The U.S. Air Force fiscal 2024 request of $429 million in research and development for Over-the-Horizon Backscatter radar (OTH-B) includes an add-on for the detection of stratospheric balloons and unidentified aerial phenomena.
Last year’s OTH-B appropriation was $12 million for theTactical Multi-Mission Over the Horizon Radar (TACMOR) to be based on the island of Palau to allow U.S. Indo-Pacific Command “to close gaps in surveillance coverage in key regions of the Pacific area of interest to the United States and its allies.”
Last December, California-based Gilbane Federal received a $118 million U.S. Navy contract to build reinforced concrete pads and foundations for TACMOR over the next three years on Palau.
The Air Force requests $5 million to finish TACMOR development in fiscal 2024 and $423 million for rapid prototyping of OTH-B to supplement the U.S.-Canadian North Warning System (NWS), including funds to satisfy a classified U.S. European Command requirement and $360 million to fund the first two OTH-B sites in the U.S. as prototypes.
The U.S.-based OTH-B is to have transmit and receive arrays 40 to 120 miles apart in four areas of the country–the Northeast, Northwest, Alaska and the South.
The effort “focuses on development of capability to extend current NWS surveillance to long range early warning for North America in response to emerging threats,” per the budget request. Such threats to be addressed by OTH-B are airborne as well as cruise missiles. The budget request says that OTH-B will have a “secondary and tertiary capability” against hypersonic missiles and ships.
“Funds were added in FY24 to evaluate and develop improvements to the [OTH-B] sensors tracking algorithms to increase probability of detection of high altitude air vehicles such as stratospheric balloons and other unidentified aerial phenomena,” per the budget request.
Last month, Raytheon Technologies [RTX]-built AIM-9X Sidewinder missiles fired from fighter jets took down a Chinese surveillance balloon off the coast of South Carolina on Feb. 4 and three other unidentified objects off the coast of Alaska, in the Yukon territory of Canada and over Lake Huron (Defense Daily, Feb. 16).
On OTH-B, the Air Force is to conduct modeling for each proposed radar site to gauge the interaction of High Frequency Radar with the ionosphere in order to finalize OTH-B requirements.
The system would be a redux for the Air Force, which began looking into OTH-B in 1966. General Electric [GE] began developing a prototype for the then AN/FPS-118 OTH-B in 1975, but it was not until 1990-1991 that OTH-B was ready for fielding in Moscow, Maine; Columbia Falls, Maine; Christmas Valley, Ore.; and Tule Lake, Calif. The AN/FPS-118 OTH-B was to detect threats up to 1,800 miles away by bouncing signals off the ionosphere and then off of incoming targets. When the Soviet Union disbanded in 1991, the relevance of OTH-B for detecting Soviet bombers and low-flying cruise missiles receded, and the sites were eventually dismantled.
U.S. Northern Command has submitted a fiscal 2024 unfunded priorities list (UPL), which includes $55 million to accelerate testing for OTH-B, NORTHCOM Commander Gen. Glen Van Herck told the Senate Armed Services Commitee on March 23. “Rather than fielding the capabilities in eight to 10 years, maybe we could shorten that to four to five years to enable me to get after the hypersonics, the cruise missiles, etc.,” Van Herck said in response to a question from Sen. Deb Fischer (R-Neb.). “I need Canada to do the same thing. Fielding of a capability in a decade is not where we need to be.”
The NORTHCOM UPL also includes $211 million for nine long-range mobile radars “that would help me plug the gaps when we have radar failures or to get after critical defense infrastructure, if tasked to do that,” Van Herck said.
“I can move those radars to give me additional domain awareness,” he said.