Report to the Subcommittee on 

Strategic Forces, Committee on Armed 

Services, U.S. Senate 

United States General Accounting Office 

GAO 

May 2003 MISSILE DEFENSE 

Alternate Approaches 

to Space Tracking and 

Surveillance System 

Need to Be 

Considered 

GAO-03-597 
MDA purposely adopted a strategy that would evolve STSS over time rather than 

trying to make a big leap in its capability, deferring some requirements, and 

calling for competition in the development of the sensors aboard the satellite. 

Recent decisions, however, will limit MDA’s ability to achieve its original goals 

as well as the knowledge that could be gained from its satellite demonstrations. 

Specifically: 

• MDA recently reduced its efforts to sustain competition by eliminating funds 

set aside to procure an alternative satellite sensor from a competing 

contractor. It now plans to fund only efforts to design an alternative sensor. 

If it chooses to pursue STSS as part of the missile defense system, STSS may 

end up being more expensive in the future because MDA could be locked 

into a single contractor for the design and production of the large 

constellation of satellites. 

• MDA decided to delay development and launch of new demonstrators in 

order to focus on completing development of two legacy satellites. MDA 

already knows that it would like to pursue different designs and different 

technologies for its target system given that the legacy satellites do not 

support a producible design. As a result, delaying work on the next 

generation of satellites will delay work that could offer a better basis from 

which MDA could build an operational capability. 

• MDA’s decision to launch in 2007 lacks important knowledge. MDA has 

established a launch date before it has completed its assessment of the 

working condition of the equipment it needs to assemble in order to finish 

building the two satellites it would like to launch. As a result, it does not 

know the extent of work that must be done or how much it will cost because 

the number components found to be in working or non-working order have 

not yet been identified. 

MDA has considered pursuing alternate approaches, but all are constrained by 

the need to participate in 2006-2007 missile defense tests. These approaches 

include (1) launching the legacy satellites in 2008 instead of 2007 and (2) 

stopping work on the legacy satellites and focusing instead on developing new 

demonstrators. Both of these approaches would enable MDA to inject more 

competition into the STSS program, reduce scheduling risks, and demonstrate 

more capabilities. However, they also have drawbacks; primarily, they would 

delay MDA’s ability to make informed trade-offs on missile defense sensors. 

The Department of Defense’s 

Missile Defense Agency (MDA) is 

developing a ballistic missile 

defense system designed to counter

a wide spectrum of ballistic missile 

threats. A future element of this 

system is the Space Tracking and 

Surveillance System (STSS). STSS 

will eventually be composed of a 

constellation of satellites that will 

work together to detect and track 

missiles throughout all phases of 

their flight. GAO was asked to 

analyze MDA’s approach to 

demonstrate capabilities for STSS.

To optimize MDA’s approach to 

demonstrating space-based missile 

tracking capabilities, GAO 

recommends that MDA focus 

spending to assessing what needs 

to be done to complete work on 

existing satellite components so 

that it has a reasonable basis for its 

cost and scheduling estimates. 

GAO also recommends that MDA 

assess alternatives to its current 

strategy that may offer 

opportunities to reduce risks and 

gain more knowledge. In 

commenting on a draft of this 

report, DOD partially concurred 

with two of our recommendations 

and concurred with two others. In 

its comments, DOD stated that it 

would not be prudent to delay 

launching satellites given the need 

to make overall ballistic missile 

defense system sensor 

assessments. 

www.gao.gov/cgi-bin/getrpt?GAO-03-597.

To view the full product, including the scope 

and methodology, click on the link above. 

For more information, contact Katherine 

Schinasi at (202) 512-4841 or 

SchinasiK@gao.gov. 

Highlights of GAO-03-597, a report to 

Subcommittee on Strategic Forces, 

Senate Committee on Armed Services 

May 2003

MISSILE DEFENSE 

Alternate Approaches to Space Tracking 

and Surveillance System Need to Be 

Considered 
Page i GAO-03-597 Missile Defense 

Letter 1

Results in Brief 2

Background 4

Capabilities Remain to Be Proven through Testing in Space 8

MDA’s Approach to Demonstrate STSS Capabilities 10

MDA May Not Be Able to Achieve Original Goals With Its Revised 

Strategy 16

Alternate Approaches May Garner More Knowledge 23

Conclusions 26

Recommendations for Executive Actions 26

Agency Comments and Our Evaluation 27

Scope and Methodology 29

Appendix Comments from the Department of Defense 31 

Tables 

Table 1: DOD’s Attempts to Demonstrate or Field Space-Based 

Missile Tracking Capabilities and Their Outcomes 7

Table 2: TRL Assessment for Critical Technologies for Legacy 

Satellites 15

Table 3: Work That Must Be Done on Legacy Satellites 15

Table 4: Potential Risks for the Current STSS Strategy 19

Table 5: Comparison of MDA’s Strategy and Alternatives Not 

Being Considered 24

Figure 

Figure 1: Notional Configuration of STSS and the Ballistic Missile 

Defense System 5

Contents 
Page ii GAO-03-597 Missile Defense 

Abbreviations 

AEHF Advanced Extremely High Frequency 

DOD Department of Defense 

MDA Missile Defense Agency 

MSX Midcourse Space Experiment 

SBIRS Space-Based Infrared System 

STSS Space Tracking and Surveillance System 

TRL Technology readiness level 

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Page 1 GAO-03-597 Missile Defense 

May 23, 2003 

The Honorable Wayne Allard 

Chairman 

The Honorable Bill Nelson 

Ranking Minority Member 

Strategic Forces Subcommittee 

Committee on Armed Services 

United States Senate 

The Department of Defense’s (DOD) Missile Defense Agency (MDA) is 

developing a ballistic missile defense system designed to counter a wide 

spectrum of ballistic missile threats. A future element of this system is the 

Space Tracking and Surveillance System (STSS), formerly known as 

Space-Based Infrared System-low (SBIRS-low). STSS will eventually be 

composed of a constellation of an as yet undefined number of satellites 

that will work together to detect and track missiles throughout all phases 

of their flight—from launch through midcourse and finally into reentry 

phase—and pass that information to other missile defense elements. The 

satellites will orbit earth at a low altitude, and they will carry infrared 

sensors and supporting subsystems based on sophisticated technologies. 

DOD currently expects to spend about $3.1 billion on STSS through 2009. 

DOD has initiated several programs and spent several billion dollars over 

the past 2 decades trying to develop a system to track missiles from space, 

but has not yet demonstrated certain critical capabilities. While some 

capabilities have been demonstrated through computer modeling and 

simulations, DOD believes all of the capabilities need to be proven in 

space before a large number of satellites can be acquired. 

Given the challenges associated with the program, you requested that we 

determine which capabilities still need to be demonstrated for STSS, 

analyze MDA’s approach for doing so, and identify alternative approaches 

for demonstrating the capabilities that may offer better outcomes. 

United States General Accounting Office

Washington, DC 20548 
Page 2 GAO-03-597 Missile Defense 

To be able to track missiles from space, MDA still needs to demonstrate 

that: 

• tracking information can be passed between sensors within a satellite; 

• tracking information can be passed between satellites; 

• missiles can be tracked in the midcourse phase of their flight; 

• data from two satellites at different locations and angles can be 

successfully integrated, processed, and analyzed; 

• data from the satellites can be successfully passed to other space-, air-, 

land-, and sea-based platforms; 

• satellites can operate and make some decisions autonomously; and 

• satellites can discriminate warheads from decoys. 

Achieving these capabilities is technically challenging given the difficulties 

associated with tracking cool objects against the cold background of 

space as well as the harsh space environment and the short time frames 

required to successfully identify, track, and intercept an incoming 

warhead. Yet MDA believes most of these capabilities are needed to have a 

system that can play a useful role in the overall missile defense system. 

Two capabilities—autonomous operation and discrimination—do not 

need to be demonstrated as quickly, but they would significantly enhance 

a space-based missile tracking system. 

MDA purposely adopted a strategy that would evolve STSS over time 

rather than trying to make a big leap in capability, as had been the strategy 

in the past. It deferred requirements that were too technically challenging 

or beyond its immediate missile defense mission. MDA also called for 

competition in the development and production of the sensors aboard the 

satellite that would detect a missile launch (acquisition sensor) and track a 

missile flight (tracking sensor) so that costs could be contained in the 

future and the best technical solution could be pursued. In addition, MDA 

opted to launch “demonstration” satellites before developing and 

producing them in large numbers. This strategy helps to reduce risks 

because it ensures technology is sufficiently mature and capabilities have 

been demonstrated before a greater investment is made. 

Recent decisions, however, will limit MDA’s ability to achieve its original 

goals as well as the knowledge that could be gained from its satellite 

demonstrations. 

• In order to take part in broader missile defense tests scheduled for 

2006 and 2007, MDA decided to retrieve satellites and ground 

components that were partially built in a previous effort and put into 

Results in Brief 
Page 3 GAO-03-597 Missile Defense 

storage 4 years ago, complete the assembly of this equipment, and 

launch two satellites in 2007. Using these satellites in the 2007 test will 

help MDA to make trade-off decisions among missile defense systems. 

To be able to launch both satellites in 2007, however, MDA eliminated 

its plans to have two contractors compete in the production of satellite 

acquisition sensors. Instead, the program office now plans to fund the 

separate development of an alternative sensor design, but if the funds 

available do not allow for a meaningful design effort, it will be 

canceled. By choosing this approach, overall program costs could be 

higher because MDA could be locked in to using a single contractor for 

the production of a larger constellation of satellites. 

• In order to complete the development of the legacy satellites for launch 

in 2007, MDA also decided to delay the development and launching of 

new demonstrators. While MDA could learn a great deal about missile 

tracking capabilities from the legacy satellites, MDA already knows 

that it would like to pursue different designs and different technologies 

for its target system given that the legacy satellites do not support a 

producible design. As a result, delaying work on the next generation of 

satellites will delay work that could offer a better basis from which 

MDA could build operational capability. 

• MDA’s decision to launch in 2007 was based on limited knowledge. 

MDA established a launch date before it had completed its assessment 

of the working condition of the equipment it needs to assemble in order 

to finish building the two satellites it would like to launch. As a result, 

it does not know the extent of work that must be done or how much it 

will cost. More specifically, while MDA may know the cost to test the 

satellite component hardware, it does not know how many components 

will be found in nonworking order, nor the costs to fix these 

components. Moreover, MDA has identified a number of activities that 

will pose scheduling risks, such as (1) completing development of 

software for the ground segment and the infrared sensor software and 

(2) integrating the payload hardware and software. Though MDA has 

set aside funds to cover the risks, it will not have the knowledge it 

needs to really know if it can meet its target date until early 2004—

when its assessment of the working condition of the existing 

equipment will be complete. 

MDA has considered alternative approaches, but has not pursued any that 

would not allow STSS to participate in 2006-2007 testing. Alternative 

approaches not considered include (1) launching the legacy satellites in 

2008 instead of 2007, which would allow another year to complete 

development of the legacy satellites and procure a sensor of different 
Page 4 GAO-03-597 Missile Defense 

design, and (2) stopping work on the legacy satellites and focusing instead 

on developing new technology, which would enable MDA to demonstrate 

and eventually field an operational capability sooner than its current 

approach. Both of these approaches would enable MDA to inject more 

competition into the STSS program, reduce scheduling risks, and 

demonstrate more capabilities. However, they also have drawbacks; 

primarily, they would delay MDA’s ability to make informed trade-offs 

among missile defense systems. 

We are making recommendations in this report that are intended to guide 

MDA in selecting the best approach for demonstrating missile tracking 

capabilities from space. DOD partially concurred with two of our 

recommendations and concurred with two others. In its comments, DOD 

stated that it would not be prudent to delay launching satellites given the 

need to make overall ballistic missile defense system sensor assessments. 

DOD is developing a ballistic missile defense system designed, over time, 

to counter a wide spectrum of ballistic missile threats. It will rely on space 

and ground-based systems to detect and track missiles; ground-, sea-, and 

air-based systems to intercept missiles in all stages of flight (which 

includes boost, midcourse, and reentry); and an overarching command 

and control system to plan and execute actions to counter enemy attacks. 

STSS will serve as the satellite network that will detect and track missiles 

throughout their flight and relay necessary cuing data to other elements in 

the missile defense system. The satellites will orbit the earth at low 

altitudes in order to allow for better missile viewing angles and high 

resolution.1

 Each satellite will contain two infrared sensors—one to watch 

for bright missile plumes during the boost phase (acquisition sensor) and 

one to follow the missile through midcourse and reentry (tracking sensor). 

To provide for worldwide coverage, STSS would consist of a large 

constellation of satellites (between 21 and 28) as well as a supporting 

ground infrastructure. MDA has decided that significantly fewer satellites 

could be used to provide a meaningful capability based on the 

contributions and configurations of the other elements in MDA’s ballistic 

missile defense system. However, at this time MDA has not decided on the 

number of satellites that it plans to acquire. 

 1

 The satellites will operate about 1,350 kilometers above the earth. By comparison, 

satellites in geo-synchronous orbit operate at about 36,000 kilometers. 

Background 
Page 5 GAO-03-597 Missile Defense 

Figure 1: Notional Configuration of STSS and the Ballistic Missile Defense System 

DOD has had considerable difficulty for almost 20 years in developing a 

space-based missile tracking capability. Though it has spent several billion 

dollars through a series of development and acquisition programs since 

1984, it has not launched a single satellite or demonstrated any spacebased missile tracking capabilities from space using technologies similar 

to those to be used by STSS. This is partly due to the technical challenges 

associated with building a system like STSS. For example, the satellites’ 

sensors need to be able to track missiles in the midcourse phase of their 

flight, when missiles can no longer be easily detected by their bright 

plume. To do this, detection sensors must be cooled to very low 

temperatures for very long periods of time to detect and track a cool 

warhead against the cold background of space. In addition, systems 

aboard the satellite and on the ground must send that data to other missile 

History of Problems in 

Developing a Missile 

Tracking System 
Page 6 GAO-03-597 Missile Defense 

defense systems quickly enough to allow them to target and destroy 

incoming missiles and they must work under harsh environmental 

conditions of space. This requires fast data processing and communication 

links as well as materials that can withstand radiation and cold 

temperatures. 

Within this environment of significant technical challenges, DOD has not 

yet established a program that it could execute. As we have reported2

 over 

the years, DOD and the Air Force did not relax rigid requirements to more 

closely match technical capabilities that were achievable. Program 

baselines were set based on artificial time and/or money constraints. Over 

time, it became apparent that the lack of knowledge of program challenges 

had led to overly optimistic schedules and budgets that were funded at 

less than what was needed. Attempts to stay on schedule by approving 

critical milestones without meeting program criteria resulted in higher 

costs and more slips in technology development efforts. For example, our 

1997 and 2001 reviews of DOD’s $1.7 billion SBIRS-low program, STSS’ 

immediate predecessor, showed that the program would enter the product 

development phase with critical technologies that were immature and with 

optimistic deployment schedules. In order to reduce costs, schedule, 

performance, and technical risks, we recommended that DOD restructure 

the program and analyze alternatives to satisfy critical ballistic missile 

defense requirements in case SBIRS-low could not be deployed according 

to the original acquisition strategy. DOD eventually restructured the 

SBIRS-low program because of the cost and scheduling problems, and it 

put the equipment it had partially built into storage. Table 1 further 

highlights problems affecting space-based missile tracking programs since 

1990. 

 2

U.S. General Accounting Office, Defense Acquisitions: Space-Based Infrared System-low 

at Risk of Missing Initial Deployment Date, GAO-01-6 (Washington, D.C.: Feb. 28, 2001) 

and National Missile Defense: Risk and Funding Implications for the Space-Based 

Infrared Low Component GAO/NSIAD-97-16 (Washington, D.C.: Feb. 25, 1997). 
Page 7 GAO-03-597 Missile Defense 

Table 1: DOD’s Attempts to Demonstrate or Field Space-Based Missile Tracking Capabilities and Their Outcomes 

Program 

start Program title Purpose/mission Problems Outcome 

1990 Brilliant Eyes Development program. Acquire 

and track missiles during late 

boost and midcourse phases 

and discriminate warheads from 

decoys. 

Program funding was sharply 

reduced for Brilliant Eyes and 

other space-based systems. 

The lack of funding hindered 

the program from meeting its 

objectives. 

No demonstration satellites 

launched. The Congress 

transferred the program from 

the Ballistic Missile Defense 

Organization (now MDA) to the 

Air Force in 1993. 

1993 Space and Missile 

Tracking System 

Development program. Acquire 

and track missiles and 

discriminate warheads from 

decoys during post-boost 

phases. 

Technical, funding, and 

management problems 

delayed the scheduled launch 

of two demonstration 

satellites. 

No demonstration satellites 

were launched. In 1994, DOD 

consolidated its infrared space 

requirements and selected the 

Space-Based Infrared System 

as a “system of systems” 

approach. Program was 

terminated. 

1996 Space-Based 

Infrared Systemlow 

Acquisition program. Support 

national and theater missile 

defense by tracking missiles 

over their entire flights and 

discriminating warheads from 

decoys in supporting the missile 

defense mission. 

Negative trends in cost, 

schedule, and performance 

estimates for the SBIRS-low 

program resulted in DOD 

taking it off an acquisition 

track, and returning it to a 

sustained and deliberate 

technology development 

track. 

Satellite demonstration effort 

canceled and the program 

development risk reduction 

phase restructured. Program 

subsequently transferred from 

the Air Force to MDA. 

2002 Space Tracking 

and Surveillance 

System 

Development program. Acquire, 

detect, and track ballistic 

missiles through a series of 

increasingly capable and 

interoperable satellites and 

ground infrastructure. 

Not applicable. Program has 

just begun. 

Not applicable. Program has 

just begun. 

Source: GAO. 

In October 2000, the Congress directed the Air Force to transfer the 

program to the Ballistic Missile Defense Organization (now MDA). The 

Senate Committee on Armed Services directed a study of alternatives to 

SBIRS-low as part of the fiscal year 2002 budget authorization process. 

These alternatives were to include ground-, sea-, and air-based sensors 

such as radar systems. MDA is currently expected to complete this study 

in 2003. The Committee directed that the report contain (1) an analysis of 

essential national missile defense requirements that SBIRS-low would 

fulfill and what alternative systems could also fulfill such requirements; (2) 

a quantitative assessment of national missile defense system performance 

without SBIRS-low or any alternative system; (3) a quantitative assessment 

of the national missile defense system performance with SBIRS-low and 

with each alternative system; (4) yearly cost estimates for SBIRS-low and 

of each alternative system beginning with fiscal year 2002, including all 

Congressional Actions 
Page 8 GAO-03-597 Missile Defense 

previous fiscal years and all fiscal years through deployment of a fully 

operational system; (5) a risk assessment of SBIRS-low and of each 

alternative system; and (6) a qualitative assessment of the strengths and 

weaknesses of SBIRS-low and each alternative system. 

In addition, the Congress denied the $385 million DOD requested for the 

program for fiscal year 2002, but it provided $250 million for a satellite 

sensor technology effort, of which STSS would be a part. MDA was also 

directed by the House Appropriations Committee to take STSS out of the 

acquisition process and manage it as a sustained and deliberate 

technology development effort. 

DOD believes the following capabilities are needed to have a space-based 

missile tracking system that can play a useful role in the overall missile 

defense system. These capabilities have not yet been demonstrated in 

space, although DOD has had successes in demonstrating some related onorbit capabilities through experimental satellites. 

• Acquisition-to-track hand over: 

The ability of one satellite to detect or “acquire” a missile launch and to 

transmit this data to its internal tracking sensor. The tracking sensor 

would then continue tracking the missile after the acquisition sensor 

has completed its detection function. 

• Satellite-to-satellite hand over: 

The ability of two or more low-earth orbiting satellites to pass along 

missile tracking data through two-way cross-links. This is a challenging 

capability to demonstrate given the low orbits and flight path geometry 

of the satellites. DOD has no military flight experience linking two or 

more low-earth orbiting satellites through two-way cross-links. The 

Iridium System, a private network of low orbiting satellites, can 

establish cross-links, but it does not have the timeliness and low bit 

error rate requirement of STSS. Further, only voice data (versus 

analytical data) is transmitted from one fixed user to another (in 

comparison with a moving satellite’s speed), there are ground stations 

to assist in the process, and dropped links are not mission-critical as 

they would be for STSS. DOD’s Milstar communication satellites use 

cross-links, but they operate in a much higher orbit in fixed positions 

Capabilities Remain 

to Be Proven through 

Testing in Space 
Page 9 GAO-03-597 Missile Defense 

relative to one another, so this experience also does not translate 

directly to STSS.3

• Midcourse tracking: 

The ability to (1) accurately track cool objects from thousands of 

kilometers away, which depends on sensitive sensors and accurate 

pointing capabilities, and (2) stereo tracking, which requires the 

capability to transfer and fuse data from multiple sensors in space 

while viewing the target missile from differing ranges and angles. 

Midcourse stereo tracking (two satellites reporting tracking 

information on one missile’s flight) is more desirable because it results 

in more precise information on the missile’s location. Some missile 

tracking capabilities were demonstrated during DOD’s 1996 Midcourse 

Space Experiment (MSX), which launched a satellite that collected 

data on a missile launch using optical sensors. However, this satellite 

did not conduct the same kind of functions that STSS would be 

required to perform, nor did it demonstrate all of the same 

technologies.4

• Dual mission data processing: 

The ability to process and analyze data from two satellites that view 

one event from two different angles and locations. 

• Missile defense system integration: 

The ability to transmit and fuse STSS data with data provided by other 

space-, air, land-, and sea-based sensors—including legacy and 

emerging systems belonging to DOD and U.S. allies—and to use the 

results effectively in missile defense operations. 

 3

 The Milstar satellite communications system provides secure, jam resistant, worldwide 

communications to meet essential wartime requirements for high-priority military users. 

4

 The MSX spacecraft had 5 primary sensors with a total of 11 optical sensors, precisely 

aligned so that activity of various targets can be viewed simultaneously with multiple 

sensors. Four months after its launch, MSX successfully observed and tracked a 20-minute 

ballistic missile test flight. MSX collected more than 800 seconds of high-quality data on 

this missile test. MSX tracked missiles by relying on a sensor that was cooled using a 

passive technique whereas the sensor on-board STSS is to rely on an active and mechanical 

approach. 
Page 10 GAO-03-597 Missile Defense 

There are two capabilities that DOD believes do not need to be 

demonstrated as quickly, but they would significantly enhance a spacebased missile tracking system. They are: 

• Autonomous operation: 

The ability of each satellite to operate as a self-contained unit and to 

perform some decision-making functions before downlinking the 

results. Because satellites will be moving at speeds of more than 15,000 

mph relative to one another and across different orbital planes, as well 

as moving in and out of the target missile’s range, calculations and 

decisions must be made and data passed between sensors and satellites 

within seconds. This is a desired future capability. 

• Discrimination: 

Countering more advanced and sophisticated threats will require DOD 

to be able to detect and track multiple objects and differentiate the 

threatening warhead from decoys. Given technical challenges, DOD 

deferred plans to achieve this capability for STSS. However, it plans to 

achieve this capability for the missile defense system as a whole before 

2015. 

MDA could demonstrate space-based missile tracking capabilities by 

either continuing earlier efforts or developing new satellites. At the 

beginning of the STSS program, MDA chose to combine both, focusing 

first on assembling and launching existing satellites and second on 

developing new satellites. MDA also sought to avoid the mistakes made in 

previous space-based missile tracking efforts by adopting a more flexible, 

knowledge-based development strategy and calling for competition in 

aspects of satellite development. Recently, MDA decided to launch the 

first two demonstration satellites in 2007 and launch the first next 

generation satellite in 2011. 

MDA’s Approach to 

Demonstrate STSS 

Capabilities 
Page 11 GAO-03-597 Missile Defense 

MDA could demonstrate space-based missile tracking capabilities by 

either relying on legacy satellites or developing new satellites or a 

combination of both.5

 Specifically, MDA could complete work on satellite 

and ground components that were partially built during the Air Force’s 

effort (SBIRS-low) and put into storage 4 years ago. The satellites were 

intended to serve as precursors to a constellation of operational satellites. 

The capabilities that were built into the legacy components include 

acquisition to track hand over, satellite-to-satellite hand over, stereo 

midcourse tracking, and a limited capability to discriminate the types of 

missiles launched. 

MDA could also develop more capable and more robust satellites based on 

newer technology. The satellites could be equipped with more accurate 

sensors, faster data processing capacity, and longer lasting components. 

The new satellites could also be designed to include features not available 

to the existing satellites, such as adding an autonomous operations 

capability. As with any approach, a ground segment capable of supporting 

future demonstration satellites would be needed. 

At the beginning of the STSS program, MDA decided it would pursue a 

combination of both approaches. Specifically, it would complete the 

assembly of satellite and ground components already in storage and 

launch them to coincide with broader missile defense tests that would 

take place in 2006-2007. This would allow MDA to establish a basis for 

making trade-off decisions between space-, sea-, and air-based missile 

defense sensors (for example, radar systems). MDA also decided to 

develop a newer design, including more robust technologies envisioned 

for the target system. 

 5

 MDA could supplement both approaches by incorporating knowledge from the results of 

tests of other satellites with missile tracking capabilities, though there are limitations to the 

knowledge that could be applied to STSS. These include past tests such as the 1996 MSX 

test discussed earlier and upcoming tests such as one MDA will be conducting in the near 

future with a satellite build by Spectrum Astro to collect infrared data on intercontinental 

ballistic missiles during the boost phase. Data to be collected under the contract will be 

used to verify MDA’s future selection of a kill vehicle and tracking sensors for missile 

engagements during the boost and ascent phases. The data will also build the foundation 

for developing guidance and homing algorithms for MDA’s ground-based, boost-, and 

ascent-phase interceptors. The satellite will be designed for an on-orbit lifetime of at least 1 

year, with the objective of a 2-year on-orbit life, and is planned for launch into low earth 

orbit in June 2004. 

Potential Approaches 

Available to MDA 
Page 12 GAO-03-597 Missile Defense 

At the onset of STSS, MDA adopted a more flexible product development 

approach that would maximize competition. For example: 

• As with all missile defense elements, MDA called for a strategy that 

would evolve STSS over time, rather than trying to make a big leap in 

its capability. This means that new technology would be incorporated 

into subsequent increments so that the product’s capability would 

evolve over time. Our work has shown this approach reduces risk 

because it introduces less new content and technology into a program’s 

design and development effort. An evolutionary strategy also enables 

developers to deliver a series of interim capabilities to the customer 

more quickly. 

• Under its evolutionary approach, MDA deferred requirements that were 

too technically challenging or beyond its immediate missile defense 

mission. For example, MDA deferred the requirement for a 

discrimination capability and has not decided whether the next STSS 

development block will perform discrimination. It also deferred 

requirements for STSS missions beyond missile defense, including 

technical intelligence and battlespace characterization. Instead, these 

missions would be addressed only to the extent that inherent or 

residual capabilities could satisfy them. Our work has also shown that 

programs are more successful when customers are willing to defer 

requirements that demand more time or unproven technologies to 

succeeding versions of the product. In essence, this flexibility helps to 

ensure the product can be developed within available resources.6

• MDA called for competition in the development and production of the 

sensors onboard the satellite that would detect a missile launch 

(acquisition sensor) and track a missile flight (tracking sensor) so that 

costs could be contained in the future and the best technical solution 

could be pursued. Specifically, one satellite would host sensors from 

one subcontractor and another satellite would host sensors from a 

competing subcontractor. Since contractors may use different 

materials to build the infrared sensors, different detector technologies, 

and different production methods, performance could vary 

considerably. In describing the STSS approach, the Director of MDA 

stated that injecting competition into sensor development was 

 6

 U.S. General Accounting Office, Best Practices: Better Matching of Needs and Resources 

Will Lead to Better Weapon System Outcomes GAO-01-288 (Washington, D.C.: March 8, 

2001). 

MDA Sought to Avoid Past 

Mistakes with a More 

Flexible Strategy 
Page 13 GAO-03-597 Missile Defense 

necessary to reduce risks, particularly since MDA planned to award a 

single contract to a prime contractor. 

• MDA decided to fly “demonstration” satellites before developing and 

producing them in larger numbers. This practice enables MDA to see 

how components and subsystems work together as a system in a 

realistic environment before a greater investment of procurement 

funds is made. Our work has also shown this to be a practice used by 

successful programs.7

After MDA laid the foundation for approaching STSS, it decided to 

complete development and testing of two satellites and ground station 

equipment it acquired under SBIRS-low; launch the first satellite in 2006 

and the second in 2007. Then, beginning in 2003, MDA would pursue 

development of new demonstration satellites with more robust technology 

and launch them beginning in 2010. It would launch and demonstrate a 

series of satellites until it arrived at a design that could be used to support 

a bigger constellation of satellites for the missile defense system. The Air 

Force signed a contract with Northrop Grumman in August 2002 valued at 

$868.7 million to (1) design, manufacture, and deliver the satellites and test 

and check out the satellites on orbit; (2) develop a ground system; and (3) 

conduct preliminary engineering analyses on the new demonstration 

satellites. 

In late 2002, MDA made significant changes to its strategy after it decided 

to allocate less funding to the STSS program in order to fund other missile 

defense elements. Specifically, it decided to continue the STSS program by 

integrating and testing the existing satellites, but launch them in tandem in 

2007 instead of sequentially in 2006 and 2007. Work on a single new 

satellite would begin in 2003, instead of a pair of satellites as had been 

originally planned. The program office plans to define the capabilities for 

the follow-on satellite in mid-2003 and until then, the design, technologies, 

and specifications for the new satellite will not be known. Work on the 

new satellite will be stretched out, but MDA hopes to launch the new 

satellite in 2011, only 1 year later than planned. The STSS program office 

has programmed about $1 billion to complete work, launch, and operate 

 7

 U.S. General Accounting Office, Best Practices: A More Constructive Test Approach Is 

Key to Better Weapon System Outcomes, GAO/NSIAD-00-199 (Washington, D.C.: July 31, 

2000). 

Recent Decisions on STSS 

Strategy Provide More 

Time to Learn from First 

Two Demonstration 

Satellites 
Page 14 GAO-03-597 Missile Defense 

the legacy satellites and $1.3 billion for fiscal years 2004 through 2009 for 

work on the new, follow-on satellite effort. 

This change has some benefits in that certain capabilities could be 

demonstrated over a longer on-orbit period of time. Under the original 

strategy, satellite-to-satellite hand over, midcourse tracking, and dual 

mission data processing would only have been demonstrated for about 8 

months since this would be the amount of time that the satellites would be 

fully operational together. By contrast, under the new strategy, these same 

capabilities could be demonstrated for as long as 2 years since the 

satellites will be launched in tandem. Moreover, under the previous 

strategy, only partial integration with the missile defense test bed could be 

demonstrated because data from the 2006 satellite would be processed off 

line. There could also be delays in processing data because the ground 

segment may not be fully integrated with the missile defense test bed until 

2008. (The completion of ground connectivity between the STSS ground 

station and the missile defense system does not yet have a definitive 

schedule.) Since satellites are expected to be fully operable for 2 years, 

integration could be demonstrated during the latter part of the second 

satellite’s life. But this would limit the extent to which MDA can assess 

STSS functions in the context of the overall system. 

MDA is using tools to measure the maturity of critical technologies on the 

legacy satellites. Specifically, as the table below shows, MDA has assessed 

critical technologies for the legacy satellites using technology readiness 

levels (TRL). TRLs measure maturity along a scale of one to nine. TRL 1 

characterizes the least mature technologies representing the point where 

scientific research begins to be translated into technologies basic 

properties. A TRL 9 represents the most mature, an actual application of 

the technologies in its final form under mission conditions. DOD guidance 

states that a TRL 7, which means the system has been demonstrated in an 

operational environment, is desired but that a TRL 6 represents acceptable 

risk for a space-related technology to enter product development. At a 

TRL 6, the subsystem or system has been demonstrated in a relevant 

environment. MDA expects critical technologies on the legacy satellites to 

be at a TRL 6 by June 2006. Moving from a TRL 5 to a TRL 6 to a TRL 7 

represents a significant investment. 
Page 15 GAO-03-597 Missile Defense 

Table 2: TRL Assessment for Critical Technologies for Legacy Satellites 

Technology area 

TRL at

fall 2002

Projected TRL

 at June 2006

Acquisition sensor 5 6

Tracking sensor 5 6

Single-stage cryocooler 5 6

Two-stage cryocooler 5 6

Satellite communication cross-links 6 6

On-board processor 6 6

Source: Air Force. 

Table 3 highlights the main activities that must be done to complete work 

on the legacy satellites. MDA developed a schedule to support the original 

plan to launch in 2006 and 2007. It is in the process of establishing the 

dates that these activities would need to be done by in order to support 

the new tandem launch date of 2007. 

Table 3: Work That Must Be Done on Legacy Satellites 

Area Work 

Systems engineering and assessment This includes validating specifications and configurations, establishing performance 

baselines, and assessing and integrating ground test data analyses. Work under this 

component also includes analyzing the performance of the satellites after launch. 

Sensor development This includes redesign efforts to the track sensor, along with assembly, and integration 

and test. The track sensor is on the critical path, and all work on this sensor needs to 

be completed in time to allow for integration onto the spacecraft. Under the original 

strategy, this meant the work should be done by July 2004. While work progresses on 

the sensor, software in support of the sensor will also be developed. 

Spacecraft development Efforts include developing the spacecraft test bed, harness, and software. Activities 

also include integration and test of the satellite before and after launch. Satellite 

integration and test is on the critical path and was to begin in February 2005 and be 

completed in November 2005 under the original strategy. At that time the satellite will 

be shipped for launch. 

Ground segment development Activities include designing and developing the ground systems, installing hardware in 

the ground facilities, and integrating and testing the systems. The ground segment will 

involve more software development than the other satellite segments. Also, 

operational procedures will be developed and training on ground systems is to take 

place. 

System test and operations planning This includes developing the system and flight test plans. Readiness reviews are to be 

complete by September 2005, under the original strategy. Other activities planned 

include training and rehearsals, operations crew test training, test operations, and site 

and satellite operations. 

Source: Air Force Space and Missile Systems Center. 
Page 16 GAO-03-597 Missile Defense 

MDA’s approach to STSS will limit its ability to achieve its original goals 

for the program as well as the knowledge that could be gained from its 

satellite demonstrations. 

• First, the program office decided to forego pursuing production of onboard sensors from competing contractors, as originally planned. As a 

result, MDA will not have the ability to benefit from competition. 

• Second, to stay within its budget, the STSS program office made a 

trade-off decision to develop only one new satellite rather than two and 

to delay work on the new satellite. This decision will delay MDA’s 

ability to learn about new satellite designs and technologies needed for 

an operational capability. 

• Third, MDA’s decision to launch in 2007 is not knowledge-based. At this 

point, it does not know the extent of work that needs be done on the 

legacy satellites since it has not completed its assessment of the 

condition of the components that have been in storage for 4 years. 

Moreover, it is uncertain as to whether some of the activities it does 

know it must undertake in order to integrate and test legacy satellite 

systems can be completed in time for the 2007 launch. To its credit, 

MDA has set aside extra funds for tasks that present particular 

scheduling risk. But until it knows more about the working condition 

of the satellite hardware and software, it cannot be sure of its ability to 

deliver on time. 

MDA’s decision to tentatively fund the design, but not the production, of a 

sensor from a competing contractor as part of the first effort will 

potentially increase long-term costs and risks. Specifically, it will preclude 

MDA from gaining knowledge about competing sensors and selecting the 

one that offers the best capability. Moreover, it precludes another 

contractor from gaining experience in building infrared sensors, 

potentially hampering MDA’s ability to compete work in the future and 

making the system more costly over the long term. 

We recently reported, for example, that DOD’s effort to develop a new 

generation of communication satellites (the Advanced Extremely High 

Frequency (AEHF) satellite program) incurred significant cost and 

scheduling problems partly because of its decision to consolidate 

contractors into one team. In commenting on our findings, DOD admitted 

that its major failing with the program was the acceptance of this team’s 

proposed approach of an overly optimistic performance, schedule, and 

MDA May Not Be 

Able to Achieve 

Original Goals With 

Its Revised Strategy 

Limiting Competition 

Could Increase Long-term 

Costs and Risks 
Page 17 GAO-03-597 Missile Defense 

profit baseline. Part of the reason DOD chose to limit competition was to 

launch a new satellite as soon as possible. In hindsight, it recognized that 

this worsened the situation because the contracting team could not follow 

through on its original promises, and DOD had nowhere else to turn to for 

a better solution. 

Also, under the SBIRS-low program, the Air Force awarded a contract in 

1995 for the development of two technology demonstration satellites to 

the same contractor. It later recognized the need for competition for the 

demonstration to lower costs and reduce schedule and technical risks 

because otherwise only one contractor would gain the experience and 

knowledge needed to build the full constellation of satellites. To prevent 

similar problems, in 1996, the Air Force requested offers for an alternative 

system concept from one or more contractors to demonstrate and validate 

critical design issues. The goal of this effort was to stimulate competition, 

resolve key technical and production risks, and create a plan to ensure 

SBIRS-low deployment schedules can be executed. 

The decision to launch the two existing satellites in tandem in 2007, 

instead of 2006 and 2007, will provide MDA with more time to assess the 

working condition of the satellites’ components and to complete work on 

assembling the satellites. It will also offer more time for MDA to assess 

capabilities such as satellite-to-satellite hand over since the two satellites 

will be operating as a pair for a longer period of time. However, MDA 

already knows that it would like to pursue different designs and different 

technologies for its target system as the legacy system is based on 

technologies that are more than a decade old. Its recent decision to delay 

work on a new satellite will merely delay the opportunity to learn more 

about a design that could offer a future operational capability and a better 

basis for making trade-off decisions among missile defense sensors. In 

fact, for the next few years, resources will largely be devoted to work on 

the legacy satellites versus the new satellites. In 2004, about 92 percent of 

STSS funds will go to the legacy satellites versus 8 percent to the new 

ones. 

MDA has not yet completed its assessment of the working condition of 

satellite hardware and software, so it does not know the full extent of 

work that needs to be done on the legacy satellites. Moreover, MDA 

officials recognize that through the process of testing, assembling, and 

integrating the hardware and software components, unforeseen problems 

could arise that may make it more difficult to complete the satellites in 

Delaying Work on New 

Design Will Delay Work 

Toward Operational 

Capability 

Decision to Launch in 2007 

Is Not Knowledge-Based 
Page 18 GAO-03-597 Missile Defense 

time for the 2007 launch. These problems could include completing ground 

segment software and the infrared sensor software as well as integrating 

payload hardware and software. Table 4 highlights these and other 

activities MDA believes have costs and scheduling risks. 

MDA and the STSS program office have set aside $47.2 million in funding 

to address these potential problems and also drafted risk mitigation plans, 

which are to be updated in 2003. This money will be used for independent 

review teams that can help the program office assess what work needs to 

be done as well as other resources (for example, more personnel) and 

activities (for example, contingency planning) needed to prevent 

scheduling delays. The program office has also identified the need for $26 

million in additional funding to more fully address the risks involved with 

hardware and software issues, which has been funded from the 

contractor’s management reserves. Program officials said that if the costs 

prove to be too high after the assessment of the working condition of the 

satellites, they will terminate the legacy effort and move onto the new 

demonstrators. 
Page 19 GAO-03-597 Missile Defense 

Table 4: Potential Risks for the Current STSS Strategy 

Risk Description Potential effect 

Risk mitigation 

funding 

(millions) 

1. Condition of the 

satellite hardware 

and software 

Hardware and software must be tested to 

determine their working condition after 

being in storage for 4 years. 

If hardware and software do not test as 

expected, launch delays could be 

significant, particularly for the first 

launch. 

$ 9.9 

2. Completion of the 

ground segment 

software 

The schedule to design, develop, and test 

the ground software is aggressive and 

requires these tasks to be done 

concurrently. Also, the requirements for the 

ground segment software were significantly 

increased. 

If the 31-month schedule does not play 

out, software costs could increase, and 

the ground segment might not meet 

the scheduled launches for the existing 

satellites. 

$ 5.0 

3. Uncertainty of the 

STSS Block 2006 

performance 

Integrated flight test scenarios and targets 

have not been defined or analyzed; STSS 

performance analyses are incomplete; and 

infrared sensor tests will not be completed 

for 2 more years. 

If problems surface, costs could 

increase, schedules could be delayed, 

and STSS could provide less on-orbit 

performance and utility for the ballistic 

missile defense system test bed. 

$14.1 

4. Completion of the 

infrared sensor 

software 

Software requirements are undefined and 

software interface issues could require 

software redesign. 

If the issues are not resolved, costs 

could increase, and payload testing 

and delivery could be delayed, which 

would delay the launch(es). 

$14.6 

5. Integration of the 

payload hardware 

and software 

Many integration and test activities 

conducted in serial must be successful. The 

schedule has little slack for test equipment 

or component failures. 

If this work does not proceed as 

planned, costs would increase and 

delivery of the payloads would be late, 

which could delay the launch(es). 

$ 2.9 

6. Thermal 

modifications to the 

infrared sensor 

payload 

Thermal performance and its impact on 

long-wave infrared performance will not be 

known until the sensor has been built and 

tested. 

If lower than expected thermal 

performance occurs, costs would 

increase and satellite-tracking 

capabilities would be reduced. 

$ 0.8 

Source: Air Force Space and Missile Systems Center. 

MDA will not know the extent of work needed on satellite hardware and 

software until late 2004. When the Air Force canceled the flight 

demonstration system satellites in 1999, the development of hardware and 

software was not completed, and the problem areas that had been 

identified had not been fully documented, leaving a knowledge gap that 

will need to be closed before MDA proceeds with further development. 

The legacy components have been retrieved from storage; however, they 

still need to be tested to determine their working condition. In November 

2002, testing started on the first satellite’s payload components (including 

the acquisition and tracking sensors). As part of the SBIRS-low effort, the 

tracking sensor was tested last year and found to be in working order. This 

testing should be completed in October 2003. The satellite’s spacecraft 

hardware has been visually inspected, and it will be tested from May 2003 

to September 2003. The spacecraft hardware for the second satellite has 

also been visually inspected. Under MDA’s schedule for its original 

Risk 1: Working Condition of 

Satellite Hardware and 

Software Has Not Been 

Assessed 
Page 20 GAO-03-597 Missile Defense 

strategy, testing for the second satellite was planned for September 2003 

through November 2003, and payload testing was planned for December 

2003 to August 2004. 

MDA expects that many tasks needed to design, develop, and test the 

ground software will need to be done concurrently to meet the new 

schedule. The effort will also be complicated by the fact that the 

requirements for the ground software significantly changed in 2002, at the 

time of the program restructure. Specifically, the software will need to 

support the future generation and eventual larger constellation of 

satellites, whereas the ground software associated with the legacy 

satellites was originally supposed to support two demonstration satellites. 

Program officials acknowledged that they would not have a high level of 

confidence in the software cost estimate or software schedule until the 

preliminary design review for the software occurred, which occurred in 

March 2003. 

Critical tests for assessing preflight performance will not be done and 

analyzed until MDA is close to the point where it needs to begin launch 

preparations. For example, integrated flight test scenarios and targets 

have not yet been defined or analyzed and, as originally scheduled, 

infrared sensor performance tests will not be completed until midcalendar year 2005—a few months before MDA would need to stop work 

on the satellites and begin launch preparations. Program officials pointed 

to other factors that will make preparing for performance tests difficult, 

including the fact that MDA had not yet identified interfaces with other 

missile defense elements or integrated test plans and schedules. 

Our reports have shown that pushing such testing to the latter stages of a 

development program is very risky. Specifically, it prevents programs from 

using test results to improve design. It also raises the risk that problems 

will not be discovered until a point where it becomes very costly and timeconsuming to fix them. Moreover, our reports have also shown that when 

testing occurs at latter stages, the amount of testing that is actually 

conducted is significantly less than planned.8

Considerable work needs to be done on the infrared sensors and software 

within a short period of time. Three activities are particularly critical: (1) 

completing software development for the acquisition sensor, (2) 

 8 GAO/NSIAD-00-199. 

Risk 2: Time for Completing 

Ground Segment Software May 

Be Insufficient 

Risk 3: Critical Tests for 

Assessing Whether 

Performance Is Acceptable Will 

Not Be Done Until Shortly 

Before Launch Preparations 

Risks 4, 5, and 6: Considerable 

Work Remains to Be Done on 

Infrared Sensors and Software 
Page 21 GAO-03-597 Missile Defense 

integrating payload hardware and software, and (3) modifying the tracking 

sensor to accommodate requirements for long-wave infrared performance. 

• Software development for the infrared sensors is on the critical path 

and must be completed in time to support integration and testing of the 

sensors. Software originally developed for the legacy satellites’ sensors 

was never completed, and the sensors’ software requirements are not 

completely defined, which may delay software development. According 

to the program office, the lack of time scheduled to perform early 

software testing on sensors could result in a delay in detecting and 

resolving errors. Most of the $14.6 million risk mitigation funding in 

this area has been earmarked to address the lack of early software 

testing. Also, software interface issues could require a redesign of the 

software. 

• Integration of the payload hardware and software will be complex 

because many serial integration and test activities must be successful, 

and the schedule has little slack for test equipment or component 

failures, according to the program office. 

• The tracking sensor needs additional modifications to accommodate 

long-wave infrared performance requirements. However, the impact of 

the modifications will not be known until the sensor has been built and 

tested. (The sensor was originally designed for mid-wave infrared 

performance. In the middle of the SBIRS-low program, the long-wave 

infrared requirements were imposed on the program. While 

modifications were made to meet this requirement, the sensor still 

generates more heat than the satellite coolers were designed to handle. 

As such, the sensor still needs thermal modifications to improve its 

long-wave infrared performance.) 

Since software development is a risk in many areas of the STSS program, 

MDA faces an overriding challenge in accurately predicting what work will 

need to be done in developing software related to the program. Reports 

show that this is a significant problem for many space and other weapon 

system programs—commercial and military. For example, in a series of 

studies completed in the 1990s, the Standish Group9

 found that the average 

cost overrun was 189 percent, the average schedule overrun was 222 

percent of the original estimate, and, on average, only 61 percent of the 

projects were delivered with originally specified features or functions 

 9 The CHAOS Report, the Standish Group International, Inc. (West Yarmouth, Mass.: 1995). 

Software Development 

Schedules Tend to Be 

Optimistic 
Page 22 GAO-03-597 Missile Defense 

attributable to software development. In November 2000, the Defense 

Science Board reported that the majority of problems associated with 

DOD software development programs are a result of undisciplined 

execution. The Board found that troubled programs lacked well thoughtout, disciplined program management and/or software development 

processes. Meaningful cost, schedule, and requirement baselines were also 

lacking, making it virtually impossible to track progress against them.10

We have stated in previous reports that software development schedules 

were optimistic for DOD’s AEHF satellite system and SBIRS-high program. 

For example, the Air Force originally estimated that the AEHF payload 

and spacecraft bus required approximately 257,000 lines of software code, 

but as the requirements and capabilities of the satellite system were better 

understood, the estimate grew to approximately 466,000 lines of software 

code. AEHF’s ground segment also increased from about 1.1 million lines 

of software code to nearly 1.7 million. In early 2002, during the last SBIRShigh program restructure, Air Force officials estimated that the amount of 

ground segment software had grown 48 percent, while the amount of 

space segment software had grown 28 percent. 

MDA and the prime contractor recognize that software presents a risk 

across the board for STSS. The prime contractor has decided to manage 

the work on the STSS program based on milestones that are 6 months 

earlier than the contractual satellite launch date milestones. This means 

that delays attributable to software development up to 6 months will not 

directly affect the satellite launch schedule. 

 10 Report of the Defense Science Board Task Force on Defense Software, Office of the 

Under Secretary of Defense for Acquisition and Technology (Washington, D.C.: Nov. 2000). 
Page 23 GAO-03-597 Missile Defense 

There are other approaches MDA could pursue, but they have not been 

considered because they would not allow STSS to participate in 2006-2007 

missile defense testing. These include (1) planning the launch of the legacy 

satellites for 2008 and (2) canceling work on completing the existing 

satellites and focusing solely on developing new satellites. These 

approaches would enable MDA to inject competition into the STSS 

program, reduce scheduling risks, and demonstrate more capabilities. 

Both approaches also have drawbacks, primarily, they would delay MDA’s 

ability to make informed trade-offs between STSS and other competing 

surveillance and tracking capabilities, such as ground-, sea-, and air-based 

radar systems. Table 5 compares these alternatives in terms of achieving 

capabilities to MDA’s original and current strategies. 

Alternate Approaches 

May Garner More 

Knowledge 
Page 24 GAO-03-597 Missile Defense 

Table 5: Comparison of MDA’s Strategy and Alternatives Not Being Considered 

One approach not being considered involves delaying the launch of the 

legacy satellites until 2008. This approach offers several advantages over 

the current strategy. 

• First, it would reduce program risks by allowing more time to complete 

the development and testing of satellite hardware and software that 

have been in storage for 4 years, and to complete software 

development and testing for the ground segment. 

Delaying Launches of 

Existing Satellites Could 

Reduce Scheduling Risk 

and Offer More Knowledge 
Page 25 GAO-03-597 Missile Defense 

• Second, it would allow time to complete integration of the ground 

segment with the missile defense test bed (scheduled for 2008) and 

ensure that both satellites would have enough on-orbit life remaining 

so that the satellites and ground segment could be tested together 

while fully integrated into the ballistic missile defense system test bed. 

• Third, it would allow MDA to fund both the design and production of a 

competing contractor’s acquisition sensor. This would ensure that 

competition remains viable for the development of future series of 

satellites, and it is key to MDA getting the best prices and technical 

solution. 

• Fourth, satellites launched in 2008 will likely still have some residual 

capability when the new satellite is launched in 2010, allowing them to 

interact together to provide increased knowledge. 

One drawback is a potential delay in demonstrating capabilities and 

technologies, since MDA’s current plan would begin to demonstrate some 

capability in 2007. But more importantly, this approach will delay the 

benefit of incorporating on-orbit lessons learned into the upgraded design, 

because this newer design will be well underway by the time the satellites 

are launched. Instead, MDA will have to wait for a future effort before it 

can incorporate these lessons learned. 

MDA is also not considering focusing solely on developing and 

demonstrating new satellites that can offer operational capability once a 

limited or full constellation is fielded. However, this approach could 

demonstrate most capabilities needed for an operational system with at 

least two satellites in orbit at the same time for some duration. 

Specifically, satellite-to-satellite hand over could be demonstrated since 

the new satellites would be designed to be compatible. Additionally, the 

new satellites could be fully integrated with the missile defense test bed. 

Midcourse stereo tracking and STSS mission dual data processing would 

also be demonstrated. Discrimination capability could be demonstrated, 

depending on the design selected. 

There are other benefits of pursuing the newer technologies beyond 

meeting these capabilities. The newer technology satellites would have 

increased lifetimes. In addition, the satellites’ sensors would likely be 

more sensitive and able to detect cooler targets. Software upgrades would 

continue to evolve to meet a newer generation of needs with the new 

technology satellites. Moreover, this approach would allow more time to 

test with the longer on-orbit life expected from these newer satellites. 

Focusing Solely on 

Developing New 

Demonstration Satellites 

Can Allow MDA to 

Develop More Robust 

Satellites Quicker 
Page 26 GAO-03-597 Missile Defense 

Finally, MDA could reach a decision to field an operational capability 

sooner than with any other approach. 

There are also drawbacks to this approach. There could be at least a 2-

year delay in demonstrating capability. In addition, the technology risk 

would be greater because the critical technology for the new satellites is 

less mature. For example, the TRLs for the new satellites currently range 

from 4 to 5, whereas the TRLs for the existing satellites, according to the 

Air Force, range from 5 to 6.11

Over about the last 20 years, DOD has invested billions of dollars to 

develop a missile tracking capability from space. Past efforts show that a 

heavy focus on meeting schedules can debilitate an effort to the point of 

failure. Yet DOD is at risk of repeating past mistakes because it has made 

decisions that are largely focused on meeting its 2007 launch date rather 

than making sure the satellites and ground station can work as intended 

and that it can gain the maximum knowledge at the lowest cost. Given the 

research and development nature of the program at this point, MDA has 

the ability to study and consider alternative ways of moving forward with 

the existing satellite components with greater emphasis on gaining 

knowledge from its demonstration satellites. If research and development 

is not the primary goal and operational capability is, MDA should stop its 

investment in completing the existing satellites and concentrate on 

developing new satellites. 

To better ensure the Missile Defense Agency’s approach to validate spacebased sensors and technologies for missile acquisition, tracking, and 

discrimination, we recommend that the Secretary of Defense direct the 

Director, MDA to take the following actions. 

• Focus spending on its STSS contract to assessing the working 

condition of the legacy satellites and what additional work is 

necessary to develop, test, and launch the existing satellites so that 

MDA has more knowledge on which to build cost and schedule 

estimates. 

 11 This means that for the new satellites, components are testable but do not exist in their 

final assembled configuration. For the existing satellite hardware, prototypes are available 

that are very close in their final form, fit, and function, and performance has been 

demonstrated in a relevant environment. 

Conclusions 

Recommendations for 

Executive Actions 
Page 27 GAO-03-597 Missile Defense 

• Use this assessment to conduct a broader analysis of alternative 

approaches, including the possibility of delaying launches to 2008 as 

well as dropping the development of the existing satellite components 

and focusing instead on developing demonstration satellites based on 

later generation technology. 

• Further, use this assessment to find ways to ensure that competition at 

the sensor level is part of all efforts to develop missile tracking 

capabilities. 

• If this assessment concludes that MDA should follow a different path 

for STSS, renegotiate the STSS contract to account for this change. 

We received written comments on a draft of this report from the Director 

of Defense Systems within the Office of the Under Secretary of Defense 

for Acquisition, Technology, and Logistics. DOD partially concurred with 

our first two recommendations and concurred with our third and fourth 

recommendations. In response to the first two recommendations, DOD 

noted that efforts to develop, test, and launch the legacy satellite hardware 

is well understood and on contract, and that a delay in launching the first 

STSS satellites is not prudent, given the overall missile defense sensor 

assessments that are to be made. In response to the third and fourth 

recommendations, DOD agreed that the sensor payload competition is 

central for risk mitigation and that if DOD pursued a different strategy, 

contract adjustments would be warranted. DOD also offered additional 

corrections and suggestions to clarify our draft report, which we have 

incorporated as appropriate. DOD’s comments appear in appendix I. 

In responding to our first recommendation, DOD agreed with the need to 

assess the working condition of the legacy satellite hardware, but did not 

explicitly concur with the need to focus spending on this assessment. DOD 

further commented that its efforts to develop, test, and launch the legacy 

hardware is well understood. This comment, however, is based on the 

assumption that all of the hardware will be found in working condition 

and performing within acceptable technical parameters. Our point is that 

the condition of the legacy hardware will not be known until after all of 

the hardware checks have been conducted. Because its knowledge of the 

condition of the legacy satellites is not complete, MDA’s decisions to 

develop older technology versus pursuing new technology and to launch 

legacy satellites in 2007 may not have the expected results. If key satellite 

components are found to be in unacceptable working condition, MDA may 

be forced to spend more time and money than currently estimated to 

execute its strategy. 

Agency Comments 

and Our Evaluation 
Page 28 GAO-03-597 Missile Defense 

In responding to our second recommendation, DOD asserted that it had 

already conducted a broader analysis of alternative approaches to 

development of space-based sensor support to the missile defense system. 

As noted in our report, however, this analysis did not include the 

alternative of launching legacy satellites in 2008 instead of 2007 or 

focusing solely on development of new technology. We also disagree with 

DOD’s comment that a delay in launching the first STSS satellites is not 

prudent, given the overall ballistic missile defense system sensor 

assessments that are to be made. First, MDA is striving to launch the STSS 

satellites in 2007 to support the 2007 test bed in order to allow DOD to 

make informed decisions about the composition of the missile defense 

sensor architecture. However, launching both legacy satellites in 2007 also 

has some long-term affordability consequences. For example, to be able to 

fund a launch in 2007, MDA has decided not to fund the procurement of a 

satellite sensor from a competing contractor. Instead, MDA plans to fund 

the development of an alternative sensor design from a competing 

contractor, if the funds available are sufficient for meaningful design 

work. By reducing competition, MDA may well face higher long-term costs 

to develop STSS because it may have to rely on a single contractor. 

Moreover, competition will enable MDA to pursue the best technical 

solution for STSS. Second, a primary goal of the initial STSS satellites is to 

demonstrate key capabilities that have never before been demonstrated 

from space. By adopting a strategy designed to meet the target launch 

date, however, MDA will be constrained in its ability to learn about these 

capabilities. For example, it will not be able to fully assess how well STSS 

will interact with other missile defense systems because the legacy 

systems will only be partially integrated with the missile defense test bed. 

Third, the history of the STSS program warrants a broader assessment of 

alternative investment approaches. The legacy satellites that MDA is 

relying on experienced technical and schedule difficulties as well as 

significant cost growth when they were developed under the SBIRS-low 

program, STSS’s precursor. The SBIRS-low program as a whole was also 

schedule driven, it faced technical challenges, and although almost 

$2 billion was spent on this program, not a single satellite was launched. 

The demonstration portion of the program was eventually canceled in 

1999. To avoid similar problems, we believe that MDA should examine 

approaches that offer ways to maximize competition and reduce cost and 

scheduling risks even if that means a delay in its assessment of STSS’s 

participation in the missile defense test bed. 
Page 29 GAO-03-597 Missile Defense 

To determine what capabilities DOD still needs to demonstrate in support 

of a missile tracking capability from space, we reviewed briefings of 

program goals, acquisition and test plans, management reports, and 

internal memoranda relevant to the development of STSS. Specifically, we 

reviewed the system element reviews, MDA’s Director Guidance, and the 

element capability specification, from MDA and the Air Force’s Space and 

Missile Systems Center. We also held discussions on STSS capabilities 

with officials at MDA, the Space and Missile Systems Center in Los 

Angeles, California, and Northrop-Grumman Space Technology in 

Redondo Beach, California. We also reviewed documentation from the 

Director, Operational Test and Evaluation, Office of the Secretary of 

Defense, regarding the SBIRS-low program and its risks. 

To identify and assess DOD’s prior and current approaches for 

demonstrating missile-tracking capabilities, we reviewed the STSS 

September and December 2002 System Element Reviews, program 

briefings, and the STSS contract. We also held discussions with officials at 

the Space and Missile Systems Center. In deriving the different 

approaches, we relied on program briefings and supplemented this 

information with our own institutional knowledge and experience in 

reviewing space systems. Through trial and error for estimation purposes, 

we extended launch dates, launched satellites in tandem, or both, to see 

which could result in increased knowledge to the program. Through 

briefings with officials from the Space and Missile Systems Center and our 

own assessments, we determined what the advantages and disadvantages 

would be to each approach. 

To determine the risk areas involved with the different alternatives for 

accomplishing the STSS mission, we reviewed our prior work on the STSS 

program and the STSS System Element Review and launch schedules and 

discussed with officials at the Missile Defense Agency, the Air Force Space 

and Missile Systems Center, and Northrop-Grumman Space Technology, 

the work needed to finish development and testing of the existing 

demonstration satellites. We reviewed schedule and funding information 

for developing both hardware and software for the demonstration 

satellites, to include whether components can be fully integrated, tested, 

and validated before launch. We also reviewed our prior reports and 

testimonies on practices characterizing knowledge-based acquisition 

processes. 

We performed our work from July 2002 through March 2003 in accordance 

with generally accepted government auditing standards. 

Scope and 

Methodology 
Page 30 GAO-03-597 Missile Defense 

We plan to provide copies of this report to the Chairmen and Ranking 

Minority Members of the Senate Committee on Armed Services; the Senate 

Committee on Appropriations, Subcommittee on Defense; the House 

Committee on Armed Services; and the House Committee on 

Appropriations, Subcommittee on Defense; the Secretary of Defense; and 

the Director, Missile Defense Agency. We will make copies available to 

others upon request. In addition, the report will be available at no charge 

on the GAO Web site at http://www.gao.gov/. 

If you or your staff have any questions concerning this report, please 

contact me at (202) 512-4841. Key contributors to this report were Cristina 

Chaplain, Art Gallegos, Tony Beckham, Joseph Dewechter, Dave Hubbell, 

Sigrid McGinty, Karen Sloan, Jim Solomon, Hai Tran, and Randy Zounes. 

Katherine V. Schinasi 

Director, Acquisition and Sourcing Management 
Appendix: Comments from the Department of 

Defense 

Page 31 GAO-03-597 Missile Defense 

Appendix: Comments from the Department 

of Defense 
Appendix: Comments from the Department of 

Defense 

Page 32 GAO-03-597 Missile Defense 
Appendix: Comments from the Department of 

Defense 

Page 33 GAO-03-597 Missile Defense (120156) 
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