Two twirls left, two more right, and the lock on the gray filing cabinet drawer flicks open. Edwin Roedder reaches inside with exaggerated care, as if he were about to pat a newborn in a crib. Grinning, he steps aside so a visitor can see.

Holy Neil Armstrong! Great intergalactic Captain Video! The drawer is lousy with moon rocks.

Gray ones and brown ones, rust-colored ones and blackish ones. Here a moon rock nugget, mounted in a plastic case. There a collection of moon pebbles, sealed in a plastic bag. A few slides of moon dust. Some envelopes full of shavings. All brought to you direct from outer space.

Those expecting speckles and sparkles would be disappointed by moon rocks. They are dull to the eye and the touch. Kick them down a country road, and you couldn't tell them from earth rocks. And if anyone still harbors illusions about green cheese-go back two spaces and forfeit your turn.

But lifeless as the moon rocks seem, they generate a jolt of fascination.

All those astronauts, all those missions, all those hours in front of the television. One tends to start composing a speech for one's grandchildren: "Sure, sure, your old granddad remembers Neil Armstrong. And he also remembers the day he tossed moon rocks around like hard-boiled eggs. Remembers it like yesterday . . ."

But moon rocks are anything but fantasy to Ed Roedder. They are the opportunity of a lifetime.

As a geologist at U.S. Geological Survey headquarters in Reston, Roedder heads one of 96 scientific teams conducting federally sponsored research in the U.S. on lunar samples brought home by Apollo missions 11, 12 and 17.

For nine years, or almost from the instant Armstrong splashed down in the Pacific with his two companions and 830 pounds of moon rocks, scientists have been examining the booty.

They have learned a lot. They know, for example, that the moon was not created in anything like the way the earth was, for moon rocks do not contain certain minerals found on earth. They know that human life cannot be independently supported on the moon's surface, for moon rocks do not contain water or oxygen. And they have been able to deduce a great deal about the way meteors have affected the moon's surface.

But as Ed Roedder says. "There are many things still to be learned from the lunar samples. Some of the rocks haven't been studied at all.

"Curiosity is just one side of it. We have to keep studying these rocks so we can learn about the earth, not just the moon."

The trouble is that mice on Capitol Hill are nibbling at the moon rock research budget.

From grants totaling more than $10 million in fiscal year 1970, the lunar sample research budget of the National Aeronautics and Space Administration has steadily dwindled.

In the current fiscal year, it is $5.7 million.Last year, it was $5.9 million. Next year, NASA is asking again for $5.7 million - but inflation makes that equivalent to cut in funds.

Meanwhile, the number of projects is declining, too. This year there are 96 projects; as recently as fiscal year 1975 there were 126. And it is not a matter of lack of demand. "I know lots of people who applied for grants and have been turned down," said Roedder.

What of the fact that $24 billion was spent on the Apollo mission? What about ongoing, multiyear research that might have to be abandoned in midstream? Isn't there other fat in the federal budget?

"Well," said a Senate source, "you've heard of cutting off your nose to spite your face, haven't you?"

According to one high-ranking staff member for the House Committee on Science and Technology, the danger of the floor falling out of federal moon research funds is very small. Rather, the staffer said, his fear is that funds will continue to be chipped away, robbing some research projects of the scope and tools they should have.

"For the first time this year, I have been hearing from ranking members of committees that, hey, isn't nine years long enough on these rocks? How can there be anything left to look at?" the staff member said.

"In the past, there was concern only about duplication of research efforts. Moon rocks were very sexy then. Now, they're starting to become just another item in the budget."

The staff member said he finds such an attitude "almost foolhardy. We spend all these dollars to get there, and now we're talking about not getting everything we can out of it. We should do whatever we can with the samples. Everything."

For Ed Roedder, it is not as if he is facing the business end of a loaded gun. He has nine projects that do not involve moon rocks at all. He would not be standing on a breadline if his grant were not renewed.

Still, the question visibly saddened him. Asked what he would do if moon-rock money were to vanish, Roedder clasped his hands and looked at the floor for 10 seconds.

"Well, I guess I'd just have to turn in my samples and go back to terrestial samples," he said. Then, gazing at the Virginia countryside outside his laboratory window, he added: "But I wouldn't like it. Not one bit."