How an oxygen shortage can delay a NASA launch
As hospitals fill up with COVID-19 patients, NASA has announced it will delay an upcoming satellite launch. The liquid oxygen needed to fuel flight is needed in hospitals, where doctors are using the important resource to keep critically ill COVID-19 patients alive.
“Medical oxygen is our members’ priority,” says Richard Craig, vice president of technical and regulatory affairs for the Compressed Gas Association, a US trade association.
A shortage of truck drivers with the necessary certifications to transport oxygen only adds to the problem, and there are concerns about the postponement of further rocket launches.
At the recent Space Symposium in Colorado, SpaceX President Gwynne Shotwell invited anyone with access to liquid oxygen to get in touch. “We’re definitely going to make sure hospitals have the oxygen they need, but for anyone with liquid oxygen to spare, email me,” she said.
Elon Musk, founder of SpaceX tweeted that the shortage was “a risk, but not yet a limiting factor”. The company plans more than 26 rocket launches this year.
Why is this delay important?
Landsat 9, whose take-off has been delayed until September 23 at the earliest, is designed to image the Earth every eight days, monitoring Earth’s resources and providing valuable information to scientists.
In a pre-launch briefing, Landsat 9 project scientist Jeff Masek compared the Landsat to a Swiss Army knife. “From a basic set of observations or measurements, we feed a whole range of different scientific applications,” he said.
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Sven Bilén, professor of engineering design, electrical engineering and aerospace engineering at Penn State, pointed out that while hospitals are crucial, the space industry also has an increased need for oxygen. “I don’t think people fully understand what space has to offer them when they say we should focus on humanitarian crises and climate change on Earth,” he says. “It’s part of a system that improves life on Earth, whether it’s through GPS signals or weather satellites capable of tracking hurricanes.”
Why do rockets need oxygen?
When you burn something, you oxidize it. On Earth, if you start a fire, it can draw oxygen from the air. But when you go up in the atmosphere, soon there isn’t much oxygen left to be drawn from the air, Bilén explains. This means that rockets need their own oxygen, and much of it, to function.
In the 1920s, Dr. Robert H. Goddard used liquid oxygen for his first tests of revolutionary rocket engines, and it is still one of the most common rocket thrusters in use today. It is also used today in many other industries, such as chemical processing and blast furnaces.
Bilén compared the burning process to those YouTube videos of people trying to start a grill faster and faster, until they finally got the idea of pouring liquid oxygen on it. This speeds up the reaction, quickly burning everything into a toast. “This is basically what you want to happen in a rocket,” he said. “You’re trying to deliver oxygen fast enough that the rocket fuel burns at the rate it needs to provide the thrust needed to lift the rocket. “
How is liquid oxygen made?
To make liquid oxygen, known as LOX in industry, engineers take air and cool it to cryogenic or extremely cold temperatures. Then this liquid is subjected to a process of distillation, sometimes several times to separate the oxygen from the nitrogen and other components of the air.
In hospitals, doctors put patients on oxygen to increase the level of oxygen they breathe above what occurs naturally in the air. “They don’t necessarily need or want 100% pure oxygen,” Bilén explains.
But from a rocket point of view, you want pretty pure oxygen, because it’s a chemical process where it will be combined with the rocket fuel. This means that the oxygen used for space launches has to be much, much purer.
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In medical settings, oxygen is almost exclusively used in the form of gas. The main reason it could arrive at the site as liquefied oxygen is because it provides much more condensed storage.
Like many industries during the COVID-19 pandemic, liquid oxygen suppliers like Air Liquide, Praxair and Airgas may have to adjust what they produce to meet the current needs of the population. “The problem is that there is currently only a certain capacity installed to create oxygen,” Bilén explains, “and there are more and more users now, especially on the medical side. “
What will happen next?
Bilén likens this to the great toilet paper shortage of 2020, when people switched to working from home and from a need for industrial-grade toilet paper to a need for smaller rolls. “The industry can’t change their mind, but after a while they’ve figured out the supply lines and figured that out,” he says.
He predicts that the market will solve this problem by starting to produce more oxygen for the people who need it most. “It’s just a temporary problem,” he said, adding that if there is a real need, the government could use the Defense Production Act to tell the airline product companies to prioritize the oxygen supply to hospitals versus companies like SpaceX.