* PURPOSE -- The new category of talks is intended to prevent an arms race in space by limiting antiballistic missile and antisatellite weapons, whether based on land or in space.

* HISTORY -- The Soviets proposed space-weapons talks in June but that effort foundered after the United States said it also wanted to discuss strategic- and intermediate-range nuclear weapons. The talks now planned look like a new verison of the 1970s negotiations on antiballistic missiles (ABMs) that led to the 1972 SALT I treaty.

* SOVIET SYSTEMS -- Moscow has for 10 years had a rudimentary, but operational, antisatellite system. The Soviets also have recently modernized that single ABM system, around Moscow, allowed by the 1972 SALT I treaty. Research on space-weapon technology, including laser and particle beam systems, has been underway for years.

* U.S. SYSTEMS -- An antisatellite weapon, to be launched from an F15 fighter, is in early development, with its first test against a target in space scheduled for this spring. The United States dismantled its one ABM site permitted by the SALT I treaty, but has an active research and experimental testing program to develop a more capable system. The president's $25 billion Star Wars research program is supposed to determine by the 1990s whether an adequate space-defense system could be developed.

* SOVIET PROPOSAL -- Moscow wants to bar testing or deployment of weapons in space that could destroy objects in space or on Earth.

* U.S. PROPOSAL -- The Reagan administration has yet to formulate a position, other than wanting freedom to pursue Star Wars research.

* CHIEF ISSUE -- At the outset, the Soviets will press for some "interim restraint" in the form of a moratorium on testing either antisatellite or antiballistic missile weapons or both.