link to page 1 link to page 2 
Updated October 3, 2022
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 National Defense Space Architecture (NDSA)
National Defense Space Architecture
and various interceptor programs. As MDA and SDA
SDA developed the National Defense Space Architecture to
continue to develop these systems, Congress may consider
“unify and integrate next generation capabilities across [the
implications for oversight and defense authorizations and
Department of Defense (DOD)] and industry.” The NDSA
appropriations.
aims to be a “single, coherent proliferated space
architecture with seven layers,” which include the data
Background
tracking and transport layers depicted in Figure 2 and
Hypersonic weapons, like ballistic missiles, fly at speeds of
discussed below. Other layers include the custody layer to
at least Mach 5, or roughly 1 mile per second. Unlike
support the targeting of mobile ground assets; the battle
ballistic missiles, hypersonic weapons do not follow a
management layer to provide space-based command and
ballistic trajectory and can maneuver en route to their
control; the navigation layer to provide “alternate
target. Russia reportedly fielded its first hypersonic
positioning, navigation, and timing for potential GPS-
weapons in December 2019, while some experts believe
denied environments”; the deterrence layer to detect
that China fielded hypersonic weapons as early as 2020.
potentially hostile actions in deep space; and the support
The United States is not expected to field hypersonic
layer to facilitate satellite operations for the other NDSA
weapons before 2023. (For an overview of hypersonic
layers. Once fully fielded, the NDSA is to include 550
weapons programs in Russia, China, and the United States,
satellites and provide full global coverage.
see CRS Report R45811, Hypersonic Weapons:
Background and Issues for Congress, by Kelley M. Sayler.)
Tracking Layer
The tracking layer is to “provide global indications,
The maneuverability and low flight altitude of hypersonic
warning, tracking, and targeting of advanced missile
weapons could challenge existing detection and defense
threats, including hypersonic missile systems.” As part of
systems. For example, most terrestrial-based radars cannot
this layer, SDA is developing an architecture of Wide Field
detect hypersonic weapons until late in the weapon’s flight
of View (WFOV) satellites, which are to eventually provide
due to line-of-sight limitations of radar detection. This
global coverage. SDA requested $81.3 million for Tranche
leaves minimal time for a defender to launch interceptors
0 tracking activities in FY2023 and $499.8 million for
that could neutralize an inbound weapon. Figure 1 depicts
Tranche 1 tracking activities (also known as Resilient
the differences in terrestrial-based radar detection timelines
Missile Warning Missile Tracking - Low Earth Orbit).
for ballistic missiles versus hypersonic weapons.
Working in tandem with the SDA’s tracking satellites will
Figure 1. Terrestrial-Based Detection of Ballistic
be the Hypersonic and Ballistic Tracking Space Sensor
Missiles vs. Hypersonic Weapons
(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. By 2023, SDA plans to expand
the tracking layer to include 70 WFOV and MFOV
satellites, which, according to SDA director Dr. Derek
Tournear, “will give us enough coverage in low-Earth orbit
Source: CRS image based on an image in “Gliding missiles that fly
so that we can have essentially regional persistence.” MDA
faster than Mach 5 are coming,” The Economist, April 6, 2019,
requested $89.2 million for HBTSS in FY2023.
https://www.economist.com/science-and-technology/2019/04/06/
gliding-missiles-that-fly-faster-than-mach-5-are-coming.
Section 1682 of the FY2020 NDAA (P.L. 116-92) tasks the
director of the Missile Defense Agency to “develop a
U.S. defense officials have stated that both existing
hypersonic and ballistic missile tracking space sensor
terrestrial- and space-based sensor architectures are
insufficient to detect and track hypersonic weapons; former
https://crsreports.congress.gov
Hypersonic Missile Defense: Issues for Congress
payload.” Section 1645 of the FY2021 NDAA (P.L. 116-
until sometime in the 2030s. MDA instead shifted focus to
283 ) affirms the MDA director’s responsibility for the
nearer-term solutions and, in April 2021, initiated the Glide
Phase Interceptor (GPI), which is to be integrated with the
Figure 2. Selected Elements of the NDSA
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
“accelerated concept design” phase of the GPI.
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
Source: CRS image; not to scale.
very long range.” DARPA requested $18.3 million for
Glide Breaker in FY2023. Overall, MDA requested $225.5
development and procurement of the sensor payload—in
million for hypersonic defense in FY2023—down from its
coordination with the director of SDA—“through, at
$247.9 million FY2022 request and $287.8 million
minimum, fiscal year 2022.” Section 1645 additionally
appropriation.
requires that on-orbit testing of the sensor payload begin no
later than December 31, 2023, and that integration of the
Issues for Congress
sensor payload into the SDA’s broader space-based sensor
Some analysts have suggested that space-based sensor
architecture begin “as soon as technically feasible
layers—integrated with tracking and targeting systems to
thereafter.” Finally, Section 1662 of the FY2022 NDAA
direct high-performance interceptors or directed energy
(P.L. 117-81) prohibits the director of MDA from
weapons—could theoretically present viable options for
“[authorizing] or [obligating] funding for a program of
defending against hypersonic weapons. The 2019 Missile
record for the production of satellites or ground systems
Defense Review notes that “such sensors take advantage of
associated with the operation of such satellites.” The
the large area viewable from space for improved tracking
Assistant Secretary of the Air Force for Space Acquisition
and potentially targeting of advanced threats, including
and Integration may waive this limitation with respect to
hypersonic [weapons].” Other analysts have questioned the
HBTSS if certain conditions are met, including a
affordability, technical feasibility, and/or utility of
determination that “that such limitation would delay the
hypersonic weapons defense. In addition, some analysts
delivery of an operational [HBTSS] because of technical,
have argued that the United States’ current command and
cost, or schedule factors.”
control architecture would be incapable of “processing data
quickly enough to respond to and neutralize an incoming
Transport Layer
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 also questioned the current division of
other weapons systems on the ground, will “enhance
labor between the SDA and MDA on hypersonic missile
several mission areas including missile defense.” According
defense. SDA director Tournear has previously responded
to DOD, SDA has awarded three prototype agreements for
to criticisms of potential redundancies between the two
Tranche 1 of the transport layer, “a mesh network of 126
agencies, stating that both report to the Under Secretary of
optically-interconnected space vehicles” that is to begin
Defense for Research and Engineering. However, as of
launching in September 2024. The transport layer is to
October 1, 2022, SDA is to instead report to the Assistant
eventually consist of a constellation of approximately 300-
Secretary of the Air Force for Acquisition and Integration.
500 satellites. SDA requested $816.4 million for “the data
Congress may monitor the implications of this new
transport layer, sensor capabilities, and alternate position,
reporting structure for efficiency and efficacy.
navigation, and timing capabilities” in FY2023.
Potential Questions for Congress
Interceptors
Is an acceleration of research on hypersonic missile
MDA has explored a number of options for neutralizing
defense options both necessary and technologically
hostile hypersonic weapons, including interceptor missiles,
feasible? Does the technological maturity of hypersonic
hypervelocity projectiles, directed energy weapons, and
missile defense options warrant current funding levels?
electronic attack systems. In January 2020, MDA issued a
How are SDA and MDA collaborating on various
draft request for prototype proposals for a Hypersonic
elements of hypersonic missile defense? Are their
Defense Regional Glide Phase Weapons System
current roles increasing or decreasing costs and the
interceptor. This program was intended to “reduce
speed and efficiency of technology development?
interceptor key technology and integration risks”; however,
Does DOD have the enabling capabilities, such as
according to then-MDA director Vice Admiral Jon Hill, it
adequate command and control architectures, needed to
would not have been ready to transition into development
execute hypersonic missile defense?
https://crsreports.congress.gov
Hypersonic Missile Defense: Issues for Congress
IF11623
Kelley M. Sayler, Analyst in Advanced Technology and
Global Security
Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan shared staff to
congressional committees and Members of Congress. It operates solely at the behest of and under the direction of Congress.
Information in a CRS Report should not be relied upon for purposes other than public understanding of information that has
been provided by CRS to Members of Congress in connection with CRS’s institutional role. CRS Reports, as a work of the
United States Government, are not subject to copyright protection in the United States. Any CRS Report may be
reproduced and distributed in its entirety without permission from CRS. However, as a CRS Report may include
copyrighted images or material from a third party, you may need to obtain the permission of the copyright holder if you
wish to copy or otherwise use copyrighted material.
https://crsreports.congress.gov | IF11623 · VERSION 6 · UPDATED