Amid all this ferment, a slight adjustment is being made to the agreed schedule for hypermedia. In theory, CD-Roms are an interim form, necessary because the carrying capacity of the telephone system is so limited. Unfortunately, in all but a few areas, the CD-Rom format has turned out costly to produce and difficult to sell. Now the industry is marketing "hybrids", disks that can dial up to their own Web sites, like a ground station beaming signals from a satellite. (Confusingly, the term "hybrid"is also applied to CD-Roms that run on both Windows and Macintosh systems.)
Although the hybrid experiment is being pioneered by the children's publisher Dorling Kindersley, the one company besides Microsoft making a conspicuous success of multimedia CD-Roms, it is a simple formula that can be implemented by any CD-Rom publisher. Maris Multimedia have adopted it for Solar System Explorer (pounds 39.99), itself a curious hybrid of game, documentary and educational genres. It is not marketed as a children's title, though it has an obvious appeal to boys at the peak of their educational efficiency, just before the pubertal hormones kick in and ruin it. It will also speak to the souls of those for whom the perfect romantic gift from an antique shop would be a slide rule.
You certainly have to like sums to get the most out of Explorer. The trouble with a simulated view from a spacecraft is that, most of the time, it consists of a very small dot, the destination planet, surrounded by lots of even smaller dots. When you reach your destination, the big excitement is launching probes towards its surface; these then crash unless you have adjusted the fuel/ payload ratio correctly. Similarly, the key to successful mission planning is the elusive "optimise" button.
Even an optimised mission has its interplanetary longueurs, though, where one wanders off to the Library or the Museum. These are the real substance of Explorer, which is an encyclopaedia rather than a simulator at heart. The on-board resources feature video clips of spacecraft, animated expositions of how earthquakes work, and discussions of questions like whether Pluto is a proper planet or not.
Once these pall, you can jump to Explorer's Web pages, which feature "Hot News" from space, and links to more than 500 space-related Web sites. A highlight, according to the Explorer site's editors, is a NASA page that tells you the exact position of the Galileo probe every minute. Apart from the neurotic frequency with which it is updated, it is typical of space sites in that it consists principally of long numbers with decimal places. The poetry of the stars eludes even those that buck the trend, such as the page headed "NASA's newest cosmonaut: Russian station immense, doesn't smell".
Space enthusiasts may welcome a convenient gateway to 500 space sites. But as it's not difficult to find such locations directly, the CD may come to look like the tail rather than the dog. However often the associated Web pages are refreshed, the disk will still have to stand on its own merits. And that means no more imitation marble or classical columns, the flock wallpaper of multimedia design. Especially not in interplanetary spacecraft of the early 21st century.