The first reason is the 鈥渁bsence of evidence鈥�. There are two parts to this:
the failure of the SETI programmes鈥攖he search for extraterrestrial
intelligence鈥攖o detect extraterrestrial radio signals, and the lack of
evidence for extraterrestrial visits to Earth. The SETI argument is admittedly
weak because only a small number of stars have so far been covered, and these at
a limited range of radio frequencies. The second argument is stronger, and was
dealt with in 1975 by Michael Hart in his seminal paper 鈥淎n explanation for the
absence of extraterrestrials on Earth鈥� (Quarterly Journal of the Royal
Astronomical Society, vol 16, p 16).

Hart pointed to the lack of evidence for alien visits to Earth. Certainly,
Earth has never been 鈥渢aken over鈥� by extraterrestrials, as this would have put
an end to our own evolution. There are only three plausible explanations. First,
interstellar spaceflight is impossible. Secondly, cultural or political factors
prevent alien civilisations from achieving interstellar travel, or otherwise
persuade them to leave life on other planets alone. Thirdly, ET civilisations
are rare or absent.

It seems unlikely that interstellar spaceflight is impossible. Even today, we
can envisage propulsion strategies which might make it possible to reach between
10 and 20 per cent of the speed of light, permitting travel between nearby stars
in a few decades (see The Starflight Handbook by Eugene Mallove and
Gregory Matloff, John Wiley, 1989). Any civilisation with this technology would
be able to colonise every planetary system in the Galaxy in about 10 million
years, which is only one-thousandth of the age of the Galaxy. Thus, any attempt
to reconcile the 鈥渁bsence of evidence鈥� with a Galaxy teeming with technological
civilisations must rely on the 鈥渟ociological鈥� explanations identified by Hart.
The most important of these are: that ET civilisations destroy themselves before
they can develop interstellar spaceflight; that ET civilisations have no
interest in colonising the Galaxy; and that ET civilisations have strong ethical
codes which prevent them from interfering with primitive life forms.

The problem with all these explanations is that they appear plausible only if
the number of civilisations is quite small. If the Galaxy contains thousands of
technological civilisations (as SETI optimists often suppose), is it likely that
they would all destroy themselves, or be content with a sedentary existence, or
be super-ethical? The implausibility of such arguments appears particularly
great if we consider that the only civilisation we know anything about, namely
our own, has not destroyed itself and shows every sign of being expansionist.
Moreover, it is not especially ethical in its treatment of other forms of life.
Earth has been wide open to interference from outside for billions of years, and
yet there is no evidence that this ever happened. This would seem to imply that
extraterrestrial technological civilisations are either absent (as Hart argued),
or at least sufficiently rare for some combination of 鈥渟ociological鈥�
explanations to plausibly account for the absence of evidence.

The history of biological evolution on Earth supports this conclusion. Life
first appeared about 4 billion years ago, yet the Earth itself is only 4.5
billion years old. The fact that life arose so quickly suggests that this step
is relatively easy for nature to achieve. This is consistent with current
biochemical thinking, which, in the words of Nobel prize-winning biologist
Christian de Duve, is coming round to the view that 鈥渓ife is almost bound to
arise . . . wherever physical conditions are similar to those that prevailed on
our planet some four billion years ago鈥� (Vital Dust, Basic Books,
1995). If life did evolve independently on Mars, this conclusion would be
greatly strengthened.

However, while the rapid appearance of life on Earth augurs well for the
prospects of simple life in the Universe, subsequent evolutionary history leads
us to expect that more 鈥渁dvanced鈥� forms of life will be quite rare. This is
because multicellular life did not appear on Earth until about 0.7 billion years
ago. For more than 3 billion years Earth was inhabited solely by single-celled
microorganisms. In contrast to the rapidity with which the first bacteria
appeared, this may imply that the evolution of more complicated life forms is
very difficult. If this was the case, the transition to multicelled animals
might occur on only a tiny fraction of the millions of planets that may be
inhabited by single-celled organisms.

These two lines of argument lead to the same conclusion: while life may be
common in the Galaxy, 鈥渁dvanced鈥� multicellular life, and therefore technological
civilisations, are probably extremely rare.

It is of course true that we can build large telescopes, such as Gemini,
whereas we cannot yet build starships. But to suggest that telescopes better
symbolise the future of science seems bizarre. The advantages of space flight
were glimpsed even before the first telescope had been turned to the heavens.
In his book De l鈥檌nfinito universo et mondi published in 1584, the Italian
philosopher Giordano Bruno expressed this view poetically:

Henceforth I spread confident wings to space; I fear no barrier of
crystal or of glass; I cleave the heavens and soar to the infinite. And
while I rise from my own globe to others And penetrate ever further through
the eternal field, That which others saw from afar, I leave far behind
me.

These few lines encapsulate all the advantages that starships will
have over telescopes. No matter how big and powerful our telescopes become,
they will always be doomed to look at the Universe from afar, and so there
will always be much about the Universe that they will never reveal. The
aim of astronomy is to maximise our knowledge of the Universe, and we must
realise that telescopes, although they have served us well for almost four
centuries, are only tools to that end. It must be admitted that starships
would be much more powerful astronomical tools.

The recent exploration of the Solar System shows that visiting other
astronomical bodies offers many advantages. Spacecraft have provided data
which could never have been obtained with telescopes from the surface of
the Earth. Take for example the structure of the lunar crust determined
by the Apollo experiments, and the composition of the Martian soil as measured
by the Viking landers. Such information could not have been obtained using
telescopes on Earth.

There is every reason to believe that, if starships are ever built,
the rest of astronomy will undergo a similar enrichment. Just imagine the
opportunities. For example, merely by opening up a baseline between the
Sun and our second nearest neighbour Alpha Centauri (4.2 light years away)
we could extend the directly measured distance scale well out into extragalactic
space. Much more exciting would be our ability to measure accurately the
properties and environments of stars of a whole range of spectral types,
together with the physics and chemistry of the interstellar medium while
en route.

Furthermore, assuming that planets will one day be discovered around
nearby stars, interstellar travel would enable us to study them in detail.
Finally, consider the possibilities for 鈥榚xobiology鈥� 鈥� the study of extraterrestrial
life. Some scientists believe that such life could be studied using radio
telescopes, but it seems much more likely that life around nearby stars,
if it exists, would be at a microbial stage of evolution, requiring microscopes
for its study.

Thus, astronomy (and indeed all science) has a vested interest in the
realisation of interstellar space flight. Although the engineering challenges
would be immense, there is nothing impossible about interstellar travel.
For data to be returned on a timescale of decades, the starships would have
to travel at 10 or 20 per cent the speed of light. Such a speed is well
within the domain of the physically possible.

All studies of interstellar travel have concluded that a significant
industrial infrastructure in space would be an absolute prerequisite. We
cannot yet build the starships, but we can at least make a start on the
infrastructure. Thus, the present lack of vision and the growing hostility
to space development in some quarters of the astronomical community is deeply
lamentable. What, after all, is the alternative to interstellar space travel?

The very best we could hope for would be to remain on this planet until
the Sun becomes a red giant, when everything that humanity has ever accomplished
will be destroyed. And as far as astronomy is concerned, it doesn鈥檛 matter
how big and sophisticated our telescopes might become in all that time.
As long as we are forced to stare across the light years from a single
location in the Galaxy, our astronomical knowledge will remain impoverished.
How much better it would be to 鈥榮pread confident wings to space鈥�, and to
get ourselves and our instruments out among the stars.

Ian Crawford is an astronomer in the Department of Physics and Astronomy,
University College London.

Immanuel Kant

THE COLD WAR was a profitable time for the armaments industry, particularly
in the US. Indeed, by 1961 the industry had grown so much that President
Eisenhower was able to point out, in his farewell address to the American
people, that its 鈥榠nfluence is felt in every city, every state house, every
office of the federal government鈥�. We may be sure that its political influence
has not declined since then, as is amply illustrated by the fact that highly
questionable military projects, most particularly the Strategic Defense
Initiative, continue to find favour in high places.

Recent political changes, however, have left the 鈥榤ilitary-industrial
complex鈥� (to use Eisenhower鈥檚 phrase) in something of a quandary. The truth
is that the recent changes that have occurred in US-Soviet relations, stemming
as they do from the emancipation of Eastern Europe and political reform
in the Soviet Union, have essentially destroyed the professed raison d鈥檈tre
of the US鈥檚 armaments industry. However, its economic and social importance
is now so great that it cannot be drastically wound down without serious
short-term consequences 鈥� and although many may consider that the arms makers
deserve little sympathy in a disarming world, we may be sure that they will
use their undoubted political influence to try to maintain the status quo.
It would therefore appear to be highly desirable that the high-technology
companies that today specialise in producing expensive weapons are able
to find alternative business. The more such alternative business that is
found, the less will be the corporate resistance to disarmament.

However, as others have pointed out, the armaments industry is not well
adapted for diversification into other fields of business (see, for example,
a paper by M. L. Weidenbaum in Disarmament and the Economy, edited by E.
Benoit and K. E. Boulding, Harper and Row, 1963). This is largely due to
its heavy reliance on a single customer (the central government), its large
investment in specialised skills organised around highly complex projects,
and the high unit cost of its products (which are, of course, paid for by
the taxpayer). This led Weidenbaum to suggest that 鈥榯he adjustments to disarmament
by companies, such as aircraft manufacturers, heavily engaged in military
production would be most fruitful in the areas of governmental and industrial
demand which are relatively closely related to their past experiences and
肠补辫补产颈濒颈迟颈别蝉鈥�.

Thus, although there are important social projects that would benefit
from the money spent on the military, these will not, in general, be sufficient
to satisfy the high-technology arms contractors. And, although the developed
world certainly has a duty to, for example, invest in global development,
an attempt to fund this solely by ending government contracts to these companies
is likely to meet serious political obstacles, even in the absence of an
actual military threat. Since the first priority at this stage in world
history must be to end the arms race and move towards disarmament, a suitable
alternative to weapons manufacture must be found. This was recognised by
the 鈥楤randt Report鈥� (North-South: A Programme for Survival, Report of the
Independent Commission on International Development Issues, MIT Press, 1980),
which stated that 鈥榯he fundamental need 鈥� from the world development standpoint
鈥� is for the industrialised countries to direct themselves towards peaceful
high-technology production, which could make use of the highly skilled manpower
currently employed in arms industries鈥� (my italics).

At least as far as the aerospace and electronics companies are concerned,
there appears to be only one obvious alternative to military production
that would fully satisfy this criterion, namely a greatly expanded programme
of space exploration and development. I would therefore like to argue that,
by providing an alternative outlet for the weapons industry, an expanded
programme of space exploration could make a significant contribution to
the primary goal of superpower disarmament. Similar views have been aired
before, for example in The Greening of Mars, by Michael Allaby and James
Lovelock (Andre Deutsch, 1984), but the ending of the cold war has suddenly
made them much more realistic.

Space is the obvious alternative for these companies because the technologies
involved are similar to those required by the military, and many of the
military contractors already have a significant interest in developing space
hardware. The table overleaf lists the annual revenues (sales) of 10 major
American aerospace companies, together with the value of NASA con tracts
awarded to these companies in the 1989 financial year. The figures for company
revenues have been taken from their 1988 annual reports (the 1989 annual
reports were not available at the time of writing), while the value of NASA
contracts is derived from NASA鈥檚 Annual Procurement Report for the fiscal
year 1989. Of course, comparison of 1989 contracts with 1988 sales will
somewhat overestimate the relative importance of the former, but this does
not affect the following argument.

The table shows that the leading aerospace companies accounted for about
45 per cent of NASA鈥檚 total 1989 procurement budget of $10.9 billion, but
that, on average, NASA鈥檚 1989 contracts amounted to only about 5 per cent
of their previous year鈥檚 sales. With the exception of Boeing, whose business
is dominated by civil aircraft, and United Technologies, Rockwell International
and Morton Thiokol, approximately half of whose total revenues are due to
their other commercial interests, the bulk of the non-NASA revenues listed
in the table are due to military projects. Thus it seems that, at least
in principle, disarmament could be gradually achieved by decreasing the
value of government military contracts, while increasing the value of (civilian)
space contracts to the same companies. Although some restructuring would
presumably be required, such an exchange would seem to hold few horrors
for the companies and their shareholders.

It is worth estimating the possible value of an expanded space programme
to the aerospace industry. Consider, for example, a recent report from NASA,
which envisions an expanded space station, a lunar base in place by 2004,
and a Mars base by 2019 (Report of the 90-day Study on Human Exploration
of the Moon and Mars, 1989). NASA estimates that the establishment of these
facilities, and their operation through to 2025, would require an annual
expenditure of about $30 billion by 1995 (approximately twice NASA鈥檚 budget
request for next year of $15 billion), growing to a roughly constant level
of about $35 billion after the turn of the century. Thus, this particular
programme of Moon and Mars exploration would require an additional outlay
of $15 to 20 billion per year. As can be seen from the table, this is comparable
to the annual revenue of one of the larger American aerospace companies.
Thus, by going ahead with this, or some similar, space mission, the US government
would be able to reduce its military expenditure significantly while maintaining
the present level of business for the aerospace industry.

What is more, the proposals in NASA鈥檚 report are rather modest. For
example, the expanded Freedom space station, which will support the Moon
and Mars operations, is envisioned as having a maximum permanent crew of
12; the maximum crew for the Moon base (after 2006) is eight, and that for
the Mars missions is only four. Thus, given the resources, there would seem
to be plenty of room for expansion. For example, a new, larger, space station
could be built to act as a dedicated space transportation node, thereby
freeing Freedom for microgravity and other research. Also, both the Moon
and Mars bases could be significantly expanded and moved towards self-sufficiency
earlier; the Mars transfer vehicles might be made larger and designed to
provide artificial gravity; a Mars-orbiting space station might be included
in addition to the surface outpost; and so on. The nice thing about space
is that it is, quite literally, open-ended, and additional military capacity
could be replaced by expanding the scale of operations appropriately.

However, an expanded space programme should not be seen merely as a
safety valve for the interests of the aerospace industry. It is not just
a case of replacing a wasteful and dangerous activity by one that is equally
wasteful, but at least harmless. Space development offers positive advantages
which military development does not. For example: (1) Space exploration
lends itself naturally to international cooperation, and can therefore continue
to foster international understanding even after disarmament has been achieved.
Indeed, it may not be too much to hope that, by providing a nondestructive
form of adventure, space exploration may be able to contribute to something
approaching William James鈥檚 鈥榤oral equivalent of war鈥�.

(2) An ambitious space programme is likely to act as a stimulus for
scientific and technical education (certainly my own interest in science
was greatly stimulated by the Apollo project).

(3) The human exploration and colo nisation of the Solar System will,
without doubt, contribute greatly to human know ledge, especially in the
fields of planetary science and space astronomy. (Although some contemporary
astronomers and space scientists have opposed ambitious manned space programmes,
these arguments arise because, at present, manned space missions compete
with low-cost automatic missions; if the former were to obtain their funding
from what is now the military budget, no such competition would occur.)
(4) It is at least possible that the development of a space-based industrial
infrastructure, based around the exploitation of extraterrestrial resources,
will one day become an economic necessity. If, by the end of the next century,
a world population of, say, 10 billion people is to be maintained with an
acceptable standard of living, and if this state of affairs is to be maintained
indefinitely but without destroying the biosphere, it may be necessary to
use extraterrestrial resources to supplement those of Earth. Although such
a possibility lies in the more distant future, this is no reason not to
make an early start on the groundwork 鈥� at least to the extent of compiling
an inventory of the Solar System鈥檚 economic potential.

The expansion of space activities, in addition to helping the disarmament
process, can therefore also be seen as an investment in the future of humanity.
No comparable arguments can be made in favour of continuing large-scale
military production.

Ian Crawford is an astronomer in the Department of Physics and Astronomy,
University College London.

鈥斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌�
RELATIVE IMPORTANCE OF NASA CONTRACTS TO TEN LEADING AMERICAN AEROSPACE
COMPANIES 鈥斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌�
Total revenue (1988) NSAS contracts (1989) NSAS contracts (millions of
Dollars) (millions of Dollars) as % of total 鈥斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌�
Boeing 16,962 436 2.6 General
Dynamics 9,551 31 0.3 Grumman
3,649 103 2.8 Lockheed 10,590
931 8.8 McDonnell Douglas 15,072
506 3.4 Martin Marietta 5,727 355
6.2 Morton Thikol 2,316 420 18.1
Northrop 5,796 18 0.3 Rockwell
International 11,946 1,979 16.6 United Technologies
18,000 133 0.7 鈥斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌�
Total 99,609 4,912 4.9 鈥斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌斺赌�