Top US defense contractors Northrop Grumman and Raytheon are competing to replace the outdated radar system on the B-52H Stratofortress bomber.

The B-52s are receiving a number of significant upgrades to ensure that the bombers can continue to fight well into the future.

Top defense contractors are competing to give America's longest-serving bomber a big-time upgrade to its onboard sensors to improve the aircraft's lethality in combat.

The radars on US Air Force B-52H Stratofortress bombers are old and haven't been updated since the 1980s.

To keep these decades-old aircraft fighting into the foreseeable future, the Air Force is pursuing new advanced radar systems that can unlock the full fighting capabilities of the older bombers, allowing them to eliminate ground targets, as well as take on non-traditional combat roles, such as taking out ships at sea and engaging in aerial combat.

Northrop Grumman, a major US defense contractor, is currently pushing to replace the B-52 bomber's outdated AN/APQ-166 radars with its AN/APG-83 Scalable Agile Beam Radar (SABR) as part of the B-52 Radar Modernization Program, Inside Defense reported Tuesday.

The SABR system pitched for the B-52 is the same as that being installed on Air Force F-16s. Northrop Grumman has an enhanced SABR variant for the B-1B Lancer as well.

Also in the running to provide improved radar systems for the B-52, Raytheon is pulling radar capabilities from the F-15’s APG-63(v)3 and APG-82 Active Electronically Scanned Array (AESA) radars and the APG-79 on the Super Hornets and Growlers, according to an earlier statement from the company.

The US Air Force is determined to see the 60-year-old bombers wage war for at least a century, so the heavy, long-range bombers are receiving a variety of upgrades to extend their length of service. Improvements include an upgraded weapons rack for smart munitions, new engines, and a new radar system, among other things.

Read More: US B-52 bombers are getting an upgrade that will let them drop smart bombs like never before

Northrop Grumman submitted a proposal this week to Boeing, which is handling source selection for the radar upgrades for the Air Force.

The company states its SABR system "leverages [the] proven, fifth-generation Active Electronically Scanned Array radar capabilities of the AN/APG-77 on the F-22 Raptor and the AN/APG-81 on the F-35 Lightning II."

Incorporating AESA radar capabilities into the B-52's sensor suite would be a big deal, The War Zone's Tyler Rogoway explains, noting that an advanced radar system like Northrop Grumman's SABR could improve targeting, surveillance, and situational awareness.

The upgrade would allow the bomber's six-man crew to simultaneously engage ground and naval targets in all weather conditions and at greater distances, target enemies using advanced electronic attack capabilities, and even engage in air-to-air combat if necessary.

With these enhanced capabilities and the B-52's ability to carry a large arsenal of weaponry into battle, the aircraft will be better prepared to fight in contested anti-access zones and defend friendly forces.

China and Russia, both of which are locked in military competition with the US, have been pursuing standoff capabilities to create anti-access/area-denial environments, and the US military is working hard to counter emerging challenges to American operations by developing its own standoff capabilities.

For instance, during last year's Valiant Shield exercises, B-52 bombers practiced dropping new 2,000-pound derivatives of the Quickstrike-ER (extended range) naval mine. The bombers can lay devastating mine fields from 50 miles away.

Read More: A B-52 bomber shows how it can lay a devastating minefield at sea from nearly 50 miles away in a warning to US rivals

Northrop Grumman and Raytheon are also competing to replace the AN/APG-73 radar systems on older-model F/A-18 Hornets, with Northrop offering the SABR system and Raytheon offering its APG-79, according to Inside Defense.