As attacks by roadside bombs increase in Afghanistan, the U.S. military is rushing protective new technology to the war zone.
Along with more blast-resistant vehicles and more bomb specialists, the Army is preparing to send a newly developed man-hunting radar designed to spot people on the ground, especially those planting deadly improvised explosive devices (IEDs).
The radar - called VADER, for Vehicle and Dismount Exploitation Radar - is sharp-eyed enough to see individuals from an altitude of about 25,000 feet.
Developed by Northrop Grumman in 18 months, then subjected to 22 months of testing, VADER borrows extensively from existing radar technology and the company's 30 years of radar-building experience, said Brian Reise, Northrop's VADER program manager.
Indeed, the radar is similar in concept to the Joint Surveillance Target Attack Radar System (JSTARS) Northrop developed in the 1980s to spot and track relatively large targets such as tanks, other vehicles and mobile missiles. More recently, JSTARS has been used to track "dismounted forces" - that is, groups of Taliban or other fighters moving on foot.
But VADER can do that better. According to Northrop, during test flights the VADER system was able to scan a wide area and detect and track individuals moving about on foot. When mounted on an Army Warrior drone, the radar can watch over an area for up to 36 hours.
Northrop won't reveal much about how VADER works - details are being closely held by the Defense Department, Reise said.
But the Pentagon's Joint IED Defeat Organization (JIEDDO) provided some basics: "The VADER system incorporates extensive improvements made to ground moving target indicator and synthetic aperture radar sensors," said W. Richards Thissel, a science and technology adviser at JIEDDO.
He called the VADER sensors similar to those used by JSTARS, but said VADER has a different mission - specifically, it can "track moving dismounted individuals and characterize suspicious actions."
VADER's sensors feed data to an on-board processor that uses "exploitation algorithms" to "detect, discriminate and track vehicular and dismounted suspicious activity in near-real time," Thissel said. His description was published in an "internal JIEDDO article," an agency spokeswoman said.
VADER employs "much more advanced techniques than were available when we built Joint STARS," Reise said.
Northrop describes VADER as operating in two modes: as a synthetic aperture radar for collecting high-resolution still images of targets, and as a real-time ground moving target indicator for spotting moving targets.
In its ground moving target indicator mode, the radar has been able to track vehicles, people, animals and watercraft, Northrop said.
In general, ground moving target indicators work by detecting the Doppler shift that moving objects produce in radar return signals. Doppler shift is a change in the frequency of the radar return caused by the motion of the target. Because there is no shift caused by stationary objects, the shift reveals moving objects.
With VADER, processed signals are transmitted from the drone to ground stations, where operators can see either still synthetic aperture radar images that look something like high-contrast black-and-white photos, or moving targets displayed as dots superimposed on a map, Reise said.
"This system brings the radar picture right to the ground so operators can see it and act on it," Reise said. "Other ground moving target indicators don't do that.
"You can track a car, see where it stops, see if someone gets out," and see whether that person buries an IED, he said.
The Defense Advanced Research Projects Agency, which helped fund VADER development, declined requests for an interview, but said in a written statement that the new radar combines "real-time detection and tracking of vehicles and dismounts in a single sensor and exploitation system. It will remove any remaining cover-of-darkness for insurgent IED emplacement and resupply operations."
The VADER system is contained in a pod that is about the size of a Hellfire missile, Reise said. That makes it about 5 feet long. It was designed to be mounted under the wing of an Army Warrior, a medium-altitude, long-endurance UAV. The 28-foot-long Warrior has a 56-foot wingspan and can fly for 36 hours at 25,000 feet.
Special operations forces have expressed interest in putting the VADER on a Hummingbird UAV. The small, unmanned Hummingbird helicopter doesn't require a runway to take off but can fly only half as long as a Warrior.
JIEDDO officials said that for now, the VADER system "will be deployed on manned and unmanned aerial platforms over the next several years for extended operational assessments."
If VADER arrives in Afghanistan soon, it will become part of a major U.S. buildup of counter-IED equipment intended to thwart a dramatic increase in IED attacks against U.S. troops. Along with Warriors, the United States is sending Predator and Reaper UAVs to Afghanistan to perform surveillance missions. It is also sending cameras mounted on tethered balloons called aerostats, said Ashton Carter, the Pentagon's acquisition chief.
Robots, hand-held metal detectors and ground-penetrating radars will also augment the anti-IED arsenal. In all, the counter-IED gear that will go to Afghanistan over the next several months is worth several billion dollars, Carter said.
The number of IEDs set to ambush U.S. and coalition troops in Afghanistan increased to 989 in March, up from 429 in March 2009, according to JIEDDO.