Vision 2001 Hearing on the Future of Space Exploration, April 3, 2001

Space Exploration, The Next Generation

Testimony of Lawrence M. Krauss

For the “Vision 2001” session of the House Science Subcommittee on Space and Aeronautics

I would like to thank the Subcommittee on Space and Aeronautics for providing me with the opportunity to testify here today, and for having the vision to consider such a long-term issue as the future of space exploration.

I should preface my remarks by stating that while I come here as someone who has written widely on this subject in a popular context, I am also here primarily as a practicing astrophysicist. So, while I will attempt to be visionary, in the sense requested by the committee, I nevertheless will also want to address various aspects of the practical relation between space exploration and science.

We live in remarkable times. One merely has to examine the awe-inspiring pictures of distant objects obtained by the Hubble Space Telescope to become aware that our entire vision of the Universe is changing with surprises beyond our wildest dreams---proving a fact that I wish more people would appreciate: science is far more exciting than science fiction. We now know of more than 400 billion galaxies in the visible universe, each of which, like our own, contains hundreds of billions of individual stars. But beyond the universe we can see around us, beyond the stars and galaxies visible to the naked eye and to telescopes, lies a vast hidden universe made up perhaps of new types of elementary particles. Stranger still, as reinforced by new evidence presented this week based on observations of an exploding star at a distance of over 8 billion light years away, the expansion of the Universe is speeding up with time. If this is the case, the future of the Universe will be vastly different than anything we had expected even a decade ago. On a truly cosmic timescale, longer than the lifetime of our Sun, the rest of the Universe will literally disappear before our very eyes---that is if there are still any eyes left to disappear before.

At the same time, recent discoveries have added great optimism to the prospect of discovering life, or at least fossil remnants of life, on a much shorter timescale either elsewhere in our solar system or in solar systems that we now know surround nearby stars. Martian meteorites discovered in Antarctica have suggested to some that microbial life may have existed long ago on that red planet, while at the same time demonstrating that Earth is not an island ecosystem, but that material, and maybe even life, can be regularly exchanged with other planets. Unmanned space probes have discovered the existence of what are probably liquid oceans under the ice-covered surface of Jupiter’s moon Europa. Observations of the Hale Bopp Comet did not demonstrate the existence of a small spacecraft behind the comet, but rather that complex organic compounds, the basis of amino acids, exist on the comet. The basic building blocks of life seem to be cropping up throughout the solar system at the same time that our understanding of the early evolution of life on this planet has been undergoing dramatic developments.

Discoveries about life and the Universe are coming at a fast and furious pace, and it is clear that Earth itself is not likely to be a big enough platform to allow us to explore some of the greatest mysteries of the Universe. We will need to escape the safety of our planet in order to search the hidden Universe around us if we are ever to ultimately answer such questions as: “How did we get here?” and “Where are we going?”

While this voyage of scientific discovery is one of the greatest intellectual voyages we are currently undertaking, I do not want you to assume that when I discuss the exploration of space that I am of necessity referring to the human exploration of space. One of the lessons I would like to leave here is that in order to develop a rational and productive long-term program of space exploration we have to distinguish between human exploration of space, and unmanned probes of the Universe. To a large extent this is a distinction between adventure and science. If we are not willing to recognize the difference between these two goals, we will risk both of them.

It is an unambiguous lesson of our experience thus far that the best science that can be performed in space usually does not involve, or at least does not require human space travel. The necessity of designing spacecraft that can successfully house, sustain, and return their occupants produces incredible cost increases that are difficult to justify in scientific terms alone. The general argument is simple: humans are heavy, and the life support systems required to keep them alive are heavier still. When it comes to the exploration of space, the great enemy is mass. The lion’s share of the cost of any such mission goes into transporting and sustaining the humans on board. The money left to do science is thus minimized.

Moreover, to be fair, I think we have to recognize that the scientific efficacy of human experimentation in space has been limited. Years of simple experiments on the Space Shuttle associated with manufacturing in space have not produced any significant breakthroughs in materials science or in understanding crystal structures, for example. And while it is true that the Hubble Space Telescope has revolutionized our understanding of the visible universe, and its repair missions have been essential to its proper functioning, it is not clear as to what extent the development of the Shuttle program itself was necessary for its ultimate creation, deployment and maintenance.

These concerns are magnified manifold when one considers the International Space Station. This project, whose total cost---approaching 100 billion dollars---is truly astronomical, if you excuse the pun, and it cannot be logically justified on the grounds of science, since very little real fundamental science will be done on the station, no matter what the NASA rhetoric is. It is for these reasons that most major scientific organizations have come out in opposition to funding Station. Let me stress this fact by repeating it. There is essentially no debate among the scientific community on this: if evaluated on the science alone, the Space Station is a colossal waste of time and money

But we should never evaluate the Space Station, or indeed the entire human space program uniquely on these grounds. Indeed I have not come here to argue that our long-term vision of space exploration should not involve humans. Like my co-witness Buzz Aldrin, I happen to believe that our ultimate destiny lies in space. I also agree with him that nothing captures the imagination of the public, or inspires generations of school children, like seeing astronauts embark to go where no one has gone before. I know because I have been one of them. I stayed up all night through every Apollo mission while I was a child. When I watched the Apollo 11 landing as a young boy I fully hoped and expected that the pioneering footsteps of those astronauts would one day open a path for me to have the same opportunity. I have written that for many individuals of my generation the fact that we are still tied to Earth and have not returned to visit even our nearest neighbor in over 30 years seems tragic in the extreme. I believe this frustration has helped drive the current interest in much of science fiction, of worlds where we are not constrained by the practicalities of money and politics, or even by the laws of physics themselves and are free to roam the galaxy with impunity.

For humanity, space is the final frontier, and our long-term future will, I believe, be tied to our ability, or lack thereof, to conquer the harsh environment beyond the protective shield of our atmosphere, and to traverse the distances to other planets, to explore them, and ultimately establish human outposts. The Space Station or its successors may be useful in teaching us how humans can survive and function for long periods in space. This information will be essential if we are ever going to send humans on long-term missions to nearby planets, establish bases on objects such as the Moon, or even plan longer-term missions to the outer reaches of the solar system and beyond.

As long as our society continues to have the resources to push forward the frontiers of human exploration, we owe it to future generations to continue the struggle. But exploration to the exclusion of science is futile, just as science without exploration may be sterile.

So, to end this rather long introduction, the future of space exploration must involve a rational division of resources. By being clear about the reasons for sending humans into space, we can then more appropriately develop strategies for space exploration that balance science and adventure. There should never be a competition between the goals of the scientific community and the goals of those who want humans to return to deep space. We need, and I think we can afford, to go in both directions, and we should not be embarrassed or deterred from pursuing either frontier. In this regard, there are several short-term recommendations that should be clear. First, there must be a clear division, in NASA and elsewhere, between human missions and unmanned satellite probes. While the total budget will depend upon political circumstances and the national will, the budgets for each should not be subject to raiding by the other. Next, the administration has recently proposed moving the support of ground based astronomy research from the National Science Foundation to NASA. This is a bad idea. The NSF is science oriented, while NASA is, of necessity, mission oriented. Missions have clear objectives and timetables, and little should be left to chance. The progress of science often requires serendipity and the unfettered ability to pursue the unexpected.

To go beyond this short-term issue and to explore the most exciting opportunities for space exploration in the next 20 to 50 years as well as the challenges that must be addressed in the process, I find it useful to first forget about practicality and to think about those fundamental questions that inspire both scientists and non-scientists to ponder and to explore the cosmos. These might serve as a useful guide to what we might want to accomplish via the exploration of space. Here is my own top ten list (in no particular order). I expect that many people would come up with something similar, even if they might express them differently:

  1. Where did we come from?
  2. What is the Universe made of?
  3. How might it end?
  4. Are the laws of nature the same everywhere? Is there just one Universe?
  5. Is there only one consistent set of laws of nature, or is our universe an accident?
  6. Is “Life” purely physical?
  7. What is intelligence?
  8. Can we, and will we travel between the stars?
  9. Are we alone?
  10. What have “they” learned? How do “they” differ and how are “they” the same?

Next, we might want to ask ourselves: How far are humans likely to venture out into space in the next 20-50 years? I shall argue that if we plan to spend no more than about $500 billion 1998 dollars over this period, we may be able to reach out to our nearest planetary neighbors, but certainly not beyond them. I expect that exploration will be constrained to the inner solar system for the foreseeable future. This is not an excessive limitation, however, because there are an incredible number of opportunities for exploration and exploitation even on this scale.

Guided on the one hand by the profound questions we want to address, and on the other hand by practical limitations, it seems best to divide our considerations for Space Exploration into two parts, as I now proceed to do. In each section, I will list what I think the various major goals should be in the next 20-50 years, and then discuss the technical challenges that must be met.

1. Space Exploration in the Solar System:

(a)   Life in the Solar System: Observations of what seems to be a large liquid ocean underneath the ice-covered surface of Jupiter’s moon Europa, combined with recent evidence of possible liquid water on or near the surface of Mars in recent times, and intriguing, if controversial hints from a Martian meteorite that it might contain some evidence of fossilized microbial life all point to a renewed excitement about the possibility that life might exist elsewhere within the solar system. If we were to discover extraterrestrial organisms, or even definitive evidence of past life-forms on now-dead planets, the implications for our understanding of the origins of life on Earth, and the likely existence of life elsewhere within the galaxy would be truly profound. An effort to directly explore possible sites for life within the solar system should clearly be a priority in the medium and long term. This should take on two forms. Development of robotic probes that can be directed from Earth, and which can either bore into or underneath the surface of extraterrestrial objects and perform remote analyses of their environment are a clear first step. Probes that can sample their environment and return these samples to Earth for further detailed investigation could follow this. As far as the subsurface oceans of Europa, or other extreme environments, only robotic exploration seems feasible. Mars, however, presents a more attractive candidate for human exploration. The cost may be immense. Using present day technology it has been estimated that a round trip mission could cost $200-500 billion dollars, if sufficient fuel is carried on board for the round trip. An interesting proposal has been made to send a vehicle to Mars to manufacture fuel there, so that fuel for the round trip would not be required on the vessel that could carry astronauts to the surface. This might reduce the cost considerably, to under $100 billion dollars. However, even in this case, numerous challenges would present themselves, including the possible need to shield the crew from harmful cosmic rays during their trip to and from the Red planet, so that the net cost will nevertheless still be very large. The potential payoff may not be merely scientific. Mars is an attractive candidate for long-term human outposts, so that exploration of techniques that allow travel to and from this planet will be necessary if we are to ultimately consider colonizing this neighbor.

These arguments suggest that research and development in order to support these explorations, both manned and unmanned, will require:

Research into small robotic devices that can function for long periods in space and in other extreme environments: As far as space travel is concerned, small is beautiful. Extra weight means extra fuel, which in turn adds extra weight. Thus, the smaller and lighter the machines we can send into space, the better. To the extent that machines can address the important scientific questions in this regard, it is clear that research in this area will be highly cost effective.

Research into new propulsion mechanism that can produce maximum ultimate velocities, even with small thrust: The term that is used in aeronautics in this regard is specific impulse. In order to minimize travel time, and more importantly, fuel requirements for both manned and unmanned travel, fuel that can be ejected with the highest possible net relative velocity is desirable. The fuel requirements tend to be exponentially sensitive to this ejection velocity. Research into such propulsion technologies as ion engines, nuclear thermal and electric engines, etc. may be very important in this regard.

Possible establishment of near earth way station: Launching vehicles for interplanetary travel from an orbiting station could be extremely useful in reducing the propulsion and weight requirements for spacecraft. Whether or not this is practical, given the concomitant requirements to maintain and resupply these stations would need to be investigated.

Research into shielding technologies: Net radiation doses for astronauts traveling for several years on round trip missions to Mars will be large. Various proposals have been made to shield them from cosmic ray bombardment, from surrounding their vessel with some large absorber, to producing large magnetic fields around the vessel that will steer particles away from the inhabited portions.

Artificial gravity: Long term missions will probably require some kind of net rotation in order to simulate gravity, to avoid the bone deterioration, and muscle atrophy that appears to accompany long periods of weightlessness.

(b)  Dynamics of the Solar System: It has become ever more clear over the past half century that the Solar System is a dynamic environment, and our long term future will ultimately depend upon our ability to understand how climate evolution depends on these dynamics, including locally induced greenhouse effects as well as more general aspects of the chaotic nature of planetary dynamics, and to understand better the evolution of comets and asteroids, and also how to build a system to reliably detect those objects which might be on Earth-crossing orbits with as much advance notice as possible. From a scientific perspective there is increasing evidence that the origin of life on Earth may have depended crucially on transport of materials to the inner solar systems by comets. These materials may include sophisticated organic molecules that may have been the building blocks of life. To address these issues, it will be useful to send probes which can approach, in close proximity, comets and asteroids (the recent unexpectedly successful “soft” landing on an asteroid gives us hope that this can be achieved with some reliability) as well as probes that can aid us in exploring planetary evolution by surveying, landing, and in some cases surviving in extreme environments such as those on planets like Venus.

In order to address these goals, essentially all of which do not involve human exploration, one must nevertheless address the following challenges:

Building machines that can survive in extreme environments: In order to reliably transmit data from the surface of a comet, or the surface of a hostile planet, we must explore techniques that allow detectors and transmitters to reliably function in environments that are extremely hostile.

Improve remote control, local decision making, maneuverability, and rocket propulsion technology: Again, to intercept objects whose orbits may not be stable, or which may be rotating, or which may have extremely large relative velocities, spacecraft that can adjust to changing situations, perhaps without remote commands, will be required. This is likely to involve issues in robotics, including neural network learning programs as well as issues in aeronautics.

Improved data storage, manipulation, and transmission technologies: These will be required for a number of reasons. First, in order to better calculate solar system dynamics, which is known to be chaotic, special purpose computers will have to be developed. At the same time, remote sensors may have limited live time in order to access important information, and transmit it to Earth.

Development of a coherent, reliable, long-term remote sensing strategy: Programs already exist on Earth for scanning the skies for large objects on possible Earth-crossing trajectories. The benefits to being able to spot such objects earlier than we can now do so are obvious. We might wish to investigate the feasibility of installing remote sensing devices in deep space that constantly monitor the motion of objects coming from the outer solar system.

(c)   Formation and Evolution of the Earth: Over the next century issues such as global warming will undoubtedly take on an increased importance, especially given the government’s recent policies on the regulation of carbon dioxide emissions. Monitoring Earth from space will become increasingly important as we attempt to build better models of Earth’s dynamics. Beyond this, as we attempt to understand other complex environmental phenomena, such as the nature of Earth’s magnetosphere, we will need a network of Earth-monitoring satellites, which can give data at many locations at the same time. Without these we are like weather forecasters who might try to predict the weather in Washington tomorrow knowing only the temperature today in Honolulu. To establish such networks will require:

Development of light satellites that can be produced and launched in large numbers with high reliability.

(d)  A Research Station on the Moon: It is difficult for me to believe that humans will ever directly explore the rest of the solar system until we can effectively establish a remote station on the Moon. Creating such a base on the Moon will serve many purposes as far as manned space travel is concerned, and will allow us to create prototype strategies for constructing extraterrestrial bases. Addressing the transport and storage requirements will allow us to determine how feasible it will be to consider the more ambitious task of visiting Mars, as well as allow the nation to develop the necessary engineering infrastructure to realistically address such a challenge. While I expect that going to Mars is more like a 50-year project, I believe it is realistic to consider establishing a continuously manned base on the Moon within 20 years. There are important scientific projects one could carry out as part of this process. For example, I would suggest building a manned observatory on the far side of the Moon, shielded from terrestrial backgrounds, as a worthwhile scientific goal in this context. The engineering challenges of returning humans to the moon, and sustaining them while there are many, including:

Development of reliable large, perhaps reusable boosters, or launching platforms in space

Development of construction techniques appropriate for the Moon’s environment

Development of large-scale storage facilities in orbit to facilitate transfer of materials to the Moon

Exploration of possible mini-terraforming technologies appropriate to use on the Moon, including possible extraction of water, etc.

(e)   Exploring the Outer Solar System: Over the next decades, opportunities will arise to utilize the alignment of planets to propel probes into the outer solar system to explore planets and satellites beyond Jupiter. These will of necessity be unmanned probes. We should be prepared to take advantage of these opportunities by developing the appropriate technologies in advance.

(f)   Understanding the Sun (and Stars): To explore the processes that govern the cyclical variation of the Sun on a monthly or yearly basis, we would benefit greatly from probes that venture close to the solar surface. Such probes would have to have very high tolerances for temperature, magnetic fields, and radiation. Research and development is certainly worthwhile in attempting to develop such radiation hardened tools in order to allow us to understand the dynamics of the central object that governs the continued existence of life on Earth.

Finally, it is worth pointing out that I have discussed primarily government-sponsored programs whose purpose is largely scientific. I think we are entering an era where commercial exploitation of space may be beginning in earnest. I am not restricting myself here to commercially launched satellites, but also the sending humans into space. We may be on the threshold of seeing the first “tourist” launched into space to visit the International Space Station. I think that over the next 20-50 years we may see this opportunity become available to the merely rich, rather than the super-rich. The point is that as long as there is the potential for some profit, even large expenditures in the private sector, with some public sector support, become possible. It is ironic, for example, that as much money was spent on a recent movie about going to Mars as might be spent to actually send a small payload to that planet. The former was possible because of the revenues that could be generated as a result of the project. As television and movie entertainment projects become ever more lavish, it is not clear to me, at least, that these might not drive some of the commercial exploitation of space. If the market is there, it will happen, and if the price were right, I might buy a ticket.

2. Space Exploration Outside the Solar System:

What of the rest of our vast Universe, beyond the domain of our Sun? Here is where the greatest opportunities exist both for probing the fundamental processes that govern the evolution of the Universe and also for potentially discovering life, perhaps intelligent life. The Universe may be the ultimate particle physics laboratory. It may be that only through explorations on large scales, or exotic astrophysical objects will we be able to probe physics relevant to the earliest moments of the Big Bang, associated with the creation of the visible Universe, the fundamental structure of matter, and ultimately our own existence. As I alluded to at the beginning of my testimony, these are areas where we have seen revolutionary new developments over the past decade.

I should make it clear right away that probing the Universe will, for the foreseeable future, be done from within the confines of our solar system. Humans, and even unmanned robotic spacecraft will NOT travel via rockets on round trip missions to the stars, requiring speeds close to the speed of light, in the next century. The costs are simply outlandish by anyone’s measure. To get an idea of the problem, consider the following: Assuming we use fuels comparable to conventional rocket fuels today, how much fuel would it take to accelerate a single atom to half the speed of light, and stop it again? The answer may surprise you: The amount of fuel required would exceed the entire mass of the visible Universe! So, while NASA might ask to appropriate funds for this purpose, it isn’t going to happen. Now, you might say, as you have a right to: Who on earth would use conventional rocket fuels for such a purpose? Surely we would use more advanced technology! While this is correct, consider next the following: Say that we use nuclear fusion to power rockets. This is the process that powers the Sun, and thermonuclear weapons. We do not yet have controlled fusion reactors on Earth, but one day we will, and these will generate a million times more energy per unit mass than even the best chemical reactors. Nevertheless, even if we had a fusion reactor on a spacecraft (as the USS Enterprise does to power the “impulse drive” on Star Trek), each time we wanted to accelerate from rest to one half the speed of light and stop again we would have to find 7000 times the mass of the spacecraft in fuel! I repeat, we would need this EACH TIME we wanted to start and stop!

Clearly, internal propulsion is simply not workable for attaining the speeds necessary to traverse distances between stars. As a result, many individuals have considered other possibilities… light sails, propulsion by lasers, etc. However, while these methodologies do not, at least, violate the laws of physics, they are far from practical from an engineering or cost standpoint in the medium term (i.e. the next 20-50 years), and from a mission standpoint they only seem best suited to unmanned spacecraft. While large final speeds might be achievable using these methods, acceleration rates are very slow, so that literally years would be required to accelerate to final velocities and to slow down again. For small unmanned payloads, these constraints might be less severe, and the stringent requirements on the propulsion technologies less demanding, so that research and development in these areas should be encouraged.

Finally, some have suggested trying to bypass known laws of physics. The original slogan for what has become the NASA Breakthrough Propulsion Program read: “Warp Drive Now!” I would be remiss if I did not point out that this program, while so small that the amount of money it wastes is minimal, is nevertheless embarrassing on a scale unequalled elsewhere. The idea behind it goes as follows: “Some people have argued (and alas, I am one of them) that the laws of general relativity, when combined with quantum mechanics, might in principle allow spacetime to be manipulated in novel ways. Thus, let us fund research “outside the box” to develop possible new methods of propulsion based on poorly understood physics concepts.” There are many problems with this approach. First, these issues involve matters of principle, and not practicality. They involve physics concepts that are not understood on a theoretical level, and at present are completely inaccessible on any experimental level. It is like asking engineers in the 16th century to design particle accelerators to explore the structure of protons, before the laws of electricity and magnetism that govern the construction of these devices were developed and understood, or indeed before the proton itself had been discovered. In addition, even our tentative knowledge suggests that in order to probe regions where new effects of this sort might be explored would require energies far in excess of anything we have been discussing in the context of mere rocket propulsion! Finally, and perhaps most important of all, while it is quite true, and quite exciting, that there is probably more we do not yet know about the universe than that we do know one should nevertheless not forget that there is A LOT we already DO know! And the projects that have been funded by the NASA BPP program either have no support in any known physics, or, in some cases appear to violate laws we clearly understand.

So much for travel to the stars. Here are my picks for the most exciting scientific explorations of the Universe that might be carried out in space in the next half century.

Terrestrial planet finding: Remarkable developments in the past decade have demonstrated that we already possess the technology to indirectly prove the existence of solar systems around other stars, by observing the gravitational wobble of the stars as their planets orbit around them. The next important step will involve trying to detect these planets directly via the light they may reflect from their host stars. If we were able to make such a detection, spectroscopic analysis of this light would reveal the composition of the planet’s atmosphere. Based on our evolving knowledge in the area now called astrobiology, one could probe for constituents, like oxygen, which appear to be byproducts of organic life.

The major challenge here involves observing the light reflected from a planet while screening out the light from its host star, which may be 100,000 to a million times more intense. Several strategies are currently being explored in order to meet this challenge---from sending up large occulting satellites that might block the light from a star, while allowing telescopes to scan for light from surrounding planets, to large interferometers in space which would carefully “subtract out” the light from stars to be able to probe for residual light from their surrounding planets. These possibilities should be vigorously pursued.

Extraterrestrial signal detection: The detection of a signal from any other intelligent life in the Universe would have profound implications for our civilization. The likelihood of making such a detection, even if the signals exist is, however, very remote. Nevertheless, the cost of scanning the skies for such signals is not large, and therefore it seems worth supporting this effort, and exploring new technologies that might make it more efficient. For example, it has recently been suggested that optical signals might have advantages over radio signals, which are the ones that have thus far received the most attention.

New Large Telescopes in Space: Escaping Earth’s atmosphere is essential for a host of important astronomical observations. We have seen the dramatic quantum leaps that have been possible via the Hubble Space Telescope, the Chandra X-Ray Observatory, and the like. The scientific opportunities provided by each new window on the Universe in space are unrivalled by almost any other space program. Each time we open up such a new window, we have been surprised. Research on the Next Generation Space Telescope (NGST) should continue at a vigorous pace. Placing a telescope in an orbit far removed from Earth has great advantages, allowing it to avoid the constant cycle of light and darkness experienced by the Hubble, for example. Beyond NGST, we should explore technologies that might allow truly gigantic apertures in space. Hundred meter telescopes are not beyond the realm of possibility. These would allow us unprecedented access to the distant universe. In order to consider launching such objects, research in new light materials, including possible inflatable structures, will be required.

Deep Space Satellites: Various exotic possibilities exist for sending satellites into deep space to make new kinds of observations. For example, two satellites located at either end of our solar system could make simultaneous observations of distant objects with a sufficiently large baseline that would allow qualitatively different sorts of observations than any current technology might allow. Applications would range from directly measuring distances to stars to resolving distant phenomena on extremely small special scales.

Seeking out the invisible universe: As we have learned over the past twenty years, much of the universe is invisible to conventional telescopes. This hidden universe holds many of the secrets of our origin, and our ultimate future. Technologies are being developed on Earth to probe for new signals such as gravitational waves from distant collapsing or colliding stars and black holes, to detect neutrinos emitted from the core of our Sun or in the collapse of distant stars, and to look for high energy cosmic rays coming from objects that we do not currently understand. In almost every case there are arguments for going into space to seek out new windows on the Universe. A large interferometer in space, for example, might allow us to “listen” for gravitational wave signals created at the very beginning of time.

Perhaps more important than any of the known rationales for building new devices to explore the hidden Universe on all wavelengths and via all types of radiation is the opportunity for uncovering the unexpected. As much as we have learned about the Universe, and as remarkable as the recent developments in our understanding of the laws of nature have been, the Universe continues to surprise us. As I alluded to at the beginning of my testimony, every year discoveries are made that are beyond the wildest dreams of science fiction writers. Truth is far stranger than fiction. If we turn back from the challenge of empirical discovery, we give up one of the greatest gifts humanity has been given. We must continue to go “where no man or woman has gone before” if our culture is to continue to thrive. In this regard it is worth recalling the congressional testimony of the late physicist Robert Wilson, first director of the Fermi National Accelerator Laboratory, who, when asked if that exotic and expensive machine might aid in national defense, said, “No, but it will help keep the nation worth defending!”

With regard to our understanding of nature, and our ability to explore the Universe on all scales, I firmly believe the best is yet to come!

Executive summary of many of the key points and proposals discussed in this testimony:

         • We must separate science and adventure when funding space projects. In this regard, the human exploration of space must be recognized as a separate activity that need not be justified primarily on scientific grounds. At the same time, some of the grandest scientific questions can only be addressed by traveling into space with unmanned spacecraft.

• Major priorities that might drive space exploration in the next half century include: The search for life elsewhere in the Universe; Establishment of a permanent human presence in space, perhaps leading in the near term to a research station located on the Moon; The effort to uncover the physics of the earliest moments of the big bang; The effort to understand the dynamics of Earth and the solar system with regard to both short term and long term issues associated with human survival.

            • Space travel, human and unmanned, will be confined to within our solar system for the foreseeable future.

            • The technologies that will be most important to the scientific and human exploration of space include: development of small intelligent robotic devices for remote exploration, development of new propulsion technologies allowing high speed travel, development of new space construction technologies, including inflatable and ultralight devices, and finally development of machines that can survive in extremely exotic environments.

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