THE LATEST word from Moscow is about reducing the prospects of war in space. Receiving a group of Democratic senators, Yuri Andropov raised the possibility of both unilateral and negotiated limits on anti-satellite weapons--those with which the superpowers might try in a crisis to blind each other's electronic eyes in space. The first reports did not make clear exactly what the Soviet leader was proposing: to eliminate the Kremlin's existing anti-satellite weapons (the United States has none so far but is on the verge of testing), to establish a moratorium on future development, or what? His interest in the subject, however, seemed intense.

As well it might be. For years the Soviet Union has enjoyed a monopoly, testing and maintaining anti-satellite systems with at least a limited capability of knocking out some of the communication, reconnaissance and navigation satellites on which the United States depends to detect enemy strategic forces and to direct its own. Only now is the United States about to test an anti-satellite weapon. But it incorporates newer and more advanced technologies and thus brings into play a scientific advantage of which the Soviet Union is justly apprehensive. The Kremlin may also feel an extra edge of concern lest the United States start forging ahead in the related field of anti-missile defense in space-- Mr. Reagan's "star wars" proposal of last April. This is the moment Mr. Andropov has chosen to speak of checking anti-satellite weapons. 2 Sen. Claiborne Pell (D-R.I.), who led the delegation received in the Kremlin, noted that the Andropov initiative would have to be studied closely to ensure it was not simply a ploy to forestall the American anti-satellite tests. That will require the Reagan administration to do something it has been slow to do in the past: to put forward an effective negotiating strategy. It has justified its slow pace in part by contending that it needed to move toward tests in order to give Moscow an incentive to go beyond its earlier paper arms control proposal in this field. With Moscow now nibbling, the Reagan team is under a burden to show that it is not so wedded to an anti-satellite test and deployment program that it cannot add a negotiating track to its policy.

Anti-satellite weapons are not the main arena of either strategy or arms control. Attempts to limit them are likely to be a rider--a satellite, if you will --on the big strategic arms talks, whose prospects remain extremely uncertain.

Anti-satellite weapons are, however, a distinct and dangerous class. One side's fear that the other might gain a decisive crisis advantage by destroying its chief means of detection and control could quicken the impulse for a first strike. An arrangement that left each side confident that its deterrent capacity would remain intact would be of immense value, even if there were no larger arms control agreement.