To land a spacecraft on Europa, with the heavy equipment needed to penetrate the ice and explore the ocean directly, would be a formidable undertaking. A direct search for life in Europa's ocean would today be prohibitively expensive. But just as asteroid and comet impacts on Mars have given us an easier way to look for evidence of life on that planet, impacts on Europa give us an easier way to look for evidence of life there. Every time a major impact occurs on Europa, a vast quantity of water is splashed from the ocean into the space around Jupiter. Some of the water evaporates, and some condenses into snow. Creatures living in the water far enough from the impact have a chance of being splashed intact into space and quickly freeze-dried. Therefore, an easy way to look for evidence of life in Europa's ocean is to look for freeze-dried fish in the ring of space debris orbiting Jupiter. Sending a spacecraft to visit and survey Jupiter's ring would be far less expensive than sending a submarine to visit and survey Europa's ocean. Even if we did not find freeze-dried fish in Jupiter's ring, we might find other surprises -- freeze-dried seaweed, or a freeze-dried sea monster.
Freeze-dried fish orbiting Jupiter is a fanciful notion, but nature in the biological realm has a tendency to be fanciful. Nature is usually more imaginative than we are. Nobody in Europe ever imagined a bird of paradise or a duck-billed platypus before it was discovered by explorers. Even after the platypus was discovered and a specimen brought to London, several learned experts declared it to be a fake. Many of nature's most beautiful creations might be dismissed as wildly improbable if they were not known to exist. When we are exploring the universe and looking for evidence of life, either we may look for things that are probable but hard to detect or we may look for things that are improbable but easy to detect. In deciding what to look for, detectability is at least as useful a criterion as probability. Primitive organisms such as bacteria and algae hidden underground may be more probable, but freeze-dried fish in orbit are more detectable. To have the best chance of success, we should keep our eyes open for all possibilities.
Had we lived, I should have had a tale to tell of the hardihood, endurance and courage of my companions which would have stirred the heart of every Englishman. These rough notes and our dead bodies must tell the tale, but surely, a great rich country like ours will see that those who are dependent on us are properly provided for.
[To] mechanical progress there is apparently no end: for as in the past so in the future, each step in any direction will remove limits and bring in past barriers which have till then blocked the way in other directions; and so what for the time may appear to be a visible or practical limit will turn out to be but a bend in the road.
When some portion of the biosphere is rather unpopular with the human race–a crocodile, a dandelion, a stony valley, a snowstorm, an odd-shaped flint–there are three sorts of human being who are particularly likely still to see point in it and befriend it. They are poets, scientists and children. Inside each of us, I suggest, representatives of all these groups can be found.
A casual glance at crystals may lead to the idea that they were pure sports of nature, but this is simply an elegant way of declaring one's ignorance. With a thoughtful examination of them, we discover laws of arrangement. With the help of these, calculation portrays and links up the observed results. How variable and at the same time how precise and regular are these laws! How simple they are ordinarily, without losing anything of their significance! The theory which has served to develop these laws is based entirely on a fact, whose existence has hitherto been vaguely discerned rather than demonstrated. This fact is that in all minerals which belong to the same species, these little solids, which are the crystal elements and which I call their integrant molecules, have an invariable form, in which the faces lie in the direction of the natural fracture surfaces corresponding to the mechanical division of the crystals. Their angles and dimensions are derived from calculations combined with observation.
In no subject is there a rule, compliance with which will lead to new knowledge or better understanding. Skilful observations, ingenious ideas, cunning tricks, daring suggestions, laborious calculations, all these may be required to advance a subject. Occasionally the conventional approach in a subject has to be studiously followed; on other occasions it has to be ruthlessly disregarded. Which of these methods, or in what order they should be employed is generally unpredictable. Analogies drawn from the history of science are frequently claimed to be a guide; but, as with forecasting the next game of roulette, the existence of the best analogy to the present is no guide whatever to the future. The most valuable lesson to be learnt from the history of scientific progress is how misleading and strangling such analogies have been, and how success has come to those who ignored them.
Science has a simple faith, which transcends utility. Nearly all men of science, all men of learning for that matter, and men of simple ways too, have it in some form and in some degree. It is the faith that it is the privilege of man to learn to understand, and that this is his mission. If we abandon that mission under stress we shall abandon it forever, for stress will not cease. Knowledge for the sake of understanding, not merely to prevail, that is the essence of our being. None can define its limits, or set its ultimate boundaries.
But why, it has been asked, did you go there [the Antarctic]? Of what use to civilization can this lifeless continent be? ... [Earlier] expeditions contributed something to the accumulating knowledge of the Antarctic ... that helps us thrust back further the physical and spiritual shadows enfolding our terrestrial existence. Is it not true that one of the strongest and most continuously sustained impulses working in civilization is that which leads to discovery? As long as any part of the world remains obscure, the curiosity of man must draw him there, as the lodestone draws the mariner's needle, until he comprehends its secret.
Far from becoming discouraged, the philosopher should applaud nature, even when she appears miserly of herself or overly mysterious, and should feel pleased that as he lifts one part of her veil, she allows him to glimpse an immense number of other objects, all worthy of investigation. For what we already know should allow us to judge of what we will be able to know; the human mind has no frontiers, it extends proportionately as the universe displays itself; man, then, can and must attempt all, and he needs only time in order to know all. By multiplying his observations, he could even see and foresee all phenomena, all of nature's occurrences, with as much truth and certainty as if he were deducing them directly from causes. And what more excusable or even more noble enthusiasm could there be than that of believing man capable of recognizing all the powers, and discovering through his investigations all the secrets, of nature!
Herschel prophetically implied that electricity and electro-magnetism still hid many secrets, and that their investigation would become the leading science of the new age. This would indeed be Faraday’s coming field of triumph. He summarised (paragraph no. 376) this pursuit in the image of a great and noble sea voyage of exploration. ‘There is something in this which reminds us of the obstinate adherence of Columbus to his notion of the necessary existence of the New World; and the whole history of this beautiful discovery may serve to teach us reliance on those general analogies and parallels between great branches of science by which one strongly reminds us of another, though no direct connection appears.’