Artist’s illustration of a hypersonic missile tracking satellite constellation. (Graphic by L3Harris)
WASHINGTON — A years-long tug-of-war over a key missile defense tracking program has taken another turn, as the Space Development Agency (SDA) is moving to develop its own high-precision space-based sensors for targeting adversary hypersonic missiles — instead of simply procuring sensors designed by the Missile Defense Agency (MDA) under the Hypersonic and Ballistic Tracking Space Sensor (HBTSS) program.
The question of HBTSS’s fate has been not just an interagency debate between MDA and SDA — which now falls under the Space Force — but also a long-standing fight between Congress and the Defense Department.
“China and Russia are testing offensive hypersonic capabilities and even using them in active operations. Without the HBTSS we have no ability to sense, detect, track, and engage these threats,” Rep. Doug Lamborn, R-Colo., chairman of the House Armed Service’s strategic forces subcommittee, told Breaking Defense.
“I am concerned about the transition of HBTSS from the Missile Defense Agency to the Space Development Agency. The apparent shift in strategy to deploy this capability does not reflect the urgency of the hypersonic threats we face.”
HBTSS was initiated by MDA in 2018 precisely to build the high-precision sensors needed to enable missile defense interceptors to hone in on incoming hypersonic missiles. Following the creation of SDA in March 2019, with a mission that included hypersonic missile tracking, DoD launched a campaign to transfer the sensor program to the newer office. Key lawmakers, however, have consistently blocked the effort.
Members on both sides of Capitol Hill and in both parties continue to argue that MDA must maintain controls of how the HBTSS “fire control quality” sensors are developed and technically configured, for two reasons.
First, according to several sources involved in the issue, is to ensure that development of the sensor satellites, which will carry medium field-of-view cameras, is given a high enough priority. Medium field-of-view cameras track missiles as they fly with greater precision than wide field-of-view sensors, but they can “see” less volume of space concurrently than wide field-of-view cameras that essentially have global vision.
Second, lawmakers have fretted that without MDA’s hands firmly on the steering wheel, the sensors may not be able to interface seamlessly with the agency’s developing Glide Phased Interceptors, which are supposed to receive the targeting data, as well as other missile defense systems.
“Missile defenses are only as good as what their sensors see with sufficient resolution and low enough latency to develop a fire control quality track. There’s a lot of attention to the early warning missions and lower fidelity track, but the elusive fire control requirements can’t be forgotten or relegated to “nice-to-have“ status,” said Tom Karako, a missile defense specialist at the Center for Strategic and International Studies.
“If HBTSS does indeed transfer from MDA to Space Force, it’s going to require attention to ensure it does not die in the valley of death and that missile-defense-centric requirements remain,” he added.
HBTSS: A Long and Winding Road
MDA intends to launch two HBTSS satellites late this year. The goal is to wrap up on-orbit demonstrations late in 2024 or early in 2025. MDA down-selected Northrop Grumman and L3Harris in January to complete Phase 2B of the HBTSS program, which runs through the launch of the two prototype medium field-of-view sensors. L3Harris was awarded $121 million; Northrop Grumman, $153 million.
MDA requested $109.5 million for HBTSS in its FY24 budget request, but the funds taper off over the five-year budget planning cycles — going to $76 million in FY25, and to $4 million thereafter — presumably reflecting a handoff of the program to SDA.
When MDA started the HBTSS program, the idea was that the agency would develop a constellation of HBTSS satellites in low Earth orbit (LEO) for precision tracking and targeting hypersonic missiles, which due to their ability to maneuver at very high speeds while flying low to the horizon are difficult for current missile warning satellites to keep tabs on.
As for the concept of operations, the HBTSS satellites would be cued by the Space-Based Infrared System (SBIRS) and Defense Support Satellites now performing the space-based missile warning mission — and in the future the Next-Generation Overhead Persistent Infrared System satellites. The HBTSS sensors then would track incoming hypersonic missiles in their glide phase, and hand off targeting coordinates to missile defense “shooters.”
The Trump administration, however, tried during the FY20 and FY21 budget cycles to shift responsibility for HBTSS development from MDA to SDA, for integration into SDA’s Tracking Layer constellation — which unlike today’s missile warning constellations is being optimized for keeping eyes specifically on hypersonic missiles.
In the FY20 National Defense Authorization Act, lawmakers mandated that MDA develop and procure the sensors “in coordination with” SDA, explains a May 2 brief by the Congressional Research Service [PDF]. The bill also required that on-orbit testing of the sensor payload begin no later than December 31, 2023, and that integration into SDA’s broader architecture begin “as soon as technically feasible thereafter.”
The FY22 authorization act further made clear that MDA was not to run the acquisition program, or operate the future HBTSS satellites, prohibiting the agency from slating any funds to initiate “a program of record for the production of satellites or ground systems associated with the operation of such satellites,” the CRS brief adds.
In response to questions from Breaking Defense about the current plan for HBTSS transition, an MDA spokesperson simply echoed the FY2022 policy bill, saying that responsibility for procuring and fielding HBTSS sensors would transition to SDA once the satellites built for MDA are on-orbit and have been tested.
“Following the successful demonstration of HBTSS capabilities, the responsibility for HBTSS operational fielding will be transferred to Space Force, and the MDA will continue the development of the next generation of space-based fire-control sensors for missile defense,” the spokesperson said.
Shifting Sands For Sensor Plans
But SDA’s current approach appears to be deviating, at least somewhat, from the earlier arrangement that would have seen SDA replicate the HBTSS sensors provided by MDA, according to several sources vested in the debate.
Through last year, both MDA and SDA characterized the two HBTSS satellites being built by MDA as the first in a future constellation to be “proliferated” and operated by SDA, explained one government source. Now, SDA is instead referring to the two HBTSS sensors for the first time as “prototypes” — indicating that they might not represent the operational version or even be used as part of the operational constellation, the source said.
The current concept, SDA Director Derek Tournear told the Mitchell Institute on April 5, is for SDA to launch four satellites equipped with medium field-of-view cameras for precision tracking as part of its first operational Tracking Layer constellation for missile warning/tracking, called Tranche 1. The first Tranche 1 Tracking Layer launches are currently planned for April 2025.
“On Tranche 1 when we go operational … we SDA, are going to have 35 wide field-of-view systems in operation and working, and we, SDA, are going to have four satellites that are flying medium field-of-view sensors that are essentially the HBTSS sensor, copies of those sensors,” Tournear said. “We’re gonna build four of those and fly those to demonstrate an operational system, how one would employ the wide field-of-view, taking the medium field-of-view and feeding all those data to the Transport Layer and sending that down to the to the warfighter.”
SDA’s Transport Layer is being designed as the space node of the Defense Department’s overarching Joint All Domain Command and Control (JADC2) concept for linking all military sensors to “shooters” — on land, it the air, at sea, in space and through cyberspace — to ensure rapid response in tomorrow’s light-speed conflicts.
An SDA spokesperson clarified that “SDA plans to include fire control capability in future tranches to deliver ‘birth through death’ tracking of hypersonic missiles for MDA. … The [Tranche 1] Tracking program includes a demonstration of four medium field-of-view (MFOV) satellites that use HBTSS payload designs. This demonstration is included in our other transaction agreements with Northrop Grumman and L3Harris.”
SDA in July 2022 awarded L3Harris and Northrop Grumman contracts worth a total of $1.3 billion to develop the Tranche 1 Tracking Layer satellites, with each company to build 14 satellites to be deployed in two different orbital planes. Under SDA’s current schedule, launches of those satellites would begin in April 2025. SDA is asking for a total of $1.5 billion in its FY24 request for the Tracking Layer, primarily to fund Tranche 1.
The SDA spokesperson, however, made a distinction between the sensors being developed by SDA and those under HBTSS.
“HBTSS is a prototype being developed and demonstrated by MDA; however, the data, payloads, and algorithms developed for HBTSS are already informing Space Force acquisitions. SDA will leverage lessons learned by the HBTSS program and the [Space Warfighting Analysis Center] analysis to inform competitive procurement of fire control sensors,” the spokesperson said. “HBTSS is a material solution that we are not designating as our solution. Fire control is the capability we are after.”
As as lawmakers dive into negotiations on this year’s defense policy and appropriation bills, the CRS report posited the following questions for Congress to consider:
“How are SDA and MDA collaborating on various elements of hypersonic missile defense? Are their current roles increasing or decreasing costs and the speed and efficiency of technology development?”
On HBTSS, Lamborn clearly is already seeking those answers.
