The Landsat system: how prospective buyer would iron out its bugs

By , Natural science editor of The Christian Science Monitor

Were Comsat to take over Landsat, it would be buying a successful but ailing system. Landsat is successful because, in a decade of experimental operation, it has established a growing data-supply business with annual sales that reached $72.5 million in fiscal 1981. While weather satellite pictures show the state of the weather, Landsat images report on the planet's surface environment. They are used to monitor the health and growth of crops, to prospect for minerals, to track pollution, to help in urban planning and in many other ways. Hence their value.

But the system is ailing because, as a government-run operation, it has an uncertain future. Also, the present working satellite, Landsat 4, has a failed radio transmitter.

Comsat would cure the uncertainty by making a long- term commitment to provide earth resources satellite data. This could be good news for Landsat data users in over 100 other countries, even though they might be charged for data which, unlike US users, they now receive directly from the satellite for free. These users have been concerned that the Landsat data flow might cease. There never has been a congressional or administration commitment to maintain that data flow indefinitely.

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As for the technical problems, Comsat considers the present Landsat technology unsatisfactory anyway. It would phase in new satellites and ground facilities.

Landsat technology was developed by the NASA Goddard Space Flight Center through a series of satellites since 1972. The first three Landsats carried an instrument called a multispectral scanner (MSS). This views Earth in four different (light) wavelength bands. It produces images with a resolution of 83 meters, or about 272 feet. Anything smaller is lost in the blur.

Landsat 4 (and its sister Landsat now in storage) has an MSS plus a new instrument, the thematic mapper, which has sharper eyes. Able to see with seven wavelength bands, it produces images with a resolution of 30 meters, or about 98 feet.

The Landsat 4 MSS system is now run by the National Environmental Data Service as an operational business. The thematic mapper still is experimental. This is just as well, since it is the orbit-to-ground transmitter in this system that has failed. Eventually, a second orbit-to-orbit transmitter can be used to relay mapper data via the new Tracking and Data Relay communications satellites to be launched by the shuttle.

Comsat would develop replacements for the Landsat system over a five- to six-year period. The new satellites would have even sharper vision, including high-resolution radar and stereo eyes.

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