The Landsat satellites continue on their lonely rounds, filming the ups and downs of the earth's resources, and 570 miles below Dr. Alden Colvocoresses studies the photos in his office overlooking the Reston woods.

Colvo, as he is known, is a scientist first, and these days he is poring over records of last winter's deep freeze in the Chesapeake, worst ever recorded.

But he's a fisherman, too, an unabashed fan of largemouth bass. And several years ago he stumbled across a Landsat shot of Lake Anna, the most productive bass Lake Anna, the most productive bass lake in reasonable driving distance of his home in Fairfax County.

The photo was from 1972, when the dams were new, the lake was still filling and the water level was a good seven feet below current average.

"Seven feet," mused Calvo. "A very interesting depth for bass fishing."

So he set to work with a magnifying glass, marking shoals and dropoffs that his trained mapmaker's eye could spot easily on the glossy print. He blew up sections of the photos and settled on what he thought would be the best place to fish Anna.

In early March, 1974, Colvo packed up his john boat, his 7 1/2-horsepower outboard, the electric troller, the depth finder, rods and lures and headed down to the 13,000-acre impoundment outside Fredericksburg.

He knew where he was going - to one of a series of three dammed-up lagoons that one day will serve as water-cooling pools when the nuclear power plant at Anna goes into operation. The lagoons are at the southern end of the lake.

Checking against his charts, he found his spot and tossed in his lure. Within 10 minutes he had a three-pound largemouth in the boat.

He's done well since, landing some 200 bass in Anna on his occasional fishing trips. And he generally sticks to his favorite spot, or others he has picked out nearby from information in the photos. "I don't have a big, powerful boat, so I have to stick to a pretty small area," he said.

Colvo calls his prime fishing spot ERTS Point, for Earth Resources Technology Satellite, but like most fisherman he's unwilling to say where it is.

In any case, he said, anglers "shouldn't get the idea that this is a fisherman he's unwilling to say where in a mess of bass in an hour's time. It still takes patience and waiting and know-how."

Colvo said the advantage he has from knowing the lake's topographical features seven feet below the current surface is that he can "see islands and features that obviously you won't see today."

There is a commercial topographical map available to Anna anglers, but Colvo doesn't think much of it. "Look here, this island isn't anything like this on the photos," he said.

What Colvo looks for in the photos are sharp dropoffs, places that bass tend to lurk where they can easily get to deep water in the heat of day and to shallow feeding grounds when it's cool.

He's catching fish, but his scientist's mind won't let him rest.

"I was interested in Lake Anna because it's the nearest bass hole. But I was also interested in it as a test site for our space satellites, to see what they could or could not do in monitoring a lake of its size."

Now that the opening of the nuclear plant is imminent, perhaps by September, Colvo sees other uses for satellite technology.

"By next summer NASA will have a satellite aloft that will show not only visible images, but also can provide temperature responses," Colvo said. That could come in handy for monitoring the effects of the nuclear reactor on water temperature.

Vepco and the Virginia Commission of Game and Inland Fisheries plan to close Colvo's lagoons to fishing when the plant opens, the scientist said. They feel the drainage system they have built to circulate hot water will raise water temperature in the lagoons to intolerable levels for sport fish.

Colvo's not so sure. He's pushing for introduction of warm-water-tolerant Florida bass and expects the thermal data from the new satellite to add evidence to his conviction they could thrive there.

Those hot-water pools could become year-round fishing hotbeds.

Meantime, Colvo ponders away in his cluttered digs at the U.S. Geological Survey and dreams of landing the big one.

He'd be happy to share his fishing fortune. If you have a favorite fishing lake you'd like to get satellite shots of, they are available from three sources.

Write to EROS Data Center, U.S. Geological Survey, Sioux Falls, S.D. 57193; Aerial Photo Field Service, Adminsitrative Service Div., ASCSUSDA, 2505 Parley's Way, Salt Lake City, Utah 84109; or NOAA Environmental Data Service, National Climatic Center, Satellite Data Services Brach, World Weather Bldg. Rm. 606, Washington, D.C. 20233

It's best to specify a general date for the photos you want, preferably whenever the water was lowest over the last five years, since that will show the most structure. The prints generally cost $3 to $8, Colvo said.

Also, specify infrared band 7 photos, or you'll get something that looks like a Jackson Pollock painting.