July 4, 2009:
The U.S. Air Force is upgrading all of its F-22s to better handle ground attack missions. This will include modifying the aircraft radar to do ground mapping and act as an electronic weapon. The AN/APG-77 radar on the F-22 has been tweaked so that it can produce photo-realistic images of what's on the ground. The AN/APG-77 is an AESA type radar, which consist of thousands of tiny radars that can be independently aimed in different directions. With sufficiently powerful computers on board, the AESA radar signals bounced back to the transmitter can be reassembled to provide a very realistic looking picture of what's out there.
AESA type radars have been around a long time, popular mainly for their ability deal with lots of targets simultaneously. But AESA is also able to focus a concentrated beam of radio energy that could scramble electronic components of a distant target. Sort of like the EMP (Electromagnetic Pulse) put out (in all directions) by nuclear weapons. AESA has demonstrated that it can disable missiles and aircraft. Ballistic missiles are another story, as they are sturdier (to handle re-entry stress) and have fewer electronics to mess with.
An F-22 with the ability to use its radar to identify vehicles on the ground is not a real big deal. That's because many less expensive aircraft can do the same thing. Targeting pods are used for this all the time, although the AESA radar approach cuts through clouds, fog and sand storms. But if this approach were important enough, an AESA radar and computers could be mounted in, say, a B-52, that could then drop missiles or smart bombs on targets it found.
Recently, an F-22 successfully dropped a SDB (Small Diameter Bomb) for the first time. An F-22 can carry eight SDBs internally. It was only three years ago that the 250 pound SDB into service, when an F-15E fighter bomber used one in Iraq. SDB is not just another "dumb bomb" with a GPS guidance kit attached. The SDB had a more effective warhead design and guidance system. It's shape is more like that of a missile than a bomb (70 inches long, 190 millimeters in diameter), with the guidance system built in. The smaller blast from the SDB will result in fewer civilian casualties when used in an urban area. Friendly troops can be closer to the target when an SDB explodes. While the 500, 1,000 and 2,000 pound bombs have a spectacular effect when they go off, they are often overkill. The troops on the ground would rather have more, smaller, GPS bombs available. This caused the 500 pound JDAM to get developed quickly and put into service.
The SDB is basically an unpowered missile, which can also glide long distances. This makes the SDB even more compact, capable and expensive (about $70,000 each.) JDAM (a guidance kit attached to a dumb bomb) only cost about $26,000. The small wings allow the SDB to glide up to 70-80 kilometers (from high altitude.) SDB also has a hard front end that can punch through several feet of rock or concrete, and a warhead that does more damage than the usual dumb bomb (explosives in a metal casing.) The SDB is thus the next generation of smart bombs.
There was never any point in building a 250 pound dumb bomb, as they would be too inaccurate to be useful. So it made sense to merge the guidance kit and the bomb itself. But the superiority of guided bombs is such that the next generation of heavier (500-2000 pound) smart bombs will probably be like the SDB.
The air force sees the F-22, using AESA for finding a target for its SDBs, as a formidable ground attack system. One reason for doing this is that first 63 F-22s built are not able to handle another upgrade that will enhance air-to-air performance. Thus these F-22 "mud fighters" will be useful for ground attack missions, especially those that require some stealth.