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Thursday, July 28, 2011

At Home in the Solar System



How far can the human horizon in space expand? Space enthusiasts should not assume that this is merely an incremental matter. Let me consider first the possibility of colonizing the solar system, and then of expanding into the galaxy.

At Home in the Solar System

Colonizing the solar system requires that we solve the serious problem of prolonged exposure to radiation. Better shields, faster spaceships, and piles of dirt on top of our outposts should help a great deal. Better shields are within our technological means, and piling dirt on top of, say, inflatable dwellings should not present any major obstacles. Faster spaceships have been on the drawing board for a long time: fission rockets, fusion rockets, ion propulsion rockets, laser-propelled rockets, and even solar sails. Fission rockets and ion propulsion rockets would use tried-and-true technologies. Ion propulsion, for example, works on the principle of particle accelerators: you take a charged particle and you accelerate it by means of electromagnetic coils; the particle picks up a very large exhaust velocity and, by Newton’s Third Law, it propels the rocket forward. The solar sail would use the solar wind to move around the inner solar system with great ease and at great speeds. It would consist of very large sails made of very thin sheets of metal that would move under the pressure of the solar wind. The Planetary Society, an organization of space enthusiasts, has arranged with the Russian space program for a deployment in space of such a device in the near future. All these three systems could in principle reduce a trip to Mars from about a year, on the average, to perhaps as little as three months or less.

We also need to solve the physiological problems created by microgravity. Perhaps the best solution is simply to create what is sometimes called "artificial gravity", which is not more than an application of the equivalence between acceleration and gravitational attraction. If a ship accelerates at a rate of approximately 10m/sec2, which is the value of 1 g, a passenger would feel as if he were on the surface of the Earth (a favorite illustration is of an elevator that ascends to the heavens unbeknownst to an unsuspecting passenger; as the elevator accelerates, its floor comes up to push against the passenger's feet, which to him feels as if he were being drawn towards the floor).

Another way to achieve the same result is to construct very large ships or habitats that rotate. At the appropriate rate of rotation someone on the ground floor -- next to the outer shell -- would experience a centrifugal acceleration equivalent to the Earth's gravity. The reason this technique is not used on present spaceships is that, since they are relatively small, they would have to rotate extremely fast, which would subject the astronauts to coriolis forces (if you are an astronaut, your head would feel a certain acceleration and your stomach another). Those effects, in addition to the extremely fast rotation may play havoc with the control of the ship. Large structures on the scale of Gerard O'Neill's space colonies would not have such problems, but using a space colony as a spaceship would require seemingly prohibitive amounts of energy, at least in the near future. The most reasonable alternative would be to connect the spaceship to a cargo module by a very long tether, and to have the two rotate around their common center of gravity. If the distance between the space ship and the axis of rotation is 200 meters, for example, we would have the equivalent acceleration that a gigantic spaceship or a small space colony might enjoy.

The first colonies on the Moon, on Mars, and on the moons of the outer planets would be dedicated mainly to the scientific exploration of those worlds, but also to determining the feasibility of even bigger settlements. As our presence grows so will the opportunities for space science (although I am sure there will be drawbacks on occasion), but I presume that another transformation of great consequence will take place: if the solar system becomes our home, then all the arguments about the serendipity of space exploration will gain additional force. Surely the change in our views will not be about alien worlds far away --it will affect our understanding of our new habitat. Once we are up there in force, the panorama of scientific, technological, industrial, and social opportunities may seem vastly different from what we may imagine today.

As those colonies grow, they will transform their extraterrestrial environments. The point may come when we engage in the science, or art, of "terraforming," which at its most grandiose envisions transforming entire planets and giant moons into habitable worlds. If a world does not have enough water, for example, we bring to it one of the thousands of small asteroids from the Kuiper belt composed mainly of water. Crashing the asteroid into that world would also help to increase the density and raise the temperature of the atmosphere. In another world, Venus for instance, that receives too much sunlight, we could place a cloud of dust around it, and then manipulate its atmosphere to reduce its greenhouse effect considerably.

Decades, probably centuries, will pass before we understand planet dynamics well enough to attempt to transform any world into a second Earth. In any event, we need remember that the initial justification for setting up human habitats in places like Mars is the possibility for the profound transformation of our planetary science. In the case of Mars, the most compelling reason is the possibility of transforming our understanding of human life by comparing it with Martian life, or at least with the fossils of Martian life. But all the other “Earth” sciences are likely to profit as well – geophysics, climatology, etc. Thus it would be highly irresponsible to begin to terraform Mars before we learn from it what it has to teach us. Indeed, we will need to learn many lessons from Mars, and Venus, and Titan, before we can begin to feel confident that our terraforming theories will be worth undertaking on them or on any other world.

Speculations of this sort are not only entertaining, they bring up the possibility that the limits to human expansion into the cosmos may be very far from our home planet, perhaps very far from the solar system. To that possibility I now turn.

Saturday, July 16, 2011

The Value of Human Exploration

Chapter 7C

The Value of Human Exploration

Still, the proponents of manned exploration have a point – or rather, several. First, they might just as well acknowledge that the Shuttle has set space science back many years. Even the head of NASA thinks it was a mistake.[1] But they might point out that the Shuttle is a very poorly designed system, not a good example of how manned exploration should be done. It is essentially a very large and heavy glider taken into low orbit by a partially reusable combination of solid and liquid fuel propulsion engines. It is at its worst when it ferries satellites into orbit, a task to which it was devoted through the 1980s, and for which it is still used. Suppose that I am eating dinner in Tokyo next to a sumo wrestler. Across the dining room a friend asks me for the small pitcher of warm saki. I could get up and take it to him. It would require me to spend a certain amount of energy, but not much, and to incur a certain amount of risk, but not much. Or I could hand the pitcher to the sumo wrestler and then carry him, saki in hand, across the room so he can give the saki to my friend. The energy required is far greater, as is the risk involved, both to the sumo wrestler and to me. Indeed, that is an extremely expensive and unsafe way to ferry satellites into orbit (or carry saki across a dining room). To make matters worse, the Shuttle is an extremely complicated machine, with more ways to fail than anything else that has flown before or since.

Was there a better way to fly people into space? Of course there was. Otherwise we would have never landed a man on the Moon and returned him safely to Earth “before the decade was out” as President Kennedy challenged us to do in the early 1960s. And when we went to the Moon, let us recall, there were also many complaints about the poor quality of the science that was expected to result. Those complaints were very misguided. The Apollo astronauts made great contributions to science, contributions, for example, to our understanding of the origin and evolution of our planet.[2]

That Apollo era saw the flowering of unmanned exploration as well, a flowering that continued through the mid-1970s, until NASA put its rockets in mothballs and forced practically the entire U.S. space program into the coming “space bus” – the Shuttle. That era also gave us a reliable and relatively inexpensive space station, Skylab, which burnt in reentry when its orbit decayed and NASA no longer had rockets to move it into a higher orbit. The Russians, with a somewhat more modest program also based on rockets, had a very active exploration of the solar system and a station of their own: Mir.

So the important question is whether we should explore with people and with machines, as long as we have a sensible means again for ferrying astronauts into space. We could, for example, jettison the shuttle and continue using the Russian rockets until we have a good rocket program of our own again.[3] We could also encourage private undertakings such as Spaceship1, which promise far cheaper access into space for astronauts.[4]

In the meantime, though, we should realize that manned exploration is once again poised to help advance the cause of space science. I am referring to the search for life, or for fossils of life, in Mars. Rovers and other machines are already exploring the planet, finding evidence of water, laying the groundwork for when human geologists and paleontologist finally arrive, for practically all agree that their presence will be needed in this extraordinarily significant endeavor.


The critics' fear is that the space station once again signals the commitment of the country to expensive manned exploration, with glamour winning over substance. I have already argued that there is more than glamour to the presence of humans in space. It is now time to take this argument further. Unless we had money to burn, it is difficult to justify a transcontinental journey to Paris for the sole purpose of sitting at a cafe to watch people go by as we sip a brandy or a cup of cafe au lait. But if we had to go to Paris for some other reason, it would make perfectly good sense to enjoy that aspect of Parisian life as well. Similarly a permanent manned presence in space – even if prompted by reasons of commerce or national prestige – would make feasible a multiplicity of scientific experiments that a society might not be willing to undertake otherwise. My suspicion is, then, that a permanent human presence in space would, if anything, help a new flowering of space science.

I am not here talking about the occasional grandiose project that becomes an end in itself and leaves more memories than it does future avenues of investigation. I am talking about a space station that marks the beginning of the sustained expansion of the human species into the solar system. Since that is the fear, that is the situation I would like to discuss. How can space science be well served by such an expansion during a period of fifty to a hundred years from today?

Since some branches of space science are obviously helped by a human presence, or so I hope to have shown, the issue is how space science as a whole is to be helped. We must consider, then, what effects that human presence will have on space astronomy, planetary exploration, and other areas where the human experimenter is either not wanted or has been traditionally absent. In space astronomy there is a clear initial benefit: the repair and regular maintenance of the large telescopic arrays in orbit. The role of servicing the Hubble visual telescope, for example, requires the ability of astronauts to fly to the telescope and work on it. (While the shuttle was out of commission, space scientists tried to design a robotic mission, but its future is uncertain; if it fails, the Hubble telescope will have its useful life cut short because astronauts could no longer reach it.) A space station would enhance significantly the capacity to support in space astronomical observatories of even larger magnitude (once we build spacecraft that station occupants can use for travel in orbit). This goal can be achieved in the next two or three decades, definitely a period in which humans are not likely to be replaced by their mechanical contraptions.

This role gives but a mere inkling of what humans in space can do for astronomy. As the expansion into space continues, it becomes possible to build even larger observatories that would be too difficult to take up in one piece. And it also becomes possible to place those observatories in many locations away from the Earth, either because of convenience – e.g., on the other side of the Moon, so as to shield them from the electromagnetic interference from the Earth – or simply to increase the baseline of the measurements. And these possibilities point to some aspects of a permanent human presence of potentially far greater significance.

Apart from producing goods that can be used on Earth, space labs and factories can build technology for space itself. There are several ways in which large space structures might be very advantageous, and some of them will merit discussion shortly. But my point goes further. A lot of the technology used in unmanned space flight today has to be built with the problems of lift-off, orbiting, and deployment in mind. It has to meet terrestrial conditions, withstand the accelerations and temperatures involved in the transportation from ground to orbit, its final stage must be fitted to the specifications of the boosters, and then it has to manage in space. But is all this necessary?

Having a technology that can meet all these challenges is no doubt beneficial. But imposing them on all technology and all experiments that go into space is not very reasonable unless there are no alternatives. It is not reasonable because it imposes greater difficulties and cost in design and production. Take the gravitational gyroscopes designed to test some extraordinary predictions of Einstein’s General Theory of Relativity (the Gravity Probe B experiment[5]). To have the spheres suspended you must use thousands of volts on the Earth, and you must design and build the sphere so it can withstand that electrical potential, even though in space the amount of electricity used will be very small. If we could do the experimental development in space, many of these specification problems would be automatically solved. Not that it would pay now to send scientists to do that development in orbit. The point is rather that a massive, permanent human presence in space opens up a lot of possibilities for space science because it would be relatively feasible to undertake them under those conditions.

In this regard planetary exploration can be a clear beneficiary, since the requirements for an interplanetary probe to be launched from space may be far more relaxed. For example, rather flimsy structures may be perfectly adequate in propulsion modules. We could also employ vacuum tubes without going to the trouble of producing a vacuum artificially – indeed without a "tube" at all, just a cathode, anode, grids, and relevant circuitry. And of course the superior semi-conductors and crystals that can be produced in microgravity would be deployed in space technology without some of the costs of transportation up and down the gravity well of the Earth. The point is that once we make ourselves at home in space many possibilities for technological innovation in space will become readily apparent.

This point is made stronger when we realize that it is possible to avail ourselves of the resources of space in the development of such technologies, as well as in the development of products for the Earth. Once in place, a vigorous exploitation of the minerals and energy of the solar system can make important contributions to an infrastructure that may support the routine exploration of the planets. This is not to say that we should commit ourselves to such exploitation at this time. Indeed one of the present tasks of solar system exploration is to determine the availability and distribution of such resources. Nor can we expect to have the complete means for taking advantage of those resources immediately, even if we wanted to. But as our presence in space becomes wider and better established it is reasonable to expect that we will begin to use the native materials. Plans are already being prepared for that eventuality, and so the promise of space may be more fully realized once we make it our environment.

The ability to create very large structures in space, which for at least many decades is likely to require astronauts, will make possible to assemble very large solar sails and other forms of propulsion that will considerably shorten the travel times and increase the distances our spacecraft can travel. That is also going to have a beneficial effect on all of space science.

The urge to explore the solar system must of necessity go hand in hand with scientific exploration. A survey of what Mars has to offer to potential colonists, for example, would require first an extensive scientific survey of Mars. And any plans for setting up such a colony, as well as for the extraction and processing of materials would at the very least challenge our talents in several branches of space science. Eventually advanced science would no longer be necessary for the technology of prospecting and colonization, since a very well tried science will become routine. This is not to suggest that science is always a prerequisite for technology. The industrial revolution was spurred as much by the development of craft as by the great intellectual feats of science. The relationship between science and technology is clearly dialectical – changes in science affect areas of technology, which in turn make scientific change possible, and so on – although just as clearly at any one time there is also a good deal of independence between them. In this case, however, the nature of the exploring to be done has a major scientific component, in that the questions that we need to ask are not different from the kinds of questions that many planetary scientists would like to ask. Thus the technology to be developed would not only depend on the scientific answers to these questions but would also to a large extent be guided by them. Even at the level of building a colony, we need to progress trough a series of experiments on ecological loops if we have any hope of designing human outposts that approach self-sufficiency.

A significant human presence throughout the solar system would not only enhance by orders of magnitude the amount and quality of space science, but also would change drastically the very conception of what may be done in and with space science. Once we are in space permanently the range of possibilities is also altered permanently, not only because humans are around to lend a helping hand, but because they are there under conditions that permit them to move with far greater ease. There are simply far more starting points for space science research, a radically different interplay with a different technology, and a qualitative difference in what may be undertaken. In areas where success turns exploration into routine colonization, the frontiers of science will move further outward, and those that remain may not be so closely connected anymore with the day-to- day activities of the ordinary humans in space. But that turning of the extraordinary into the commonplace will not happen overnight. And when it does, it may simply point to a new horizon of opportunity for science and technology beyond what has just been reached.

The first colonies on the Moon, on Mars, and on the moons of the outer planets would be dedicated mainly to the scientific exploration of those worlds, but also to determining the feasibility of even bigger settlements. As our presence increases so will the opportunities for space science (although I am sure there will be drawbacks on occasion. Once we are up there in force, the panorama of scientific, technological, industrial, and social opportunities may seem vastly different from what we may imagine today.

As those colonies grow, they will transform their extraterrestrial environments. The point may come when we engage in the science, or art, of "terraforming," which at its most grandiose envisions transforming entire planets and giant moons into habitable worlds[6]. If a world does not have enough water, for example, we bring to it one of the thousands of small asteroids from the Kuiper belt composed mainly of water. Crashing the asteroid into that world would also help to increase the density and raise the temperature of the atmosphere. In another world, Venus for instance, we could place a cloud of dust around it to reduce the amount of light it receives from the sun, and then manipulate its atmosphere to reduce its greenhouse effect considerably. We might thus achieve a range of temperatures amenable to life.

Decades, probably centuries, will pass before we understand planet dynamics well enough to attempt to transform any world into a second Earth, a task that should not begin until we have learned the scientific lessons those worlds have to teach us. But eventually, it may open up new niches to our species. In the truly long run, but long before the sun becomes a red giant, the Earth’s “thermostat” is likely to malfunction. James Lovelock, of Gaia fame, and M. Whitfield argued in a 1982 article that life was steadily removing CO2 from the atmosphere – it actually has been doing so for the last 400 million years, since plants conquered the land – and in about 100 million years the level of CO2 will go below 150 parts per million (ppm) of air.[7] This level is important because most plants require at least as much atmospheric CO2 to survive. Newer forms of plants – grass, palm trees – use slightly different mechanisms for photosynthesis and can go well below the 150 ppm. The flora of the future, then, will have a very different view: gone will be the apple orchards and the rose gardens, replaced by new and exotic varieties of plants. Inexorably, unless we intervene, the level of atmospheric CO2 will go below 10 ppm and photosynthesis will come to an end altogether. More recent studies following on Lovelock and Whitfield’s footsteps have revised their estimate to between 500 million and a billion years.[8]

The loss of plants will be a catastrophe for animals, obviously, but also for marine life, since it depends so much on the run-off of the soil nutrients that result from the presence of plants. Those few animals that can manage to survive will be done in a few million years by the rising temperatures, for eventually geological processes will bring again significant levels of atmospheric CO2 , which will no longer be kept in check by photosynthetic organisms. Several scenarios have been proposed to explain what will happen after that point. Likely, the expected increasing level of solar energy, coupled with high levels of atmospheric CO2, will quickly lead to the sort of runaway greenhouse effect that vaporized Venus’ oceans. Thus life will come to an end billions of years before the sun’s transition to a red giant obliterates the atmosphere and the oceans altogether.

In those perilous days the full development of space exploration will come to humankind’s rescue. It could, for example, “terrraform” its own home planet so it will adjust to the new conditions. When that is no longer feasible because the sun’s sphere will expand beyond Venus, we might be able to change the Earth’s orbit. And on failing that, humankind will hang on, on terraformed Mars and Titan, as well perhaps on artificial worlds along the lines of Gerard O’Neill’s space colonies.[9] As humanity expands in search of resources in the solar system, the size and complexity of its space habitats is likely to increase. Eventually our species may move into the Oort Cloud. We will then have followed in space the example of expansion set by our ancestors in our own planet. To accomplish that will require many but plausible advances in propulsion systems, with concomitant increases in the speed of travel. Under those conditions, migration from the Oort Cloud to the stars may well be possible. Humankind will then be able to survive in the truly long run.

Eons before then, a large human presence will make it easier to track, and then to deflect asteroids and comets most in danger of colliding with the Earth, thus saving millions of human lives, and even preventing a repeat of the global catastrophe that wiped out the dinosaurs and most other life 65 million years ago.[10]

It all begins with astronauts.

[1] Tracy Watson, “NASA Chief: Shuttles were a Mistake,” reprinted from USA Today in Detroit Free Press, September 28, 2005, p. 13A.

[2] See S.G. Brush, "Harold Urey and the Origin of the Moon: The Interaction of Science and the Apollo Program," in the Proceedings of the Twentieth Goddard Memorial Symposium, 1982, published by the American Astronautical Society; and "From Bump to Clump: Theories of the Origin of the Solar System 1900-1960," in P.A. Hanle and V.D. Chamberlain, eds. Space Science Comes of Age: Perspectives in the History of the Space Sciences, Smithsonian Institution Press, 1981, pp.78-100.

[3] The Constellation program, which NASA has proposed for returning to the Moon is a high-tech update of the Apollo program.

[6] See, for example, James E. Oberg, New Earths, Stackpole Books, 1981.

[7] J.E. Lovelock and M. Whitfield. 1982. “Life Span of the Biosphere.” Nature 296, pp. 561-563.

[8] This account is borrowed from Peter D. Ward and Donald Brownlee, The Life and Death of Planet Earth, Times Books, 2002, pp. 101-116.

[9] See Gerard O'Neill's The High Frontier, Anchor Press/Doubleday, 1982 (2nd edition). See also T. Heppenheimer, Colonies in Space, Stackpole Books, 1977.

[10] The probability of such collisions can be found Dana Desoinies Cosmic Collisions, a Scientific American Focus Book, Henry Holt & Co., 1996, pp. 100-101. Thermonuclear weapons are the first choice, although ONeills mass drivers might also do the job. He envisioned using such drivers to transport asteroids rich in valuable minerals to a lunar orbit, op.cit.

Friday, July 8, 2011

Robots in Space

Chapter 7B

Robots in Space

In this posting I will continue with the critique of manned exploration. In the next posting I will include a response that aims to make a case for manned exploration. Before getting to the case for robots in space, I should mention, in connection with the previous posting, that the newest think about teleoperators will have the operator wear a sort of exoskeleton. As the exoskeleton moves, so does the machine in outer space.


The other hope of the opponents of manned spaceflight is the development of intelligent machines. As those critics constantly remind us, computers can already perform better than humans in several areas. One such area is in geology itself – apparently in contradiction to my earlier remark – where expert programs do a better job in the exploration of underground oil deposits. All we need to do is develop expert programs about the solar system and we will produce robot spacecraft that can do the exploration for us. It may be more heroic to do it with humans, but, according to the critics, at those prices we can afford a bit less heroism and a lot more common sense. Some NASA officials fear that unmanned programs will not enjoy as much public support. In their view, the public derives great satisfaction from the vicarious participation in the grand adventure of space exploration. But opponents of manned exploration argue that robots will permit vicarious participation by the general public in the unraveling of the mysteries of the solar system. We have already experienced that pleasure with the Viking landings and the recent rovers on Mars, with the Voyager missions to Jupiter and Saturn, the Galileo spacecraft, and more recently with Cassini’s visit to Saturn and Titan.

There is no question that our exploration of the solar system will be more fruitful the more independent and flexible our spacecraft become. But we should not turn this reasonable wish into wishful thinking. The truly successful expert programs are very few; and the successful ones have very limited applications. The spacecraft cannot take expert programs for every contingency unless the mission is rather simple and we have a fair idea of what those few contingencies may be. An expert program, whether for diagnosing diseases or finding oil, works by compiling a large set of techniques and rules of thumb used by the human experts in the field. The programmer discovers what rankings and relative values those human experts give to those techniques and rules of thumb in typical cases of application. Such a program can thus do a better job than an individual human expert because the computer can keep track of a larger number of considerations.[1] But when the situation is not typical, when it demands different rankings and values, as it is normally the case with the scientific exploration of the unknown, then the expert program soon exhausts its usefulness. Nor can we program in advance those different assignments of rankings and values, precisely because their appropriateness will be determined by unknown circumstances. This is not to say that human beings seldom make mistakes in the way they grasp the situation. Nonetheless, their flexibility does give them an edge where they meet an open-ended environment.

This problem of flexibility is perhaps the greatest barrier to artificial intelligence. There are many programs that perform very well in restricted domains, but no one has an inkling of how to make a program of general application. All too often what from a distance seems to be a difference in degree that can be overcome with larger computing power and memory storage, up close becomes an insuperable difference in quality. The things that computers cannot do are those like using language or going shopping that come so naturally for even the dullest of human beings. Live intelligence constructs a world for itself, i.e., “interprets” the world as it interacts with it. But being able to tell that much does not amount to knowing how it all works, and thus we are certainly in no position to provide electronic equivalents. We have no idea how to make a computer with the world smarts of a dodo. Newspaper headlines about the wonderful things robots will be able to do in ten years or less are simply pipe dreams that cannot be backed up by any actual research in artificial intelligence.[2]

Whether this barrier can be overcome in principle I will not discuss here. For our purposes, the important consequence is that we have no reason to suppose that it will happen in the next decade or so. It is true that we have often achieved what pundits had declared impossible. The space program is one of our very best examples of that. But the history of our scientific civilization is also full of projects that we later discovered could not be realized. Among those projects we should include the proposals made in their youth by Tsiolkovsky, Goddard, and Oberth, the three pioneers of space flight, for a machine that could lift itself into orbit by its self-generated centrifugal force. As it turned out, the device violated the law of conservation of momentum.

In any event, the success of artificial intelligence is not likely to come soon enough to contribute with robots what humans have to offer now to the progress of space science. Where it is inconvenient for humans to go, we must settle for what robots and teleoperators can do. But where we already know that humans can deliver the goods, it is not reasonable to snub them in favor of an uncertain technology. These remarks are not intended to argue against the development of more sophisticated teleoperators and robotics. On the contrary: There are many environments where humans cannot yet go, and will not go for a long time, and others where they should never go. If machines can go in our stead to those environments, we are so much further ahead.

Nevertheless, opponents of manned flight take a look at the costs of the International Space Station (about $130 billion) and point out that a lot of space science could be done for that amount. For example, the NEAR mission to investigate Eros, an asteroid that comes as close to the Earth as 14 million miles, had a price tag of about $211.5 million dollars, which is pretty standard nowadays. Apart from its scientific value, this mission may someday allow us to figure out how to divert from our planet a similar asteroid. It seems incongruous that for the price of one space station we could fly instead between 400 and 500 interplanetary missions!

Let us consider some of the important missions, scientifically and otherwise, whose funding has been affected by the diversion of monies into what some believe is a manned sinkhole in the sky:

  1. NASA’s “system of environmental satellites is at risk of collapse”[3] because the agency has shifted to the Shuttle and the Space Station $600 million from the Earth sciences.
  2. NASA, for similar budgetary reasons, has downsized the next generation of the National Polar-Orbiting Operational Environmental Satellite System. In particular, it has stripped out “instruments crucial to assessing global warming, such as those that measure incoming solar radiation and outgoing infrared radiation.”[4]
  3. For $100 million of fine-tuning the Large Synoptic Survey Telescope (LSST) we could identify 90 percent of asteroids between 100 and 1000 meters in size. And since the LSST is Earth-bound and thus is limited (can spot the asteroids the come closest only at dusk or dawn, when the sun’s glare may obstruct our vision of them), for $500 million we could place in orbit around the sun an infrared telescope that “could pick up essentially every threat to Earth.”[5]
  4. For $400 million, the proposed Don Quijote would fire a 400 kg projectile into a small asteroid to see how it affects its trajectory. This would begin to help us figure out how to deflect asteroids bound to collide with our planet.
  5. An orbiter around Europa could determine once and for all whether that Jovian moon really has an ocean. A wandering hot-air balloon in the atmosphere of Titan can tell us whether there are traces of self-organization by the organic substances found there by the Cassini mission. Given NASA’s need to pump money into manned exploration, the agency will have to choose between these two missions. Shouldn’t we do both?

These examples were current as of 2008; by now new cuts in space budgets will probably make the situation worse. Nevertheless, they still give us an inkling of how far space science could go if not for our mania to send humans into space.

When the space station was first proposed, most space scientists feared, with good reason, that, on the whole, the space station was going to take money away from space science. I say with good reason because that is exactly what happened during the construction of the Space Shuttle. As the new vehicle could not be brought in under budget, the space sciences suffered a double jeopardy. First, their funds for many science projects were transferred to the shuttle. And then many experiments were not performed because they had been scheduled to go in the shuttle but the shuttle was not ready. The two shuttle disasters made the situation a lot worse. Money has and will continue to be drained from the space sciences to keep astronauts flying (to accomplish very little science by comparison). It was quite proper for scientists to want to ensure that a commitment to the space station would not be underwritten on the back of space science. Now we can see that their worst fears have been realized.

According to the bioengineer and NASA adviser Larry Young, “NASA always uses research as justification for its large manned missions, but once they are under way the engineering, political, and fiscal factors take over and the science constituency is often cast aside.”[6] Weinberg is far bitter: Of five missions proposed to challenge and expand Einstein’s General Theory of Relativity, only one is likely to survive. "This is at the same time,” he says, “that NASA's budget is increasing, with the increase being driven by what I see on the part of the president and the administrators of NASA as an infantile fixation on putting people into space, which has little or no scientific value."[7] For Weinberg, what has happened to the Beyond Einstein program reminds him of the time when the most grandiose particle-physics project, the Superconducting Super Collider, which was being built in Texas, was scrapped by Congress because funds were needed to build the International Space Station.

It should not be surprising, then, that a great many space scientists are now opposed to the new proposals to send humans back to the Moon and on to Mars. And we cannot blame them for, as we have seen, money is already beginning to drain from unmanned exploration.

As for the disadvantages of teleoperators and robots, the opponents of manned exploration point out, we can send dozens of dumb robots or clumsy tele-operated contraptions to take on the sundry jobs a human could theoretically do in space. Certainly, we will fail far more often, but the failures will not be as costly or devastating; we will save money; we will get the job done; and we will be forced to improve our science and technology. It is not just that we can try with machines again and again until we get it right, but also that we can divide the tasks humans would have performed into many simpler tasks and then try to accomplish those with swarms of new machines.

And let us not forget that machines have traveled tens of thousands of times further than humans have ever gone. What sense does it make to restrict exploration to dipping our toes when we could swim across the English Channel?

[1] Hoegland, John. Artificial Intelligence: The Very Idea, MIT Press, 1985.

[2] This point was made as early as 1972 by Hubert Dreyfus in his What Computers Can’t Do: A Critique of Artificial Reason, Harper & Row.

[3] This and most of the examples that follow are taken from George Musser, “5 Essential Things to do in Space,” Scientific American, October 2007, pp. 75. The present quote is from p. 70.

[4] Ibid.

[5] Ibid, p. 71.

[6] Science, Vol. 310, 25 November 2005, p. 1245.

[7], op. cit.

Saturday, July 2, 2011




The famous scientist Steven Weinberg, 1979 physics Nobel Laureate, claimed that “the whole manned spaceflight program, which is so enormously expensive, has produced nothing of scientific value." This remark capped a scathing critique in which he also said that "The International Space Station is an orbital turkey…. No important science has come out of it. I could almost say no science has come out of it.”[1] And a New York Times columnist reportedly stated matter-of-factly that “Three decades after going to the moon, NASA is sending astronauts a few hundred miles above Earth to conduct high school science experiments.”[2] Nor is the value of manned exploration likely to change, for according to Weinberg, "Human beings don't serve any useful function in space," he told "They radiate heat, they're very expensive to keep alive and unlike robotic missions, they have a natural desire to come back, so that anything involving human beings is enormously expensive." This derisive view of manned exploration is widespread amongst space scientists themselves. Indeed space scientists are likely to object bitterly to projects like the space station and President Bush’s proposals to send humans to the Moon and eventually to Mars. My sympathies are with those scientists: Manned exploration has indeed been detrimental to space science. And in the short run it will continue to be so. But in the long run manned exploration will help greatly the cause of space science while providing great benefits to the human species.


Some space scientists argue that we can achieve the goals of space science better with machines than with astronauts. Their feeling is that the money and effort that could be spent on driving science and technology to explore the cosmos is in large part lost when we concentrate instead on ensuring the safety of astronauts and on developing very expensive and cumbersome life-support systems. An astronaut needs air, water, food, and protection from a hostile environment. The satisfaction of these needs requires bigger rockets to handle the far heavier payloads – as well as far more reliable spacecraft. A human being is a delicate creature. Even with the best of our technology we could not easily send astronauts into the hell of Venus or the intense radiation of Jupiter's vicinity. A trip to Mars would also be very difficult, since it would take months under constant bombardment from the solar wind, enough to destroy upwards of ten percent of the astronauts' brain cells unless the spacecraft is especially protected – in addition to the possible adverse physiological effects from such a long exposure to weightlessness. Machines, on the other hand, can go practically everywhere in the solar system, for far less money.

Proponents of manned spacecraft reply that humans can do many things that machines cannot. For example, humans can perform experiments that require great dexterity, and they can retrieve and fix satellites. That is true, but according to their critics, not relevant. First, machines can do their more limited job in places where humans cannot or should not do any job at all. This includes not only trips of very long duration and hazardous environments, but also dangerous experiments. Second, in many space science experiments the presence of man is a hindrance. For example, telescopes have to be so precisely aimed that someone moving around in the spacecraft would disturb the observations. Third, even if astronauts can retrieve and fix satellites, and build and operate industrial facilities, whereas present machines cannot, we can design our space equipment so robots or teleoperators could handle the job. This of course requires that we develop robots and teleoperators equal to the task. Thus on the whole, the impetus that technology receives is greater from exploring space with machines than from worrying about the safe transportation of astronauts. Furthermore, advances in machine operations in low orbit can be applied throughout the solar system, whereas astronauts will be unlikely to venture beyond Mars in the next fifty years, and even that looks to the critics like pie in the sky (pun intended).

The tragic destruction of two Space Shuttles, Challenger and Columbia, threw into disarray the space program and has done great harm to space science. They have clearly shown the risks both to human life and to science from too great a reliance on manned exploration. Indeed, even when the space shuttle flies normally, space science suffers, and, as we will discuss below, the space station makes matters worse. Why should we then insist on manned exploration when we can accomplish far more, and to do it far more cheaply, safely and efficiently with machines?

Exploring with Machines

Let us take a look at the two main technologies favored by the critics of manned exploration: robotics and teleoperators.


Teleoperators permit us to handle via radio and television tasks that must be carried out at a distance. For example, a television camera on a machine transmits to the ground an image of two building blocks, and a human operator makes the arms in the machine put the two blocks together by radio transmission. Interaction between ground crews and a variety of orbiting observatories has actually become routine. We can change orbits, aim cameras and telescopes, and even perform experiments. An advance in the various aspects of teleoperators -- sensors, arms, fingers, grip, and dexterity -- will increase the range of activities that we can perform by remote control in space. Teleoperators combined with robotics can go even further: The human operator would perform certain repairs, say, in a comfortable laboratory, while a robot would mimic the same actions in a far more hostile environment.[3]

But some serious problems remain. The most obvious problem is that the farther away the spacecraft is, the harder it is to run it by remote control. Imagine that a roving vehicle on the Moon comes suddenly upon a hole or an unexpected rock. Its television camera will immediately send a picture of the obstacle to an operator on Earth. But on the average it takes that signal one and a half seconds to arrive. If the human operator reacts instantly, the instruction will arrive at the Moon one-and-a-half seconds after that. Any one who has driven a car knows very well that many disasters can be crammed into three seconds, which is the minimum time that it would take for the earthbound human operator to react to the lunar environment. For a rover on Mars that time would be of the order of eight to forty minutes, and for the outer planets we have to allow hours.

There are two ways to reduce this difficulty. One is to anticipate as much as possible and build our space machines accordingly. We could, for example, provide the lunar vehicle with a computer map of the land it must travel (drawn from photographs taken by orbiting spacecraft). Any deviation from that landscape will automatically force it to stop until it receives fresh instructions from its human operator.

On the Earth, of course, an attentive human driver is able to detect a nasty pothole and get out of harm's way in less than three seconds. But to do so he uses a variety of perceptual clues that allow him to spot a hole for what it is and to tell just how far it is. The teleoperator, by contrast, is looking trough a television camera at an alien landscape: his remote vision is poorer than the terrestrial driver’s, and he does not have all the perceptual clues that his perceptual apparatus needs to come to a quick decision. The upshot of all this is that the roving vehicle must move very slowly. That is so even when the terrain is reasonably well known. When the vehicle is called upon to do some honest-to-goodness exploration, the difficulty becomes acute.

As a matter of fact, the Russians sent one such vehicle to the Moon. And NASA had plans for another at one time. But when the best hopes for its performance were so clearly surpassed by the actual performance of the astronauts, the project – called "Prospector" – died of natural causes.

The teleoperator is then at a disadvantage with respect to a human on the spot, at least for certain kinds of jobs. Not only is his camera not as good as a human eye, it does not receive the correcting feedback of the other human senses. Human beings do not just see what is out in the world and correctly report it to consciousness. They pick out and concentrate instead on a variety of subtle clues as to what is most relevant and worthy of attention. A human observer looking through a television camera has fewer of those clues (he will be missing clues that are peripheral, in the background, or correlated with hearing, smell, or touch). Even if he is highly trained, in a new situation his degraded experience may not suffice for him to recognize objects and situations in the way he has been trained to do. A laboratory biologist can tell at a glance that a guinea pig is ill because somehow its behavior differs subtly from patterns to which the biologist responds even if he cannot describe them. It is our hands-on experience that allows us to gain what appears to be an intuitive "feel" for our surroundings. Geologists and materials experts may also depend on the immediacy of contact in order to grasp the object of study in this quasi-intuitive way.

In space, it is true, many of the associations between the senses may be disturbed by the absence of gravity, and thus previous training may lead a scientist on the spot to misjudge the situation. But human beings have the capacity to adapt and to form new associations. A biologist making slides of a rat's brain can learn how to compensate for the new environment. The teleoperator, on the other hand, faces two different problems. First, at present his artificial “hand” simply does not have the dexterity to carry out that refined a task. Second, even if it did, and eventually it might, he could not use that artificial hand the way he would on Earth; he would have to be retrained so as to make that artificial hand do from Earth what the biologist does with his real hand in space.

To make a better artificial hand (or other appropriate tools) it would be wise to observe what the human biologist does in his space laboratory, and then slowly refine the technology until it is acceptable. Cutting a rat’s brain in weightlessness may be quite different from doing it on the surface of the Earth. It makes sense, then, first to try to learn what it is like to do that kind of lab work in space. That is, we need to develop a space expertise in those activities – a human expertise. Only then we might be in a position to calibrate our teleoperations.

The obvious conclusion of all this is that teleoperating technology is best developed in cooperation with human activity in the relevant areas. To perform at the level that the proponents of unmanned flight hope for, we would require to have a joint, and to some degree a prior human presence in space. This might be a useful technology to develop in the International Space Station. Although a space station is not very useful to all branches of space science, it may be very valuable to biology, materials processing and medical technology. Moreover, as our experience with the Shuttle has demonstrated, there are experiments in physics that require a high degree of finesse or complexity in the handling from space (for example, electron beam experiments to examine the interaction of charged particles with the Earth's magnetic field). Without the mission and payload specialists in the spacecraft, those experiments could not have taken place for decades, if at all.

For materials processing, one of the most promising areas of space industrialization, artistry is as crucial as scientific craft. We must not forget that the initial purpose of the space station, apart from science, is to do industrial research rather than to set up actual industries. If it were the latter, then there might be some hope for combining teleoperators and a high level of automation. But insofar as the purpose is largely one of exploration, the machine technology is not yet up to the challenge. Nor are our teleoperating abilities so developed that we could build those completely automated factories without the help of human workers in space.

[1] Kerr Than,, September 8, 2007.

[2] Reported by John Tierney, “Outer Space on Earth: NASA Should Try It,” reprinted in Detroit Free Press, August 2, 2005, p. 7A.

[3] Gilster, Paul (2002). Centauri Dreams, Copernicus Books, p. 216.