Nanotechnology may hold the key to making spaceflight more practical. Advancements in materials to make lightweight solar sails and the cable for the space elevator could significantly cut the cost of reaching orbit and traveling in space, as well as dramatically reducing the amount of rocket fuel used. Also new materials, along with nanosensors and nanorobots could improve the performance of spaceships, spacesuits and equipment used to explore planets and moons, making a big difference on the ‘final frontier.’
The space elevator is a device that will dramatically reduce the cost of sending cargo into orbit. Like any elevator the space elevator will have a cable, however it will need to be stronger than any existing cable. Roughly 90,000 kilometers long, the space elevator cable will probably be made from carbon nanotubes. It will be anchored at the top to an asteroid (called the counterweight) in orbit around the earth, and at the bottom by an anchor station, perhaps floating in the ocean similar to a drilling rig.
This device would eliminate the need to use rocket fuel, and dramatically reduce the cost of sending cargo into orbit (about 95% of the weight of the space shuttle at blast off is rocket fuel). Instead, solar cells on space elevator cars would convert light from a laser beam mounted on the anchor station into electricity to drive the car up or down the cable like a vertical monorail.
While there are some engineering challenges, to me the most intriguing of which is actually stringing this 90,000 kilometer cable between the anchor station in the ocean and the counterweight asteroid in orbit, steps are underway to address these challenges. A report by NASA’s Institute for Advanced Concepts gives a very good introduction to the techniques necessary to construct the space elevator. Yearly competitions conducted by the Elevator 2010 group are providing a focus for energetic minds to demonstrate prototypes with some substantial cash prizes, totaling one million dollars in 2007.
Once you have people and cargo in orbit nanotechnology can be used to reduce the rocket fuel needed to travel to the moon or planets. Just as sailboats are propelled by wind while on the seas, spaceships can be propelled by light from the sun reflected off of solar sails while travelling through space. That means that the only fuel required would be during liftoff, docking, or landing.
However solar sails will have to be very large, spreading for kilometers, and very thin to keep their weight low. That’s where nanotechnology enters the picture. Researchers at the University of Texas have used carbon nanotubes to make thin, lightweight sheets that may replace the polymer sheets that have been experimented with to date. While there are details still to be worked out (such as how to unfurl a thin, fragile sail in orbit, along with the continual struggle to reduce weight) this method has great potential for reducing the amount of fuel needed to travel between planets.
For those times when spacecraft need engines there’s a type of engine called ion thrusters that uses less fuel than chemical rockets. Unlike chemical rockets, which push a spaceship by burning fuel and expelling the resulting hot gasses ion thrusters use electricity gathered from solar cells to generate electric fields that push ions away from the spaceship.
Researchers at the University of Michigan have developed ion thrusters that use MEMS devices to accelerate charged nanoparticles. This Nanoparticle Field Extraction Thruster or NanoFET is designed to allow it to last longer than other types of ion thrusters and allow multiple NanoFETs to be clustered together. This could simplify the job of spacecraft engineers by allowing the same thruster design to be used on spacecraft over many different missions just by changing the number of NanoFETs mounted on the spacecraft.
Regardless of how fuel efficient propulsion systems are, it’s still important to make spacecraft lightweight. Researchers are investigating nanotube composites from which they can manufacture strong and lightweight skin and structural members for spacecraft. However this is just the start of how nanotechnology could change the way that spaceships are made. NASA has included a concept called self healing spaceships in their 2030 nanotechnology roadmap. Just as your skin heals a small puncture wound NASA is looking to nanotechnology to provide a way for the skin and structural components of a spaceship to seal up damage from meteors that strike the spaceship.
NASA is also planning to use nanosensors to improve the monitoring of spaceship systems such as life support. The ability of nanosensors to quickly report changed levels of trace chemicals in air could be very useful to keeping life support systems working correctly in a spaceship’s closed system. A longer term proposal is to place nanosensors throughout the skin of a spacecraft to act like nerve endings in your skin. When a particular region of the spacecraft skin becomes is stressed or damaged, the main computer is alerted to take action and alter the spaceship’s course, just as you would jerk your hand away from a hot stove.
Occasionally astronauts have to leave their spaceships, so researchers at Northeastern University and Rutgers University propose that we protect the astronauts by including layers of bio-nano robots in their spacesuits. The outer layer of bio-nano robots would respond to damages to the spacesuit, for example to seal up punctures. An inner layer of bio-nano robots could respond if the astronaut was in trouble, for example by providing drugs in a medical emergency.
The term bio-nano robots comes from the use of biological molecules to provide portions of the robots mechanism. For example, proteins have mechanisms to travel within a body that enable it them to work as a motor for a nano robot. These proteins could be connected to carbon nanotubes that link parts of the nano robot together. When you think about it, this idea is just like harnessing a horse to a cart as the nano robots hitch a ride on the proteins. There’s a lot of development work to be done, but it will be interesting to see how these self-healing suits turn out.
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