IS THERE URGENCY IN COLONISING SPACE

For I dipt into the future

               far as human eye could see

Saw the vision of the world and all

               the wonder that would be,

Saw the heaven fill with commerce

               argosies of magic sails

Pilots of the purple twilight dropping

               down with cosdy bales

Alfred Lord Tennyson

in Locksley Hall

For the first time in human history, man has the technological capability to establish colonies in space. As our population continues to mount, we must look to outer space for new minerals, and other raw materials. Such colonisation seems feasible since the development of reusable spacecraft like Skylab, because they could be used to assemble in orbit the large emi­grant spaceships needed. The task of lifting such an emigrant craft away from the surface of the Earth and assembling it in orbit would definitely require very advanced technology.

Where could the emigrants go? At present no planet in our solar system has conditions suitable for human habitation. Mars is too cold, lacks water, its atmosphere is too thin and has too little oxygen. Venus is inhospitable with its enormous atmospheric pressure, lacks oxygen and has a corrosive carbon dioxide atmosphere. Mercury is too hot and virtually has no atmosphere, it is blasted by harmful ultraviolet radiation, X- rays and cosmic rays.

Some suggestions have been made about setting up an astronomical observatory on the moon with the astronauts living inside man-made domes. But while that may be possible for a few scientists it would not do for a colony. One of the most revolutionary ideas put forward in recent years has been that we should modify conditions on some of the planets in the solar system to make them suitable for human habitation. Can we?

We cannot modify say Mercury or which has no hospitable atmosphere. The Sun’s heat combined with the small gravitational pull of Mercury would cause it to evaporate. But it should be possible to turn Mars into a habitable planet by “terra-forming” it. Heat would obviously be essential. The rocks on the Martian surface are covered by iron oxide (rust), and if the surface were heated it would give off oxygen. A rise in temperature would also cause the ice caps to melt thus increasing the amount of water vapour in the atmosphere. All this has to be done to alter the composition of the planet’s atmosphere which also would increase the atmospheric pressure there. Only then it would become suitable for us. To heat the Martian atmosphere sufficiently it has been suggested that we should deflect the nucleus of a comet onto Mars or could force one or more of Jupiter’s satellites to drop down large chunks of their surfaces on to the planet. The material falling on the planet would cause heating of the surface and would also lead to the addition of some useful vaporised material to the atmosphere. Any terraforming of Mars would seem to require such a large- scale effort that if practicable at all, certainly lies very many years in the future.

By contrast changing the environment of Venus seems to be far more of a practical possibility. One famous American astronomer put forth an ingenious suggestion in 1975 in this connection. He took into account the fact that the atmosphere of Venus is very thick and composed mainly of carbon dioxide and exerts a pressure of 88 kg per square centimetre. He suggested that algae should be dropped into the upper atmo­sphere of Venus. Once there they would float in the clouds and under the brighter conditions would begin to photosynthesise . Thus the immediate result of the algae would be to reduce the carbon dioxide in Venus’ atmosphere and to replace it with oxygen. In due course the algae would drop down lower in the atmosphere where they would be burnt up in the great heat near the planet’s surface. The charring of the algae would release carbon, carbon compounds and oxygen with the result that all the atmospheric carbon dioxide would be ultimately separated into carbon and oxygen. Any water present would be retained while oxygen would combine with the surface rocks as had clearly happened sometime during the history of Mars. With all the carbon dioxide and some of the oxygen removed from the atmosphere three things would be likely to happen. In the first place the “green house effect” would be severely curtailed which would bring about a considerable reduction in temperature. Secondly because of the absorption of some of the oxygen, Venus’s immense atmospheric pres­sure would be reduced.Thirdly the presence of oxygen higher up in the modified Venusian atmosphere could lead to the formation of a layer of ozone which would absorb the ultravio­let and X-rays from the sun.

Some researchers feel that a more practical way of emigrat­ing into space would be to construct space colonies and put them into orbit around the sun. It is suggested that such colonies should be put into the same orbit as the Moon moving round the Earth in one of the so-called “Lagrangian points” on the Moon’s orbit. (These points which are found in the orbit of every planet or satellite were discovered some two hundred years ago by the French astronomer, Jospeh Lagrange. He stated that there are five such points in every orbit equally spaced from each other at 60 degrees intervals away from the orbiting-body where small objects could keep a stable orbit. We can observe such points in Jupiter’s orbit where in spite of the huge mass of Jupiter, minor planets are found to be in orbit. These two “Trojan” groups lie one 60 degrees ahead of Jupiter’s position and the other 60 degrees behind. There are no minor planets at the other three Lagrangian points because the pull of Saturn and the Planets would disturb any bodies orbiting there.

The idea is that space colonies should orbit with the Moon at the Lagrangian point that lies 60 degrees behind the Moon itself. There are sound reasons for choosing the Moon’s orbit. It is near enough and would provide most of the material for the colonies. The main bodies of the colonies will be con­structed of aluminium which is ideally suited to the job and is abundant on the Moon. (600,000 tonnes will be required for each colony). But aluminium will not afford protection against ultraviolet radiation, X-rays or cosmic rays. As such shielding is essential it is proposed that it should be made from lunar rock probably using the “slag” left over after the aluminium has been extracted. About 3 million tonnes of “slag” will be needed to make the shielding fully effective.

The colonies could be shaped like cylinders or like spheres. In both cases they would have to be kept rotating on their axes to give the inhabitants the effect of living under gravity as on Earth. This is necessary as prolonged exposure to low gravity weakens the body and for an artificial colony sufficient gravity would have to be created. By rotating the colony, the inhabit­ants would experience a centrifugal force pushing them to the inside surface of the cylinder or sphere. Energy for rotating the colony and for supplying it with power would come from the Sun. Such colonies would have to be large enough to prevent the people from feeling too cooped up; they would need to be pleasant, comfortable and to give a feeling of security. In the first stage they would probably need to be very like an Earth environment and it is expected that they would contain plants and animals as well as people. The “Bernal Sphere” as the colony would be named (after a British Scientist who thought up of this scheme many year ago) would be about 460 meters in diameter.

Another project is the suggestion for a space Ark to carry emigrants on the long journey to some other planetary system possibly putting the occupants into suspended animation by freezing, slowing down the ageing process itself. But even with such a project life could not be kept going on indefinitely— not if our universe becomes no more than a collection of black holes. Unless of course astronomers do find there are other universes and discover a way of reaching them then it might be possible to carry on life for ever. But this is pure speculation.

Some scientists are justifiably inclined to regard projects such as the “Bernal Sphere”, “Space Ark”, and “terraforming” as ambitious and bold schemes for the future which should be given up having regard to the more urgent and essential problems man has to face today. But at the same time considering the population expansion, and the limited resources available on this planet, no scientist would resist the temptation of coming up with such schemes for the colonisation of space. The explorers of tomorrow would sail to far off planets, just as Magellan and Columbus crossed the hostile seas centuries ago in search of distant lands—lands where huge buildings reaching out to the skies have now sprung up on mighty cities.