The U.S. Air Force is moving ahead with plans to change its approach to national security satellites, including greater use of government sensors on commercial satellites and possible launches of cheaper, less-complex satellites for other missions, a top Air Force general said on Thursday.

General William Shelton, who heads Air Force Space Command, told reporters that he expected to issue an open-ended, multiyear contract in 2013 that would allow the government to use more “hosted payloads” in which government sensors are launched aboard commercial satellites.

He said the contract would be valued at under $500 million.

The Air Force was also looking at launching an additional navigational satellite as part of its Global Positioning System that would save money by dropping the sensor used on existing satellites to detect nuclear detonations, he said.

The new satellite would be used to address the lack of coverage in urban areas and mountainous terrain such as in Afghanistan, he said.

Other ideas included expanding communications needs by leasing satellites or using commercial satellites in much the same way the military now uses commercial airlines to transport troops.

On missile-warning satellites, the Air Force was looking at launching separate satellites to carry out specific tasks, rather than one big “bus” that carried a variety of complex sensors.

Shelton said the Air Force was also conducting an analysis of alternatives for a follow-on weather forecasting satellite, with an eye to making the new system smaller and less expensive.

“We are changing direction,” he said. “In terms of the overall capability it is much the same ... but how we achieve that capability is going to be fundamentally different.”