The unexpected success of the heavy bombers was largely the result of the effectiveness of the new JDAM GPS (space satellite) guided bombs. Unlike the earlier, laser guided, smart bombs, JDAM could ignore weather and did not need someone on the ground, or in the air, pointing a laser at the target (to provide reflected laser light that the bombs guidance system homed in on.) With JDAM, the bomber merely had to be close enough to the target (meaning within about 40 kilometers) for the bomb to be dropped. GPS simply went to a specific location and detonated. No laser needed. Bad weather and dark of night were not a problem. At the same time, the troops on the ground had better GPS, radio and laser range-finder equipment. With the latest gear, the guy on the ground looked through what appeared to be binoculars. But these binoculars contained a laser range finder and GPS. Press a button to get the range and GPS location, press another button to send the GPS data to the bomber overhead. The bomber pilot pressed a button to transfer the GPS data to a bomb, then released the bomb. In 2001, the equipment was rather more crude and cobbled together, but the potential for point (the binoculars) and press some buttons was there. All this meant that the most useful type of bomber, for the ground troops, was one that could carry lots of bombs, and circle the area for hours, waiting for requests to release a bomb. The ground troops never knew exactly when they would need another smart bomb, but it was important that when they needed one, it would be instantly available. The heavy bombers were the best for this kind of work. They carried lots of bombs and could stay in the air longer than smaller warplanes. JDAM was more accurate than any air force bombing, ever. After decades of getting hit, by accident, with less accurate air force bombs, American troops were now enthusiastic about American bombers. JDAM is a bomb that is considered "safe," for the users on the ground.
The air force has, since 2001, been rapidly upgrading all three of its heavy bombers (B-1, B-2 and B-52) with the latest electronics and bomb racks so that all the current smart bombs can be carried and used. This includes not just JDAM, but also JASSM (AGM-158, the Joint Air-to-Surface Standoff Missile). This is a 2,300 pound missile with a 1,000 pound warhead and a range of 350 kilometers. And then there is SDB (Small Diameter Bomb), a 250 pound JDAM which is 70 inches long and 7.5 inches in diameter. With special bomb racks, heavy bombers can carry over 200 SDBs at a time. That means 200 targets can be attacked in one sortie.
Until it was discovered just how effective JDAM was on the battlefield, the heavy bombers had been largely ignored when it came to upgrades. B-52s were carrying a lot of 1980s era computers (think Commodore 64 class, current CPUs provide over 5,000 times as much computing power). That has all changed now.
Because of the effectiveness of the heavy bomber, not many of them needed. The air force plans to maintain a force of about 100 of them (20 B-2s, 40 B-1s and 40 B-52s) with another 60 B-1s and B-52s held in readiness to replace losses. The B-52s, built in the early 1960s, can remain in service for another 40 years. The B-52 is also the cheapest and most reliable of the heavy bombers. The B-1 and B-2 were designed and built to replace the B-52, but have been outperformed, in actual practice, by the older aircraft. Plans to build another heavy bomber to replace the B-52 are currently on hold. The B-52s ultimate replacement might be a large UAV that could stay in the air for days at a time.
The U.S. Air Force sees a bright future for heavy bombers, even though it is unclear what the design of the next one will be like. But the heavy bomber is still considered a valuable asset because of its impressive performance in Afghanistan and Iraq. In both cases, a small number of heavy bombers did most of the damage. This was thanks to long range, long loiter tine (how long the bomber could just circle in the sky waiting for a bomb request) and large bomb load. The 2003 Iraq campaign brought in eleven B-1B's, four B-2A's and 28 B-52H's. These 43 aircraft flew some 500 missions, and were responsible for dropping a third of the bombs that hit targets during the campaign. Also, the increased dependence on Special Forces and commando operations make the heavy bombers particularly attractive. With them, you can put a Special Forces or commando team anywhere on the planet, and have one or more heavy bombers overhead with a load of smart bombs. This does wonders for the performance, and morale, of the troops below.