First the rhapsody, then the grumble.

We live in a fantastic age of astronomical discovery. No one is a greater fan of space-probe epics than I. As Voyager 2 passed no less than four giant worlds and their satellite families in 1979, 1981, 1986 and 1989, I was hooked on the news as I avidly imbibed the experience, which will not come again at any time in history, of seeing these worlds imaged in detail from close-up for the first time. (All right, Pioneers 10 and 11 preceded the Voyagers, but were relatively primitive efforts.) And the views from the Martian surface, in 1976 and 1997 and then in 2004, the latter ongoing.... the mind boggles with delight. In a sense.

Switch to grumble mode. As a result of these meddlesome probes, people have stopped writing (or publishers have stopped printing) old-style Solar System Planetary Romance (SSPR).

Planetary Romance is that subgenre of SF in which the plot of the story is rooted to a significant degree in the nature of a particular world. SSPR is the sub-sub genre, in which the planet in question belongs to our own sun's family of worlds. Advances in astronomy during the past half century have had an inhibiting effect on SSPR, but this does not have to be so.

Critics tend to assume that SSPR must die out just as stories such as Rider Haggard's She could not be written nowadays. But the analogy with Terrestrial exploration and its literary effect is, I would argue, a weak one. Sure, one could point out that writers increasingly set their Utopias or their adventures in outer space as the Earth's blank areas were filled in. But to go on from this and suggest that the Solar System's blanks are being filled in, in the same way, is a fallacy.

My justification for saying so is as follows.

For a long time the planets of the Solar System have been accumulating what one might call planetary personalities, in human thought and fiction. This process has some origin in myth, as with warlike Mars and feminine Venus, but most of the tradition has accumulated in the nineteenth and early twentieth centuries, when astronomers and early science fiction writers put forth their ideas. These depictions, were not all random but formed certain streams, so that the Mars of Burroughs, Bradbury, Brackett, Heinlein and Lewis, though differing tremendously with each writer, shares some soul in common. All of these writers, and early scientists too, did things to our image of the worlds in question, so that it is now too late to destroy - not that one would wish to destroy - the archetype they created. You could say that the many fictions and speculations concerning the planets are like the planting of flags, staking claim to the terrain of the imagination. Finders keepers! Too late for space probes to enforce their realism to the exclusion of the worlds' literary personalities, which are now part of our heritage.

As such, they are still legitimate scenes for novels. If only writers were to realize this! A lot of works that should have been written, remain unwritten. For example there's a vacancy for a good yarn set on Mercury, the old Mercury of the Twilight Belt and the eternally cold and hot hemispheres. There's a vacancy for a tale set among Jupiter's four large moons. Lin Carter made a reasonable effort in his first three Callisto books, but the rest tailed off in quality, and anyhow they missed, in my view, a great chance to connect the series with the other Galilean satellites: imagine a series of adventures spanning all four! As to Jupiter iself, imagine the treat we'd have had if Edgar Rice Burroughs had continued with his Sassoom adventures that began with "Skeleton Men of Jupiter"! Vacancies exist for tales set on Saturn; the only one I know of is the Donald Suddaby juvenile, Prisoners of Saturn, which is hard to get hold of - I read a library copy. It is an original tale, and its Saturn is unforgettable, though there isn't enough of it. A vacancy exists for stories set on an inhabited Moon; H G Wells' The First Men in the Moon and Edgar Rice Burroughs' The Moon Maid being the only two such novels I know of. Both of them are set largely inside the Moon rather than on its surface; no novel that I know fills the vacancy for a tale set on an inhabited Moon in ancient times, a Moon that still retains a civilization on its outer surface.

In the outer solar system, the planet Uranus is being taken care of by the Ooranye Project, which currently (as of November 2007) has produced five stories set on that world, with a sixth soon due. Neptune has featured in quite some detail in Olaf Stapledon's Last and First Men and Last Men in London, though these are not planetary romances so much as visionary chronicles. Pluto (still counting as a planet in the world of the imagination) is too cold and small and distant to have had a novel devoted to it.

C S Lewis' Narnia tale The Voyage of the Dawn Treader, has the Narnian firmament peopled by living stars - eliciting the remark from the English boy Eustace that in our universe a star is a huge ball of flaming gas. In other worlds, nothing magic here. Aslan however replies: "Even in your world that is not what a star is but only what it is made of."