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Updated January 26, 2022
Hypersonic Missile Defense: Issues for Congress
The Missile Defense Agency (MDA) and Space
insufficient to detect and track hypersonic weapons; former
Development Agency (SDA) are currently developing
Under Secretary of Defense for Research and Engineering
elements of a hypersonic missile defense system to defend
Mike Griffin has noted that “hypersonic targets are 10 to 20
against hypersonic weapons and other emerging missile
times dimmer than what the U.S. normally tracks by
threats. These elements include the tracking and transport
satellites in geostationary orbit.”
layers of the National Defense Space Architecture (NDSA)
and various interceptor programs. As MDA and SDA
National Defense Space Architecture
continue to develop these systems, Congress may consider
SDA developed the National Defense Space Architecture to
implications for oversight and defense authorizations and
“unify and integrate next generation capabilities across [the
appropriations.
Department of Defense (DOD)] and industry.” The NDSA
aims to be a “single, coherent proliferated space
Background
architecture with seven layers,” which include the data
Hypersonic weapons, like ballistic missiles, fly at speeds of
tracking and transport layers depicted in Figure 2 and
at least Mach 5, or roughly 1 mile per second. Unlike
discussed below. Other layers include the custody layer to
ballistic missiles, hypersonic weapons do not follow a
support the targeting of mobile ground assets; the battle
ballistic trajectory and can maneuver en route to their
management layer to provide space-based command and
target. Russia reportedly fielded its first hypersonic
control; the navigation layer to provide “alternate
weapons in December 2019, while some experts believe
positioning, navigation, and timing for potential GPS-
that China fielded hypersonic weapons as early as 2020.
denied environments”; the deterrence layer to detect
The United States is not expected to field hypersonic
potentially hostile actions in deep space; and the support
weapons before 2023. (For an overview of hypersonic
layer to facilitate satellite operations for the other NDSA
weapons programs in Russia, China, and the United States,
layers. Once fully fielded, as is planned by 2025, the NDSA
see CRS Report R45811, Hypersonic Weapons:
would encompass 550 satellites and provide full global
Background and Issues for Congress, by Kelley M. Sayler.)
coverage.
The maneuverability and low flight altitude of hypersonic
Tracking Layer
weapons could challenge existing detection and defense
SDA began the process of building the tracking layer—
systems. For example, most terrestrial-based radars cannot
which is to “provide global indications, warning, tracking,
detect hypersonic weapons until late in the weapon’s flight
and targeting of advanced missile threats, including
due to line-of-sight limitations of radar detection. This
hypersonic missile systems”—through the Tracking
leaves minimal time for a defender to launch interceptors
Phenomenology Experiment (TPE). The TPE objective is to
that could neutralize an inbound weapon. Figure 1 depicts
develop a missile sensor algorithm capable of tracking
the differences in terrestrial-based radar detection timelines
hypersonic weapons. In parallel, SDA plans to develop
for ballistic missiles versus hypersonic weapons.
eight satellites as part of a Wide Field of View (WFOV)
architecture. SDA then intends to expand this architecture
Figure 1. Terrestrial-Based Detection of Ballistic
to provide global coverage. SDA requested $287.1 million
Missiles vs. Hypersonic Weapons
for WFOV and related capabilities in FY2022.
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
Source: CRS image based on an image in “Gliding missiles that fly
ground-based interceptor. By 2023 SDA plans to expand
faster than Mach 5 are coming,” The Economist, April 6, 2019,
the tracking layer to include 70 WFOV and MFOV
https://www.economist.com/science-and-technology/2019/04/06/
satellites, which, according to SDA director Dr. Derek
gliding-missiles-that-fly-faster-than-mach-5-are-coming.
Tournear, “will give us enough coverage in low-Earth orbit
so that we can have essentially regional persistence.” MDA
U.S. defense officials have stated that both existing
requested $256.2 million for HBTSS in FY2022.
terrestrial- and space-based sensor architectures are
https://crsreports.congress.gov
Hypersonic Missile Defense: Issues for Congress
Figure 2.Selected Elements of the NDSA
In addition, Section 1664 of the FY2022 NDAA (P.L. 117-
81) grants the director of MDA “the authority to budget for,
direct, and manage directed energy programs applicable”
for hypersonic missile defense. The Defense Advanced
Research Projects Agency (DARPA) is also working on a
program called Glide Breaker, which is to “develop critical
component technology to support a lightweight vehicle
designed for precise engagement of hypersonic threats at
very long range.” DARPA requested $7 million for Glide
Breaker in FY2022. Overall, MDA requested $247.9
million for hypersonic defense in FY2022—up from its
$206.8 million FY2021 request and down from the $272.6
million FY2021 appropriation.
Source: CRS image; not to scale.
Issues for Congress
Some analysts have suggested that space-based sensor
Section 1682 of the FY2020 NDAA (P.L. 116-92) tasks the
layers—integrated with tracking and targeting systems to
director of the Missile Defense Agency to “develop a
direct high-performance interceptors or directed energy
hypersonic and ballistic missile tracking space sensor
weapons—could theoretically present viable options for
payload.” Section 1645 of the FY2021 NDAA (P.L. 116-
defending against hypersonic weapons. The 2019 Missile
283) affirms the MDA director’s responsibility for the
Defense Review notes that “such sensors take advantage of
development and procurement of the sensor payload—in
the large area viewable from space for improved tracking
coordination with the director of SDA—“through, at
and potentially targeting of advanced threats, including
minimum, fiscal year 2022.” Section 1645 additionally
hypersonic [weapons].”
requires that on-orbit testing of the sensor payload begin no
later than December 31, 2023, and that integration of the
Other analysts have questioned the affordability, technical
sensor payload into the SDA’s broader space-based sensor
feasibility, and/or utility of hypersonic weapons defense. In
architecture begin “as soon as technically feasible
addition, some analysts have argued that the United States’
thereafter.”
current command and control architecture would be
incapable of “processing data quickly enough to respond to
Transport Layer
and neutralize an incoming hypersonic threat.”
SDA has stated that the NDSA’s transport layer, which is
intended to connect the tracking layer to interceptors and
Some analysts have questioned the current division of labor
other weapons systems on the ground, will “enhance
between the SDA and MDA on hypersonic missile defense.
several mission areas including missile defense.” SDA has
SDA director Tournear has responded to criticisms of
awarded two contracts to build a total of 20 satellites, which
potential redundancies between the two agencies, stating
are to compose the initial tranche of the transport layer.
that they both report to the Under Secretary of Defense for
SDA intends to field this initial tranche in FY2022, adding
Research and Engineering and are co-contributors to a
an additional tranche every two years. SDA requested
hybrid architecture.
$172.6 million for “the data transport and other capability
layers” in FY2022.
Potential Questions for Congress
Is an acceleration of research on hypersonic missile
Interceptors
defense options both necessary and technologically
MDA has explored a number of options for neutralizing
feasible? Does the technological maturity of hypersonic
hostile hypersonic weapons, including interceptor missiles,
missile defense options warrant current funding levels?
hypervelocity projectiles, directed energy weapons, and
How are SDA and MDA collaborating on various
electronic attack systems. In January 2020, MDA issued a
elements of hypersonic missile defense? Are their
draft request for prototype proposals for a Hypersonic
current roles increasing or decreasing costs and the
Defense Regional Glide Phase Weapons System
speed and efficiency of technology development?
interceptor. This program was intended to “reduce
Does DOD have the enabling capabilities, such as
interceptor key technology and integration risks”; however,
adequate command and control architectures, needed to
according to MDA director Vice Admiral Jon Hill, it would
execute hypersonic missile defense?
not have been ready to transition into development until
sometime in the 2030s. MDA instead shifted focus to
Other Resources
nearer-term solutions and, in April 2021, initiated the Glide
Department of Defense, Missile Defense Review: Executive
Phase Interceptor (GPI), which is to be integrated with the
Summary, 2019.
Aegis Weapon System and notionally provide a hypersonic
missile defense capability by the mid- to late 2020s.
Lockheed Martin, Northrop Grumman, and Raytheon
Missiles and Defense have been awarded contracts for the
Kelley M. Sayler, Analyst in Advanced Technology and
“accelerated concept design” phase of the GPI.
Global Security
Stephen M. McCall, Analyst in Military Space, Missile
Defense, and Defense Innovation
https://crsreports.congress.gov
Hypersonic Missile Defense: Issues for Congress
IF11623
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