BY : DEFENCENEWS

Ten years after the U.S. Air Force retired the SR-71 spy plane, Lockheed Martin’s legendary Skunk Works appears back at work developing a new Mach-6 reconnaissance plane, sources said.
The Air Force has awarded Lockheed’s Advanced Development Projects arm a top-secret contract to develop a stealthy 4,000-mph plane capable of flying to altitudes of about 100,000 feet, with transcontinental range. The plan is to debut the craft around 2020.
The new jet being referred to by some as the SR-72 is likely to be unmanned and, while intended for reconnaissance, it could eventually trade its sensors for weapons.
The Air Force is working on several programs to improve its global intelligence-gathering. Satellites offer global coverage, but the ones with the highest resolution operate on largely predictable orbits, and many countries have mastered the art of hiding from them. Moreover, China’s successful anti-satellite missile test in January hinted that U.S. satellites might become vulnerable.
The new aircraft would offer a combination of speed, altitude and stealth that could make it virtually impervious to ground-based missiles, sources said. Even the SR-71 is said to have evaded hundreds of missiles fired at it during its long career, although some aircraft sustained minor damage. But experts say enormous challenges remain. First, the SR-71’s top speed was about 2,200 mph. Pushing a plane at twice the speed in the thin air of the upper stratosphere would require exceptionally powerful engines. Second, friction at high speeds could reduce stealth.
“An aircraft with these characteristics could prove a potent response to anti-satellite weapons,” said Loren Thompson of the Lexington Institute. “If U.S. reconnaissance satellites were lost, an SR-72 could get to areas of interest quickly and provide persistent surveillance in place of the satellite.”
And don’t bother asking the Air Force or Skunk Works execs about their work. Neither is commenting and Skunk Works is skipping next week’s Paris Air Show.
“As a matter of policy, we don’t talk about classified programs whether or not they exist,” said Lockheed’s Tom Jurkowsky.