There is no question that the greatest challenges in the space program that we face today are:

1. Performance
2. Reliability and Safety
3. Cost

Nanotechnology has the capability to improve this situation dramatically. In the previous section we have spoken of the advantages that nanotechnology can bring to general manufacturing and the electronics industry. Clearly both would have a substantial effect on the space program, improving each of the three factors noted above. For example spacecraft can be made 90% lighter, while stronger and a much greater safety margin by using the diamondoid fibres that nanotechnology can produce.
This could improve the ratio of payload mass to empty vehicle mass from 1:3 to 3:1 or more.
The tiny flaws in today's manufacturing will also be eliminated improving reliability and safety, and the use of active materials improves the situation still further.

Let us take a brief look at some more specific benefits nanotechnology will bring:

• The exterior of the craft will be full of nanosensors and nanorobots, such extensive monitoring together with increasingly efficient control of propulsion systems, life support, etc, mission success rates would increase at lowered cost.
• Nanotechnology will also greatly improve the viability of the spaceplanes by making them structurally much lighter.
• As we have mentioned many times today's chemical rockets are no good for deep exploration because of their poor specific and total impulse. It would take nearly 2 years to reach Mars with a conventional rocket. Laser Sails have been suggested as a possible alternative. With today's technology they are rather limited, however nanotechnology can greatly improve their performance, by constructing vastly superior sails. With nanotechnology sails could be constructed that are just 20 nm in thickness (less than a soap bubble). This would make the sail and necessary mountings extremely light but still very durable. Drexler suggests such a craft with no payload could create an acceleration of 0.16 m/s² at one AU from the sun and an acceleration of 0.08 m/s² with a payload mass equal to the sail mass.
• There could be substantial performance increases from solar powered ion engines with nanotechnology. The technology could improve the efficiency of solar panels from less than 30% to nearly 100% and together with structural improvements (making the craft very light) could potentially increase the performance to an ideal exhaust velocity of 1,000,000 m/s and provide ~9.8 m/s² acceleration. These figures may be somewhat optimistic though.
• The performance of conventional rockets can be improved in more dramatic ways, consider that parasitic mass can be converted to useful payload in flight. On-board nanosystems could take a used fuel tank and use it as raw materials to build a solar sail.
• With current technology one of the most difficult problems is the time and cost of developing new technologies. It may take 5 or 10 years and cost anywhere from 10's to 1000's of millions of dollars to develop a new space system. Nanotechnology offers the solution here with automated engineering (using a combination of AI and nanorobotics). Computer controlled manufacturing systems will reduce the time to develop and fully test a new system to a few days and the cost will be almost negligible!
• Nanotechnology will offer extreme efficiency in both materials and energy. This could be extremely important in space missions, as materials will have to be shipped in and in some cases the materials could be extremely rare at that particular location, nanotechnology will enable us to make sure not a single atom is wasted.
• Improvements in spacesuits (Drexler uses this as an excellent example of the possibilities of nanotechnology, the important points are included here). Today's suits are bulky and cumbersome, work is extremely difficult and sometimes impossible. Imagine the possibilities of what nanotechnology can do for the world of spacesuits. They will be light, thin, comfortable and easy to work with but they have enhanced strength. The suit will automatically adjust to the contours of your body when you put it on, making it barely noticeable. If we assume the suit to be a single millimetre thick that provides room for a 1000 micron thick layers of active nanocomputers and nanoelectronics. If we increases thickness slightly we can now include a three dimensional weave of diamond based fibres. These will be capable of mimicking muscle fibres, as they will be controlled by nanocomputer and nanomechanics. Now the suit will feel as if it is not really there as the computers will immediately sense any move and the suit will follow. Perhaps most impressively the suit will be sensitive to the touch due to its active structure including sensors, these will calculate the pressure exerted and the structure transmits this force to you. When you touch something with your finger you feel exactly what you will feel without the glove. Both the strength enhancement and the sensitivity of the suit can be increased or decreased as desired, so it may be used for protection by reducing sensitivity. 100% recycling of all wastes means there will always be food and water available. The suit will be able to repair itself due to its active structure. Further enhancements, could include information (all text of every published book could be held on disk smaller than pinhead) brought up on the visor's HUD.
• The space elevator will become a realistic possibility with diamondoid fibres that anotechnology will provide. Maximum stress is at geosynchronous altitude so the cable must be thickest there and taper exponentially as it approaches Earth. Materials may be compared using the taper factor, or the ratio between cable's radius at geosynchronous altitude and at the Earth's surface. For steel the taper factor is tens of thousands (impossible), for diamondoid fibres the ratio is calculated as in the low 20's including safety factor. Large supplies of carbon will be necessary, probably using both asteroid resources and the atmosphere. Using this material a cable could be constructed, probably downwards from the space station, and the cable may be thickened from carbon in the atmosphere. At that point, "elevators" will lift people and payloads into space, and bring others down. Launch costs to LEO will be minuscule. The system could be mechanical, or better electromagnetic. There is another major problem with the space elevator, safety. If something so large broke its long fall to Earth would be disastrous, again nanotechnology may provide the answer by using active materials as previous discussed. This would allow the cable to detect and repair any small flaws as they occur.
• Space colony structures could be substantially improved with the structural advantages of nanotechnology. Gerard K. O'Neill suggested his colonies could be 3.2 km in radius if the colony was made of steel. It has been noted that by using titanium this could be increased to 14 km, but using diamondoid fibres the potential radius of the colony is nearly 1000 km. Clearly this would require access to substantial carbon deposits.
• Using advanced nanotechnology, including vascular systems in the spacecraft, the vehicle may adapt to conditions in space by rebuilding itself as needed while in flight, using solar energy to power the computers and assemblers. This would also allow general repair and maintenance to occur without bothering the crew. The spacecraft, being built of active materials, continually monitors itself and takes any action necessary.
• Rather than having to store large numbers of spares and tools on spacecraft, stations and bases assemblers can construct tools to exact specifications as and when is needed. Once they are finished with they can be disassembled, thus recycled for the next time tools are required. The addition of new tools would simply be a case of introducing a new piece of software with the building instructions.
• The technology can be used to make food by molecular manufacturing, while this may be the most attractive means available, in an emergency it will be a valuable capability.
• Recycling will be greatly improved by nanotechnology with all waste molecules being recycled and used elsewhere. Nanosystems will directly disassemble waste products, and directly assemble consumables. Recycling at the atomic level will be very efficient and in closed environments, such as space stations this will be crucial. Nanotechnology should also be able to recycle the air efficiently as well, providing a high-class life support system. Recycling water is also well within the capabilities of nanosystems.
• Spacecraft docking would be much easier by extending a swarm of active materials out to each other and allowing this to bring the spacecraft together.
• The advantages of nanomedicine on remote, self-sustaining colonies should not be overlooked.
• There are many advantages for terraforming with nanotechnology. Self-replicating devices can be placed on the surface and in the atmosphere to make chemical modifications, absorbing sunlight and raw materials and creating the desired products, such as greenhouse gases, converting gases to oxygen or even creating water from hydrogen and oxygen. These devices could change environments much like plants did on Earth, only much faster and more efficiently.
• Very precise mirrors will improve current space telescopes, allowing us to peer deeper into space.
• If we are to discover extra-terrestrial materials and alloys we will need to understand the atomic structure to recreate the sample whenever and wherever we want. Nanotechnology will allow this be using disassemblers (analysers) to carefully take the sample apart atom by atom. A nanocomputer will carefully record the structure as it is taken apart. This can then be transmitted to as software to other locations and the new atomic structure can be reconstructed.
• Nanotechnology will allow us to analyse new environments by creating self-replicating sensors and probes, billions or even trillions would be used to record details in the atmosphere and on the surface of the Earth or extra-terrestrial worlds. These probes are sometimes referred to as 'smart dust'.
• With nanotechnology we shall be able to construct much lighter, but more efficient solar panels to increase energy generated from about 118W/kg to 10⁵ (10^5 or 100,000) W/kg. This will be beneficial for space stations, colonies and spacecraft, and together with the construction advantages nanotechnology brings it will make a SPS a cheap and easy project with high performance results.
• Nanotechnology will allow storage of oxygen and hydrogen at much higher pressures, allowing more to be stored in less space. This will also be crucial to storing chemicals as cryogenic solids, which will be necessary for HEDM etc.
• Re-entry protection can be greatly enhanced using nanotechnology materials, providing high temperature protection at very low mass to volume ratios.
• Imagine the capabilities of nanotechnology, an assembler and energy source could be delivered to a carbonaceous asteroid. Then, consuming the asteroid, the assembler will self-replicate and enable the construction of vast solar panels to power a vast construction project, resulting in the building of an immense space station. This could be accomplished in a relatively small amount of time (days, perhaps weeks rather than years or even decades), with a very small initial payload and no human interaction following the launch.

At various points in the above lists we have referred to using great amounts of resources and energy in space. It must be remembered that there are considerable amounts of both in our solar system. The total energy of the Sun is a billion times greater than what hits the Earth and even small asteroids are able to bury all Earth's continents 1 km deep in raw materials. Within these small asteroids there are billions of tonnes of rare and precious metals, cobalt, nickel and even completely new alloys for the disassemblers to investigate.

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