Space: Orbital tracking of land and sea vehicles
JEAN BEAUDIN
© 2008 FrontLine Defence (Vol 5, No 6)

Media accounts often manage to couple attention-grabbing headlines, such as “Canada’s plan for a super spy in the sky,” with accurate content to drive the point that space-based tracking is clearly a take-notice innovation – one Canadians will eventually hear about, one way or the other.

Many people are aware that RADARSAT-2 is currently in orbit, launched in December 2007, but haven’t heard much about the Ground Moving Target Indicator. The GMTI is an experimental mode of the satellite that stems from research into the feasibility of monitoring, from space, vehicular movements anywhere in the world, day or night, and regardless of environmental conditions.

As one might expect, Hollywood tends to over-hype such capabilities. Films like Enemy of the State and Behind Enemy Lines have depicted satellites visually tracking vehicles, even people, on the ground. There is no evidence pointing to such technology existing at this time. Spy satellites may be able to collect static images of metre-length objects, but they still don’t have the means to detect movement and determine the speed and direction of vehicles over large areas. Current methods still require GPS monitoring devices and transponders attached to the target vehicles, as in civilian company fleets being monitored as a ­business flow management system.

But space-based GMTI may represent a significant leap forward. DRDC Ottawa’s Dr. Chuck Livingstone, the chief scientist and project manager, points out that: “the RADARSAT-2 GMTI experiment is dem­onstrating how we can quickly and efficiently detect and pinpoint movement on the Earth’s surface. We now have the means to detect someone who doesn’t want to be found. This radar can be configured to act as two radars that are set to measure the world from the same point in space, but with a shift of 1/1000 second. Changes in the position of objects on the Earth by fractions of a radar wavelength (approximately 1/36 wavelength or 1.6 mm for RADARSAT-2) can be measured by the radar – and where there’s change, there’s movement.”

Initial results obtained from the RADARSAT-2 GMTI tests have been promising. Earlier simulation results are now being vetted through a set of RADARSAT-2 experiments started on July 31, 2008 and continuing until September 2009. The testing program is comparing the GMTI measurements with the positions and speed of many types of GPS-monitored land and marine targets to determine the sensitivity and capability of the RADARSAT-2 GMTI operating modes.

Joint Cooperation
In addition to using directly instrumented vehicles as reference targets, a group from the US Air Force Research Laboratory has been operating radar calibration equipment of their own design to provide a known moving target signature. In addition, the City of Ottawa has provided access to their radar speed display boards to monitor normal traffic, and the Canadian Forces Joint Imagery Centre has provided camera operators to monitor in-situ traffic.

 
Canadian Forces personnel monitor traffic flow along Highway 417 in Ottawa for ground-truthing purposes.

Precisely because civilian applications of space-based moving object measurements may include traffic monitoring in urban environments and improvements in traffic control designs for cities, the project is working with the Canadian Space Agency and the German Aerospace Center, (DLR), to combine moving object measurements from RADARSAT-2 and the German TerraSAR-X satellite (launched in June 2007) to investigate traffic monitoring in Canada and Germany. In the Joint Canadian and German research activities, both satellites are operated to monitor selected sites in close time proximity and each national group provides direct measurements of the observed traffic movement at its own test sites.
 
 
City of Ottawa speed display boards are used to monitor traffic flow for ground-truthing purposes.

“In terms of border and sea protection,” adds Dr. Livingstone, “once a target has been determined to represent a risk, this information would be used to cue the Navy, Air Force, or a public security agency for additional surveillance.”

Further investigation might include the use of manned or unmanned vehicles. “We are now ascertaining, to the direct benefit of operational requirements, whether we can consistently detect the mover,” notes Dr. Livingstone. “Given Canada’s vast and varied geography, tracking terrorist or drug-related movements at sea and across our border would be of great assistance to law enforcement.”

One of the primary objectives of the project is to define the radar and processing designs for next generation GMTI space systems.
 
====
Jean Beaudin is Head of Communications and Information Management at Defence R&D Canada – Ottawa.
© Frontline Defence 2008

RELATED LINKS

Comments