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High-tech sensor in the shuttle search

A high-tech military sensor is being used to search for debris from Columbia, but it may soon be withdrawn, sources tell
/ Source: NBC News

The search for debris from the space shuttle Columbia is receiving valuable support from a little-advertised U.S. Army sensor program whose important role has remained unsung, probably due to security concerns connected with the sensor’s primary mission to detect land mines in combat zones such as Iraq. However, the future of this effort is now in doubt, and the equipment may be withdrawn from the search as early as this week.

The plan to discontinue use of the Compact Airborne Spectral Sensor, also known as Compass, appears to be due to a combination of factors — including lack of appreciation by local search officials as well as an urgent need for the equipment elsewhere. The U.S. military wants to use Compass during a counter-mine test at an Army testing ground near Yuma, Ariz.

The Compass imaging system is mounted in a vintage commercially leased DC-3 aircraft now operating out of Lufkin, Texas. Since early March, operators have been calibrating the sensor against known ground targets and then surveying marked zones of open land in East Texas.

Over the weekend the system scored a major success when ground teams, guided by images made on March 21, located three pieces of shuttle tile that were only a few inches across. Tests against other types of expected shuttle debris — from aluminum to the reinforced carbon-carbon of the wing’s leading edges, to various types of thermal tiles — had suggested that the experimental system could prove effective, and observations over the past few days have vindicated these hopes.

NASA’s chief field collection manager, Michael Rudolphi, mentioned the sensor briefly on Wednesday in his testimony to the Columbia Accident Investigation Board at Cape Canaveral, Fla. “We do have a DC-3 that is working some equipment,” he told the investigators. ”[But] it’s yet to be decided if that gives us the success we’d like to have.”

Aside from adding to the collection of thousands of pieces of shuttle debris recovered in the main search zone in East Texas, Compass promises to provide the long-sought capability to search vast open areas in Nevada, Utah, Arizona and New Mexico, where isolated but critically important debris is known to have fallen.

Questions about application
So far, ground searches have proved fruitless in regions near Caliente, Nev., and Albuquerque, N.M. Video imagery, air traffic control radar and eyewitness accounts have helped NASA searchers concentrate on high-probability areas. However, rough terrain and the snow that fell after the Columbia broke up on Feb. 1 have hampered ground access.

Rudolphi told the investigation board that the sensor was intended to be used out west, but he did not express great confidence in it. “We do have a plan, we do have a method,” he testified, “it’s just not very productive.”

Sources close to the search efforts told that cooperation was being hindered by a cultural chasm between the groups. “The guys with the sensor are scientists,” one NASA manager reported privately. “They don’t understand operations and communications issues.”

But the interface problem goes both ways, another official told on condition of anonymity. Managing the sensor effectively is “an issue bigger than they can get their hands around.”

Even the most enthusiastic admirers of the system admit it is still largely experimental.

“It isn’t even close to being a perfect sensor, and it won’t work in all conditions,” the official continued. “So we should use it to search areas that it fits.”

The Compass sensor, about the size of a breadbox and weighing less than 100 pounds (45 kilograms), can be mounted in a wide variety of airborne platforms. For the space shuttle search, it is being operated from an altitude of about 2,000 feet (610 meters).

According to experts familiar with its use in the debris search, it collects data for up to four hours. The data must then be laboriously processed by ground computers to produce ground maps with possible “hits.” Field searches have demonstrated that the sensor produces hits within 20 feet (6 meters) of actual locations of detected objects as small as an inch (2.5 centimeters) across.

Hyperspectral sensor
Compass is what is called a “hyperspectral sensor.” It’s a more sophisticated version of remote sensing systems that used multispectral imaging — measurements of light intensity at many colors — to identify materials observed on the ground below the airborne or space-based sensor. It measures reflected light in 256 different “colors,” or wavelengths. A number of commercial systems of this new type are now becoming available.

Developed at the U.S. Army’s Electronic Sensors Directorate at Fort Belvoir, Va., Compass is part of an array of amazing new sensors with direct military applications.

The hardware was described by Rudolphi and by a NASA briefing book at the Lufkin command post as a Drug Enforcement Agency system. However, DEA spokesman Robert Paiz in Houston told that he was unfamiliar with any DEA participation in the shuttle debris search.

“We do have a small air force,” he said, “but I’m not aware we have a DC-3.”

An employee at Lufkin’s airport confirmed to that the DC-3 has operated out of his field, but he did not give his name and referred all requests for information to NASA officials. The on-duty public affairs officer at the Lufkin command center for debris search, Kim Pease of the Federal Emergency Management Agency, also told that “all information about the DC-3 has to come from NASA.”

David Drachlis, the NASA public information officer in Lufkin, said, “I don’t know much about it — it’s some kind of imaging device to search for material.” However, he was able to obtain a hitherto-unpublished photograph of the DC-3 for made multiple requests to the Columbia Accident Investigation Board and to the Fort Belvoir Public Affairs Office for further information and on-the-record interviews with specialists. Public affairs officers for those entities were unable to provide the specified information.

Although the Compass data has so far only supplemented search work in East Texas that is already being conducted by ground teams, its critical value could come in areas in the western United States, where early debris is known to have fallen but where there is just too much land to be searched on foot.

Columbia investigators were briefly elated last Friday when black ceramic debris recovered by hikers in Zion National Park in Utah arrived in Houston. To all outward appearances, the handful of fragments looked like the reinforced carbon-carbon shielding used on the shuttle’s leading wing edges.

But analysis with an electron scanning microscope at NASA’s Johnson Space Center in Houston quickly established that the materials were old Indian pottery shards.

Meanwhile, the future application of this potentially valuable sensor is now in doubt. Some observers have voiced concern that the right officials may not have adequate information to make the best decisions about using Compass for the application it seems best suited for: searching the wide open spaces out West where critical clues to the onset of the Columbia catastrophe may lie awaiting discovery.

James Oberg, space analyst for NBC News, spent 22 years at the Johnson Space Center as a Mission Control operator and an orbital designer.