Politician Read Free

space there is constantly explored by radar. Nevertheless, subs often evade detection. To understand how this is possible, it is necessary to grasp the general nature of radar and similar systems.
    Radar is simply an electronic signal broadcast into space. When it encounters an object, it bounces back to its source. A receiver notes that returning signal and calculates the distance by the time required for the signal to return. This is normally a reliable procedure, except when the region is crowded with a confusing number of objects, such as the particles of a planetary ring system. Even then, a properly programmed computer can identify all of the natural and “friendly” objects in the vicinity and highlight the suspicious ones. But the principle remains: The computer depends on the returning signals to spot the objects. If no signal returns the machine assumes that region of space is clear. This seems reasonable enough.
    But suppose you could evade or divert the signal, so that it did not bounce back? Reflect it to the side instead of back? Or simply absorb it? That is what a sub does. It uses a special gravity shield to form a black-hole effect that absorbs all incoming energy, including the radar signals. That makes it effectively invisible to radar. Of course some care is necessary; if a sub passes between a person and the sun, it will show up as a dark blot. It also blots out the light of any star it occludes. Parties watching for subs are alert for this and pay close attention to what isn't visible, such as a particular star, as well as what is.
    Again, a programmed computer can constantly verify the positions of all light sources and signal alarm when any fail even momentarily. But a carefully maneuvered sub can avoid occluding any sufficiently bright stars while it floats near a planet and so remain invisible—up to a point. Close to a planet there are too many watching satellites, and the silhouette of the sub looms proportionately larger until concealment is impossible.
    So most subs remain deep enough in space to hide but as close to the target planet as feasible, covering it with their deadly missiles. Jupiter subs surround Saturn, and Saturnine subs surround Jupiter. If war should break out the planet-to-planet missiles might well be intercepted before scoring, but sub-to-planet missiles could devastate any city on any planet. That is the true balance of terror. Subs, more than any other factor, contribute to the general feeling of insecurity on every planet; no one can be sure that his city would survive a third System war—and there is a general fear that such a war is inevitable. It makes planetary populations edgy, in much the way that a man threatened with arbitrary execution might be edgy. There are reasonably frequent flare-ups of protest and even violence scattered around the System, but no one has found a way to diffuse the threat. Perhaps one of the major appeals of the difficult life in the Belt is that the widely scattered settlements there would be most likely to survive a System war.
    So I was in a sub. What was the significance of that? This was surely not a missile sub; those were too precious for the mere torturing of mem-washed captives. But escape from any sub was hopeless to the n th power. I couldn't flash a light out a porthole, for the signal-damping field would extinguish that.
    Theoretically I might surprise someone, grab a weapon, and take over the ship, but that sort of heroic is feasible only in fiction, and not the best fiction at that. In real life ships have safeguards, such as automatic sleep gas released into the air when unauthorized personnel step onto the bridge, and secret codes for the life systems support and drive computers. Only the regular personnel could operate this ship; I knew that without needing verification. It was one of the advantages of my Navy experience: I knew what wasn't practical. All I could do was try to steal a suit and escape the ship—and outside