, launch on two days’ notice and be available starting around 2018.

The service is planning a subscale demonstration of the Affordable Responsive Spacelift (ARES) system in 2010, and expects to award study contracts for that effort this summer, according to Col. William Dean, director of development and transformation at the Air Force Space and Missile Systems Center in Los Angeles.

The Air Force has budgeted about $250 million through 2010 for the demonstration , Dean said in an April 21 telephone interview. He declined to comment on the expected overall cost of the program through 2018, citing the preliminary nature of the numbers.

As envisioned, the ARES rocket would launch satellites weighing 2,300 to 6,800 kilograms, which today often are handled by Boeing Co.’s Delta 2 rocket, according to Air Force Lt. Gen. Brian Arnold, commander of Space and Missile Systems Center.

The Air Force is working to shrink the size of key components like antennas and begin launching a significant number of spacecraft in this class by the end of the next decade, Arnold said in a brief interview April 20 . The ARES system in theory could launch satellites at one-third to one-sixth the cost of today’s rockets, he said.

A Delta 2 rocket costs about $65 million to $75 million.

The ARES rocket would have a reusable first stage that would take the vehicle up to about 61 kilometers, Dean said. The system would then fire an expendable second stage that would take the payload to any of the orbits used by the military today, including geostationary positions, he said. The winged first stage would make a jet-assisted return to Earth and land like a conventional aircraft, he said.

By flying the first stage to the edge of space, but not beyond, the Air Force would not have to equip it with expensive and technically challenging thermal protection systems necessary for atmospheric re-entry, Dean said.

Fast preparation and launch-turnaround time is another key attribute envisioned for the ARES system , Dean said. The ability to launch satellites inexpensively and quickly in response to emerging requirements would allow the military to build more of them because they would not have to be equipped to last for a decade or more on orbit, he said.

Gen. Lance Lord, commander of Air Force Space Command, has asked to see options for having the first ARES system ready for operations before 2018, and program officials are preparing a set of alternatives that they expect to submit in about a month, Dean said.

The Air Force plans to award up to four preliminary design contracts worth a combined $6 million to $8 million in June or July for an ARES demonstrator , Dean said. Depending on the availability of funds, the service could either select one concept for development or two for more detailed design studies in 2006, he said.

An open competition for the operational ARES system would follow the 2010 demonstration, Dean said.

The Air Force conducted an industry day for the program in March, and the event was well attended by the traditional aerospace prime contractors as well as smaller entrepreneurial firms , Dean said. The Air Force is open to having a large or small company build the system, he said.

Congressional staffers said they were pleased to hear that the Air Force is working to reduce its launch costs, but raised concern that launch rates might not be high enough to warrant development of a new rocket by 2018.

Jeff Faust, an industry analyst with the consulting firm Futron Corp. of Bethesda, Md., questioned whether the Air Force has budgeted enough money for the ARES program thus far, and said the service might need to scale back its objectives for the demonstration. The Air Force estimate of $250 million likely would not cover the cost of demonstrating launches on one or two days notice and the ability to recover and reuse the first stage, he said.

Demonstrating both capabilities likely would require a far more expensive vehicle or perhaps two separate vehicles, Faust said.