Space Tracking and Surveillance System (STSS)

In December 2002, SBIRS Low Research & Development (SBIRS Low R&D) was renamed Space Tracking and Surveillance System (STSS). The Space Tracking and Surveillance System (STSS) Demonstration Satellites provide a space-based demonstration of key ballistic missile tracking capabilities, adding two space based sensors controlled and operated from the MDSEC and associated ground station processing capability to the BMDS Test Bed. MDA's STSS element is being developed in incremental, capability-based blocks designed to track enemy missiles throughout their flight. The initial increment is composed of two demonstration satellites built under the Space Based Infrared System Low program. MDA planned to launch these satellites to assess how well they work within the context of the missile defense system. MDA is also studying improvements to the STSS program, and it will be building next-generation satellites.

DOD has had considerable difficulty for a quarter of a century 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 space-based 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 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.

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.

The STSS project integrates key members of previously competing teams to focus industry's best talent on reducing technology risk for this vital capability. Under subcontract to Northrop Grumman Space Technology, Spectrum Astro will play a key role in spacecraft development; Raytheon and Northrop Grumman Electronic Systems will develop sensor payloads under competitive subcontracts. STSS will be developed using an evolutionary, capabilities-based approach. Today's hardware and software technologies will be demonstrated quickly and cost-effectively. On-orbit evaluation will identify opportunities to insert advanced technologies downstream. This approach allows the prudent use of new developments and lays the groundwork for intelligent production decisions.

STSS will build a few satellites at a time with later satellites being more capable than earlier ones. The program will be fully integrated into the nation's ballistic missile defense system architecture, contribute to MDA's ballistic missile testbed, and focus resources on highest leverage technologies. Using the advantage of a lower operational altitude, STSS will track tactical and strategic ballistic missiles. The satellite's sensors will operate across long and short-wave infrared, as well as the visible light spectrum. These wavebands allow the sensors to acquire and track missiles in midcourse as well as during the boost phase, substantially improving the performance of ballistic missile defenses.

STSS Demonstration Satellites

The STSS program was structured in two-year "blocks" with upgrades and fielding opportunities occurring throughout the blocks. STSS Block 2006 consists of two Low Earth Orbit (LEO) research and development satellites with infrared and visible sensors as test tools for MDA to track missile launches, midcourse travel, and atmospheric reentry. It uses an acquisition sensor for missile launch detection and a movable tracking sensor to follow midcourse objects in space. This program is preparing to launch in 1QFY08. The STSS Block 2006 ground segment will be located at the Joint National Integration Center (JNIC), and is designed reuse with subsequent satellites. The Block 2006 STSS system will demonstrate the ability to pass missile tracking data to Ballistic Missile Defense System interceptors with the accuracy and timeliness necessary to enable them to successfully intercept missile targets. From the data obtained from these satellites, the Missile Defense Agency will be able to make more informed decisions regarding the fielding of satellites for the operational architecture.

The STSS contract, with a value of $868.7 million, was awarded August 2002. The contract calls for completing and launching two satellites (designated Cycle 1, Flights 1 and 2) in the FY06 and FY07 time frame. The the SBIRS Low Flight Development System (FDS) spacecraft buses developed by Northrop Grumman Space Technology (formerly TRW Space & Electronics) and the FDS infrared sensor payloads developed by Raytheon are the basis for Flights 1 and 2 of Cycle 1 of the current R&D phase.

Evaluation of Cycle 1 performance will lead to recommendations for new technology insertions into satellites of following cycles and continued development of capabilities for the entire system. The Cycle 1 satellites will be integrated as part of the Ballistic Missile Defense System (BMDS) Block 2006 Test Bed. The BMDS test bed is designed to allow the assessment of the ballistic missile defense system elements alone and in concert with other assets as part of the layered missile defense architecture.

The STSS Demonstration Satellites will furnish key knowledge on which to base the design of a future constellation. The STSS Demonstration Satellites effort delivers a ground segment to the MDSEC in FY07 and launches two satellites with visible and infrared sensors into low earth orbit in FY08 for testing with other BMDS elements. These two satellites will provide valuable risk reduction for acquisition, tracking, and discrimination functionality including stereo data fusion, cueing radars over the horizon and over-the-horizon fire control. Key demonstrations will be performed showing the ability to close the global BMDS interceptor fire control loop with data from the STSS Demonstration Satellites. To provide STSS with appropriate test opportunities, MDA is procuring dedicated ballistic missile targets for on-orbit testing. The STSS-centric tests conducted with these targets will also include opportunities for secondary participation from other BMDS Elements.

STSS is contracting with National Aeronautics and Space Administration (NASA) for launch services for the two demonstration satellites using a single Delta II launch vehicle. 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.

Both satellites' acquisition and tracking sensors, which are the satellites' payloads, were delivered in 2006. However, continuing quality and workmanship problems with the first satellite's payload as well as space vehicle integration and test issues, according to MDA, caused the contractor to overrun its fiscal year 2006 budget and experience schedule delays. This and a funding reduction have caused a 5-month slip in the launch date for the demonstration satellites. As of mid-2007 the launch was scheduled for December 2007. As of January 2008 launch of the pair of satellites was scheduled for 4QFY2008.

Thermal vacuum testing is conducted to confirm that the satellite will operate according to specifications in its space environment. Testing is done to confirm the satellite will operate according to its specifications in its space environment. The first STSS space vehicle completed thermal vacuum testing in May 2007. The second of two Space Tracking and Surveillance System (STSS) demonstration satellites being built by prime contractor Northrop Grumman Corporation successfully completed thermal vacuum testing in November 2007. A key mission element demonstrated was the space vehicle's ability to detect and track a target missile.

The STSS demonstration satellites will communicate with the MDA's Ballistic Missile Defense System (BMDS) Test Bed via the Missile Defense Space Experimentation Center ground station. These demonstration STSS satellites will support the BMDS Test Bed by detecting and tracking missiles in all phases of flight. The test bed will allow the assessment of the STSS system's capabilities and its ability to operate in concert with other parts of a multi-layered missile defense architecture.

The STSS Demonstration Satellites effort is being pursued through a single prime contractor, Northrop Grumman Space Technology (NGST), with the subcontractor Raytheon providing the sensor payload. The program develops a ground station at the MDSEC and series of R&D satellites aligned to the BMDS. A contract for the first R&D spiral, the STSS Demonstration Satellites effort, was awarded in third quarter of FY02. This contract implements MDA's capability-based acquisition strategy by a) using largely existing satellite hardware as a low risk opportunity, b) building upon the lessons learned from previous development efforts and c) establishing a series of planned enhancements to bring added capability to the BMDS.

The Missile Defense Agency, supported by the National Aeronautics and Space Administration, the U.S. Air Force Space and Missile Systems Center Missile Defense Systems Group and the commercial United Launch Alliance, successfully launched two Space Tracking and Surveillance System (STSS) Demonstrator satellites from Launch Pad 17-B at Cape Canaveral Air Force Station, Fla., at approximately 8:20 A.M. September 25, 2009. The satellites were launched in tandem on a Delta II 7920-10 launch vehicle into low-Earth orbit.

In orbit the satellites will use onboard infrared sensors to detect, track and discriminate ballistic missiles throughout their trajectories for the layered Ballistic Missile Defense System (BMDS). The satellites will communicate with the BMDS via the Missile Defense Space Experimentation Center at Schriever Air Force Base, Colo., and connect to the BMDS Command, Control Battle Management and Communications (C2BMC) system. The satellites will contribute to the BMDS test bed, which will assess STSS system capabilities and its ability to operate in concert with other parts of the multi-layered missile defense architecture.

STSS is a key component in MDA's development of a space-based sensor layer to detect missile launches, provide continuous target tracking, and pass track data to missile defense interceptors with the accuracy and timeliness necessary to enable successful target interception. Each satellite is equipped with an acquisition and a tracking sensor. On-orbit sensor performance will be tested in a series of scheduled events involving ground targets, airborne targets and short and long range ballistic missile targets.

The BMDS space sensor layer will provide combatant commanders with the ability to continuously track strategic and tactical ballistic missiles from launch through termination. Early launch detection and continuous midcourse tracking of target missiles will significantly increase the engagement time and defended area of the BMDS.

STSS Future Development Program

The Future Development Program will take lessons learned from design, development and early on-orbit testing of the Demonstration Program satellites and use them to upgrade the Space Tracking and Surveillance System. By upgrading ground station and spacecraft software, this effort will improve the Demonstration Satellite experiment, reduce risk for the Space Tracking and Surveillance System Follow-on program, and improve the contingency operations capability.

STSS Follow-on Program

The Missile Defense Agency is continuing to plan for the operational constellation of Space Tracking and Surveillance System satellites to enable missile tracking. Improvements will be made in satellite lifetime, producibility, and ability to process and communicate missile tracking data to interceptors.

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. The satellites will operate about 1,350 kilometers above the earth. By comparison, satellites in geo-synchronous orbit operate at about 36,000 kilometers. 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 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, as of 2003 MDA had not decided on the number of satellites that it plans to acquire.

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, as of 2003 it planned to achieve this capability for the missile defense system as a whole before 2015.

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. Work on a single new satellite would begin in 2003, instead of a pair of satellites as had been originally planned. The program office planned 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 programmed about $1 billion to complete work, launch, and operate the legacy satellites and $1.3 billion for fiscal years 2004 through 2009 for work on the new, follow-on satellite effort. As of March 2007 delivery of the first operational STSS satellite was slipped from 2012 to the 2016-2017 timeframe, prolonging the time MDA will be without a capability to integrate the system globally.