This is the first MMSG newsletter in a long time. A very long time. We have had a lot of failures, and a lot of successes in the last year.
Our biggest and most obvious failure was the loss of our treasurer and secretary without replacements. Steve Williams, our former secretary, is a wonderful person. In the last several years has gone on to graduate school, and fathered two children. In 1994 he told us that the mounting time pressures would force him to regretfully step down as our secretary. Even more unfortunately, at our meeting at 1994's ISDC, no one else was willing to accept the secretariat. In extremis, he agreed to continue for some time, but said time pressures were getting worse, and he really, really would have to step down soon. Being an honorable man, he was telling the truth, and stepped down last Spring. Since then, we have had no formal secretary, which is a major reason why it has been so long since you received this newsletter. This fall, charter member Tihamer Toth-Fejel got a new computer for his birthday, and so agreed to take over for the time being as Secretary. He has taken over all of the former secretary's files and activities.
Unfortunately, the loss of our previous treasurer was not as smooth. She had been treasurer for some time as well, but with less coordination, stopped. As things stand now, all of our files are not yet as in order as we would like them to be, and maintaining proper chapter relations with the NSS National headquarters has been difficult.
One of the major lessons from all this is how difficult it is to keep an organization going when it is as spread out as MMSG. Finally, with all of the turmoil in who are our officers, only one attended the last ISDC in Cleveland. So, there was no MMSG business meeting as it is supposed to be at ISDC. This was particularly bad. Since we are so spread out, the annual ISDC is the best chance to get together and build cohesion. Further, we missed an opportunity to fully and properly replace the secretary and treasurer.
All has not been failure, however, and and we can be proud of our successes. One of the most obvious successes is our position paper. MMSG and several members jointly developed a position paper on MMSG and Space. After some thought and revision, National Space Society adopted the position paper as an official NSS postition paper (http://www.islandone.org/MMSG/NSSNanoPosition.html), which got the paper some exposure in Washington DC, and publication in Ad Astra. Another benefit of the position paper was indirect. Early drafts of the position paper were written by engineers, and despite being ostensibly a statement of policy, lacked political savvy. I asked Max Nelson, who was a graduate student at RAND, to look over the paper. He provided very useful and incisive comments, and in the process he was introduced to molecular nanotechnology. That became particularly evident this year, when RAND released a study he coauthored, "The Prospects of Nanotechnology for Molecular Manufacturing" (http://www.rand.org/publications/MR/MR615/mr615.html) This is an accurate and useful report, which is helping legitimize nanotechnology in some eyes, and usefully guiding public policy. I made arrangements for as many of you as possible to receive copies. For those who did not, you may call RAND at (310) 451-7002, and order a copy. Ask for MR-615-RC.
Another success is attributable to one member, Dale Amon, who set up an MMSG site on the World Wide Web ( http://www.islandone.org/MMSG/). This site has been running for over a year, and has thus become well integrated into the web of molecular nanotechnology-related web sites. We can be proud, in fact, that we are among the few sites pointed to by the Foresight Instutute's Web page (http://www.foresight.org/). This honor creates a duty to maintain a good site, and we could use much more material related to MNT and space.
I have also done some work educating the public about molecular nanotechnology and space. On the usenet group sci.nanotech, a message was posted by Lenny Shaw looking for someone to interview about nanotechnology on a TV show. I volunteered as President of the Molecular Manufacturing Shortcut Group. (There was insufficient room to display all that on the TV, so I became electronically "Tom McKendree, Nanotechnology Expert" :-) The show, an episode of "Studio Seven," was recorded last spring, and shown last summer on public access cable in LA. The show is a basic introduction of molecular nanotechnology for the general TV audience, using a "talking heads" format. It is possible to order copies of the tape for personal use at (Price and Studio 7, 827 Lincoln Blvd, Ste G, Santa Monica, CA 90403, (310) 394-7847, fax: (818) 341-0642, email: ad541@lafn.org). They are $15.00 per tape for 2 to 5 tapes, $10 for 6 to 10, and $8 for 11 to 20, plus postage. We may make arrangmenets to ensure that everyone can buy tapes at the $8 price. Also, once you have a tape in hand, you can go to your local cable operator and request that it be shown on the public access channel.
My other two MMSG efforts were papers that I presented. The first, "Planning Scenarios for Space Development," was invited from the Space Studies Institute for their tenth Space Manufacturing conference May 4-7, 1995. It presents two scenarios for how space development may proceed over the next couple decades. In each case, molecular nanotechnology becomes the most important factor for space operations. The scenarios differ in how thought out and well prepared the world is for molecular nanotechnology and its space application. This paper will be made available on the MMSG website. The second paper was for the Foresight Conference. "Implications of Molecular Nanotechnology Technical Performance Parameters on Previously Defined Space System Architectures" discussed what space transportation and space colonies could look like, given molecular nanotechnology. A draft of the paper is available on the web (http://nano.xerox.com/nanotech/nano4/mckendreePaper.html). The intent is that this will help kick-start a process of developing worked out mission and system concepts for space operations using molecular nanotechnology.
Having discussed our successes and failures from the past, let me turn to our needs needs for the future. Our membership sign-up and renewal process is broken, and our first need is for someone who can come in and fix it. For organizational reasons, it would be best if this person could become our treasurer. If anyone is willing to help with this, particularly someone who has experience as an NSS chapter officer, please contact me. If we cannot fix this, it will be very difficult to do anything else as an organization.
Our second need is for web support. MMSG has a web site ( http://www.islandone.org/MMSG/), but we need to place as much good material as possible on that site. This is the one area where we can reach a large number of people, many of whom are in a position to influence how humanity deals with the prospects of nanotechnology and space. How well the MMSG web site educates visitors may become synonymous with how well does MMSG achieve its goals.
Finally, we need good support for our newsletter. Someone willing and able could relieve Tihamer Toth-Fejel of desktop publishing and the distribution function, but what we really need are people to write articles. Could you write a review of the Ed Regis book Nano? How about reviewing fiction, like The Bohr Maker (Linda Nagata) or The Diamond Age (Neal Stephenson)? If nothing else, write letters to the editor discussing what you believe MMSG should be doing.
Molecular nanotechnology has done very well over the last couple years, gaining a great deal of creadibility and academic respectability. MMSG is well positioned to capitalize on that interest, explaining why space is important in a future with molecular nanotechnology, and what we need to do about this. Now is the time to rededicate MMSG
Ad Astra per nanotechnologia!
Tom McKendree
Meanwhile, the NASA educational web page on nanotechnology (http://www.nas.nasa.gov/NAS/Education/nanotech/nanotech.html) has a pointer to the NSS Position Paper that MMSG members worked so hard to bring to completion. NASA employees Al Globus and Creon Levit are responsible for including a link called "Nanotech in Space Essay", which points to Iowa State University's Brad Hein's directory (http://www.public.iastate.edu/~bhein/txt/mmsg.txt) In addition to the Nanothink page (http://www.nanothinc.com/NanoWorld/NanoSpace/nspace.html), to which Paul Green added the Ad Astra version including the flexible lunar crawler image, and our own MMSG web page ( http://www.islandone.org/MMSG/), maintained by Dale Amon), and the NSS copy (http://www.global.org/bfreed/nss/papers/molenano.html [Note: This site has since closed]) that means that the NSS position paper has four copies on the World Wide Web! Congratulations to all concerned! The word is getting out!
Joseph Michaels, whose article on flexible robots was published in The Assembler recently (Vol 3, No. 2), was just named "European Inventor of the Year" by the Government of Monaco, winning first prize for creativity in an invention. He also had an eight page article in Electronics Today International (December 1995 issue). It feels good to scoop the world!
They found that actuator methods which have already been realized as micro machined products or in advanced laboratory studies include electromagnetic, electrostatic, piezoelectric, thermomechanical, phase change, and shape memory alloy technologies. Methods for actuation which have been demonstrated in the laboratory on a micro scale include electrohydrodynamic, magnetostrictive and diamagnetism technologies. The other methods have been demonstrated in macro devices and will likely be studied in micro devices in the near future.
For use in small spacecraft, different technologies have different advantages. For example, electrostatic and electromagnetic type devices provide efficient operation and low forces. Piezoelectric devices are excellent for large force, small displacement applications where higher voltages are available. Phase change actuators exhibit large amounts of work output per unit volume and are good choices for applications where ambient temperatures remain fairly constant. Shape memory alloy devices provide extremely high work output density and can be actuated directly by joule heating. Both of these technologies, as well as thermomechanical methods, are best suited to applications with moderate ambient temperature variations.
Several methods await appropriate space applications. Magnetostrictive can provide extremely high work output density and fair energy efficiency. Electrorheological and electrohydrodynamic techniques provide ways of directly manipulating fluids and may provide great mass savings by reducing the supporting parts needed for pneumatic and hydraulic systems. Superconducting materials exhibiting the Meissner effect should find wide use in space applications, where low operating temperatures are readily produced.
Additionally, appropriate combinations of various methods should lead to synergetic gains. For example, the Meissner effect may find application in reducing friction in micro scale electromagnetic and electrostatic devices, thereby increasing their performance and efficiency.
The full report, with excellent graphics, is available on the web at http://www.nanothinc.com/nanosci/microtech/mems/ten-actuators/gilbertson.html
or write to:
Greg Zsidisin, Chair
c/ o Space Expos
PO Box 71, Maplewood, NJ 07040
We will be making even more extensive use of the web for the 1997 conference. In particular, all papers must be submitted in HTML. For more info, see http://nano.xerox.com/nanotech/nano5.html
Secretary Tihamer (Tee) Toth-Fejel (810) 229-0040
Email: Tihamer_Toth-Fejel@stercomm.com
MMSG Home Page
http://www.islandone.org/MMSG/
Editorial Office
6479 Hollyhock Trail
Brighton, MI 48116
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The best and shortest review of the Fourth Foresight Conference on Nanotechnology is to say "go to the conference web site (http://nano.xerox.com/nanotech/nano4.html)." What follows is an extensive personal review.
The conference was held in Palo Alto November 9-11, 1995, with side meetings on November 11 and 12. It was clear from the meeting that molecular nanotechnology has turned a large corner in terms of growth, interest, and acceptance.
His second point was to emphasize using the World Wide Web:
He then discussed a figure that showed branching growth from our current capabilities due to experimental progress. At the same time, there could be work using computation exploration, branching backward from the final goal of molecular nanotechnology. At some point nearer the middle, a branch from one direction will link up with a branch from the other direction, and we will have a final roadmap for developing molecular nanotechnology.
Research can fall into a number of points in such a figure. We can examine proposals in remarkable detail, even though we cannot yet build them. This "meet in the middle" strategy will allow us to get to our goals more quickly and effectively. Since there are multiple pathways, the answer to the question: "Is a particular experimental result moving us towards MNT?" depends on an assumption of what MNT is.
Dr. Merkle suggested that the goal looks something like Convergent Assembly (http://nano.xerox.com/nanotech/convergent.html). He discussed the results in this paper, the main conclusion being that high throughput low cost manufacturing of large, complex, atomically precise products is scientifically feasible.
Dr. Merkle then previewed the various speakers, and discussing where each person's work fit into Dr. Merkle's figure. His concluding chart was:
"Molecular Manufacturing:
Its feasible -- Its valuable. -- Let's do it."
He discussed the Nanotechnology Initiative at Rice. The first premise is that the size scale of 1-100 nanometers is a key future area for nearly all science and engineering disciplines. The second premise is academic departments form self-centered clusters, like Feudal Kingdoms. The Rice Nanotechnology Initiative is increasing interactions between disciplines. He said, "The science/engineering barrier is one of the hardest to break down."
Dr. Smalley sees three parts to nanotechnology, Dry, Wet, and Computational Nanotechnology. Different Institutes at Rice are already focusing on these different areas. The Nanotechnology Initiative is meant to bring them together. The initiative's External Advisory Board includes such luminaries as Heinrich Rohrer, Peter Schultz, Paul Chu, Jean-Marie Lehn, George Whitesides, J. Fraser Stoddart, Calvin Quate, and Stanley Williams (of UCLA).
The rest of his talk focus on particular capabilities and projects in wet and dry nanotechnology, particularly at Rice. One key point was that he did not want the whole field to be identified with the necessity of a universal assembler. There was discussion during and after the talk on what this meant, and it was made clear that the proponents were in favor of a very flexible assembler, but not a "universal" assembler. Part of the difference was clearly different time scales. Discussing one project, Dr. Smalley said "In the long distant future, we hope meaning within a year, ..." while none of the proponents believe that an assembler is plausible before the turn of the century.
Recent work includes a simulation of all the roughly 516,000 atoms of the protein coat of a virus, and a simulation of the molecular planetary gear from Nanosystems. The gear was loaded with a 500 GHz impulse on the axle, which is much greater than the gear was designed for. It survived in the simulation, but wobbled and slipped in ways it would not have if run slower. Dr. Goddard made some suggestions for how the gear could be improved for greater performance. He reviewed other work in his group, including computational examinations of self assembled monolayers, and a proposed mechanism for the formation of C60 from the roll up of two C30 rings.
This year's winner was Nedrian Seeman, who has been working on building complex structures out of DNA. The advantage of this approach is that he can easily define complimentary surfaces, and have particular parts bond to particular other parts.
The first year's award was $5000. This year the award was $10,000. At the conference, the idea of a permanent endowment for the Feynman Prize was raised. This led to the donation of $200,000 for the endowment, with the intention of establishing a grand prize, for the major final step, perhaps building the first self-replicating, easily programmable, general purpose assembler, which will pay-out the entire endowment to the recipients.
He then discussed a series of molecular designed mechanical parts. A particularly difficult challenge had been designing properly behaving molecular springs. This part of the talk culminated with of summary of how the parts fit together into a 6 degree of freedom fine motion controller (a very accurate robot). In the approximation that a cam can be called a program, it is a programmable machine. This device consists of roughly 10,000 atoms.
His overview of long-range goals set the target of simultaneously accomplishing synthesis that is: 1) atomically precise; 2) aperiodic; and, 3) three dimensional. Examples of 2 and 3 are trucks and nanolithography. Examples of 1 and 3 are crystals. Examples of 1 and 2 are one dimensional DNA and two dimensional surface modifications using scanning probe devices, such as the 35 Xenon atoms that spelled out "IBM" on a Nickel surface. Combining 1, 2, and 3 will give us molecular manufacturing.
In a review of how achievable performance parameters will improve, one we develop molecular nanotechnology, Dr. Drexler sees the strength of materials going from ~1 GPa to ~50 GPa, power conversion densities going from ~10 megawatts per cubic meter to ~10^9$ megawatts per cubic meter (for systems small enough to not melt themselves), desktop computation going from~10^9$ IPS (Instructions Per Second) to ~10^18 IPS, and the period required for capital doubling to go from ~1 decade to ~1 Hr. To accomplish this, he sees as necessary, and feasible parts density going from ~10^9 to ~10^26, and parts counts for systems going from ~10^6 to ~10^26. His sense of the time scale for all this is that it will occur early in the 21st century. In less than 10 years would be surprising. In more than 30 years would also be surprising. Maybe 20 years. This was a particularly compelling talk.
A group of researchers from Oak Ridge National Labs presented a number of posters on different molecular modelings of nanotechnology possibilities.
His group has mounted individual tips and made and measured nanoindentures, which may be systematically underestimating material properties. On the other hand, thin film mechanics could be different than bulk mechanics, so there are many unknowns involved. Dr. Colton thought buckytubes would work ok tips, as long as they were not too long. Their lab plans on using the SPMs to measure chemical affinities.
New top-down approaches are coming, delaying the need for bottom-up methods. Trying to make small things which are not at thermodynamic minima is too hard, he claimed, arguing for chemical self-assembly.
He suggested that when thinking of assembly, think about assembling molecules, not assembling atoms. Atoms and molecular fragments are real reactive--avoid this pain. He urged us to think about cells, which have a lot to teach us, at every level. He also discussed work on self assembled monolayers (SAMs), and suggested examining various light technologies, such as light molasses, subtractive patterning of light and guiding patterning with light, optical tweezers, and optical traps. Much of his talk was also on microcontact printing (an alternative to photo-lithography), which has a limit of a few tens of nanometers.
Molecular manufacturing will do to molecules what computing did to bits. This will provide precision, speed, scale, programmability, economics, radically new application possibilities. It is important to remember, however, that a technological revolution by itself does not equal to a business. A business needs revenues and profits. Most of the talk was Jacobstein's ten lessons for businesses, taken from the computer industry, which he felt would be applicable to molecular nanotechnology. Each was discussed in some detail.
He showed a design of two wheels on bearings with a conveyor belt running between them, all of several thousand atoms. This software does not do the energy minimization for finding the exact relative positions of atoms. His software is intended to be available on the web in a couple of months.
He found that nanotubes can experience local buckling without breaking, which pinches off potential flow, and perhaps could be used as a switch. Nanotubes often have internal closures. These act as local reinforcement, so buckling tends to occur nearby. Theoretical calculation says that one can stretch a nanotube 50% and still be in the elastic range. Nanotubes could be used as plumbing, axles, tension elements (wires), joints (bending at specific points), mechanical switches, and conducting elements. Nanotubes could be the fiber of choice for fiber composite materials.
There was discussion of attaching chemicals to the end of a nanotube. Enormous functionalization may be possible. One audience comment near the end was "Nanotube is a two-by-four, and all we need is a nail."
There is a great deal of computing power at NASA Ames. They have several supercomputers, including two C-90 clusters, and an aggregate capability of 80 GFLOPS with 44 Gbyte of storage. He showed several pretty pictures illustrating their computational fluid dynamics efforts. These took many hours of supercomputer time.
He mentioned as possible NASA-related uses for molecular nanotechnology nanocompters and smart nanorobots for in situ exploration. Much of the talk was devoted to a review of different possible future computing approaches, including some exotic approaches (e.g. Single-Flux- Quantum Circuits), and different supercomputer architectures. He presented a roadmap for improving silicon computer chips -- a roadmap that started to run into significant uncertainty in the 2004 time period.
He also discussed the different models of molecules that exist, from Semi-Empirical through Full Configuration Interaction, and their tradeoff of more speed and complexity or faster running time. Their approach will be to do extremely accurate simulations in small systems, and fold up the results to larger objects.
Their long term goal is the "modeling capacity to simulate the entire assembly of a hundred million to on billion atom assembler." They presented a roadmap for the development of molecular nanotechnology, and of the computers necessary to support that development. The roadmap had in 2005 Peta Flops available for nanoCAD and nanoCAM, planned for nano devices in 2010, and saw in 2015 both future nanocomputers and nanotechnology based future aerospace systems.
One of the questions asked how we could say that we will need a certain shown level of computing power for atomic modeling years in the future, given ongoing work in developing faster running and better scaling algorithms? The answer was that the charts shown assumed no improvements in algorithms, and algorithm improvements would lead to the capability to design and model more powerful molecular systems sooner.
Note: NASA Ames is holding a "Computational Molecular Nanotechnology Workshop" at Moffett Field on March 4-5. Information on this workshop will be maintained at http://www.nas.nasa.gov/NAS/Training and there will be no registration fee.
Her most significant point was that molecular nanotechnology is being taken so seriously in Japan that the Ministries are talking to each other about it, which is nearly unheard of behavior. She discussed many projects and organizational structures that seem to be related. One the phenomena is that Japan has decided that it is behind and needs to catch up on biotechnology, and this is creating a great deal of related effort that is confusing when looking at molecular nanotechnology.
She spent some time on a Delphi study conducted by NISTEP that expects some molecular nanotechnology precursors in 2001, and more mature molecular nanotechnology in the 2008-2011 time frame. She said that despite appearances to the contrary, Eric Drexler's ideas of "strong nanotechnology" have not yet permeated the Japanese research establishment. This is in part because Japanese research projects are defined at policy level, and these people do not really understand the technology or its implications.
Nonetheless, work is going on in all the relevant areas, except virtual [computational] nanotechnology. When asked if Japan was in a state where, given some motivation, the nation could refocus ongoing projects into a very powerful effort focused on strong nanotechnology, Ms. Sienko said that this could happen very fast.
Dr. Merkle also discussed the involvement of NRL, and noted that the military does have efforts in long-range planning that reaches out 20 years (and even 40 years sometimes), and they are technologically informed. Almost no other institution in the US even looks out this far. It came out in the discussion that NRL has put together a report on nanotechnology efforts in Europe, and is trying to do one for Japan.
Dr. Merkle also discussed briefly the limited assembler design he is working on. When done, he will then work on creating an even more primitive and limited design, that possibly could be built from proteins or macromolecular synthesis, and could lead to the fabrication of the design he is currently working on.
Simple-minded calculations suggest that the total level of investment, e.g. people working per year in the field, must grow at an annualized rate of ~100%. The main presenter then argued that this growth cannot be a sudden jump, but must be smoothed out somewhat for various reasons of institutional inertia. Many of these phenomena imply that in the later stages the revenues would also be growing at an annualized rate of ~100%.
In summary, the conference went very well. Molecular nanotechnology is starting to enter the main stream of thought in long-range science and technical research, although the implications of actually developing molecular nanotechnology remain largely unexplored in the policy mainstream. From MMSG's point of view, it is important that the NASA Ames research goes well because it may be important for the development of molecular nanotechnology for space operations.
%From nanotech@cs.rutgers.edu Tue Apr 4 18:43:22 1995
Space advocates have long desired to decrease the cost of space travel. A method known since the 1960s is the construction of an orbital tower, a long structure or cable in synchronous orbit with one end touching the surface of the Earth. Such a tower could support elevators moving freight and passengers up to synchronous orbit and beyond, and down to the surface, at a cost per kilogram orders of magnitude less than modern rocketry, with passenger safety comparable to a train or subway. However, no ordinary material has the tensile strength needed to build such a structure.
Nanotechnology is the anticipated industrial capability of specifying and building products atom by atom, resulting in atomically perfect structures of any desired chemical composition. A favorite product material of nanotechnologists is diamondoid, a generic word describing any mechanosynthetic object that relies on tetrahedrally (sp3) linked carbon atoms forming a rigid, space-filling lattice as a major part of its design. Diamondoid should be strong enough to serve as a construction material for an orbital tower, and cheap enough to make the tower's construction feasible, given an already orbiting source of carbon and other elements. The construction of an orbital tower would be an excellent bootstrap project for nanotechnology specifically, and a huge benefit to humanity in general.
An essential attribute of the orbital tower is that, despite appearances, it is in orbit. In order to keep that perspective, the following visualization exercise is helpful.
Start with a synchronous satellite (technically, an object in a 36,000km circular prograde orbit of zero inclination). Its orbital period is 24 hours, in lockstep with the Earth below. To an observer on the Earth, the satellite appears motionless in the sky, because it is orbiting the Earth at the same speed with which the Earth is turning. This is very useful for communications satellites, because ground antennas can be pointed once and then left alone. (I am ignoring orbital perturbations and station keeping for now.) Now give the satellite a rotational period of 24 hours, so that it always presents the same face to the Earth. (Commsats do this as well.) The satellite can be any shape, as long as its center of attraction is at the proper distance from the Earth. Now elongate the satellite like a spear, with the point towards the Earth and the tail away from Earth. Again, as long as the center stays where it was (meaning for every bit of stretching of one side towards the Earth, there is a complementary stretching of the other side away from Earth), the situation remains the same, that is, the satellite still orbits the Earth, apparently motionless as seen from the ground. As it gets longer, the near end gets closer to the Earth. Eventually you can stretch the satellite so that one end touches the surface.
What you have now is a solid object, in orbit, that looks like a very tall tower, stretching 36,000km over your head and beyond. If it had an elevator, or an electric car, or steps, you could climb it, right up to orbit. In fact, in order to maintain its center of attraction at 36,000km, the tower must extend significantly further than this, because of decreasing Earth gravity and increasing centrifugal force. Pearson [3] and Forward [5] assume cables extending 110,000km beyond synchronous orbit, rather than Clarke's [4] more solid structure, extending a shorter distance. Despite appearances, the tower is actually in orbit, and its attachment to the ground is for tension, not stability. If the ground attachment were severed, the tower would probably drift upwards in response to its counterweight; it certainly would not crash to Earth.
At the center of the tower (synchronous orbit), a passenger experiences free-fall, because she's in orbit next to the tower's center. At the Earth end of the tower, a passenger experiences 1G, just as if she were standing on the Earth next to the tower. At the far end of the tower, centrifugal force far exceeds the Earth's gravity, and our passenger has to hang onto the tower to avoid being thrown into space. Thus, apparent gravity varies smoothly from 1G at the Earth's surface, to free-fall at the center, to some significant value outwards at the outer end of the tower. The far end is useful for launching objects away from Earth; just wait for the right time and let go of the tower. Alternatively, cargo destined for off-Earth can simply be flung off the end without stopping, or accelerated electrically for even greater range. Pearson [3] and Forward [5]'s design places the end of the tower 150,000 km from the center of the Earth, moving at a horizontal speed of 11 km/ sec. Thus, simply letting go of the end of the tower at the right time is adequate for a minumum-energy orbit to Saturn, or a faster orbit to planets closer than Saturn. (Nothing is free; the energy to launch an escape payload comes from the Earth's rotational energy.)
Using the orbital tower, the energy cost of placing a kilogram of cargo in orbit is simply the cost of the electricity needed to lift that cargo against Earth's dimishing gravity, counteract any atmospheric friction for the first 100km or so, and stop it at the end of its trip. Forward [5] quotes a price of\$2 per kilogram, compared to $5000 per kilogram using rocket-based methods. Note that this price does not take into account the fact that electricity can be generated by the momentum of incoming cargo, so the entire system can be rigged to be pretty energy-efficient.
Like any object in orbit, the tower would be subject to a variety of perturbations that would tend to degrade its orbit. The Moon and the Sun are the chief contributors, along with irregularities in the Earth's mass distribution and shape. Proper scheduling of incoming and outgoing loads can help maintain the tower's orbit. Note that if the tower were to break, the first 25,000 km of it could fall to Earth, but anything higher would remain in orbit.
A counterweight is required at the far end of the orbital tower, to maintain tension along the structure. Forward [5] notes that diamond fiber would be a suitable material for construction of the tower, but laments the unavailability of an industrial source of diamond fiber. This situation, however, may change within the next 10 to 50 years, as described below.
Assemblers themselves are expected to be very small, atomically precise machines. Thus, it is expected that assemblers will be able, once properly programmed, to build additional assemblers. This allows assemblers to be created in geometrically increasing numbers, once the first one is created through some non-nanotechnological means. Such replication is required to build products at a reasonable rate; although a million operations per second sounds fast, a kilogram of carbon contains over 5x10^25 atoms.
For a variety of reasons (see [7]), many mechanosynthetic products will be built around diamondoid, a lattice composed chiefly of tetrahedrally-linked carbon atoms. Diamondoid is expected to have many of the mechanical properties of naturally occurring diamond, especially hardness and tensile strength. However, constructing diamondoid products through mechanosynthesis is expected to be no more or less expensive than constructing any product through mechanosynthesis. In fact, because of assemblers' ability to self-replicate, all mechanosynthetic products are expected to be very inexpensive (comparable to agricultural products) and extremely high quality (atomically perfect, with a defect rate less than 1 in 10^15) by today's standards.
Estimates also vary on the timeframe within which assemblers and other nanotechnological capabilities will be available. Most estimates range from between 10 and 50 years. Progress on a variety of fronts (microscale electronics, biochemistry, human genome decoding, electron microscopy) is encouraging, and seems faster than recent progress in space development. It is possible that mechanosynthetic capabilities will exist to build an orbital tower well in advance of the availability of any off-Earth carbon resources (asteroidal or Lunar) from which to build it.
Many proponents of nanotechnology are concerned about the use of assemblers in any context in which they might be introduced to the biosphere. They believe that a nanomachine is a potential threat to the biosphere because it may somehow compete (with machine-like and potentially brutal efficiency) with lifeforms for some essential resource. Because of their self-reproductive capabilities, if nanomachines "get loose", they could cause irreparable damage to the Earth and its life.
Orbital construction of an orbital tower is an excellent opportunity for nanotechnology to prove its worth and extend its capabilities, with only minimal risk to the biosphere. Working in orbit, with appropriate self-destruct devices as needed, nanomachines can perform useful work in complete safety and isolation, improving along the way as new efficiencies and capabilities are invented. The orbital tower could be to nanotechnology what the Apollo program was to miniaturized electronics and ultimately the computer industry -- simultaneously a market, proving ground, and stimulus.
2 - John D. Isaacs, Allyn C. Vine, Hugh Bradner, and George E. Bachus, "Satellite Elongation into a True 'Sky-Hook'", Science 151 (1966),p. 682.
3 - Jerome Pearson, "The Orbital Tower: A Spacecraft Launcher Using the Earth's Rotational Energy", Acta Astronautica 2 (1975), p. 785.
4 - Arthur C. Clarke, "The Fountains of Paradise", Ballantine Books, 1978 (ISBN 0-345-25356-6).
5 - Robert L. Forward, "Future Magic", Avon Books, 1988 (ISBN 0-380-89814-4).
6 - K. Eric Drexler, "Engines of Creation", Anchor Books, 1986 (ISBN 0-385-19973-2).
7 - K. Eric Drexler, "Nanosystems", Wiley Inter Science, 1992 (ISBN 0-471-57518-6).
Compared to the other planets in our Solar System, Mars is the best candidate for terraforming. It has a reasonable gravity, sunshine, rate of rotation, and length of seasons. The Martian surface gravity is 38% of Earth's, and the amount of sunlight that reaches Mars is only 43% of what we are used to, but it is sufficient for photosynthesis.
There are two major problems for human habitation on Mars -- a lack of atmosphere, and very low temperatures.
The Martian atmosphere is presently 6-7 millibar's, less than one tenth of Earths. For plants and anearobic microorganisms pressures as low as 10mbar [MCKAY C P, TOON O B, KASTING J F, Making Mars Habitable, Nature, Vol 352, 8 August 1991.] would be adequate, but to exploit the resources of Mars fully it would be advantageous to have a biosphere that is compatible with human needs. For human habitation, the minimum tolerable partial pressure of oxygen is 130mbar. For the entire atmosphere to be oxygen only, it's known that long term exposure to pure oxygen at 345 mbar (a more comfortable pressure) can be tolerated but oxygen is flammable, and there are problems with oxygen toxicity. Consequently, a buffer gas is necessary, and this buffer gas can be nitrogen, which might be available from nitrates in the regolith.
The average surface temperature on Mars is 210K, [MOORE P, HUNT G, The Atlas of the Solar System, Royal Astronautical Society, 1984, p.212.] far too low for human habitation -- a minimal temperature of 273 K is preferable, though anything above the freezing point of water would be even better. Since the surface temperature of a planet depends very much upon the difference between the differences beween incident sunlight and reflected radiation, the primary means for raising the temperature will involve increasing the mass of the atmosphere to keep more solar energy from re-radiating into Space.
At present, the Martian energy flow is one of interception and dissipation with no useful work, biological or otherwise, done. It's energy budget is never in any really useful surplus.
Models for energy systems of useful work include biospheres with one bar pure carbon dioxide atmospheres with mean temperatures just above freezing [FOGG, M J, Dynamics of a Terraformed Martian Biosphere, JBIS, Vol 46, 1993]. Mars in this state can be described as a slowly thawing anaerobic desert. For Mars to be habitable for humans, the atmosphere will need to hold this dissipated solar energy, trapping this warmth so there is a net energy gain from the solar radiation. Molecules with infrared absorption abilities, e.g. carbon dioxide, would be of most use to us by creating a greenhouse effect on Mars.
Another mechanism for raising average Martian temperature is to reduce the albedo by darkening of the planets surface. Unfortunately, this method may have a limited efficiency after the biosphere's average temperature has increased by 10K.[FOGG M J, A Synergic Approach To Terraforming Mars, JBIS, Vol 45, 1992.]
The ten millibars of nitrogen may also be a maximum amount possible due to the fact that little nitrogen has been located on Mars so far and questions exist as to the quantities of nitrates that could really exist in the regolith. So 390 mbar (or 1.5 x 10^14 kilograms of [ideal] gas) could be a target value.[MCKAY C P, TOON O B, KASTING J F, Making Mars Habitable, Nature, Vol 352, 8 August 1991]
1. 195 mbars of Oxygen
2. 10 mbars of Nitrogen
3. 185 mbars of Carbon Dioxide
The total atmospheric mass of 390 mbar, is;
These new quantities of atmospheric gas will mean a change of the mean molecular weight of the Martian atmosphere, to the values shown below:
mb Molecule MolarFraction Mi(g) Mean Mole Mass 185 CO2 0.470(47%) 44 20.68 10 N2 0.025(2.5%) 28 00.70 195 O2 0.500(50%) 32 16.00The total of 37.38 is then the mean molecular weight of one mole of the new Martian atmosphere.
To calculate the number of particles in this atmosphere, that is the number of molecules that need to be processed by these molecular machines, the molecular weight of the elements/ compounds involved (see above) are divided into the mass quantities previously calculated.
Number of Oxygen Moles:
Number of Nitrogen Moles:
Number of Carbon Dioxide moles:
Avogadro's law [LAPHAM C W, Letts Chemistry, p.37, Charles Letts and Co., 1983.] states that for one mole of any element or any compound there will be 6.02 x 10^23 particles (molecules). Therefore;
195 mbar Oxygen = 2.38 x 10^19 x 6.02 x 10^23 = 1.43 x 10^43
10 mbar Nitrogen = 1.36 x 10^18 x 6.02 x 10^23 = 8.18 x 10^41
185 mbar CO2 = 1.6 x 10^19 x 6.02 x 10^23 = 9.85 x 10^42
Total: 2.496 x 10^43
The new mean molecular weight and volume will give the Martian atmosphere a new height value:
With the new atmospheric mass and height, how will the temperature rise required to achieve 280K be accomplished?
One part per billion of CFC's will increase the temperature by about 0.1 Kelvin [LOVELOCK J E, ALLABY M, The Greening of Mars, Warner 1984). For a real temperature increase, CFC levels really need to be at parts per million, this is not toxic and this would result in 0.01 mbar's of the atmosphere being CFCs and this requires 4 x10^13 kilograms of material. Concentrations of 0.06 or 1 part per million might warm Mars by 40K, that's two thirds of the target value needed.[MCKAY C P, Terraforming: Making An Earth Of Mars, The Planetary Report, VII(6), 1987.]
Due to ultraviolet damage there would have to be continuous production of CFC's though UV destroyed CFC's could be reconstituted from their parts that would then be floating in the atmosphere; annual production quantities given are around 3 x10^15 kilograms, deemed impractical previously [FOGG M J, A Synergic Approach To Terraforming Mars, JBIS, Vol 45, 1992.] although such quantities are plausible with molecular machines.
Extraction methods for carbon that have been suggested have included atomic explosions, heat rays [BIRCH P, Terraforming Mars Quickly, JBIS, Vol 45, 1992], orbiting mirrors, and seeding the surface with cyanobacteria [FRIEDMANN EI, HUA M, OCAMPO-FRIEDMANN R, Terraforming Mars: Dissolution Of Carbonate Rocks By Cyanobacteria, JBIS, Vol.46, 1993.].
Dr. Eric Drexler, states that disassembling molecular machines could break down rock, thus release the carbon, or any other necessary material that resides in the regolith; and with better process energy efficiencies than bulk technology methods, e.g. heat rays from space.
Estimates for heating layers of regolith to release carbon dioxide have suggested figures of 10^6 J/ cm^2 for 2 bars of carbon dioxide.[MCKAY C P, TOON O B, KASTING J F, Making Mars Habitable, Nature, Vol 352, 8 August 1991] This estimate though (which assumes 100% efficiency) is for 2 bar of carbon dioxide, the target value here is only 185 millibars, less than one tenth of that value.
A figure of 92,500 J/ cm^2 is therefore acceptable, for the release of the 185 mbar of carbon dioxide through the warming of the regolith. Another method of obtaining the 185 millibar of carbon dioxide wanted would be to heat the southern polar cap of Mars and sublime the 100 millibars that exists there into the atmosphere.
The carbon dioxide is frozen at a temperature of -190 farenheit. At -20 Farenheit the energy required to turn frozen CO2 to vapor would be 70 Calories per gram. Therefore with 4 x 10^20 grams of CO2 to turn to vapor, 2.8 x 10^22 calories will be needed to bring the CO2 to it's latent heat of vaporisation. The energy required for vaporising this carbon dioxide at -190F could be as high as, 664 calories per gram.
If this were done then the regolith carbonate needed would decrease to only 85 millibars. The choice as to which strategy was best, all-regolith or a regolith-polar cap combination would depend upon which was quickest, and most cost effective.
Multiplying the molecular energy requirement by Avogrado's constant to obtain the Joules per mole figure, the answer is:
6.02 x 10^23 x 2.34 x 10^-18 = 1,408,680 Joules.
For the total energy requirement for the entire mass of oxygen gas needed;
1,408,680 Joules x 2.37 x 10^19 = 3.35 x 10^25 J
Estimates for the photosynthesis of carbon dioixde to obtain oxygen [BIRCH P, Terraforming Mars Quickly, JBIS, Vol 45, 1992.] with efficiencies of 8% state that 240 mbars of oxygen can be obtained from 330 mbars of CO2 in around 140 years. For 195 mbar (our target figure) the period would still exceed one hundred years, according to Birch's figures.
With molecular machinary you have the ability to directly affect events at the smallest level. If the splitting of the water molecule into it's constituent parts involves 2.5 electron Volts [source: Chris McKay, NASA Ames, E-mail dated 9th November 1994, 18:17:23 hrs.] then with a requirement of 1.43 x 10^43 oxygen molecules the total energy required with this direct process is 3.6 x 10^43 electron volts or 3.44 x 10^45 kJ/ mole.
Another method is electrolysis, yet this does require, relative to photosnythesis, a lot more energy. [FREITAS R A, Terraforming Mars And Venus Using Machine Self Replicating Systems (SRS), JBIS, Vol 36, No.3, 1983.].
Electrolysing the water for oxygen will generate hydrogen. Molecular machinery could utilise this hydrogen, for molecular fuel cells utilising hydrogen and oxygen, though it may be that the quantities of oxygen needed to produce the energy required to extract the oxygen from the ice cap may preclude this method.
Another option is to store the hydrogen, as levels of storage of 10% of the total volume, for a cell, of 'waste' material is seen as plausible, without affecting the functioning of the molecular machines operations [DREXLER K E, Engines of Creation].
Such hydrogen waste problems will need to be addressed as excess hydrogen is expected to be a by-product of diamondoid structures built from molecular manufacturing [K E DREXLER, Nanosystems, p.425].
These highly pure deposits of nitrates within the top 1 kilometre of the Martian regolith could generate 84 millibars of nitrogen through the use of great heat rays which devolatise/ vaporise the regolith releasing, as well as the nitrogen, 240mbar of oxygen, in 10 years [BIRCH P, Terraforming Mars Quickly, JBIS, Vol 45, 1992.]. However, it would seem much more efficient, and less capitol intensive to use molecular machinary instead of giant orbital mirrors to break the bonds of the nitrate N2O5 in the martian soil to release nitrogen.
In a paper given at a USA/ Japan symposium on nanotechnology and it's affect on manufacturing the time line given for the development of nanotechnological manufacturing systems gave the year 2010 as the year inwhich systems that could synthesise substrate would be viable. This would appear to be a complex task, with atom deposition rates far higher than we have today[HOCKEN R J, MILLER J A, Nanotechnology And It's Impact On Manufacturing, JAPAN/ USA Symposium on Flesible Automation - Volume 1, ASME 1992.]. Yet the numbers of particles required already presented show that productivity rates will have to be substantially improved.
Von Neumann suggested architectures for self replicating systems, with two main components, the universal computer and the universal constructor [VON NEUMANN J, Theory of Self-Reproducing Automata, University of Illinois Press, 1966.].
Of course the self replicating systems will need to be able to peform the terraforming processes as well and whilst initial design specifications will stress simplicity, Dr. Drexler believes that one day, "the difference between an assembler system and a replicator will lie entirely in the assembler's programming." [DREXLER K E, Engines of Creation, p.58].
These self replicating molecular factories, yet to be designed in atomic detail even theoretically, would broadly consist of, a static structure, actuators, sensors, internal transport mechanisms - for moving those various molecules into position - sensors and information processing capabilities.
Estimates for the mass of these molecular devices state atomic mass units of 10^9 AMUs [DREXLER K E, Engines of Creation, p.57]. Even if we had 1.8 x 10^17 of these machines they would only weigh 30 grams, yet their 'body weight to material-released weight' ratio could be great.
With molecular nanotechnology the Neumann architecture description can be modified to consist of a molecular computer with molecular positional capabilities and tip chemistries which will construct copies or diassemble martian rock.
The expected environment is particularly important because of the unique Martian environment, which has temperatures ranging from 150K to 210K.
Present thinking also views the external environment as being one of liquid (the gas Xenon is at it's triple point at 161K therefore at temperatures of 150K it may exist as a liquid and could be a candidate as an inert liquid for the internal structure of the molecular machine) because liquid is seen as the medium for fuel delivery and heat loss for Earth based manufacturing systems [MERKLE R C, Self Replicating Systems And Molecular Manufacturing, JBIS, Vol 45, 1992.].
Yet on Mars, heat is what is needed and therefore the initial low pressure/ enthalpy of Mars external to the cell wall will provide a great dissipator of heat energy.
Materials will need to be transferred through this wall to 'feed' the machine. A rotating cylindar has been put forward as one possible inter-environment transfer system [K E DREXLER, Nanosystems, p. 374]. Such a cylindar with pockets in it's exterior to capture molecules is assumed to operate in a liquid environment.
In an environment where the fuel is ice, probably including impurities, and the molecules are locked into a lattice structure, the external-internal environmental interface may need to be more proactive than the passive systems that Drexler suggests ie the cylinder with pockets. Perhaps a 'molecular drill' which uses shear forces at a molecular level to break apart the lattice structure to guide, molecular 'swarf' into a collection channel for transfer to the internal environment.
These electron computers which will control these devices could fit into an area less than one cubic micron, using some 10 nanowatts of power[DREXLER K E, Molecular Engineering: Assemblers and Future Space Hardware, (AAS 86-415) Aerospace Century XXI: Space Sciences, Applications, And Commercial Developements, Vol 64 (Part III), Advances in the Astronautical Sciences, Proceedings of the 33rd Annual AAS International Conference, Colorado, October 1986.].
The orbiting solar mirrors [BIRCH P, Terraforming Mars Quickly, JBIS, Vol 45, 1992.] that have been suggested to re-direct and magnify solar energy could increase this 590 Watts to 1370 Watts, like on Earth, and there is work on going (Green Energy, New Scientist, 14-20th November issue) to create artificial solar energy collectors that mimic plants; which would eventually lead to artifical photosynthesis processes.
Power density being a measure of the potential power within a given mass of a battery/ fuel cell, if 100 million atoms (1.66 x 10^-19 kg) or 16,666,666 molecules (6 atoms per molecule of 2H2+O2) of Dr. Drexler's billion (10^9) atom replicating assemblers were hydrogen and oxygen molecules then the potential power for each machine could be 7,916,666,666 maJoules (1 maJ = $10^-21 Joules.).
To convert the materials we know we can find on Mars into the gases we need to support life we would need a highly energy efficient conversion organism. Molecular mechanosynthesis appears to present one possible answer to the energy quantities, that are necessary to process the billions (10^9) of kilograms that have to be produced to create the 390 mbar atmosphere.
Fast enzymes such as carbonic anhydrase or ketosteroid isomerase can both process almost a million molecules per second [DREXLER K E, Engines of Creation, p.57].
There are other enzyme molecules which can break down 40 million (hydrogen peroxide) molecules per second, forty times the speed of carbonic anhydrase [K E DREXLER, Engines of Creation, p. 251].
The molecular 'break down' speed ("at Earth temperatures") can be 100 molecules per trillionth of a second (mps) or $10^14 molecules per second. With two oxygen atoms to every oxygen molecule that means that it has, for oxygen, an atomic productivity rate of 5 x 10^13 atoms per second.
For the man made terraforming assembling replicators projections for productivity rates are currently in the 1 million atoms per second range [K E DREXLER, Nanosystems, p.407].
Assemblers with production rates of 1 million atoms per second per atomic robotic assembly arm could complete 100 atomic layers per second, a paper thick object would take an hour. As atomic deposition rates increase to 1 meter per day a great deal of heat will also be generated [DREXLER K E, Engines of Creation, p.57-58].
The masses of material needed for the 390 mbar atmosphere were given previously to show the great volumes of gas needed and the apparently insurmountable task ahead.
Questions must now be answered, to the best of our abilities, one, how fast can these machines replicate, two, how fast can these molecular machines release the material required.
These machines, assuming adequate material and energy supplies, will have exponential growth, and therefore, Dr. Drexler calculates, after ten hours there will be 68 billion molecular machines. If each assembling replicator has a mass of 10^9 AMU's and one AMU has a mass of 1.66 x 10^-27 kilograms [K E DREXLER, Nanosystems, p.514] then this would give a total mass of 1.13 x 10^-7 kilograms. Not much.
Yet, as it will be shown below a greater mass of machines will be needed though the geometric rate at which replicators replicate will mean that within forty eight hours the machines would out weigh the Earth [K E DREXLER, The Engines of Creation, p.58].
The replication requirements may specify a replication rate less than 1000 seconds, or more than 1000 seconds; it will depend upon the rate at which the terraforming project is required to progress.
From calculations above the total number of molecules in a CFC free Martian atmosphere of 390 mbar (at 210K) will be 2.5 x 10^43. To process this many molecules within twenty years, productivity will need to be very high.
To process 2.4 x 10^43 molecules in twenty years there would need to be a production rate of 3.95 x 10^34 molecules per second. If there were 68 billion assemblers on Mars each machine would have to have a productivity of, 5.8 x 10^23 molecules per second.
Taking the time frame of one year, the time it would take for astronauts to efficiently travel to Mars, there are 1,314,000 seconds available in which to complete the terraforming process. If all of the molecular machines needed could be manufactured spread across the equator and the polar caps these machines, upon receiving an activation signal could operate all at once, their energy consumed in an instant, heating, subliming, the effect would release the required material in a very short time frame, perhaps the time it takes to process one mole, perhaps a year.
The total number of atoms is (3.12 x 10^43 + 2.86 x 10^43) 5.98 x 10^43. Divided by the time allotted this gives a figure of 4.54 x 10^37 atoms per second, which, at 1 million atoms per second means a need for 4.54 x 10^31 machines which have a mass of 75,500,000,000,000 kilograms.
Twenty years, within a life time, within a generation, a second biosphere for humanity, where as other periods for terraformation given are in the order of 300 years. Twenty years and there could be an atmosphere which will last for thousands of years. The Valles that exist on Mars could eventually be filled with water and the canals that Lowell saw would be a reality. By 2055 a habitable Mars could exist and the author will only be 84 years of age. But the only intelligent life there will be human life. A Martian Gaia will come alive, it will be, life from lifelessness, literally, Genesis.
The author acknowledges the aid of Chris McKay (NASA Ames), Dr. Jackson (University of Birmingham, UK) and the support of the Molecular Manufacturing ShortCut Group.
Editor's note: A significantly revised and greatly expanded version of this article will be published as a chapter in "Tools for the Next Millenium: The Promise of Molecular Nanotechnology", Lance Chambers, Ed.