A B-52 drops a load of bombs in Afghanistan. U.S. Air Force/Master Sgt. Ralph Hallmon/AP

That the B-52 Stratofortress is still in service for the U.S. Air Force is something of a minor miracle.

Designed by Boeing, the 160-foot-long strategic bombers weren’t much to look at when the first operational prototype took flight in 1952, earning the new class of bomber the unofficial nickname “BUFF” — short for “Big Ugly Fat Fuckers.”

But for decades, the B-52 has remained the backbone of America’s global military presence, from relentlessly trolling the nuclear-armed Soviet Union and bombarding enemy forces during the Vietnam War to providing close air support in modern conflicts from Serbia and Yugoslavia to Iraq and Afghanistan. According to the Air Force, B-52s delivered 40% of all the weapons dropped by coalition forces during Operation Desert Storm in 1991.

“The long rifle was the great weapon of its day,” Air Force Chief of Staff General Nathan Twining reportedly declared during the unveiling of the first 10 B-52Bs to enter into service in March 1954. “Today, this B-52 is the long rifle of the air age.”

As Wired observed in 2016, “recent crew members have been sons and grandsons of previous-generation B-52 crew members.” If the Air Force gets its way, a few more generations will be able to make the same boast.

In an interview with Task & Purpose, Eric Single, acquisition chief of the Air Force Global Strike Division, said the Pentagon intends to keep the B-52 in service through 2050 — at least.

As of this year, 76 of the 742 B-52 models produced between 1954 and 1963 remain in service, most of them culled from the late-model 102 B-52H bombers that rolled off the assembly line after 1961 and flew missions out of Barksdale Air Force Base and Minot Air Force Base. And with good reason: According to Single, the B-52 was intended from the outset for both high and low altitude bombing operations, the airframe, power plants and engines designed for maximum durability.

A B-52 takes off in support of Giant Lance. US Air Force Photo

“Global Strike Command intends to keep [the B-52] flyable and viable through that date, even as we deliver on the new B-2s in the mid-[20]20s,” Single said. “It has a structural service life that’s good well beyond 2050.”

While most bombers are “very heavily engineered,” Single told Task & Purpose, the aircraft’s longevity is thanks to “both over and under-engineering,” as an Air Force Global Strike Command representative told Wired in 2016: A relatively low empty weight, low drag, expansive wingspan, and the specially engineered airframe mean maximum adaptability. The B-52 may be a big, ugly fat fucker, but it’s the most versatile airframe in the Air Force fleet, well suited for successive upgrades throughout its life.

“It was meant to withstand the [buffeting] of nuclear explosion,” Air Force Magazine editorial director John Tirpak told NPR in 2014. “There have been other attempts to replace it with other bombers, and through the years a lot of those bomber programs got canceled. It has a very long range, and it can be used for all kinds of missions, and it’s just been a very rugged, adaptable design for a long time.”

Despite frequent updates — 17 B-52s go through a tip-to-tail refurbishment and maintenance annually, and 30 aircraft have had their nuclear weapons systems removed in recent years, as part of the New START treaty — the Pentagon’s fleet is certainly showing some wear and tear after more than 60 years of service. But in 2010, the Air Force announced $11.9 billion umbrella contract with Boeing for a decade of support services, including a far-ranging modernization plan.

While the Air Force Global Strike Command directorate of logistics has been engaged in modernization efforts for the legendary bomber since the command initiated its B-52 Avionics Midlife Improvement Program in 2004, the Boeing package is both comprehensive and impressive.

The command is giving the historic bomber not just new ears and eyes, but new teeth.

Starting in 2005, Air Force Global Strike Command initiated the Combat Network Communications Technology (CONECT) program, a $40 million fleet-wide modernization of the B-52’s tactical datalink and voice communications capabilities, along with improved threat and situational awareness — the bomber’s first avionics upgrade since the 1960s.

The modern integrated communications and mission management systems don’t just give B-52s the ability to rapidly retarget weapons in flight, it brings the aircraft’s avionics into the late 20th century, finally. Until 2014, when the first B-52s upgraded with CONECT officially returned to service, this backbone of America’s Cold War strategy relied on fuzzy green screens powered by cathode-ray tubes, like your grandmom’s old television. “Even the flight controls—the yokes in the cockpit, the seats, the control surfaces on the wings and tail assembly, the cable linkages between them—are largely the same as they were when they were built in 1960 and 1961,” observed Wired.

It’s hard to overstate how significant this upgrade is. “I was an operational bomber pilot for my whole career,” Single said. “I flew both the B-52 and the B-2, and it’s a night-and-day difference between initial capabilities of the two aircraft.” Single was commander of the 393rd Bomb Squadron at Whiteman on the night the then-controversial stealth B-2 first saw combat during 1999’s Operation Allied Force in Yugoslavia.

The B-52 isn’t just behind when it comes to internal systems architecture. Single says the bomber remains the only aircraft in the Pentagon’s inventory without LINK 16, a tactical data link that connects with other aircraft and strike packages and funnels targeting data and new intelligence through the bomber’s command and control platforms, providing real-time situational awareness.

But the most exciting part of the B-52 modernization program is, naturally, on the weapons side. The DoD’s plan includes $163 million for a 1760 internal weapons bay upgrade, or IWBU, to convert the bomber’s carrying capacity. While the B-52 has been raining the advanced GPS-guided bombs that grew out of the Gulf War for more than 15 years, the upgrade will enable them to carry more “smart” bombs than ever in the internal space usually reserved for conventional “dumb” munitions.

Chart showing the conventional munitions currently in development for the B-52. DOD

The internal weapons bay upgrade focuses on the J-series munitions that are a staple of Air Force ordnance, and consists of eight Joint Direct Attack Munitions (JDAM) and assorted variants, including the laser-guided variety, on a rotary launcher; eight Joint Air-to-Surface Standoff Missiles (JASSM), including variants designed for extended range; and eight Miniature Air Launched Decoys used to confuse and disrupt enemy radar.

“The B-52 used to carry JDAM on the wing pylons, but now we can carry far more internally and get GPS data directly from the bomber itself,” Single says. “That’s huge. Right now, the B-52 carries the largest range of munitions of any platform out there. This just allows you to carry more.”

The key to the upgrade is the Conventional Rotary Launcher, which boasts “multiple types of munitions, which will allow mission planners and weaponeers to pick the perfect cocktail of weaponry for a given mission or target set,” Tyler Rogoway reported in 2015. “For instance, a B-52H assigned to close air support duties may have its CRL loaded a third full of 500lb laser JDAMs, a third full of large 1,000 JDAMs and the rest filled with deadly CBU-105 Sensor Fused Weapons.”

Additionally, the B-52’s expansive 185-foot wingspan will receive modifications to house additional JDAM and JASSM weapons packages.Overall, the upgrade will increase the B-52’s carriage capacity by some 66%, Single says. The weapons upgrades, divided into two tiers, are expected to finish by 2022.

Chart showing the timeline for the internal weapons bay upgrade’s (IWBUY) expanded smart munitions capability as part of Air Force Global Strike Command’s B-52 modernization program DOD

The weapons’ upgrades will make their way into the fleet sooner than you think. A B-52 dropped a JDAM precision-guided bomb from an internal weapons bay for the first time in July 2016 and JASSMs the next month. But while the CONECT, IBWU, and LINK 16 upgrades have clear roadmaps ahead for development and adoption, the B-52 faces another major update on the horizon: the possible replacement of its legendary engines.

For the last two years, Air Force Global Strike Command has been actively evaluating potential replacements for the B-52’s eight Pratt & Whitney TF33 turbofan engines, according to Defense News. GE, Rolls-Royce, and Pratt were vying for the contracts as recently as March.

“I think this year will be the point of some decisions on how or if the [engine] program would go forward,” Scot Oathout, Boeing’s director of bomber programs, told Defense News in February. “We’re estimating that [each substitute engine is] roughly at least 30% more efficient on the fuel, which gives us huge operational benefits.” (The Air Force loves to brag that “two B-52s, in two hours, can monitor 140,000 square miles of ocean surface.”)

The engine upgrades are still an over-the-horizon project, likely hamstrung by design and procurement constraints, but the weapons and data updates can’t come soon enough. In April 2016, a B-52H Stratofortress out of Barksdale Air Force Base landed Al Udeid Air Base, Qatar, to take part in combat operations as part of Operation Inherent Resolve, the first deployment of a B-52 in U.S. Central Command’s area of responsibility since Desert Storm in 1991.

With more than 9,000 airstrikes (and more than 65,000 bombs) dropped on jihadi targets between mid-2014 and the end of 2016, according to U.S. Central Command, the B-52 may just be the arsenal plane the multinational coalition needs to bring the pain to ISIS.

“We still rely heavily on it,” Single says. “B-52s are heavily in the fight, every day, and they will be for years to come.”