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Updated June 24, 2024
Hypersonic Missile Defense: Issues for Congress
The Missile Defense Agency (MDA) and Space
Under Secretary of Defense for Research and Engineering
Development Agency (SDA) are currently developing
Mike Griffin has noted that “hypersonic targets are 10 to 20
elements of a hypersonic missile defense system to defend
times dimmer than what the U.S. normally tracks by
against hypersonic weapons and other emerging missile
satellites in geostationary orbit.”
threats. These elements include the tracking and transport
Proliferated Warfighter Space
layers of the Proliferated Warfighter Space Architecture
Architecture
(PWSA) and various interceptor programs. As MDA and
SDA developed the PWSA, formerly known as the National
SDA continue to develop these systems, Congress may
Defense Space Architecture, to “unify and integrate next
consider implications for oversight and defense
generation capabilities across [the Department of Defense
authorizations and appropriations.
(DOD)] and industry.” According to SDA, the PWSA aims
Background
to be a “single, coherent proliferated space architecture with
seven layers,” which include the data tracking and transport
Hypersonic weapons, like ballistic missiles, fly at speeds of
layers depicted in
at least Mach 5, or roughly 1 mile per second. Unlike
ballistic missiles, hypersonic weapons do not follow a
Figure 2 and discussed below. Other layers include the
ballistic trajectory and can maneuver en route to their
custody layer to support the targeting of mobile ground
target. Russia reportedly fielded its first hypersonic
assets; the battle management layer to provide space-based
weapons in December 2019, while some experts believe
command and control; the navigation layer to provide
that China fielded hypersonic weapons as early as 2020.
“alternate positioning, navigation, and timing for potential
The United States does not have any fielded hypersonic
GPS-denied environments”; the deterrence layer to detect
weapons. (For an overview of hypersonic weapons
potentially hostile actions in deep space; and the support
programs in Russia, China, and the United States, see CRS
layer to facilitate satellite operations for the other PWSA
Report R45811, Hypersonic Weapons: Background and
layers. Once fully fielded, the PWSA is to include 550
Issues for Congress, by Kelley M. Sayler.)
satellites and provide full global coverage.
The maneuverability and low flight altitude of hypersonic
Tracking Layer
weapons could challenge existing detection and defense
SDA states that the tracking layer is to “provide global
systems. For example, most terrestrial-based radars cannot
detect hypersonic weapons until late in the weapon’s flight
indications, warning, tracking, and targeting of advanced
missile threats, including hypersonic missile systems.” As
due to line-of-sight limitations of radar detection. This
part of this layer, SDA is developing an architecture of
leaves minimal time for a defender to launch interceptors
Wide Field of View (WFOV) satellites, which are to
that could neutralize an inbound weapon. Figure 1 depicts
eventually provide global coverage. SDA requested $108.7
the differences in terrestrial-based radar detection timelines
million for Tranche 0 tracking activities in FY2025 and
for ballistic missiles versus hypersonic weapons.
$1.5 billion for Tranche 1 tracking activities (also known as
Figure 1. Terrestrial-Based Detection of Ballistic
Resilient Missile Warning Missile Tracking - Low Earth
Missiles vs. Hypersonic Weapons
Orbit).
Working in tandem with the SDA’s tracking satellites will
be the Hypersonic and Ballistic Tracking Space Sensor
(HBTSS), previously known as the Space Sensor Layer,
which is being developed by MDA in collaboration with
SDA and the U.S. Space Force. HBTSS is to provide more
sensitive, but more limited (or Medium Field of View
[MFOV]) coverage, compared to WFOV. For this reason,
WFOV is intended to provide cueing data to HBTSS, which
could then provide more specific, target quality data to a
ground-based interceptor. MDA requested $76 million for
Source: CRS image based on an image in “Gliding missiles that fly
HBTSS in FY2025.
faster than Mach 5 are coming,” The Economist, April 6, 2019,
https://www.economist.com/science-and-technology/2019/04/06/
The Space Force’s Space Systems Command (SSC) is
gliding-missiles-that-fly-faster-than-mach-5-are-coming.
developing a third set of tracking satellites called Resilient
Missile Warning Missile Tracking - Medium Earth Orbit
U.S. defense officials have stated that both existing
(MEO). According to SDA, the MEO satellites will add
terrestrial- and space-based sensor architectures are
“low-latitude coverage and track custody” and enhance
insufficient to detect and track hypersonic weapons; former
resilience in the nation’s missile defense architecture. The
https://crsreports.congress.gov
Hypersonic Missile Defense: Issues for Congress
Space Force requested $846.3 million for Resilient Missile
In addition, Section 1664 of the FY2022 NDAA (P.L. 117-
Warning Missile Tracking - MEO in FY2025.
81) grants the director of MDA “the authority to budget for,
direct, and manage directed energy programs applicable”
Section 1682 of the FY2020 NDAA (P.L. 116-92) tasks the
for hypersonic missile defense, while Section 1662 of the
director of the Missile Defense Agency to “develop a
FY2023 NDAA (P.L. 117-263) directs MDA to produce a
hypersonic and ballistic missile tracking space sensor
strategy to use asymmetric capabilities (e.g., directed
payload.” Section 1645 of the FY2021 NDAA (P.L. 116-
energy, microwave systems) to defeat hypersonic missile
283) requires that integration of the sensor payload into the
threats. The Defense Advanced Research Projects Agency
SDA’s broader space-based sensor architecture begin “as
(DARPA) is also working on a program called Glide
soon as technically feasible.” In 2022, the Space Force
Breaker, which is to “develop critical component
established a Combined Program Office to coordinate
technology to support a lightweight vehicle designed for
missile warning and tracking efforts, including SDA’s
precise engagement of hypersonic threats at very long
PWSA, MDA’s HBTSS, and SSC’s MEO satellites.
range.” DARPA requested $38 million for Glide Breaker in
FY2025. Overall, MDA requested $182 million for
Figure 2. Selected Elements of the PWSA
hypersonic defense in FY2025.
Issues for Congress
Some analysts have suggested that space-based sensor
layers—integrated with tracking and targeting systems to
direct high-performance interceptors or directed energy
weapons—could theoretically present viable options for
defending against hypersonic weapons. The 2019 Missile
Defense Review notes that “such sensors take advantage of
the large area viewable from space for improved tracking
and potentially targeting of advanced threats, including
hypersonic [weapons].” Other analysts have questioned the
affordability, technical feasibility, and/or utility of
hypersonic weapons defense. In addition, some analysts
have argued that the United States’ current command and
Source: CRS image; not to scale.
control architecture would be incapable of “processing data
Transport Layer
quickly enough to respond to and neutralize an incoming
hypersonic threat.”
SDA has stated that the PWSA’s transport layer, which is
intended to connect the tracking layer to interceptors and
Some analysts have also questioned the current division of
other weapons systems on the ground, will “enhance
labor and level of coordination between the SDA and MDA
several mission areas including missile defense.” According
on hypersonic missile defense. SDA director Tournear has
to DOD, SDA has awarded prototype agreements for
previously responded to criticisms of potential redundancies
Tranches 1 and 2 of the transport layer. The transport layer
between the two agencies, stating that both report to the
is to eventually consist of a constellation of approximately
Under Secretary of Defense for Research and Engineering.
300-500 satellites. SDA requested $1.4 billion for “the data
Since October 2022, SDA director Tournear instead reports
transport layer, sensor capabilities, and alternate position,
navigation, and timing capabilities”
to the Assistant Secretary of the Air Force for Acquisition
in FY2025.
and Integration. Also in 2022, the Space Force created the
Interceptors
combined program office overseeing missile warning and
MDA has explored options for neutralizing hostile
tracking efforts to address concerns about integration.
hypersonic weapons, including interceptor missiles,
Congress may monitor the implications of this reporting
hypervelocity projectiles, directed energy weapons, and
structure and new combined program office for efficiency
electronic attack systems. In January 2020, MDA issued a
and efficacy.
draft request for prototype proposals for a Hypersonic
Defense Regional Glide Phase Weapons System
Potential Questions for Congress
interceptor. This program was intended to “reduce
• Is an acceleration of research on hypersonic missile
interceptor key technology and integration risks.” In April
defense options both necessary and technologically
2021, MDA then shifted to the Glide Phase Interceptor
feasible? Does the technological maturity of hypersonic
(GPI), which is to be integrated with the Aegis Weapon
missile defense options warrant current funding levels?
System. Although GPI was to notionally provide a
• How are SDA, MDA, and SSC collaborating on various
hypersonic missile defense capability in FY2034, Section
elements of hypersonic missile defense? Are their
1666 of the FY2024 NDAA (P.L. 118-31) directs DOD to
current roles increasing or decreasing costs and the
achieve initial operational capability for the program by
speed and efficiency of technology development?
December 31, 2029, and full operational capability by
• Does DOD have the enabling capabilities, such as
December 31, 2032. Lockheed Martin, Northrop Grumman,
adequate command and control architectures, needed to
and Raytheon Missiles and Defense have been awarded
execute hypersonic missile defense?
contracts for the “accelerated concept design” phase of the
GPI. In May 2024, DOD signed a formal agreement with
Jennifer DiMascio, Analyst in U.S. Defense Policy
Japan to cooperatively develop GPI.
Kelley M. Sayler, Analyst in Advanced Technology and
Global Security
https://crsreports.congress.gov
Hypersonic Missile Defense: Issues for Congress
IF11623
https://crsreports.congress.gov
Hypersonic Missile Defense: Issues for Congress
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https://crsreports.congress.gov | IF11623 · VERSION 12 · UPDATED