12.7.1 Text 12 D Read, match paragraphs and headings

The Right Materials for Super Spaceships

Our exploration of the solar system will need to expand in the decades to come. The new vehicles must be faster, lighter, cheaper, more durable and more functional, all at the same time.

Revolutions in technology – like the Industrial Revolution that replaced horses with cars – can make what seems impossible today commonplace tomorrow. Such revolution is happening right now. Three of the fastest-growing sciences of our day – biotech, nanotech and information technology – are converging to give scientists unprecedented control of matter on the molecular scale. A new class of materials with striking properties that seem to come from a science-fiction novel has appeared.

For example, a substance with 100 times the strength of steel and only 1/6 the weight; materials that instantly reconstruct themselves when damaged; surfaces that can “feel” the forces pressing on them; wires and electronics as tiny as molecules; structural materials that also generate and store electricity; and liquids that can instantly switch to solid and back again at will (if desired). All of these materials exist today and more are on the way.

The challenge of the next-generation spacecraft is cost. Lowering the cost of space flight primarily means reducing weight. Each pound cut away is a pound that will not need propulsion to escape from the Earth’s gravity. Lighter spaceships can have smaller, more efficient engines and less fuel. This, in turn, saves more weight, thus creating cost reduction.

So the problem is to lower weight while increasing safety, reliability and functionality. Scientists are exploring a range of new technologies that could help spacecraft become lighter. For example, there are materials, which are ultra-thin films and might be used for antennas or instrument panels in place of the larger components, used today, or even for vast solar sails that provide propulsion while weighing only 4 to 6 grams per square meter.

Materials that make up critical systems in spaceship could be embedded (вставлять, внедрять) with nanometer-scale sensors that constantly monitor the material’s condition. If some part is starting to fail, these sensors could warn the central computer before tragedy strikes.

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

Some advanced materials made of long-chain molecules called ionomers react to penetrating object such as a bullet by closing behind. Spacecrafts could use such skins (обшивка) because space is full of projectiles – fast moving bits of debris (осколки) from comets and asteroids. Should one of these tiny-sized objects hit the ship’s armor, a layer of self-reconstructing material would keep the cabin airtight.

Meteoroids are not the only danger; space is filled with radiation too. Scientists are still searching for a good solution. The aim is to provide adequate shielding without adding extra weight to the spacecraft. Some lightweight radiation – shielding materials are currently being tested in an experiment onboard the International Space Station.

The real danger is Galactic Cosmic Radiation produced in the distant supernova explosions. It turned out that the worst materials that you can use for shielding against cosmic radiation are metals. Ironically, light elements like hydrogen and helium are the best defense against the cosmic radiation. Some specialists have suggested surrounding the living quarters of the ship with a tank of liquid hydrogen. A very thin layer of hydrogen would provide adequate shielding. But the tank and the cryogenic system are likely to be heavy.

Nanotubes might be useful. Carbon nanotubes can store hydrogen at high densities, and without the need for extreme cold. So if the spacecraft of the future already uses nanotubes as an ultra-light structural material, could such tubes also be loaded up with hydrogen to serve as radiation shielding? Scientists are looking into the possibility.


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