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Updated June 11, 2021
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
Back ground 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
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.
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
Source: CRS image; not to scale.
the large area viewable from space for improved tracking
and potentially targeting of advanced threats, including
Section 1682 of the FY2020 NDAA (P.L. 116-92) tasks the
hypersonic [weapons].”
director of the Missile Defense Agency to “develop a
hypersonic and ballistic missile tracking space sensor
Other analysts have questioned the affordability, technical
payload.” Section 1645 of the FY2021 NDAA (P.L. 116-
feasibility, and/or utility of hypersonic weapons defense. In
283) affirms the MDA director’s responsibility for the
addition, some analysts have argued that the United States’
development and procurement of the sensor payload—in
current command and control architecture would be
coordination with the director of SDA—“through, at
incapable of “processing data quickly enough to respond to
minimum, fiscal year 2022.” Section 1645 additionally
and neutralize an incoming hypersonic threat.”
requires that on-orbit testing of the sensor payload begin no
later than December 31, 2023, and that integration of the
Some analysts have questioned the current division of labor
sensor payload into the SDA’s broader space-based sensor
between the SDA and MDA on hypersonic missile defense.
architecture begin “as soon as technically feasible
SDA director Tournear has responded to criticisms of
thereafter.”
potential redundancies between the two agencies, stating
that they both report to the Under Secretary of Defense for
Transport Layer
Research and Engineering and are co-contributors to a
SDA has stated that the NDSA’s transport layer, which is
hybrid architecture.
intended to connect the tracking layer to interceptors and
other weapons systems on the ground, will “enhance
Potential Questions for Congress
several mission areas including missile defense.” SDA has
Is an acceleration of research on hypersonic missile
awarded two contracts to build a total of 20 satellites, which
defense options both necessary and technologically
are to compose the initial tranche of the transport layer.
feasible? Does the technological maturity of hypersonic
SDA intends to field this initial tranche in FY2022, adding
missile defense options warrant current funding levels?
an additional tranche every two years. SDA requested
How are SDA and MDA collaborating on various
$172.6 million for “the data transport and other capability
elements of hypersonic missile defense? Are their
layers” in FY2022.
current roles increasing or decreasing costs and the
speed and efficiency of technology development?
Interceptors
Does DOD have the enabling capabilities, such as
MDA has explored a number of options for neutralizing
adequate command and control architectures, needed to
hostile hypersonic weapons, including interceptor missiles,
execute hypersonic missile defense?
hypervelocity projectiles, laser guns, and electronic attack
systems. In January 2020, MDA issued a draft request for
Related CRS Products
prototype proposals for a Hypersonic Defense Regional
CRS In Focus IF10541, Defense Primer: Bal istic Missile Defense,
Glide Phase Weapons System interceptor. This program
by Stephen M. McCal .
was intended to “reduce interceptor key technology and
CRS Report R45811, Hypersonic Weapons: Background and
integration risks”; however, according to MDA director
Issues for Congress, by Kel ey M. Sayler.
Vice Admiral Jon Hill, it would not have been ready to
transition into development until sometime in the 2030s.
MDA instead delayed the program and, in April 2021,
Other Resources
initiated the Glide Phase Interceptor (GPI), which is to be
Department of Defense, Missile Defense Review: Executive
integrated with the Aegis Weapon System. GPI seeks to
Summary, 2019.
provide a hypersonic missile defense capability by the mid-
to late 2020s.
In addition, the Defense Advanced Research Projects
Kelley M. Sayler, Analyst in Advanced Technology and
Agency (DARPA) is working on a program called Glide
Global Security
Breaker, which “will develop critical component
Stephen M. McCall, Analyst in Military Space, Missile
technology to support a lightweight vehicle designed for
Defense, and Defense Innovation
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Hypersonic Missile Defense: Issues for Congress
IF11623
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