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Updated January 13, 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 China is expected to
positioning, navigation, and timing for potential GPS-
field its first in 2020. The United States is not expected to
denied environments”; the deterrence layer to detect
field hypersonic weapons before 2023. (For an overview of
potentially hostile actions in deep space; and the support
hypersonic weapons programs in Russia, China, and the
layer to facilitate satellite operations for the other NDSA
United States, see CRS Report R45811, Hypersonic
layers. Once fully fielded, as is planned by 2025, the NDSA
Weapons: Background and Issues for Congress, by Kelley
would encompass 550 satellites and provide full global
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 $72.4 million
Missiles vs. Hypersonic Weapons
for TPE and related programs in FY2021.
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 and funded by SDA.
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.
Source: CRS image based on an image in “Gliding missiles that fly
By 2023 SDA plans to expand the tracking layer to include
faster than Mach 5 are coming,” The Economist, April 6, 2019,
70 WFOV and MFOV satellites, which, according to SDA
https://www.economist.com/science-and-technology/2019/04/06/
director Dr. Derek Tournear, “will give us enough coverage
gliding-missiles-that-fly-faster-than-mach-5-are-coming.
in low-Earth orbit so that we can have essentially regional
persistence.”
U.S. defense officials have stated that both existing
terrestrial- and space-based sensor architectures are
https://crsreports.congress.gov
Hypersonic Missile Defense: Issues for Congress
Figure 2.Selected Elements of the NDSA
FY2021—down from $10 million in FY2020. Overall,
MDA requested $206.8 million for hypersonic defense in
FY2021—up from its $157.4 million FY2020 request—and
$659 million across the FYDP.
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
Source: CRS image; not to scale.
hypersonic [weapons].”
Section 1682 of the FY2020 NDAA (P.L. 116-92) tasks the
Other analysts have questioned the affordability, technical
director of the Missile Defense Agency to “develop a
feasibility, and/or utility of hypersonic weapons defense. In
hypersonic and ballistic missile tracking space sensor
addition, some analysts have argued that the United States’
payload”; however, HBTSS was not funded in MDA’s
current command and control architecture would be
FY2021 budget request due to “competing priorities.”
incapable of “processing data quickly enough to respond to
Section 1645 of the FY2021 NDAA (P.L. 116-283) affirms
and neutralize an incoming hypersonic threat.”
the MDA director’s responsibility for the development and
procurement of the sensor payload—in coordination with
Some analysts have questioned the current division of labor
the director of SDA—“through, at minimum, fiscal year
between the SDA and MDA on hypersonic missile defense.
2022.” Section 1645 additionally requires that on-orbit
SDA director Tournear has responded to criticisms of
testing of the sensor payload begin no later than December
potential redundancies between the two agencies, stating
31, 2023, and that integration of the sensor payload into the
that they both report to the Under Secretary of Defense for
SDA’s broader space-based sensor architecture begin “as
Research and Engineering and are co-contributors to a
soon as technically feasible thereafter.” Overall, SDA
hybrid architecture.
requested $99 million in FY2021 to “develop and
demonstrate a hypersonic tracking layer by FY2023.”
Potential Questions for Congress
Is an acceleration of research on hypersonic missile
Transport Layer
defense options both necessary and technologically
SDA has stated that the NDSA’s transport layer, which is
feasible? Does the technological maturity of hypersonic
intended to connect the tracking layer to interceptors and
missile defense options warrant current funding levels?
other weapons systems on the ground, will “enhance
How are SDA and MDA collaborating on various
several mission areas including missile defense.” SDA has
elements of hypersonic missile defense? Are their
awarded two contracts to build a total of 20 satellites, which
current roles increasing or decreasing costs and the
are to compose the initial tranche of the transport layer.
speed and efficiency of technology development?
SDA intends to field this initial tranche in FY2022, adding
Does DOD have the enabling capabilities, such as
an additional tranche every two years.
adequate command and control architectures, needed to
execute hypersonic missile defense?
Interceptors
In September 2018, MDA commissioned 21 white papers to
Related CRS Products
explore hypersonic missile interceptor options including
CRS In Focus IF10541, Defense Primer: Ballistic Missile Defense,
interceptor missiles, hypervelocity projectiles, laser guns,
by Stephen M. McCall.
and electronic attack systems. In January 2020, MDA
CRS Report R45811, Hypersonic Weapons: Background and
issued a draft request for prototype proposals for a
Issues for Congress, by Kelley M. Sayler.
Hypersonic Defense Regional Glide Phase Weapons
System interceptor. This effort is intended to “reduce
interceptor key technology and integration risks, anchor
Other Resources
modeling and simulation in areas of large uncertainty, and
Department of Defense, Missile Defense Review: Executive
to increase the interceptor technology readiness levels
Summary, 2019.
(TRL) to level 5” (validating components in a relevant
environment).
In addition, Defense Advanced Research Projects Agency
Kelley M. Sayler, Analyst in Advanced Technology and
(DARPA) is working on a program called Glide Breaker,
Global Security
which “will develop critical component technology to
Stephen M. McCall, Analyst in Military Space, Missile
support a lightweight vehicle designed for precise
Defense, and Defense Innovation
engagement of hypersonic threats at very long range.”
Quintin A. Reed, Research Assistant
DARPA requested $3 million for Glide Breaker in
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Hypersonic Missile Defense: Issues for Congress
IF11623
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