Engineers quip that FOD is a four-letter word, but there is nothing funny about foreign object debris and its potential to trigger disaster.
The incident occurred on October 5 around 10:25 am ET, as the SpaceX crew was preparing the Dragon pad patience to launch above a Falcon 9 rocket. With the four Crew-5 astronauts inside the capsule already closed and locked, a close eye spotted a single human hair in the seal enclosure. The piles are designated FOD – a technical term for foreign object debris – requiring the crew to act as a pad.
The countdown clock ticked just past T-90 minutes, so time was of the essence. The code crew calmly digs patiences embraced and moved the offensive shore. They did another inspection, thoroughly cleaned the seal, and shut it down for the second and last time. The following pressure check confirmed the tight seal.
The whole thing took a few minutes, and the launch didn’t suffer. The launch of Falcon 9 took place at noon on the schedule with Crew-5 astronauts—Nicolas Aunapu Mann, Josh Cassada, Koichi Wakata and Anna Kikina-International Station arrived successfully the next day.
That the SpaceX pad crew would take the time to remove a single hair in advance of the rocket launch is telling and totally understandable. In the aerospace industry, FOD is defined as any object that does not belong to a specific location, whether that location is a seal, an engine, a cockpit or a bridge. Obstruction in the wrong place can facilitate damage to equipment, suboptimal performance of systems, and even trigger malfunctions.
The flow is across many industries, but for the aerospace industry, it’s a problem that comes with a $4 billion tag per year; second to Boeing NASA runs a FOD program at the Kennedy Space Center, whose goal is to “reduce the possibility of loss or damage to flight hardware or injury to persons due to lost items in flight hardware that result in the maintenance of national capabilities.”
Speaking with me about the film, Tom Simon, deputy space manager at NASA’s Johnson Space Center, said, “We’ve all been trained before day one, when we’re dealing with flight systems, to look at the FOD.” Foreign objects, such as pencils, paper, curling irons, hair, and dust, “might be less visible,” but among other things, they could result in “a seal that comes off more slowly,” he said. “When we build systems, we take them seriously,” he added.
As an engineer, FOD is “burnt into your system,” John Posey, NASA’s lead engineer for Crew Dragon, told me on the same call. It is “considered the highest risk in the training program”, as the FOD has the potential to “bring down rocks and debris”.
Simon and Posey couldn’t speak to the specific policies and protocols of SpaceX, but they weren’t surprised by the pad’s actions in removing human hair. FOD related to sealing surfaces is a serious concern. When you seal the surface, and when you have a tight seal, “you don’t want anything pressing against it,” Posey said. “Something like a hair-depending on its size and orientation, can travel in a leak.”
Posey said that for sensitive situations like the last closed box closure, an emergency FOD type should be built in time and process, in addition to a contingency plan if this mission were to arise. Code crews should “remove the outside, item, re-inspect, and even clean the seal, and then move on when you’re trying to do the work,” Posey said.
This does not only exclude those who are prone to the risk of FOD. Operators should implement procedures to mitigate the risk of FOD, such as using covers or shields in work such as cutting or cutting needs to be done near boats. And of course we need the clean workers themselves. Propulsion systems, in which fuels and oxidizers are pumped through high-pressure systems, can be affected by FOD, says Posey, who worked in space in his last days and spent “thousands of hours on propulsion systems, on the ground with work.” technicians, make it good. “
As Simon explained, the level of cleanliness often depends on the nature of the project or mission itself. Posey said each system needs its own design, with engineers defining acceptable limits and determining what needs to be accomplished.
Clean room protocols for satellite launches tend to be minimal, “to the point of washing hands and wearing gloves,” he said. But the crew’s missions are different. “With crews, you don’t just want to have the avionics system working, you also don’t want to have pilots all over the place,” Simon said, in addition to clean seals. Once in orbit, microgravity can suddenly bypass FOD flying around, including dust and dust. Posey said filtration systems are designed to handle such materials, “but you want to stop the hassles,” such as lids that seal off, among other measures. And “even the lids to clean and lower the drip,” he added.
Posey offered some sage advice: “Always make sure you open the system in a clean room, the only thing you need to do, and close it before inspection.” And “if you see something that doesn’t look right, go in and investigate,” as it is “a necessary burden,” he said. The other line of sight will not hurt, he added. “FOD will find a way to get into your system,” Posey said, hence the term “Smart FOD.” It happened in which the booty or shoe cover was suddenly caught in the cell. “It’s like someone’s foot slipped, and these types of things can be funny in retrospect,” Posey said, but loot or tape or other things that don’t belong, flammability can be a concern.
Measures to prevent FOD from entering complex elements or systems are initiated in a clean place, and every clean place has its own cleanliness requirements, depending on the purpose. Clean rooms are “specially certified and monitored for a certain cleanliness rating based on what’s in there,” and items typically have to be approved before being allowed into the clean room, Posey said.
Lockers available to hold loose items; adhesive tape and floor pads can secure what will be in the room; and the nerves catch up with whatever may have been left out. Overalls, known to engineers as “bunny suits,” cover the arms and legs and usually include a hood. Their beards are covered with nets, and their shoes receive booty.
“Once you’re ready and you’re all geared up, you’ll enter a double door,” Posey said, the first of which “closes behind you and then into a clean room.” In the middle of some double doors, “the air blows all over you, sucking up all the dust or debris,” he explained. Staff will collect any FOD found and investigate where it came from and whether any additions are needed. Clean rooms are “never clean enough,” Posey added.
These are added overhead but necessary. The good news is that FOD detection improves over time. Cameras are now used to observe virtually every corner of the missile pad, while X-rays and CT scans can see inside objects and create 3D images of the interior. With these tools, engineers can “see the outcome of the assembly” and “detect FOD that would otherwise not be found,” Posey said. The increased ability to smell FOD is important for private individuals, especially in times of component reusability.
A human hair found inside a wasp seal or a question on a disturbed flight cannot make 5, but this does not matter. This thing is safety, and there is no thing that could put human life in danger. Engineering will continue to seek FOD, regardless of the cause of the inconvenience.
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