What was going on when I was born?

Two astronauts glided, tumbled and somersaulted through the vacuum of space today in a successful test of their abilities to serve as orbital repairmen. Bundled in thick white spacesuits, they stepped out of the Challenger's cabin like children going out for a romp in the snow. The astronauts, tethered to keep from drifting away, ''walked'' to the rear of the space shuttle's 60-foot-long cargo bay and forward again, checking their maneuverability in the new, more flexible 250-pound suits on which their lives depended. Working in the open cargo bay, they practiced rigging a winch cable, unstowing and handling tools and generally evaluating how well astronauts of the future could perform repairs on satellites or on the shuttles themselves.

A bipartisan majority of the Senate Budget Committee today approved a 5 percent increase in the military budget next year, just half the increase that President Reagan has insisted is necessary for the nation's security. The vote was 17 to 4. Eight Republicans, including the committee chairman, Pete V. Domenici of New Mexico, joined nine Democrats in voting for a rise of only 5 percent after making up for the effects of inflation. Four Republicans voted against it, and one Democrat, Ernest F. Hollings, of South Carolina, was absent.

A NEW tradition may be entrenching itself in the art world, that of the two-gallery show. Initiated by the dealers Mary Boone and Leo Castelli, with whom most of such shared exhibitions have taken place, it goes like this: A ''hot'' artist produces so much work, or work of such a size, as to require his dealer to find more than one space - usually that of another dealer - in which to show it. What this provides for the artist, of course, is more impact; the cachet of a double exhibition, and twice the publicity. As for the viewer, he or she gets to see a larger slice of the artist's effort, while at the same time developing a possibly exaggerated idea of his importance. And the dealer? Ah, the dealer. His artist (and he) may benefit from the extra fanfare, but on the other hand, the double show not only requires more arranging; it also involves the risk of ''sharing'' him with another gallery. Nevertheless, the concept may be here to stay, taking off from the two-gallery shows already racked up this year by Julian Schnabel, David Salle and Robert Morris, among others.

More than 40 churches around the country are giving sanctuary to illegal aliens from Central America who would face deportation to their war-torn nations if they were caught by Government agents. Hundreds of other churches, with the support of some of the nation's largest religious denominations, have pledged to give support to the refugees, most of them Salvadorans and Guatemalans who have been denied political asylum. By giving temporary shelter until the refugees can be resettled with families, some church leaders say, the churches are taking a humanitarian stand and calling attention to what they consider the unfair application of the Refugee Act of 1980. The act requires refugees requesting political asylum to prove to both the Attorney General's office and the United States Immigration and Naturalization Service that they would be persecuted if they returned to their homeland. Some church leaders oppose sanctuary as a form of civil disobedience, but a Government spokesman said it was not clear if the churches were violating any laws in harboring the illegal aliens.

New York City's freshly painted white subway cars are quickly turning all shades of red, green, blue and black. Graffiti scrawlers have struck the white cars to such an extent that Transit Authority officials are now considering halting the creation of what they once envisioned as ''a great white fleet.'' To date, about 25 percent of the system's 6,000 cars have been painted with a graffiti-resistant white compound. The cost has been $2,200 a car.

Friday NEW YORK POPS DEBUT A 90-member orchestra makes its debut tonight at 8 in Carnegie Hall: the New York Pops, conducted by its founder, Skitch Henderson. It is the fulfillment of a longtime dream, says Mr. Henderson, who has conducted virtually every orchestra in the country, but is probably best known for his television work. Mr. Henderson will talk about some of the pieces on the program, which will include music by Victor Herbert, Ferde Grofe and the Beatles, as well as excerpts from Leonard Bernstein's ''On the Town'' and a tribute to Irving Berlin. Tickets: $7.50 to $20. To charge tickets, 247-7459. STANWYCK DAYS IN QUEENS Tough-talking women of questionable character became a specialty of Barbara Stanwyck's during nearly 20 years in the 1930's and 40's, even though the actress also played virtuous heroines. The Astoria Foundation, 34-31 35th Street, in Queens, is running a ''Bad Barbara'' film retrospective tonight, tomorrow and next Friday and Saturday. Tonight's fare is a double bill, starting at 7:30: ''10 cents a Dance'' (1931) and ''Baby Face'' (1933). Tomorrow, ''Double Indemnity'' (1944) will be shown at 3 P.M., ''The Lady Eve'' (1941) at 5:15 and ''The Strange Love of Martha Ivers (1946). Tickets: $3.50. Reservations and information: 784-4742.

The Federal Communications Commission today approved new rules allowing FM radio stations to use their facilities to transmit data such as electronic mail and offer nationwide paging services, competing directly with phone companies and other communications concerns. The rules will allow both commercial and noncommercial stations to provide the services, using the idle subchannels of their main signals. Public stations, which had sought the new authority as a way to bring relief to their beleaguered finances, expressed delight with today's announcement.

''It is so American. It is big. It is, if I may say, crazy.

Here at the military headquarters of anti-Vietnamese Cambodians loyal to Son Sann, a former Prime Minister, all the camp's residents - 8,000 civilians as well as several thousand soldiers -are aware that the settlement can be overrun at any moment. But the civilians remain, tending their gardens, eating rice supplied by the United Nations and supporting their troops, most of whom are preparing for possible attack by a nearby Vietnamese force. The camp, which is made up of barracks and houses, administrative buildings, hospitals and schools, is less than a mile from the border with Thailand, and the red and yellow flags of what is known as Democratic Kampuchea fly from its flagpoles. That is the name of the Cambodian Communist regime of Pol Pot that Vietnamese troops expelled from the capital, Phnom Penh, more than four years ago, installing in its place a Communist regime headed by Heng Samrin. But the Pol Pot Government is still recognized by the United Nations, and its leaders were joined last June in an insurgent political coalition by both Mr. Son Sann's Khmer People's National Liberation Front and a faction loyal to Prince Norodom Sihanouk, the former head of state.

President Reagan today turned down a request by Governor Cuomo to intercede in the Metro-North railroad strike. Federal intervention in the month long dispute ''could set an unfortunate precedent,'' according to a letter that Transportation Secretary Elizabeth H. Dole wrote today to Mr. Cuomo on behalf of Mr. Reagan. ''We believe that labor disputes on local transit systems should be resolved locally through collective bargaining,'' the letter said.

The Going Out Guide last Monday gave an incorrect date for readings by Betty Comden and Adolph Green at the Donnell Library Center. They will take place Monday at 12:30 P.M.

International World bank lending rules would be tightened in return for bigger U.S. contributions to the I.M.F. under a plan bank regulators will submit to Congress today. Among other things, officials said, banks would be barred from enhancing their current income through fees they get for rescheduling loans to developing countries. (Page D1.) Trade and finance ministers of six other leading industrial nations were invited by Treasury Secretary Donald T. Regan to talks in Paris. The purpose of the May meetings, he said, is to help prevent clashes between trade and monetary policies. (D14.)