ASU Research E-Magazine: A View From On High

For years, American taxpayers have picked up the tab for the Mars Global Surveyor Space Flight Facility. Now, it’s payback time.

The same remote-sensing technology that Arizona State University’s MGS researchers apply to the Red Planet already has saved the city of Scottsdale $1.5 million on a water management project. Millions of dollars more in savings are in the pipeline.

“If everything turns out like we think it’s going to, and the accuracy of the remote-sensing data comes in as well as it has, we could perhaps save anywhere from eight to $15 million, maybe $20 million in our 10-year capital-improvements program,” said Scottsdale planning engineer Bill Erickson.

From the Moeur Building on ASU’s main campus in Tempe, the MGS Facility monitors and controls one special instrument—the thermal emission spectrometer (TES). Scientists will use TES to map the surface minerals of Mars. Launched in November 1996, MGS began its mapping mission in March 1999.

Before MGS, staff at the ASU facility had devoted themselves to preparing the same instrument for the Mars Observer probe. NASA engineers lost contact with Mars Observer in August 1993, just as the spacecraft was about to enter Martian orbit.

The city of Scottsdale began talking with ASU about a collaboration within weeks of the loss of Mars Observer.

“The timing couldn’t have been better,” says ASU geology Professor Philip Christensen, who directs the MGS Facility. “I had this team of excellent people who were really well-trained and had nothing to do. Scottsdale needed exactly the type of expertise that we had.”

The program began in July 1994 with a $625,000 grant from NASA to Scottsdale and ASU. Their task: to test the feasibility of using spacecraft and aircraft images as aids for city planning and operations. The success of the pilot project led NASA Administrator Daniel Goldin to announce a two-year funding extension at an April 1995 press conference in Scottsdale.

ASU collected the largest chunk of the grant when the program began. But as ASU has become more involved with MGS—the Mars Observer replacement mission—the funding has evened out. Now ASU receives about $85,000 a year. The city’s Advanced Technology Program receives the balance.

Christensen and former ASU research associate Doug Howard devoted most of the first year to proving the concept’s feasibility. One early project involved helping the Arizona Department of Environmental Quality track a bacteria problem at Lake Havasu. The bacteria became such a public-health threat that swimmers were temporarily banned from the water.

The NASA Ames Research Center near San Francisco dispatched a C-130 aircraft carrying a Thermal Infrared Multispectral Scanner (TIMS) to overfly the lake. The data collected by the aircraft helped pinpoint the lake’s bacterial hotspots. The warmer the water, the more the bacteria grew, and the TIMS instrument detects heat.

“You can see the boat trails because they are a different temperature than the surrounding water,” Howard explained. “You could look at the hotspots and tell the investigators out on the lake places to go. They didn’t have to go everywhere to get their samples to find out where the bacteria were starting to grow.”

City and ASU researchers also used the C-130 overflights to help crews fight the Rio fire of July 1995 that burned 23,000 acres of land in and near Scottsdale’s McDowell Mountain Preserve.

The day after the fire started, the city learned that a NASA C-130 aircraft was on its way to gather some routine data for ASU. The city arranged for the aircraft to fly over the area to get some images of the fire.

NASA quickly transmitted the images to ASU. NASA flew two additional missions to provide updates on spread and location of the fire. Response-team commanders deployed crew and aircraft based on these images.

The NASA support was the main factor in bringing the fire under control one day earlier than expected. This saved taxpayers $250,000, according to city estimates.

A month and a half after the fire, Howard, ASU colleague Don Anderson, and Agrometrics Inc., of Tucson, conducted a follow-up study of the preserve. They used temperature data, again, to map the burn and non-burn areas to help park managers plan their reclamation efforts.

Bill Erickson then presented his request to use remote sensing to assess the city’s capital-improvement needs for flood control. It costs the city about $45,000 per square mile to put together a drainage plan because of the many hours city personnel spend gathering information in the field. Even then, because it is only a projection, the plan is only 75 percent accurate in its determination of land-surface characteristics.

Erickson suspected that he could update drainage plans less expensively with remote-sensing technology. He did not expect, however, that Howard would be able to use the technology to describe existing surface characteristics with 90 percent accuracy as later verified by ground surveys.

Similar studies had been done before, but never with such accuracy. Most city planners simply try to identify the urban fringe, so that they can see where future urbanization is likely to occur. They can use low-resolution data to group residential, industrial, and commercial developments into the urban category, farm fields and desert sands into the rural category, and see where they border each other.

“But if you want to conduct land-use planning in an urban environment, you need higher resolution,” Howard says. ASU already had such high-resolution data on file for the Scottsdale area. The NS001 instrument, which collects infrared and visible data, including photography, can detect ground features that measure less than 10 feet across. The commercially available data, by comparison, can image features ranging from 66 to 99 feet in diameter.

Howard ran the NS001 data through several different computer programs to determine which one could best quantify the amount of pervious and impervious surface that existed within the 4.5- square-mile test area in southeast Scottsdale. Parking lots, rooftops and other impervious surfaces shed water, while pervious surfaces such as soil and grass absorb it.

Then he went into the field to check ground truth. He discovered that his computer program was 95 percent accurate. Erickson also asked Howard to run his computer program on a four-square-mile area that he was unfamiliar with, the Scottsdale Ranch area near Shea Boulevard. City staff, who had already checked the area on the ground, found that Howard’s analysis was 95 percent accurate.

City planners took the data and plugged it into an engineering model that estimates storm water runoff. It turned out that the city did not need $1.5 million worth of retrofits to a storm water detention basin that officials had planned for the Scottsdale Ranch neighborhoods.

“The design for that basin was done in the late 1970s, without aid of computers or state-of-the-art equipment,” says Erickson, the Scottsdale engineer. Following construction of the Price-Pima Freeway in Scottsdale, the Arizona Department of Transportation re-evaluated the basin. ADOT concluded that a 100-year flood would overtop the basin, potentially damaging several U.S. Army Corps of Engineers projects and the Salt River Pima-Maricopa Indian Community.

Howard’s data showed that the basin would not overtop after all in a 100-year flood. The city presented Howard’s data to ADOT, the Corps of Engineers, and the Indian community. All agreed that Scottsdale did not need to upgrade the storm water detention basin.

“We’ve barely scratched the surface of what can be done,” Erickson adds.

Up until now, ASU has done the science, while leaving the decision-making to city planners. Howard is now training Scottsdale personnel to do the science as well.

Other cities could also benefit from the technology, although the computer program that worked in Scottsdale won’t work in, say, Des Moines, Iowa. Researchers would first, once again, have to spend a lot of time cross-referencing what they find in the field with what they find in their remote-sensing data.

“That’s the time-consuming part of doing the computer analysis,” Howard explains. “But as soon as you get that down, you can go anywhere in the world, to any urban or any agricultural or any rural area at all.”

Both Howard and Christensen have found it gratifying to shift the focus of their technology from Mars to the red-tiled roofs of Scottsdale.

“We’re not hoarding this science just to solve problems that not everybody can understand. We can use it to help local and state government,” Howard adds.

It was, in fact, a move that Christensen, who had been trained as a terrestrial geologist, had been thinking about making for a long time.

“It’s fun to study Mars. There’s no doubt about that,” Christensen says. “It captures a lot of people’s imaginations. But I don’t like the fact that pollution is getting worse here in Arizona and all the good desert land is being covered up with homes. When the quality of life issues come up you say, ‘Hey, what can we do to help?’ It turns out there is a lot we can do that’s useful.”—Steve Koppes