Martin Balsam, Arthur Hill, Wilford Brimley and...

Martin Balsam, Arthur Hill, Wilford Brimley and Michael Ironside are starring in an unusual movie for Showtime. It’s a mystery called “Murder in Space,” about a series of fatalities aboard a spaceship carrying scientists from the United States, the Soviet Union and other countries. The twist is that while most of the film will be shown in July and August, the ending won’t be shown until September. Viewers will have an opportunity to guess at the outcome and win prizes from the pay-cable network.

NBC News is preparing a new series for children, “Time Out.” Eight hourlong episodes will air on a monthly basis next season on weekday afternoons. The magazine-format shows will be geared toward teen-agers.

China is the subject of several upcoming programs on KCET Channel 28. In addition to the ongoing Monday night series “The Heart of the Dragon,” the station will be airing two specials June 25: “Adam Smith’s Money World in China,” about the country’s economic system, and “The Yin and the Yankee,” about a hot-air balloon trip that Malcolm Forbes took across China. Another documentary due June 30 is “China: The Year of the Counting,” about the difficulties of conducting a census there.

And speaking of China, ABC Video Enterprises is helping to underwrite a major documentary series about China’s 3,600-mile Yellow River, which, like the Nile in Egypt, played an important role in the development of civilization in that part of the world. “The Yellow River” is being produced by China Central Television and Japan Broadcasting Corp. and will run 10 to 12 hours. The series may air in the United States on public television and the Arts & Entertainment cable service, and portions of it could turn up on ABC in 1987.

Ellen Burstyn will star in “Brian Walker, Please Call Home,” a TV movie for CBS. She plays the mother of a 19-year-old son who mysteriously disappears while driving from his home in Ottawa, Canada, to Boulder, Colo. Based on a true case, the film shows what she and her other son (played by Sam Robards) had to go through to learn what happened to him.

Briefly noted: The comic strip Marvin will be turned into an animated special for CBS this fall. . . . Jim Caldwell, formerly a “PM Magazine” host in New York, has been signed to host “Tic Tac Dough” next season. . . . Production is under way on the 18th season of “Hee Haw,” with Roy Clark and Buck Owens back as hosts.

The 1988 Winter Olympics are more than two years away, but ABC Sports already has set up its broadcast plans. The network intends to televise 97 hours of competition from the Games in Calgary, Canada, 53 of them in prime time. The total represents a 33% increase over 1984, but part of that is accounted for by the fact that the 1988 Games will be three days longer than their predecessor.