Seeking More Help from Above

Next-Generation Space-Based Sensors
Eyed to Support Earlier and Additional
Missile Intercept Opportunities.

by Peter Buxbaum, MSMF Correspondent

There were more than 120 foreign ballistic missile launches around the world in 2007, considerably more than in previous years, Air Force Lieutenant General Henry A. Obering III, director, Missile Defense Agency (MDA), told Congress in April. And the global missile landscape is becoming increasingly complex.

Thirty nations around the world have deployed a ballistic missile capability, compared to only eight in 1972, an MDA report released earlier this year stated. North Korea and Iran have both demonstrated complex missile operations capabilities and are capable of attacking U.S. forces in Asia and the Middle East with short- and medium-range ballistic missiles. Other nations, such as Syria and Pakistan, are expanding the number and range of their missiles.

All of this makes the missile defense mission of the U.S. military more critical even than during the Cold War. Then, the focus was on the strategic threat posed by Soviet intercontinental ballistic missiles. That threat has since expanded to short- and mid-range ballistic missiles in the hands of many nations.

The MDA is seeking to field a Ballistic Missile Defense System (BMDS) that includes a set of complementary interceptors, land-, sea- air- and space-based sensors, and a battle management command and control system, in order “to engage all classes and ranges of ballistic missile threats,” according to an agency mission statement.

Before hostile missiles can be engaged, they must be sniffed out. To that end, the MDA and the armed services are deploying a range of ground-, sea- and space-based sensor systems. Ground-based radar systems and the Navy’s Aegis program form part of the first two elements in that architecture.

SPACE-BASED SYSTEMS

Space sensors already play a role in global missile defense by detecting the infrared signature emitted by missile launch exhaust systems. A legacy satellite system managed by the Air Force called the Defense Support Program (DSP) has been performing that function for over three decades. DSP added the last of its 23 satellites to its constellation last year, and will continue to operate until the capabilities of its follow-on program, the Space Based Infrared Systems (SBIRS), also managed by the Air Force, become operational. Still other enhanced infrared detection capabilities are being developed within the MDA’s Space Tracking and Surveillance System (STSS), which was split off from the original SBIRS program.

The ultimate vision is for space-based sensors to provide the continuous tracking of ballistic missiles, provide coverage in locations inaccessible to BMDS radars, and to pass tracking information to MDA’s battle management system and to BMDS interceptors. More accurate tracking data would allow additional and earlier missile intercept opportunities.

“DSP is a legacy program that has been operating since the 1970s,” explained Colonel Scott Larrimore, commander, SBIRS Space Group, Los Angeles Air Force Base’s Space and Missile Systems Center. “It just passed its 38th year of operation. The last of the DSP line of satellites was launched in 2007. SBIRS will be picking up the operational continuum for that mission, to carry it into the future.”

SBIRS capabilities include two sensor payloads aboard host spacecraft already deployed in high elliptical orbit (HEO) and providing polar coverage. These HEO payloads will be complemented by four geosynchronous (GEO) satellites that will complete the SBIRS constellation. The first GEO launch is planned for December 2009.

Another infrared tracking capability, currently in the experimental phase is the Space Track and Surveillance Satellites (STSS). Originally part of the “SBIRS–Low” program, STSS is run by the MDA.

The STSS contemplates the launch of two low-earth orbit research and demonstration satellites with infrared and visual sensors to track missile launches, midcourse travel, and atmospheric reentry. Each satellite would use an infrared sensor for missile launch detection and a movable tracking sensor to follow objects in space. The STSS experimental satellites intend to demonstrate additional capabilities for identifying missile launches and tracking their trajectories, thus providing shooters with additional views and options for interception.

“SBIRS used to have broader profile, with both low-earth and high-earth orbit satellites,” explained Colonel John G. Mueller, vice commander, Space Based Infrared Systems Wing, Los Angeles Air Force Base. “The high-orbit satellite is supposed to function essentially as a bell ringer to indicate that something is being launched. Then the low-orbit satellite would track the rocket as it was burning out and became progressively colder. Tracking would later be taken over by ground-based radar systems.”

STSS was split off from SBIRS for programmatic and administrative reasons, Mueller added. This move did not alter SBIRS requirements.

Both DSP and SBIRS support fourmission areas, Mueller explained:

•      Warning, to provide faster and more accurate reporting on theater and strategic missile launches;
  
•      Defense, supporting operation of missile defense systems against missile threats;
  
•      Intelligence, by gathering data on infrared signatures to enable rapid identification of events; and
  
•      Battlespace awareness, supplying infrared data to characterize battlespace conditions, supporting force protection, strike planning and other missions.

SBIRS involves a partnership between the U.S. Air Force and an industry team led by prime contractor Lockheed Martin. Lockheed is providing the space vehicle and all support and ground systems. Its principle subcontractor, Northrop Grumman, is providing the payload and sensor packages. The first phase of SBIRS, which involved replacement and consolidation of four legacy ground stations with a single mission control station (MCS) and backup, and new relay ground stations, has already been completed.

The second phase includes the two HEO sensor payloads and the four GEO satellites. “The HEO payloads require one final checkout before going into operational use,” said Mueller. “HEO is expected to go operational early in calendar year 2009. The first SBIRS GEO satellite is expected to go online in calendar year 2010 after a check-out period.”

SBIRS sensors are designed to identify when a launch occurs, by detecting and tracking the infrared radiation from the missile’s hot exhaust. Onboard satellite systems process and transmit the data to relay ground stations, located around the globe, which in turn forward the data to the MCS for further processing. MCS software generates launch reports by fusing data from multiple satellites that include missile type, launch point, and predicted impact point. Air Force Space Command operators then review these reports and release them to strategic and tactical users around the world. “Raw unprocessed data from SBIRS GEO and HEO sensors will be down-linked to the ground,” explained Larrimore, “so that the same radiometric scene observed in space will be available on the ground.”

SBIRS capabilities represent a generational step forward over DSP, according to Larrimore. “SBIRS will provide greater sensor flexibility and sensitivity compared to the DSP satellites,” he said. “Sensors detect short-wave and expanded mid-wave infrared allowing it to perform a broader set of missions.

“The DSP sensor is just a linear strip that is able to detect a hot spot as it scans the earth,” he added. “SBIRS is leveraging developments in microelectronics technology in the last couple of decades. Sensors have been getting larger, which makes them more sensitive and also provides more capabilities at less cost. SBIRS sensors provide a refresh rate approximately five times the rate of DSP.”

The SBIRS GEO spacecraft will be equipped with both a scanning sensor and a staring sensor. “The scanning capability allows us to take in a wide geographical area,” Larrimore explained, “while the staring sensor is a special capability that will allow us to focus on specific geographic areas to support battlespace awareness for a theater area.”

The GEO staring sensor will have high agility to rapidly stare at one earth location and then step to other locations, with improved sensitivity compared to DSP. “Several areas can be monitored by the staring sensor with revisit times significantly smaller than that of DSP,” said Larrimore. “A continuous staring mode will also provide an even smaller revisit time.” The SBIRS HEO sensor also has scanning capabilities.

The SBIRS program requested $530 million for fiscal year (FY) 2009 to finish development of the second GEO satellite, as well as $1.7 billion for spacecraft procurement, according to Mueller, in addition to smaller amounts for maintenance and operations. He anticipates requests for finding of satellite acquisitions to build out the four-satellite GEO constellation through FY 2011.

STSS is still in an experimental phase while it works out its bugs. Like SBIRS, STSS also represents a next-generation capability to a currently deployed asset.

The Near Field Infrared Experiment (NFIRE) satellite was launched in April 2007, and has since been collecting signature data on boosting ballistic missiles at close range. The data collected by NFIRE will contribute to the design of future interceptor hardware, software and algorithm development, according to the MDA.

But NFIRE’s capabilities are “relatively crude,” said Colonel J.P. Morgan, STSS program manager. “NFIRE does what it was specifically designed to do very well, which is to track missiles in a manner that drives target acquisition,” he said. “Both NFIRE and STSS are designed to detect and target launches near the satellite vehicle itself.”

But STSS boasts more sophisticated technology, Morgan added, with a gimbaled telescope that better tracks targets and two satellites that are able to hand off information to each other. “STSS also takes technology to the next level with much more sophisticated infrared sensors,” he said.

Morgan expects measurements taken by STSS’s IR sensors to be integrated in the BMDS architecture in order to enhance its capabilities. “The ability to acquire, track, and disseminate reports on various ballistic missile events from liftoff to the reentry period phases of flight is something the current architecture is unable to do,” he said. “The idea behind STSS is to learn how well it can provide cues to the ground-based and sea-based portions of the BMDS architecture as well as to provide more of a global perspective than ground-based and seabased radars can.”

STSS has experienced some program delays. “It was supposed to have been on orbit by now,” admitted Morgan. MDA is now targeting a November 2008 launch date, if it’s able to work out the remaining bugs in the system, or, failing that, January 2009.

Morgan was reluctant to divulge the problems STSS is experiencing, saying, “We don’t know all of the root causes yet.” But the chances of a January 2009 launch are good, he added, “depending on the outcome of our analysis and our willingness to accept certain risks. We still have to do some additional testing on the ground. It could be ready for launch by November but that would take a high-risk approach.”

STSS satellites have been built and the software is ready to go, according to Morgan. “The ground stations are in the process final integration,” he added. “The two satellites are getting ready to go into an acoustic test to make sure they can handle the launch environment. We’re having some challenges trying to get that going. We’re trying to chase down anomalies on the ground, recreate them, and fix them before launch.”

The ultimate goal of STSS is to collect information and lessons learned and integrate them into a hoped-for STSS follow-on program, which would differ form the experimental STSS by being an operational program.

Morgan envisions another three–to-five years of STSS experiments. He does not expect Congress to provide much funding for a follow-on program unless and until the STSS demonstration satellites perform on orbit. STSS is currently receiving funding of $180 million per year.

An STSS follow-on effort would require funding of $500 million-to- $600 million per year for five or six years before it could launch operational capabilities. The number of satellites required for a follow-on program has yet to be determined, Morgan said, and the objective of such a program would be to provide global coverage.

“You can’t see the whole world with just two satellites,” Morgan said. “When the follow-on program becomes operational, we would want to take on more of a global coverage area. We would be interested in tracking the threat of missiles launched against our interests from anywhere on the globe.” ♦