Here Asaph Hall went to a lot of trouble discovering the two satellites of the planet Mars, right in this city, a century ago, and it was a very great thing.

But why bother? It now turns out the satellites, the little moons, will crash into Mars and be absorbed by it within the next 70 million years.

So much for discovery, so much for giving birth. A little day, a little night, and it's gone.

But astronemers, easily impressed with passing phenomena and ephemeral flashes, still honor Hall's discovery, even if the moons are temporary, and the Naval Observatory honored Hall's memory and work with a reception, a group of technical meetings, a dinner and - best of all - entry in the observatory's log yesterday morning.

A young astronomer, Mihran Miranian (who fell in love with astronomy as a kid by watching those space fantasies for children on television) stood by the big 26-inch refracting telescope under the dome and said that at precisely 2:30 a.m. he was observing Mars, just as Asaph Hall had done a precise century ago through the same telescope.

And he wrote in the observatory log book that he hoped another future astronomer would observe the same thing through the same telescope a century hence.

Miranian had spent some little time polishing his log entry, and read it several times aloud to the general approval of the dozen or so persons who had joined him to celebrate the great moment.

The day before there had been a reception in the observatory's library with astronomers young and old, gravely drinking inexpensive wine and Catawba Grape Juice against the curved walls of books and lacy white iron stairways.

Randolph Clarke, a young astronomer from Southside Virginia, was in charge of seeing the libations did not dry up, and said between runs that he fell into astronomy through a third-grade science class.

The observatory's scientific director. Gart Westerhout, greeted guests amid the tables full of cheeses ample enough to have suited Andrew Jackson. The guests were learned, and moved with the unobtrusive air of those who are concerned more with the mind and the heavens than with worldly pomps.

The circular walls, all nicely ringed with shelves promising such delights as observations from Greenwich, Moscow, Glasgow, Madrid, etc., on celestial bearings, enclosed the astronomers like a fenced garden, and on top of the bookshelves a great many pots of pink petunias, visible to the naked eye if you were searching, enforced the impression.

Asaph Hall was a man of modest education, at first, but his wife encouraged him in all ways and deserves much credit for this eventual learning. They bought a stucco house on Gay Street (later changed to N Street) in Georgetown, and before they were dome room from the Vice President's big bulging bays and a porch of elegant iron.

Their descendants, especially a fine corp of teen-agers and young adults, turned out for the commemoration.By 2:30 yesterday morning the guard. McCray Whitley, was phoning the dome oom from the Vice President's Gate (the Vice President's official house is on the observatory grounds, and they keep guards there) to say another Hall or two had arrived, and they were admitted through the dark grounds beneath the meteor showers (a regular specialty of the August sky, even in cloudy Washington) into the dome.

It was a wonderful thing to see with the naker eye, as the great-great-grandchilren and grandchilren of Hall assembled in their summer dresses or sports shirts and jeans from Kensington, Washington, New Jersey, New York and Colorado to sit in little chairs on the polished floor under the dome. The astronomer in charge then wheeled the great telescope to the eastern sky, commanded the dome to open to the sky, and ordered the floor to rise a good many feet on its elevator apparatus.

The observatory computes and guards the world's time - officially it provides the Bureau of Standards with precise time, and unofficially it sets time for the world. Washington skies are polluted, but this observatory is chiefly concerned with astrometrics, the position of stars, so that as long as they can be seen at all, it makes no difference, how dimly they shine.

The "stagnant air," as the director observed, which is such a trial in Washington summers, is very nice for observing stars with telescopes, since there is no draft to distort the image.

Washington is better - it is not every day such a tribute is paid - with its stagnant air than the fresh and windy plains.

"Tell me by that clock when it is precisely 2:30," said Miranian, and various Halls gave various opinions of when, precisely, the clock said 2:30, Miranian peered steadily for quite a spell, and despite the 30-second variation given by the various Halls, it is certain Miranian was observing Mars at 2:30 (Standard Time, though it was 3:30 Washington time).

There is also the matter that Asaph Hall said he had first seen the first satellite at 14:40 and, later, at 2:30. But maybe the 14:40 was not the hour but a position.

Anyway, he first saw the outer satellite, then a few days later, the inner one.

He named them Deimos (Flight) and Phobos (Fear) for the horses that drew the war god's chariot.

Peering through the telescope visitors could see the fierce planet, glowering in yellow and tangerine. It was similar to observing, through the cardboard tube of a roll of toilet tissue, a bright orange M&M candy. The satellites could not be seen.

They are still being studied, and rocket flights have given more information about them, including the bad news that they will probably fall onto Mars in the next 70 million years or so.

"It was great," said James Hall, 25, of New York. "I guess it looked pretty much like that to my great-great-grandfather."

"Doubt is's changed all that much," someone said.

It was too bad one could not see Flight and Fear, the Martian moons. On the other hand, it was nice to see a great-granddaughter, Zoe. Named for Life.