USAF Boosts Space Situational Awareness
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By Amy Butler
U.S. military officials say they expect to have enough personnel and new computing power in place by October to warn U.S. and foreign satellite operators of possible collision hazards to their roughly 800 maneuverable platforms.
An initiative to boost so-called conjunction analysis—prediction that two orbiting objects could collide at high speeds—took center stage for military officials after a defunct Russian communications satellite crashed into an operational Iridium spacecraft on Feb. 10, creating a new debris cloud comprising about 700 objects (AW&ST Feb. 16, p. 20).
At the time, the Joint Space Operations Center (JSPOC) at Vandenberg AFB, Calif., was monitoring about 140 spacecraft for possible collisions. That number has been on the rise since, and officials plan to routinely conduct potential-collision analyses on 800 spacecraft by this fall. As of May, the center was scrutinizing 330 satellites.
However, this will require more workers to be assigned permanently to the mission; the center has been using personnel pulled from other assignments to fill in since the collision.
“Our ability to track objects is pretty good down to roughly 10 cm. and above” in diameter, says Lt. Gen. Larry James, 14th Air Force commander. “But, we are not good enough. There are certainly inabilities that we have to do things.”
At the time of the Iridium impact, the JSPOC had five operators supporting a single position for conjunction prediction. After the collision, another four were added, to provide two positions doing 24/7 analysis. A 24-member staff (19 additional people over the five currently assigned) is needed to support collision analysis of 800 maneuverable satellites, according to space center officials. The center also has added two new computer servers to the ops center, James says. These servers are in a testing phase; but once the systems are approved by a configuration control board, they will be considered operational.
Once the solar panels are added, the Boeing/Ball Aerospace SBSS satellite will be ready for launch, which is likely this fall.Credit: BALL AEROSPACE In addition, officials are adding two people in Colorado Springs to support the Commercial and Foreign Entities (CFE) program; conjunction assessment will be among their tasks. The Colorado site also can act as a backup in the event that operations at Vandenberg are compromised. Additional services such as end-of-life support, anomaly resolution and threat notification will be added for CFE members through 2014, according to U.S. military officials.
Military officials plan to move from a “pull” to a “push” system later this year. This will involve automatically pushing data on various maneuverable satellites to operators based on agreements with the U.S. government.
The Commercial and Foreign Entities program was a pilot effort that began in 2004. It allows satellite operators to share basic information such as orbiting locations using a Web-based tool. CFE will be “operationalized” under U.S. Strategic Command in October.
Personnel and computing requirements still have to be set for a goal of conducting collision analysis on 1,300 satellites, including about 500 that are not maneuverable. Gen. Robert Kehler, commander of Air Force Space Command, says he wants to provide collision data on as many satellites as possible to avoid creating more debris clouds, which would pose an additional hazard to other orbiting systems. James says collision analysis on the 500 additional satellites that are not maneuverable could require roughly 20 more people to sustain operations.
“Once the computer tells you there is a potential conjunction, then you actually have to go in and potentially do some follow-on that just takes human capital to do,” he says. “Even if we do conjunction assessment . . . all we can do is stand back and watch” if an object cannot be moved.
Since the February Iridium accident, collision alerts have risen. “It is happening a bit more frequently, but primarily because of the Iridium and [Russian] Cosmos collision, which created a new debris field in the Iridium orbits.” Collision warnings have been sent to at least 17 different operators, including foreign companies and agencies, since February.
The JSPOC uses data collected from a series of ground-based radars and optical sensors to track about 19,000 objects. The Space Catalogue of orbiting objects comprises data from what U.S. Strategic Command calls “spot checks,” which are periodic looks at spacecraft or debris from the Space Surveillance Network’s 29 optical and radar sites. Continuous tracking of satellites is not possible with today’s sensors. About 10% of the objects being spot-checked include functioning spacecraft; 15% are rocket bodies and another 75% are fragments or inactive satellites, according to Strategic Command.
Many space surveillance sensors are old and their locations were selected during the Cold War primarily to surveil space activities of the former Soviet Union. With the cast of spacefaring nations growing, James says more coverage is needed, specifically in the southern hemisphere, to sufficiently track launches headed into a polar orbit. Current capability is lacking to adequately track Chinese launches. Also, today’s optical sensors are only usable at night and can be obscured by weather. So operators must sometimes backtrack to pinpoint the satellites’ locations amid gaps in sensor data.
Moreover, James says the command wants to have a “cradle-to-grave” ability to track a satellite from launch until it deorbits. “If I want to make sure I always know where everything is 24 hr. a day, seven days a week, I can’t do that because I just don’t have the sensor capability to monitor everything that is up there all the time.”
Coverage should improve with the launch this year of the Space-Based Space Surveillance satellite made by Boeing and Ball Aerospace. James says SBSS is expected to use its two-axis, gimballed visible-light sensor to surveil every satellite in geosynchronous orbit once every 24 hr. This is more than what is possible today, he says. Once in orbit, SBSS also can be tasked to image satellites in other orbits or those that are transiting from low Earth orbit to a higher position.
SBSS was supposed to have been launched earlier this year, but it remains on the ground pending a review into a failed Orbital Sciences Taurus XL flight in February. Taurus XL has some of the same components as the Minotaur IV that will boost SBSS into orbit, likely this fall.
Also, a new Space Fence (a series of ground-based sensors) is being developed. However, it will not begin to be deployed until 2015. The new Space Fence—estimated to cost more than $1 billion to design, procure and field—will likely include S-band radars in at least three disparate locations. Until it is operational, collision prediction is constrained by sensor performance.
In the meantime, the command is working with research laboratories to find ways to cull data from sensors not primarily tasked to support the space situational awareness mission. These could include the Missile Defense Agency’s growing fleet of radars.
In one program, Massachusetts Institute of Technology’s Lincoln Laboratory is developing “sidecars.” These are software packages designed to put data collected by sensors that are not dedicated to space situational awareness into a format that can be “ingested” by the JSPOC’s system. “The intent is to ultimately sort out how we operationally [employ] those concepts,” says James.
Image: ESA
