We Have Lift-off: How Linde Supports the Space Industry
From the 3D printing of rocket engines to launch propellants and in-space propulsion, Linde’s industrial gases play a critical role to accomplishing any space mission.
When NASA's deep space rocket, the Space Launch System (SLS), took off on its first flight as part of the Artemis I mission in the early hours of Wednesday, November 16, 2022, it did so using several hundred thousand gallons of Linde’s liquid oxygen and liquid hydrogen as propellants. These gases thereby launched what will be a series of complex missions to build, as NASA puts it, “a long-term human presence at the Moon for decades to come.”
Such strong resolve to return to the moon and onward to Mars, along with increasing satellite deployment, the pursuit of privatized space stations and the emergence of space tourism, means commercial opportunities in space are themselves, rocketing. And while launches tend to steal the headlines, industrial gases are involved in various stages before and after lift-off. When every stage is mission critical, quality and reliability are key. That’s why the space industry has Linde onboard to support its programs.
Stage 1: Manufacturing Spacecraft Components
Today, more and more of the rocket engines that ascend layer by layer through the Earth’s atmosphere are themselves built layer by layer. “Our gases and specialized alloy metal powders are used in the 3-D printing of engine components like turbopumps and combustion chambers,” explains Richard Novak, Senior Technology Expert at Linde. Additive manufacturing has become the preferred method for engine parts where low weight, high strength and complex geometries are required. As Novak points out: “When you’re sending something into space, every gram matters.”
With light weight in mind, aerospace companies also often use carbon-fiber composites in their spacecraft structures. The “lay-up” or molding process for these parts involves the composite material being cured in an autoclave. These large vessels are pressurized with nitrogen - just one of the many gases Linde supplies for critical manufacturing steps.
Stage 2: Component Integrity Testing
The components have been manufactured - now it’s time to test their integrity. That means simulating space here on Earth. Components, sub-systems or even full satellites or spacecraft are subjected to their future in situ conditions in so-called space simulation chambers or thermal vacuum chambers for many hours on end. The entire James Webb Space Telescope, for example, was put in a vacuum chamber to be tested for the rigors of space. At this stage, gases are crucial for simulating the extreme parameter changes that the spacecraft may encounter. “Our cryogens like liquid nitrogen and liquid helium are used to cool the chambers and create a vacuum,” says Novak.
Stage 3: Engine Testing and Launch Fuels
When it comes to sending a rocket skyward, the heavy lifting is done by gases. “In a typical launch, around 90% of the rocket’s mass at take-off is the propellants,” explains Robert Sever, Linde Technology Director, with liquid oxygen and liquid hydrogen being two of the signature gases of most modern space programs. But engine testing before a launch requires more gas supply than the launch itself - as Sever further describes: “These engines are tested on the ground in test stands and tested again when they are on the rocket.” And they will burn for the full duration as if in an actual launch - usually around eight or nine minutes.
The number one factor on the supply of gases for launch and testing is not necessarily cost: it’s reliability. Launch companies will need truckloads of gases - several waves of Linde deliveries over a few days. And then there might be a last-minute change to the mission timeline - so flexibility is critical too. “We are one of very few companies that can manage these challenges thanks to our large supply network and best-in-class operations,” explains Holly O’Donnell, Director of Space Programs at Linde.
Stage 4: In-Space Propulsion
With the rocket and its payload successfully reaching space, the mission - and Linde’s involvement - continues. Said payload - a satellite for example - begins orbiting the earth. To reach and maintain their desired orbits, such spacecraft also use propulsion - typically high efficiency electric propulsion that relies on rare gases like xenon and krypton.
In so-called ion-drives (or ion-thrusters), heavy ions of these rare gases are accelerated to create just enough propulsion to move satellites in a void. The drives are solar-powered and are so efficient that 10 kg of xenon gas can see a small satellite through its multi-year lifecycle. “These rare gases are not highly abundant in our atmosphere - so we need to perform specialized separation work to get a meaningful quantity of the gas,” says Matt Coffman, Linde’s Market Manager for Rare Gases. “Our expertise makes Linde a leading supplier of these important propellants.”
The Next Frontier
The steep increase of space activity in recent years means an increased frequency of launches. This fact alone provides opportunity for Linde to continue supporting its customers in the aerospace industry today. But what about tomorrow … and beyond?
Trends like “in-space manufacturing” are already emerging, where specialized materials and products are produced in the unique environment of space for use on Earth. In situ resource utilization like mining the Moon or asteroids is another exciting endeavor. Many industries on Earth today rely on Linde’s products, and their analogues in space will likely be no different. As Sever says, “If you look further into the future and imagine space colonization and a broad space economy, you have to imagine a vital role for gases.” And where there is a vital role for gases, there is a vital role for Linde’s expertise.