Fall  >>  2005

The Landsat Saga:

Reflecting and Projecting

Every so often a reporter calls to ask for my views on the Landsat program or its follow-on, the Landsat Data Continuity Mission (LDCM). First, I usually issue a long sigh — not the journalist’s fault — he or she is just trying to do a credible job of gathering news and viewpoints. I sigh from the apparent inevitability of policy stumbles in providing Landsat data to the remote sensing community.

The status of the Landsat program has been precarious at least since the late 1970s when the Carter administration decided to turn Landsat operations over to the private sector. NASA officials, who wanted relief from the responsibility for operating the Landsat system, also urged a transfer. Market optimists argued that the private sector would be able to develop sufficient data sales to support continued Landsat operations.

Even then, most analysts realized that such a move was ill advised; for them, a viable Landsat data market was more wishful thinking than reality. By the late 1970s, sales of Landsat data were extremely small, and even the more powerful Landsats 4 and 5 (launched in 1982 and 1984 respectively) were unlikely to generate an adequate market. Most of the government-funded studies supported this dismal conclusion.

The Reagan White House was even more supportive of a transfer. That administration wanted to move as many government programs as possible into private hands. Congress followed along by passing the 1984 Land Remote-Sensing Commercialization Act, which transferred Landsat operations to NOAA and directed that agency to select a commercial operator for Landsats 4 and 5. Over the next few years, EOSAT, the private operator NOAA selected, was unsuccessful in building sufficient data sales, and EOSAT’s Landsat 6 failed to reach orbit, dooming the commercial program.

This experiment in privatization lasted only until 1992 when Congress reacted to the impending lack of Landsat data by passing the Land Remote Sensing Policy Act (Public Law 102-555). The law moved the development and operation of Landsat 7 back under government control, setting the stage for a very successful Landsat 7 mission. Under NASA development, and with operations by the U.S. Geological Survey (USGS), the spacecraft has collected thousands of high quality images of most of the land area of planet Earth, imagery that has proved highly useful for hundreds of scientific and governmental applications around the world, wherever wide coverage and high radiometric fidelity are required.

Fortunately, even the failure of the sensor’s scan line corrector in May 2003 has not shut down Landsat 7 operations. NASA and USGS have devised a means to patch in data from the corrupted areas of the scene with data acquired either before or soon after. While this fix does not substitute entirely for the “real thing,” it vastly improves the utility of the data. Each scene comes with a key showing precisely where data from a different scene have been added.

>> Valley glaciers appear as fingers of blue ice reaching out from the Vatnajökull Glacier in Iceland’s Skaftafell National Park. The park lies on the southern edge of Vatnajökull, Europe’s largest ice cap. Landsat 7 image captured August 4, 1999, courtesy of USGS and NASA.

The 1992 law made private sector ownership and operation of remote sensing systems more commercially attractive. Now three U.S. companies operate highly capable, high resolution commercial systems. The three competitors will soon reduce to two when OrbImage completes its buyout of Space Imaging. The combined company will then compete for market share only with Digital Globe. The U.S. high resolution industry, if not yet robust, is now growing in size and global reach. With U.S. policy and companies in the lead, the rest of the world is moving into orbit with a wide variety of spacecraft.

Meanwhile, U.S. policy towards Landsat data continuity falters. Data continuity is required by Public Law 102-555 because it is important for the many applications of Landsat data to federal and state agency needs. Nevertheless, it is continually at risk from infighting among the various federal agencies that use the data. Basically, they all want the data, but only if another agency pays for the system. Because the Landsat series serves a varied set of users in both the scientific and applied communities, it has never had a strong agency champion.

Even though its scientists make extensive use of Landsat data, NASA does not want to continue building and launching Landsat satellites. It would like to move on to more challenging engineering and scientific projects. However, without major changes in their budgets and focus, neither NOAA nor USGS can support such a project. As agencies within much larger departments, they also have a difficult time justifying a large budget increase. The Department of Defense (DOD), which yearly uses thousands of landsat scenes, is not willing to pay for the system either.

After many false starts and delays, there is now a plan that would place a Landsattype Operational Land Imager (OLI) on the NPOESS satellites. These are the new, improved meteorological satellites developed by NOAA, NASA, and DOD. However, the first of the NPOESS birds is now scheduled for launch only in 2010 (http://ldcm.usgs.gov). Thus there will likely be a significant Landsat data gap, as the only Landsat satellites now operating are the damaged Landsat 7 and, amazingly, Landsat 5, which was launched in 1984.

The NPOESS satellites will fly in a different orbit from Landsat 7, yielding a smaller scene size (177 km, versus 185 km) and different scene center line. The OLI, which is not yet designed, would maintain the same 30-meter multispectral and 15-meter panchromatic resolutions and contain three additional spectral bands compared to Landsat (one blue and two short wavelength infrared). Unlike Landsat 7, it would not carry a thermal band. It is not clear that data users will find such changes immediately workable, since even relatively small changes in the data characteristics may require significant changes in their applications algorithms. Users of the thermal band are simply out of luck in the OLI era.

Still to be worked out is the funding for the sensor, additional ground systems, and operations costs, which could further delay the system. In other words, do not expect to see the impending data gap filled any time soon.

Ray A. Williamson is research professor of space policy and international affairs in the Space Policy Institute of The George Washington University, Washington, D.C.

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