Considerations For Materials Used In Space
Space is an exotic environment, utterly different from conditions here on Earth. There is almost no atmosphere, radiation levels are much higher, and there is a real risk of getting hit by debris traveling at supersonic speeds.
Given all these, designing equipment for aerospace travel can be very challenging. However, understanding the unique characteristics of space can help scientists design special materials that can protect spacecraft as well as crew members. With proper knowledge and extensive research, materials engineering for space can allow humanity to traverse the stars someday.
One of the most well-known properties of space is its near-vacuum state, as it contains an almost negligible atmosphere. One effect of this is that temperatures become more unstable, as no atmosphere can carry heat away from hot objects or add heat into cold ones
Temperatures are dictated alone by radiation heat transfer, which can vary depending on whether the object is exposed to sunlight as well as its surface properties. As space objects orbit around the Earth, their temperatures can reach as high as 100°C and as low as -100°C.
Another significant effect observed in space is that liquids will tend to evaporate quickly. The boiling point of fluids is dependent on pressure; the atmosphere mainly exerts a force on liquid molecules that tend to suppress evaporation.
Therefore, materials such as some coatings that rely on the presence of some moisture to work may fail in space. This evaporative effect, combined with the lack of oxygen, also makes space very hazardous for most life forms. Humans will die within one minute when exposed directly to space.
Another major concern is radiation. The earth’s atmosphere contains ionosphere, a charged layer that helps stop most of the radiation from reaching the surface of the planet. The Earth’s ozone layer also protects Earth’s inhabitants from most UV radiation.
These shields do not reach out into space, so objects there will be constantly bombarded by radiation. In addition, the magnetic field of the Earth tends to trap radiation into specific regions of space called radiation belts, and objects that enter these regions will receive high radiation doses.
Ionizing radiation such as X-rays and gamma rays are powerful enough to degrade electronic devices, which can ruin sensors and corrupt data. Ionizing radiation can also damage DNA, causing radiation sickness and cancer in people.
Non-ionizing radiation such as infrared rays and visible light are less energetic, but they can still damage equipment by increasing their temperature until they overheat. Spacecraft must have adequate radiation shielding and use materials that are resistant to radiation damage.
Since space has almost no atmosphere, traveling objects experience no friction and will continue to move until they hit another object or enter Earth’s atmosphere. Debris from past space missions, such as loose metal fragments or flecks of paint, can travel faster than bullets and remain in orbit for several decades.
Even the smallest debris can inflict massive damage on spacecraft if they are moving fast enough. Debris is hard to track and are often hard to detect, let alone dodge, so spacecraft must be built with impact-resistant materials to minimize the risk from space debris.
When objects enter Earth’s atmosphere, their high velocities cause the air in front of them to compress and heat up. The friction from the air also adds to the generated heat. The high temperatures and shear forces can rip off the outer shell of the spacecraft unless special materials are used to cover the vehicle exterior. These materials must be able to dissipate heat and still maintain structural integrity quickly.
By accounting for the peculiar conditions of space, scientists and engineers will be able to research new and exciting materials for space travel. Only with appropriate materials can we build spacecraft capable of enduring the rigors of space. Hence, materials engineering is a critical player in spearheading humanity’s spacefaring efforts.