Followers of our blog, no doubt, know that aluminum alloys are a critically important material for the aerospace industry. The same is true for the ever-developing world of spacecraft manufacturing. They require materials that can withstand intense vibrations and the unique hazards of space. To this end, aluminum provides the perfect answer.
Since Sputnik was launched more than half a century ago, aluminum has been the go-to material for space vehicles and structures. It’s remarkable light weight, high-strength, mechanical stability and dampening properties exceed other materials and make it the first choice for spacecraft – from the International Space Station and the Mars Curiosity Rover, to the spacecraft of the future like NASA’s Orion project. All modern spacecraft are made from anywhere between 50-to-90% aluminum alloy.
Hazards of Space
The extreme environment of space presents unparalleled challenges to engineers, as they must build structures in space that can operate within its harsh conditions. This is what is called a material’s environment stability – this means that the material can remain stable while being subjected to radiation and the vacuum of space.
Some of the hazards that must be accounted for include:
Aluminum is often used as a shielding material that absorbs radiation from stars. Space radiation can cause direct damage to an astronaut’s DNA and cells. Aluminum can absorb up to half of the radiation being emitted, bringing it down to non-threatening levels for the space crew.
Wild fluctuations between heat (250°F) and cold (-200°F)
The temperature of space is varying constantly, depending on where you are within it. This constant flux in temperature causes materials used in spacecraft to consistently expand and contract. Aluminum’s dimensional stability allows it to maintain its shape and size despite the changing temperature.
Spacecraft are constantly peppered with objects that are floating through space, including micro-asteroids, meteorites, and comets. Aluminum’s strength and rigidity allow it to maintain it’s structural integrity to these types of hazards.
Launch and re-entry
During the launch and re-entry sequence of space travel, the materials that comprise the spacecraft will be put under stresses that exceed three times the force of gravity – effectively making it weigh three times as much as it would in Earth’s gravity. As such, the material must be able to maintain its structural integrity and resist bending or breaking, lest it fall apart on the launchpad.
How is aluminum used in modern spacecraft?
Below, we review some of the major modern spacecraft, and how each utilizes aluminum alloys. Beyond being made of mostly space-grade aluminum, these craft use aluminum in some ingenious and unorthodox ways.
INTERNATIONAL SPACE STATION
The exposed exterior metal of the station is anodized, or otherwise coated for thermal efficiency and to prevent atomic oxygen reactions that occur in the vacuum of space. Also found on the exterior are aluminum whipped shields that absorb the impacts of space debris. In addition, each of the Node modules later added to the craft were made from single blocks of aluminum. In the interior of the station, most objects are made from aluminum for similar weight-saving purposes.
MARS CURIOSITY ROVER
Several components of the Mars Curiosity Rover’s launch vessel were made from aluminum. The launch vessel’s core was made from an aluminum structure that was sandwiched between graphite-epoxy face sheets. The parachute deployment mechanism, which slowed the Rover’s descent onto the Martian surface, was hand forged from an aluminum billet. The frame and wheels of the nine-foot-long, 1,875 lb. Curiosity Rover itself are made of aluminum, as well. “NASA could not have made it to the surface of Mars without aluminum.” Dr. John Grotzinger Chief Scientist and Head of Strategic Planning for the 2012 Mars Rover mission.
SPACE X’S FALCON 9
The fuel tanks of the Falcon 9 are made from an aluminum-lithium alloy, which is an aluminum that has been infused with lithium. The Falcon 9 is a two-stage spacecraft. Inside both stages are aluminum-dome-tipped tanks, which store the fuel used to launch. The first stage engines are gradually throttled near the end of first-stage flight to limit launch vehicle acceleration as the rocket’s mass decreases with the burning of fuel. The second stage delivers Falcon 9’s payload to the desired orbit. Like the first stage, the second stage is made from a high-strength aluminum-lithium alloy.
Quite famously, common household aluminum foil was used to save the Voyager 2 mission very late in the development process. The probe was going to pass Jupiter in 1979, a year and a half into it’s mission. The probe was going to slingshot using Jupiter’s gravitational pull and propel itself towards Saturn. There was a slight problem, though – Jupiter’s magnetic field and emitted radiation were very likely to fry most of the internal systems of the Voyager 2 probe, rendering the entire mission useless. The cables onboard the craft needed to be shielded to avoid damage from radiation. Due to the unique planetary arrangement at the time, which only happens once every 175 years, the Voyager team could not delay the mission. Doing so would lose them both their opportunity and billions of dollars. Without the time to do proper due diligence, they instead sent one of their technicians to a local supermarket to by all the kitchen-grade aluminum that they had available. They wiped down the foil with alcohol and exposed it to every exposed cable on the craft. This last-minute addition to the craft ensured the success of the mission!
NASA’s Orion MPCV (Multi-Purpose Crew Vehicle) will serve as the next-generation space exploration vehicle. The primary structures of the Orion spacecraft are made from an aluminum-lithium alloy and will be covered by an advanced version of the thermal protection tiles used on the space shuttle.
About Taber Extrusions
Founded in 1973, Taber Extrusions originally pioneered a process for extruding rectangular billet which enables the company to extrude solid profiles up to 31 inches wide or hollows up to 29 inches. Taber expanded with the purchase of an extrusion facility in Gulfport, MS in 1995 which houses a new state of the art cast house, two additional presses, and a fabrication area that has been expanded multiple times. Taber continues to extrude billet in a wide range of alloys and sizes.
Your full service partner from start to finish, Taber is proud to announce expanded capabilities to include ultra-precision aluminum extrusions®. Delivering a wide array of features and surface finishes, Taber’s microextrusions provide an additional design alternative at machined tolerances.
In the modern era, aluminum alloys are the integral element that keeps the aerospace industry on the cutting edge. Metallurgists are constantly seeking and developing new aluminum alloys to increase the speed, strength, and safety of aircraft. Strong alloys are used to protect aircraft from the stresses of flight; light alloys are used for heat and cold resistance and insulation.
Aluminum is naturally strong, lightweight and very workable. These powerful natural properties are enhanced by combining it with elements such as zinc, copper, and silicon to create a variety of aluminum alloys; some strong, some more malleable for complex aluminum shapes. Modern aircraft parts are made primarily from these alloys, and not just the frame- everything from the engine to the nuts and bolts are made from aluminum due to its attractive cost to weight ratio. Below, you will find some of the most common aluminum alloys found in aircraft, and what they’re used for.
One of the most common of the aluminum alloys, 2024 is primarily alloyed with copper, which gives it incredible strength and high fatigue resistance. This makes it the ideal alloy when a high strength to weight ratio is needed, making it perfect for wings and fuselages which are the parts of the aircraft that undergo the most tension.
Containing magnesium and silicon, aluminum alloy 6061 is very corrosive resistant and is known for its great weldability. The premiere alloy in aluminum extrusion, 6061 is also used to create fuselages and wings- but is very rarely found in airliners. Mostly, it’s used in small, personal airplanes.
Aluminum alloy 6063 is very similar to alloy 6061. Because of this, it’s the most popular alloy for aluminum extrusion.
Because of its light weight and incredible strength that is comparable to most steels, alloy 7075 is used for the main frame of aircraft structures. No other aluminum alloys can match 7075 in fatigue resistance, and its reliability is constantly being worked upon to create faster, safer and cheaper airplanes, and its great anodization quality gives it a great finish. Due to this alloy’s high copper content, it is hard to weld.