Tihamer Toth-Fejel ttf@rc.net W: (313) 741-3421 H: (313) 662-4741 and Tom McKendree tmckendree@hacemx.hac.com W: (714) 732-2228 H: (714) 374-2081
The National Space Society believes that developing molecular nanotechnology will advance the exploration and settlement of Space. Present manufacturing capability limits the performance, reliability, and affordability of space systems, but the bottom-up approach of molecular nanotechnology has the potential to produce space hardware with tremendous improvement in performance and reliability at substantially lower cost.
Molecular nanotechnology "expresses the concept of ultimately being able to arrange atoms in a predetermined fashion by manipulating individual atoms" [Aono]. Its principles were first espoused by Nobel prize winner Richard Feynman in 1959, when he said "the principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom" [Feynman]. As an engineering discipline, molecular nanotechnology promises revolutionary advances not only in manufactured products, but in the processes used to make them. It is the culmination of many fields:
Each of these fields reaches its ultimate in precise, molecular control, which is the ability to build large structures to complex, atomic specifications by direct positional selection of reaction sites [Drexler1]. These systems should be able to assemble any configuration of atoms, limited only by the laws of nature and human knowledge -- hence they are called universal assemblers. Because these assemblers would themselves be made of atoms, and because they would be able to assemble these atoms in arbitrary ways, they should be able to self-replicate, or make copies of themselves. NASA, SSI (Space Studies Institute) and others have recognized the potential impact of applying self-replication to space exploration and development [NASA, SSI, Merkle] , but have found that self-replication is difficult for macro-molecular devices, partially because each subcomponent level must deal with errors caused at lower sublevels [Neumann, Toth-Fejel, Freitas and Gilbreath] <1>.
Space exploration and development has benefited enormously from the advances in these fields, especially microelectronics and materials science, because they reduce payload mass and because they improve reliability. As we converge on the ability to control matter with atomic precision, space development can probably become one of the first and foremost beneficiaries.
Molecular nanotechnology can be confused with the micromachines being produced by microlithographic processes, but the two are very different<2>.
The principles of molecular nanotechnology are being demonstrated daily in government and industry laboratories world wide, including the arrangement of 35 xenon atoms to spell out "IBM" [Eigler] , the construction of three-dimensional structures from DNA [Seeman] , and then engineering of branched, non-biological protein with enzymatic activity [Hahn]. Computer software designed for aiding the development of molecular nanotechnology is also proceeding through the use of tools such as computer-aided design and modeling software [Merkle2].
Since the settlement of Space is not a near-term endevour, it would be a grave mistake to consider only the short term applications of molecular nanotechnology to Space, though there may be a few. In the near term, the chief benefits would most likely be in basic research. For example, improved scanning probes similar to Scanning Tunneling Microscopes (STM) could give researchers a powerful, general technique for characterizing the atomic structure of molecular objects. Such capabilities would be valuable in discovering and designing stronger materials, faster and smaller electronics, and exotic chemicals with unique properties. These incremental improvements would offer the possibility of small improvements in capability across the broad spectrum of space activities, ensuring mission completion, prolonging spacecraft life, and fostering the safety of human crews.
As nanosystems used in research are constructed and commercialized, they will move from gathering basic knowledge in laboratories to collecting data in engineering applications<3>. The first applications would be those in which the relatively high cost and limited capabilities of these first generation devices will still provide significant improvements in overall system capability to justify the costs. Since sensors and actuators could be significantly reduced in size and mass, planetary probes and other space-based applications would probably one of the first beneficiaries of these nanosystems.
In the medium term, the nanosystem devices would be directly involved in the manufacturing process. Products might include bulk structures such as spacecraft components made of a diamond-titanium composite, or other "wonder" materials. The theoretical strength-to-density ratio of matter is about 75 times that currently achieved by aerospace aluminum alloys, partially because current manufacturing capability allows macro-molecular defects that weaken the material. The bottom-up approach promises to virtually eliminate these defects, enabling the fabrication of stronger materials that could improve reliability and reduce spacecraft dry weight, resulting in increased payload capacity and higher orbital altitude, ultimately reducing the cost to orbit [DrexlerJBIS].
In the electronics arena, devices might use a few atoms to store a bit of information (as already demonstrated at IBM [Eigler2]). In addition, VLSI (Very Large Scale Integration) would shrink by three magnitudes and extend in three dimensions instead of just two. At this stage, molecular nanotechnology would likely continue to improve capabilities, increase reliability, and lower costs in a wide variety of space projects.
These projected advances would expand the complexity/reliability tradeoff envelope for orbital and lunar systems. Tiny, inexpensive inertial guidance systems could assist unmanned exploratory spacecraft, planetary rovers, and interplanetary probes. A dense network of distributed embedded sensors throughout a manned or unmanned spacecraft could continuously monitor (and affect, if they could be operated as actuators) mechanical stresses, temperature gradients, incident radiation, and other parameters to ensure mission safety and optimize system control. In an advanced spacecraft, the outer skin would not only keep out the cold and the vacuum, but it might also function as a multi-sensor camera and antenna. With such extensive monitoring and increasingly efficient control of propulsion systems, life support, and other spacecraft systems, mission success rates would increase at lowered cost. Advanced materials may also enhance on-orbit human activities by providing more effective spacesuits, and may foster more extraterrestrial endeavors by developing more efficient and degradation-resistant solar cells.
As capabilities increase, the molecular techniques used in the actual manufacturing of the spacecraft (i.e. the tools and processes that transform raw materials into advanced sensors and materials) would themselves increase in capability. This advance would make it much easier to build spacecraft systems that could take advantage of in-situ extraterrestrial resources.
Since the settlement of Space is a long term enterprise, these long-term benefits of molecular nanotechnology are the most relevant. And these benefits are considerable. The most important arises from the general ability to build nanosystems, especially the ability to bootstrap production via self-replicating universal assemblers. This capability would probably lower manufacturing costs by many magnitudes, down to the order of $1 per kilogram. It would also make possible to build tapered tethers from geosynchronous orbit to the ground, and to build human-rated SSTO vehicles with a dry mass around sixty kilograms [DrexlerJBIS]. Such capabilities should make possible inexpensive access to space. Mature nanosystems might make possible affordable and robust closed environment life-support systems that could take advantage of in-situ resources, such as asteroidal metals and cometary organics. Such a capability would potentially enable many people to affordably live in space. Tiny computers, sensors and actuators, trivially cheap on a per-unit basis, may allow things like smart walls to automatically repair micrometeorite damage, comfortable and unobtrusive space suits, and terraforming tools. By providing instrumentation that allows the development of medical knowledge at the molecular level, advanced nanosystems might enable in vivo repair of cellular damage. This capability should mitigate the dangers of ionizing cosmic radiation.
Further long term effects of this technology are completely unpredictable, but would undoubtedly be quite significant. Absolute and relative costs will still constrain space activities, however, and some desired activities will remain impossible.
Before applications can be developed for the exploration and development of Space, molecular nanotechnology itself must become an practical discipline instead of just a theoretical one. There are three promising paths to the building of universal assemblers: genetic engineering, physical chemistry, and scanning probe microscopy. Uncertainty remains as to which path is easiest and quickest, and hybrid approaches appear quite promising, so efforts should be spread across these three areas. There are likely to be a very large number of expensive blind alleys, so it is important to not invest too much money in any one area.
Japan is aggressively pursuing molecular nanotechnology by investing approximately $200 million over 10 years with industry matching government funding in over twenty companies, while funding for the Atomcraft Project [Aono] is being continued by six Japanese companies as it completes its five year plan. Attempts are underway to start a similar program in Switzerland. If the U.S. fails to engage in activities leading to expanded and well-implemented research with commercially relevant goals, we will probably find ourselves critically behind in the broader economic, military, and specific space-related benefits that may accrue from these technologies. The cost of trailing behind in this technology would be very high.
Many potential threats consist of someone using molecular nanotechnology for aggressive purposes. Thus, efforts must be undertaken to ensure that both global security and U.S. national security are safe against this potential threat. One strategy for ensuring US and global security is to develop molecular nanotechnology in a collaborative, multi-lateral manner. This addresses fears of many nations that they will be caught behind in development, and maintains trust since open collaboration is de facto open and mutual inspection.
There is a possibility that due to some unforeseen law of science, universal assemblers may be impossible to build. In this case, the risk consists of a zero return on investment. But in the ten years since the concepts of molecular nanotechnology have been made public, no one has proposed any scientific reasons for its impossibility. The absence of these reasons might be explained by the fact that numerous objects around us (all carbon-based life-forms) have been formed using the bottom up approach, and by the fact that long-range trends in technology show a continually increase in the precision with which matter can be controlled.
There is a fear that spending money on molecular nanotechnology will reduce the amount of money spent on Space development, since research funding is sometimes perceived as a zero sum game. One version of this argument asks why the small amount of money available for research should be spent on speculative ventures such as molecular nanotechnology when projects such as DC-X seem to be much closer to success.
The opposite version of the ``space versus molecular manufacturing'' argument ask why money should be spent on expensive Space hardware when exploring and developing Space would be less costly with advanced molecular nanotechnology. While it is true that nanosystems could significantly lower the cost of Space missions, other factors must be considered.
In conclusion, the National Space Society believes that since the settlement of Space is a long range project that will benefit the entire human race, the serious development of the long range field of molecular nanotechnology must be supported. Extraterrestrial activities are a natural application for nanosystems, and synergistic effects between Space and Molecular Nanotechnology can and should be encouraged.
Thanks to the following people for their input and constructive criticism: Max Nelson, Jamie Dinkelacker, Scott Pace, Glenn Reynolds, Bill Higgins, Keith Henson, Craig Presson, Chris Peterson, Jim Bennett, K. Eric Drexler, and the loyal opposition, Allen Sherzer.
Aono, Masakazu, "Atomcraft", JPRS-JST-92-052-L, 22 June 1992.
Feynman, Richard, "There's Plenty of Room at the Bottom", Engineering and Science, California Institute of Technology, 1960.
K. Eric Drexler, Nanosystems: Molecular Machinery, Manufacturing, and Computation, John Wiley and Sons, 1992.
John von Neumann, Self-Replicating Automata, edited and completed by Arthur Burks, University of Illinois Press, Urbana, 1966.
Toth-Fejel, Tihamer, Self-Test: From Simple Circuits to Self-Replicating Automata, Master's Thesis, University of Notre Dame, 1984.
Robert A. Freitas Jr., William P. Gilbreath, eds., Advanced Automation for Space Missions, NASA Conference Publication CP-2255 (N83-15348), 1982; http://www.islandone.org/MMSG/aasm/ (Of all applications studied, participants believed that space-based applications of self-replication would have the highest payoff).
Merkle, Ralph, Self Replicating Systems and Molecular Manufacturing, Journal of The British Interplanetary Society, Vol. 45, No. 10, October 1992.
Maryaniak, Greg, Self-Replicating Machines for Space, SSI Update: The High Frontier Newsletter, May/June 1985, Space Studies Institute, Princeton, NJ.
Eigler, D. and E. Schweizer, Positioning single atoms with a scanning tunneling microscope. Nature. 344:524-526, 1990.
Seeman, N., Construction of Three-dimensional Stick Figures from Branched DNA. DNA Cell Bio., 10:475-486, 1991.
Hahn, K., W. Kliss, and J. Steward. Design and Synthesis of a Peptide Having Chymotrypsin-Like Esterase Activity. Science, 248:1544-1547, 1991.
Merkle, Ralph, "Computational Nanotechnology" Nanotechnology Vol. 2, No. 3, pp 134-141, 1991.
K. Eric Drexler, Molecular Manufacturing for Space Systems: An Overview, Journal of The British Interplanetary Society, Vol. 45, pp 401-405, 1992.
Eigler, Donald, Christopher Lutz, and William Rudge, Nature, August 15, 1991.
Zubrin, Robert, ``The Significance of the Martian Frontier'', Ad Astra, September/October 1994.
<1>: In top down technologies, as the manufacturing tool no longer directly affects the workpiece, it must rely on indirect means to add or remove portions of subcomponents. When indirect operations increasingly deal with quantized subcomponents (atoms) as if they were continuous (the top-down assumption), errors grow exponentially.
<2>: First, their components differ in scale by a factor of a thousand. Second, while micromechanical systems are built from the top down (as are all manufactured goods today), nanosystems would be built from the bottom-up, as are chemical feed stocks and biological systems. Finally, self-replication is much more difficult in microtechnology than in molecular nanotechnology, and therefore it lacks the impact such a capability can bring. Because we can manipulate individual atoms with large tools such as scanning probe microscopes, microtechnology is probably not a prerequisite to molecular nanotechnology.
<3>: By exploiting concepts from other technologies, especially biochemistry and microlithography, the cost of scanning probe microscopy will continue decreasing as capabilities simultaneously increase. In addition, the structures of manufactured bulk chemicals, such as buckytubes, will continue increasing in complexity, possibly allowing switching behavior and other non-linear phenomena. Finally, genetic engineering processes will probably continue becoming more flexible and precise, possibly enabling ribosomal construction of quasi-biological structures increasingly different from natural biology.
<4>: Science discovers what is, while engineering creates what has never been.
<5>: The Turner thesis demonstrated that our western progressive humanist civilization depends on frontiers.