Super Spaceships

Beyond merely being strong, nanotubes will likely be important for another part of the spacecraft weight-loss plan: materials that can serve more than just one function.

"We used to build structures that were just dumb, dead-weight holders for active parts, such as sensors, processors, and instruments," Marzwell explains. "Now we don't need that. The holder can be an integral, active part of the system."

Imagine that the body of a spacecraft could also store power, removing the need for heavy batteries. Or that surfaces could bend themselves, doing away with separate actuators. Or that circuitry could be embedded directly into the body of the spacecraft. When materials can be designed on the molecular scale such holistic structures become possible.

Humans can feel even the slightest pinprick anywhere on their bodies. It's an amazing bit of self-monitoring - possible because your skin contains millions of microscopic nerve endings as well as nerves to carry those signals to your brain.

Likewise, materials that make up critical systems in a spaceship could be embedded with nanometer-scale sensors that constantly monitor the materials' condition. If some part is starting to fail - that is, it "feels bad" - these sensors could alert the central computer before tragedy strikes.

Image courtesy NASA's Morphing Project at LaRC. This piezoelectric material, developed at NASA's Langley Research Centre (LaRC), can "feel" deformations such as bending or surface pressure, producing a small voltage in response that can act as a signal for a central computer.

Molecular wires could carry the signals from all of these in-woven sensors to the central computer, avoiding the impractical bulk of millions and millions of today's wires. Again, nanotubes may be able to serve this role. Conveniently, nanotubes can act as either conductors or semi-conductors, depending on how they're made. Scientists have made molecular wires of other elongated molecules, some of which even naturally self-assemble into useful configurations.

Your skin is also able to heal itself. Believe it or not, some advanced materials can do the same thing. Self-healing materials made of long-chain molecules called ionomers react to a penetrating object such as a bullet by closing behind it. Spaceships could use such skins because space is full of tiny projectiles - fast-moving bits of debris from comets and asteroids. Should one of these sand- to pebble-sized objects puncture the ship's armor, a layer of self-healing material would keep the cabin airtight.

Meteoroids aren't the only hazard; space is filled with radiation, too. Spaceships in low-Earth orbit are substantially protected by our planet's magnetic field, which forms a safe bubble about 50,000 km wide centred on Earth. Beyond that distance, however, solar flares and cosmic rays pose a threat to space travelers.