For a week or so in the middle of July, several very interesting stories about events well beyond Earth’s atmosphere populated the news. In one — similar to the movie Gravity — some space debris from a defunct Russian weather satellite had drifted near the International Space Station (ISS) without sufficient warning to move the station cleanly out of the way. The ISS crew was forced to retreat to the shelter of the attached Soyuz space capsule in case an evacuation was necessary. Fortunately, no impact occurred and operations resumed, but it brought to my mind that I often forget the ISS is up there, and what a remarkable scientific achievement it is.
Around the same time, Asteroid UW-158 passed within 2.4 million km of Earth. Such an event typically would not receive a lot of attention, except that astral spectrometry has determined this asteroid contains upwards of US$5.4 trillion of platinum and other rare metals! This reignited a lot of speculation about one day “roping” asteroids and mining them.
Finally, there was very big news when the New Horizons space probe flew by Pluto and beamed stunning photos back to Earth. After nearly 10 years and 3 billion miles, we were treated to a lot of information about what was once considered (and still considered by some) the ninth planet in the solar system. New Horizons will continue exploring other objects in the Kuiper Belt, where Pluto is located, and beyond, perhaps out to 2030, depending on how long its onboard plutonium fuel lasts.
My point? Some 46 years after Apollo 11 made history by landing the first men on the moon, it’s easy to take what goes on in space lightly. But space exploration, and the funding behind it, have led to numerous inventions that are now ubiquitous in daily life — most notably, live transmission of data and video around the world, and highly accurate GPS services that get us from point A to point B. Closer to home, along the way, advanced composites have played a major role in these advances.
Such materials are, in fact, vital to success in space. Compared to the automotive sector, where the value of a kilogram of weight savings is difficult to quantify, or commercial aviation, where it is thought to be about $660/kg, composites bring to satellites, orbital telescopes and space probes savings that can reach US$10,000/kg, because reduced mass permits more fuel to be carried, extending the spacecraft’s useful life. Beyond weight reduction, high-modulus carbon fiber prepregs can be fabricated to achieve exceptional stiffness and near-zero coefficients of thermal expansion, improving the accuracy of reflectors, solar panels and cameras in the extreme heat and cold of space. Until 1990, these were almost exclusively 1970s-generation epoxies reinforced with 75- or 100-Msi, pitch-based carbon fiber. At that time, a new generation of high-modulus PAN-based fibers was developed, and a new resin system was introduced, based on cyanate ester chemistry.
The new fibers offered improved tensile strength and processability, and a key feature of the cyanate ester resin was a very low level of moisture absorption compared to epoxy. This was important to the space industry because it reduced substantially the need to dry composite parts before launch, where, in the vacuum of space, entrapped moisture evaporates, condensing on critical lenses and instruments, making them less effective. Inside of two years, the entire satellite industry converted to use of these new materials — remarkable, given the generally conservative nature of the aerospace composites community.
What does the future hold? Although colonization of Mars or other planets still seems a fantasy, other opportunities to capitalize on what’s “out there” will start to become realities. In 2016, for example, NASA will launch OSIRIS-ReX on a seven-year mission to collect samples from carbonaceous asteroid Bennu, to study the formation of organic compounds and the origins of life. On another front, research has already commenced on combining materials of differing densities in the microgravity of space, offering some unique potential for 3D printing and other manufacturing techniques. Of course, there is still the promise of commercial space travel for humans, being pursued by multiple companies. And on July 16 this year, asteroid mining firm Planetary Resources (Redmond, WA, US) deployed a demonstration probe from the ISS on a 90-day mission to test critical electronic systems and software, as part of a long-term plan to, yes, harvest resources from asteroids. Whether we actually latch onto and extract minerals from space rocks on a commercial scale remains to be seen and might be decades away. But no matter, all of these (and other) avenues will have one thing in common: Advanced composites will be there for the ride.