films. If there is an Earth-size planet out there, it is at least three times as
distant as Pluto, and a gas giant would have to be six times as far. Negative data
win
no prizes but they are the bedrock of science.
Until James W. Christy on 22 June 1978 discovered Pluto’s satellite, Charon,
it was possible for us romantics to entertain the happy thought that Pluto was
loaded with valuable heavy metals; the best estimate of its density made this
plausible. But the mass of a planet with a satellite can be calculated quite easily
and accurately, and from that, its density.
The new figure was much too low, only half again as heavy as water. Methane
snow? Perhaps.
So once again a lovely theory is demolished by an awkward fact.
Nevertheless Pluto remains a most mysterious and most intriguing heavenly
body. A planet the size and mass of Mars might not be too much use to us out there .
. . but think of it as a fuel dump. Many stories and many nonfictional projections
speak of using the gas giants and/or the rings of Saturn as sources of fuel. But if
Pluto is methane ice or water ice or frozen hydrogen or all three, as a source of
fuel- conventional, or fusion, or even reaction mass-Pluto has one supremely
important advantage over the gas giants: Pluto is not at the bottom of a horridly
deep gravity well.
Finished calculating? Good. Please turn to page 368 and see why I wanted our
trip to Pluto to be a distance of 31.6 A.U.-plus other goodies, perhaps.
11. 1950 Your personal telephone will be small enough to carry in your
handbag. Your house telephone will record messages, answer simple inquiries, and
transmit vision.
1965 No new comment.
1980 This prediction is trivial and timid. Most of it
has already come true and the telephone system will hand you the rest on a custom
basis if you’ll pay for it. In the year 2000, with modern telephones tied into home
computers (as common then as flush toilets are today) you’ll be able to have
3-dimensional holovision
along with stereo speech. Arthur C. Clarke says that this will do away with most
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personal contact in business. I agree with all of Mr. Clarke’s arguments and
disagree with his conclusion; with us monkey folk there is no substitute for
personal contact; we enjoy it and it fills a spiritual need.
Besides that, the business conference is often an excuse to loaf on the
boss’s time and the business convention often supplies some of the benefits of the
Roman Saturnalia.
Nevertheless I look forward to holovideostereophones without giving up
personal contacts.
12. 1950 Intelligent life will be found on Mars.
1965 Predicting intelligent life on Mars looks pretty silly after those
dismal photographs. But I shan’t withdraw it until Mars has been thoroughly
explored. As yet we really have no idea-and no data-as to just how ubiquitous and
varied life may be in this galaxy; it is conceivable that life as we don’t know it
can evolve on any sort of a planet. . . and nothing in our present knowledge of
chemistry rules this out. All the talk has been about life-as-we-know-it-which means
terrestrial conditions.
But if you feel that this shows in me a childish reluctance to give up
thoats and zitidars and beautiful Martian princesses until forced to, I won’t argue
with you-I’ll just wait.
1980 The photographs made by the Martian landers of 1976 and their orbiting
companions make the prediction of intelligent Martian life look even sillier. But
the new pictures and the new data make Mars even more mysterious. I’m a diehard
because I suspect that life is ubiquitous-call that a religious opinion if you wish.
But remember two things: Almost all discussion has been about Life-as-we-know-it.. .
but what about Life-as-we-don’t-know-it? If there were Martians around the time that
those amazing gullies and canyons were formed, perhaps they went underground as
their atmosphere thinned. At present, despite wonderful pictures, our data are very
sparse; those two fixed landers are analogous to two such landing here: one on
Canadian tundra, the other in Antarctica-hardly sufficient to solve the question: Is