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Updated January 24, 2023
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
layers of the Proliferated Warfighter Space Architecture
Proliferated Warfighter Space
(PWSA) and various interceptor programs. As MDA and
Architecture
SDA continue to develop these systems, Congress may
SDA developed the PWSA, formerly known as the National
consider implications for oversight and defense
Defense Space Architecture, to “unify and integrate next
authorizations and appropriations.
generation capabilities across [the Department of Defense
(DOD)] and industry.” The PWSA aims to be a “single,
Background
coherent proliferated space architecture with seven layers,”
Hypersonic weapons, like ballistic missiles, fly at speeds of
which include the data tracking and transport layers
at least Mach 5, or roughly 1 mile per second. Unlike
depicted in Figure 2 and discussed below. Other layers
ballistic missiles, hypersonic weapons do not follow a
include the custody layer to support the targeting of mobile
ballistic trajectory and can maneuver en route to their
ground assets; the battle management layer to provide
target. Russia reportedly fielded its first hypersonic
space-based command and control; the navigation layer to
weapons in December 2019, while some experts believe
provide “alternate positioning, navigation, and timing for
that China fielded hypersonic weapons as early as 2020.
potential GPS-denied environments”; the deterrence layer
The United States is not expected to field hypersonic
to detect potentially hostile actions in deep space; and the
weapons before 2023. (For an overview of hypersonic
support layer to facilitate satellite operations for the other
weapons programs in Russia, China, and the United States,
PWSA layers. Once fully fielded, the PWSA is to include
see CRS Report R45811, Hypersonic Weapons:
550 satellites and provide full global coverage.
Background and Issues for Congress, by Kelley M. Sayler.)
Tracking Layer
The maneuverability and low flight altitude of hypersonic
The tracking layer is to “provide global indications,
weapons could challenge existing detection and defense
warning, tracking, and targeting of advanced missile
systems. For example, most terrestrial-based radars cannot
threats, including hypersonic missile systems.” As part of
detect hypersonic weapons until late in the weapon’s flight
this layer, SDA is developing an architecture of Wide Field
due to line-of-sight limitations of radar detection. This
of View (WFOV) satellites, which are to eventually provide
leaves minimal time for a defender to launch interceptors
global coverage. SDA requested $81.3 million for Tranche
that could neutralize an inbound weapon. Figure 1 depicts
0 tracking activities in FY2023 and $499.8 million for
the differences in terrestrial-based radar detection timelines
Tranche 1 tracking activities (also known as Resilient
for ballistic missiles versus hypersonic weapons.
Missile Warning Missile Tracking - Low Earth Orbit).
Figure 1. Terrestrial-Based Detection of Ballistic
Working in tandem with the SDA’s tracking satellites will
Missiles vs. Hypersonic Weapons
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 $89.2 million for
HBTSS in FY2023.
Source: CRS image based on an image in “Gliding missiles that fly
Section 1682 of the FY2020 NDAA (P.L. 116-92) tasks the
faster than Mach 5 are coming,” The Economist, April 6, 2019,
director of the Missile Defense Agency to “develop a
https://www.economist.com/science-and-technology/2019/04/06/
hypersonic and ballistic missile tracking space sensor
gliding-missiles-that-fly-faster-than-mach-5-are-coming.
payload.” Section 1645 of the FY2021 NDAA (P.L. 116-
283) affirms the MDA director’s responsibility for the
U.S. defense officials have stated that both existing
development and procurement of the sensor payload—in
terrestrial- and space-based sensor architectures are
coordination with the director of SDA—“through, at
insufficient to detect and track hypersonic weapons; former
https://crsreports.congress.gov
Hypersonic Missile Defense: Issues for Congress
minimum, fiscal year 2022.” Section 1645 additionally
Lockheed Martin, Northrop Grumman, and Raytheon
requires that on-orbit testing of the sensor payload begin no
Missiles and Defense have been awarded contracts for the
later than December 31, 2023, and that integration of the
“accelerated concept design” phase of the GPI.
sensor payload into the SDA’s broader space-based sensor
architecture begin “as soon as technically feasible
In addition, Section 1664 of the FY2022 NDAA (P.L. 117-
thereafter.” Finally, Section 1662 of the FY2022 NDAA
81) grants the director of MDA “the authority to budget for,
(P.L. 117-81) prohibits the director of MDA from
direct, and manage directed energy programs applicable”
“[authorizing] or [obligating] funding for a program of
for hypersonic missile defense, while Section 1662 of the
record for the production of satellites or ground systems
FY2023 NDAA (P.L. 117-263) directs MDA to produce a
associated with the operation of such satellites.” The
strategy to use asymmetric capabilities (e.g., directed
Assistant Secretary of the Air Force for Space Acquisition
energy, microwave systems) to defeat hypersonic missile
and Integration may waive this limitation with respect to
threats. The Defense Advanced Research Projects Agency
HBTSS if certain conditions are met, including a
(DARPA) is also working on a program called Glide
determination that “that such limitation would delay the
Breaker, which is to “develop critical component
delivery of an operational [HBTSS] because of technical,
technology to support a lightweight vehicle designed for
cost, or schedule factors.”
precise engagement of hypersonic threats at very long
range.” DARPA requested $18.3 million for Glide Breaker
Figure 2. Selected Elements of the NDSA
in FY2023. Overall, MDA requested $225.5 million for
hypersonic defense in FY2023—down from its $247.9
million FY2022 request and $287.8 million appropriation.
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
Source: CRS image; not to scale.
affordability, technical feasibility, and/or utility of
hypersonic weapons defense. In addition, some analysts
Transport Layer
have argued that the United States’ current command and
SDA has stated that the PWSA’s transport layer, which is
control architecture would be incapable of “processing data
intended to connect the tracking layer to interceptors and
quickly enough to respond to and neutralize an incoming
other weapons systems on the ground, will “enhance
hypersonic threat.”
several mission areas including missile defense.” According
to DOD, SDA has awarded three prototype agreements for
Some analysts have also questioned the current division of
Tranche 1 of the transport layer, “a mesh network of 126
labor between the SDA and MDA on hypersonic missile
optically-interconnected space vehicles” that is to begin
defense. SDA director Tournear has previously responded
launching in September 2024. The transport layer is to
to criticisms of potential redundancies between the two
eventually consist of a constellation of approximately 300-
agencies, stating that both report to the Under Secretary of
500 satellites. SDA requested $816.4 million for “the data
Defense for Research and Engineering. However, as of
transport layer, sensor capabilities, and alternate position,
October 1, 2022, SDA is to instead report to the Assistant
navigation, and timing capabilities” in FY2023.
Secretary of the Air Force for Acquisition and Integration.
Congress may monitor the implications of this new
Interceptors
reporting structure for efficiency and efficacy.
MDA has explored a number of options for neutralizing
hostile hypersonic weapons, including interceptor missiles,
Potential Questions for Congress
hypervelocity projectiles, directed energy weapons, and
Is an acceleration of research on hypersonic missile
electronic attack systems. In January 2020, MDA issued a
defense options both necessary and technologically
draft request for prototype proposals for a Hypersonic
feasible? Does the technological maturity of hypersonic
Defense Regional Glide Phase Weapons System
missile defense options warrant current funding levels?
interceptor. This program was intended to “reduce
How are SDA and MDA collaborating on various
interceptor key technology and integration risks”; however,
elements of hypersonic missile defense? Are their
according to then-MDA director Vice Admiral Jon Hill, it
current roles increasing or decreasing costs and the
would not have been ready to transition into development
speed and efficiency of technology development?
until sometime in the 2030s. MDA instead shifted focus to
Does DOD have the enabling capabilities, such as
nearer-term solutions and, in April 2021, initiated the Glide
adequate command and control architectures, needed to
Phase Interceptor (GPI), which is to be integrated with the
execute hypersonic missile defense?
Aegis Weapon System and notionally provide a hypersonic
missile defense capability by the mid- to late 2020s.
Kelley M. Sayler, Analyst in Advanced Technology and
Global Security
https://crsreports.congress.gov
Hypersonic Missile Defense: Issues for Congress
IF11623
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