Nanotechnology in Space
Nanotechnology will play an important role in future space missions. Nanosensors, dramatically improved high-performance materials, or highly efficient propulsion systems are but a few examples.
Most of today's rocket engines rely on chemical propulsion. All current spacecraft use some form of chemical rocket for launch and most use them for attitude control as well (the control of the angular position and rotation of the spacecraft, either relative to the object that it is orbiting, or relative to the celestial sphere). Real rocket scientists though are actively researching new forms of space propulsion systems.
One heavily researched area is electric propulsion (EP) that includes field emission electric propulsion (FEEP), colloid thrusters and other versions of field emission thrusters (FETs). EP systems significantly reduce the required propellant mass compared to conventional chemical rockets, allowing to increase the payload capacity or decrease the launch mass. EP has been successfully demonstrated as primary propulsion systems for NASAís Deep Space 1, Japanís HAYABUSA, and ESAís SMART-1 missions.
A nanotechnology EP concept proposes to utilize electrostatically charged and accelerated nanoparticles as propellant. Millions of micron-sized nanoparticle thrusters would fit on one square centimeter, allowing the fabrication of highly scalable thruster arrays.
nanoFET characteristic size scales (Image: University of Michigan Department of Aerospace Engineering)
Pretty far out are proposals that the manipulation of Casimir forces could lead to a propulsion system for interstellar spaceships. The basic idea is that if one could exploit the fact that vacuum is an energy reservoir, thanks to zero-point energy, future space travelers would have access to a limitless energy source. The only thing they need, of course, is some kind of propulsion system that harvests the required energy from the vacuum. That this is not totally crazy was demonstrated in a 1984 paper. Serious research efforts are being made in various laboratories to harness the Casimir and related effects for vacuum energy conversion (read more: "nanotechnology, the mysterious Casimir Force, and interstellar spaceships").
Radiation shielding is an area where nanotechnology could make a major contribution to human space flight. NASA says that the risks of exposure to space radiation are the most significant factor limiting humansí ability to participate in long-duration space missions. A lot of research therefore focuses on developing countermeasures to protect astronauts from those risks. To meet the needs for radiation protection as well as other requirements such as low weight and structural stability, spacecraft designers are looking for materials that help them develop multifunctional spacecraft hulls.
Advanced nanomaterials such as the newly developed, isotopically enriched boron nanotubes could pave the path to future spacecraft with nanosensor-integrated hulls that provide effective radiation shielding as well as energy storage.
Another area of required radiation shielding is the protection of onboard electronics. It has been reported previously that electronic devices became more radiation tolerant when their dimensions are reduced. For example, multi-quantum well or quantum dot devices can be tens or hundreds times more radiation tolerant than conventional bulk devices. It even was shown that quantum dot/CNT-based photovoltaic devices were five orders of magnitude more resistant than conventional bulk solar cells.
Recently, a few studies on radiation effects of high energetic particles such as proton, electron, and
heavy ions on nanomaterials like carbon nanotubes and nanowires have focused on the changed structural properties of the nanomaterials after irradiation (read more: "Carbon nanotubes harden electronics for use in aerospace").