The first journalist in space could be a young reporter, a seasoned editor, a radio reporter, a free-lance writer, a staffer from The New Yorker, a photographer, a broadcast journalist, even Walter Cronkite. He or she could be from almost anywhere in the country, almost any age (Cronkite is 69), from a small radio station or a big metropolitan daily.

Thus, the announcement yesterday of the 100 semifinalists for the first shuttle ride for a reporter gave little hint of what sort of journalist best fits NASA's billing for the newsonaut.

The Association of Schools of Journalism and Mass Communication, which is screening the journalists for NASA until the pool is narrowed to five finalists, yesterday announced the 20 semifinalists from five regions.

Journalism officials said that the 100 will be winnowed to 40 by early May. Those 40 will then stay in the running until NASA makes a decision about when a journalist will be on the shuttle. Then the contest will begin again, narrowing the 40 to five from which NASA will pick the winner and alternate.

Most journalists contacted yesterday said they were excited about being chosen but did not know if the journalist-in-space program was one that would ever get off the ground.

And some were concerned privately at least that NASA's keeping them on the list of possible bridesmaids for so long could be an effort to earn some good publicity after more than two months of investigations of the Challenger crash on Jan. 28.

Several reporters made it clear that they are determined to make certain that NASA doesn't use them as a public relations gimmick.

"It seems absolutely paramount that whoever the reporter is that is picked, they are a pool reporter for the rest of the press corps, not for NASA," said Thomas Fiedler, political editor for The Miami Herald, who was among the 100.

To the surprise of some working on the project, the shuttle explosion did not deter any of those 100 selected to continue in the competition, even though their applications were all written before the accident. However, several said that they had discussions with their families before they decided to go ahead.

"My husband thinks it's a stupid idea," said Linda Kohl, a special projects writer for the St. Paul (Minn.) Pioneer Press and Dispatch.

James T. Wooten of Washington, one of four ABC-TV correspondents among those still in the running, said that when he returned home after the shuttle accident one of his daughters asked, " 'Okay, Dad, do you still want to go?' My response was, 'You're damn right, I want to do it,' " he said.

Other ABC reporters on the list were Lynn Sherr, William Blakemore and Barry Serafin. Former ABC superstar Geraldo Rivera is still on the list. Cronkite was the only one from the CBS network, and John Noble Wilford, who is also in the running, was the only candidate whose name was submitted by The New York Times.

At NBC, Science correspondent Robert Bazzell and Cocoa Beach, Fla., radio reporter Jay Barbree are still in the contest. So are Roger Rosenblatt of Time magazine, Newsweek's Michael A. Rogers, Richard Gore, assistant editor of National Geographic, Burton Bernstein, a writer for The New Yorker, and Jerry Flint, national editor of Forbes magazine.

Included in the first round are:

*SOUTHEAST REION: Jay Barbree of Cocoa Beach, Fla., NBC News, correspondent, Marcia F. Bartusiak of Norfolk, Va., free-lance science writer. Warren P. Corbett of Washington, BIZNET, national correspondent. Thomas E. Fiedler of Miami, Miami Herald, political editor. Jon D. Franklin of Glen Burnie, Md., free-lance writer. Richard S. Gore of Washington, National Georgraphic magazine, assistant editor. James L. Hartz of Chevy Chase, Md., WNET-TV, correspondent. Malcolm A. McConnell of Queenstown, Md., Reader's Digest, feature writer. Thomas Mintier Jr. of Atlanta, Cable News Network, reporter. robert A. Navias of Coral Gables, Fla., United Press International, correspondent. Mark J. Prendergast of Boca Raton, Fla., Ft. Lauderdale News-Sun Sentinel, Latin America correspondent. Boyce C. Rensberger of Frederick, Md., Washington Post, staff writer. James B. Reston Jr. of Bethesda, Md., Newsweek correspondent. Alexander H. Rossiter Jr. of Columbia, Md., UPI science editor. Ann K. (Kathy) Sawyer of Washington, Washington Post, reporter. Barry D. Serafin of Fairfax, Va., ABC News, correspondent. james J. Snyder (Jim Slade) of McLean, Va., Mutual Broadcasting System, correspondent. Mary E. Thornton of Washington, Washington Post, reporter. Frank V. Tursi of Clemmons, N.C., Winston-Salem Journal, reporter. James T. Wooten of Washington, ABC News, national correspondent.

*NORTHEAST REGION: David B. Arnold of North Quincy, Mass., Boston Globe, reporter. Robert J. Bazzell of New York, NBC News, science correspondent. J. Kelly Beatty of Chelmsford, Mass., Sky and Telescope magazine, senior editor. Burton Bernstein of Bridgewater, Conn., The New Yorker magazine, writer. William B. Blakemore of New York, ABC News, correspondent. Mark Bowden of Philadelphia, Philadelphia Inquirer, staff writer. Walter L. Cronkite of New York, CBS News, special correspondent. Morton N. Dean of Ridgefield, Conn., Indepdendent News Network, correspondent. Jerry M. Flint of New York, Forbes magazine, national editor. Maximo M. Gomez of Philadelphia, KYW-TV, health and science editor. Stanley S. Grossfield of Squantum, Mass., Boston Globe, director of photography. Mark A. Patinkin of Providence, R.I., Providence Journal, columnist. Geraldo Rivera of New York, free-lance journalist. Roger Rosenblatt of New York, Time magazine, senior writer. Peter L. Salgo of New York, WCBS-TV, correspondent. Lynn B. Sherr of New York, ABC News, national correspondent. Dorothy D. Storck of Philadelphia, Philadelphia Inquirer, columnist. Lindsey E. Van Gelder of New York, Ms. magazine, contributing editor. John Noble Wilford of New York, New York Times, science news reporter. Gayle Young of Westport, Conn., UPI, science reporter.

*SOUTH CENTRAL REGION: Diane Ackerman of St. Louis, Parade magazine, contributing editor. James R. Asker of Houston, Houst Post science, technology and space reporter. Mark C. Chamberlin of Wichita, Kan., KAKE-TV, associate news director. Frederic K. (Ted) Conover of Denver, free-lance writer. Diane Eicher of Lakewood, Colo., Denver Post, health writer. Steven S. Gauvain of Houston, KTRK-TV, reporter. Larry M. Hatteberg of Wichita, Kan., associate news dirctor. Chris Rene Marrou of Boerne, Texas, KENS-TV, in San Antonio, managing editor. John C. Hockenberry of Chicago, National Public Radio, reporter. Michael R. Masterson of Little Rock, Ark., WEHCO Media, special writer. John S. Meyer of Lakewood Colo., Rocky Mountain News, reporter. Robert P. (Chip) Moody II of Houston KHOU-TV, anchorman. Alcestis R. Oberg of Dickinson, Texas, free-lance reporter. Daniel T. O'Rourke of Houston, Texas, KPRC-TV, reporter. Scott C. Pelley of Dallas, WFAA-TV, reporter. Storer H. Rowley of Washington, Chicago Tribune, national correspondent. Charles W. Sasser of Gore, Okla., free-lance writer. Colice Kathryn (Katie) Sherrod of Fort Worth, Tex., Fort Worth Star-Telegram, columnist. Robert M. White II of Mexico, Mo., Mexico Ledger, editor and publisher. Al J. Wiman of St. Louis, KMOX-TV, medical-science editor.

*NORTH CENTRAL REGION: Theresa M. (Terry) Anzur of Chicago NBC News reporter. Linda Yu Baer (Linda Yu) of Chicago, WLS-TV, reporter. Dennis L. Breo of Chicago, American Medical News, special a Minn., Minneapolis Star and Tribune, columnist. Linda Y. Kohl of St. Paul, Minn., St. Paul Pioneer Press and Dispatch, reporter. Ronald M. Kotulak of Chicago, Chicago Tribue, science writer. Caroline T. (Terry) Marotta of Winchester, Mass., free-lance journalist. Mary D. Murray of Iowa City, Iowa, Des Moines Register, reporter. Donn. A. Pearlman of Chicago, WBBM-AM and WBBM-TV, staff newsperson. Paul H. Recer of Houston, Associated Press, correspondent. Robert B. Shaw of Des Moines, Des Moines Register, reporter. Barbara M. Stanton of Detroit, Detroit Free Press, reporter. Thomas W. Tulley of Newburgh, Ind., Evansville Press, editor. Steven J. Vogel of Bloomington, Ill., WJBC-WBNQ Radio, news director.

*WESTERN REGION: A. Blaine Baggett of Los Angeles, KCET-TV, executive producer. Marcida A. Dodson of Irvine, Calif., Los Angeles Times, reporter. Susan A. Farrell of San Diego, KGTV, newscaster. Timothy T. Ferris of Hollywood, Calif., free-lance journalist. Willard E. (Gene) Gleeson of Los Angeles, KABC-TV, reporter. Michael W. Gold of San Rafael, Calif., constributing editor for Science 86 magazine. Steven R. Goldsmith of Seattle, Seattle Post-Intelligencer, reporter. Richard Hart of San Francisco, KPIX-TV, reporter. Michael F. Hegedus of San Rafael Calif., KPIX-TV, feature reporter. Patricia E. Klein of Chatsworth, Calif., Los Angeles Times, reporter. Martin Kimball Livingston of San Francisco, San Francisco Chronicle, reporter. Thomas J. (Jay) Mathews of Pasadena, Calif., Washington Post, bureau chief. Lee N. McEachern Jr. of Greenbrae, Calif., KGO-TV in San Francisco, reporter. Michael D. Parfit of Santa Barabara, Calif., free-lance writer. Charles W. Petit of San Francisco, San Francisco Chronicle, reporter. John Popejoy of Los Angeles, KCOP-TV, reporter. Peter M. Rinearson of Seattle, Seattle Times, reporter. Michael A. Rogers of Oakland, Calif., Newsweek, general editor. Jim L. Schefter of Playa del rey, Calif., free-lance writer. Douglas W. Struck of San Francisco, Baltimore Sun, correspondent.