How a Single Human Hair Nearly Halted a SpaceX Launch

Engineers quip that FOD is a four-letter phrase, however there’s nothing humorous about international object particles and its potential to set off catastrophe.

The incident occurred on October 5 at round 10:25 a.m. ET, as a SpaceX pad crew was getting ready Crew Dragon Endurance for launch atop a Falcon 9 rocket. With the 4 Crew-5 astronauts already contained in the capsule and the hatch closed, an attentive eye noticed a single human hair within the latch seal. The hair was designated FOD—an engineering time period for international object particles—requiring the pad crew to take motion.

The countdown clock had simply ticked previous T-90 minutes, so time was of the essence. The pad crew calmly reopened Endurance’s hatch and eliminated the offending strand. They carried out one other inspection, totally re-cleaned the seal space, and closed the hatch for the second and last time. A subsequent strain examine confirmed a good seal.

The complete affair took just a few minutes, and the launch wasn’t affected. Blast off of the Falcon 9 occurred at midday as scheduled, with the Crew-5 astronauts—Nicole Aunapu Mann, Josh Cassada, Japan Koichi Wakata, and Anna Kikina—efficiently reaching the International Space Station on the next day.

That the SpaceX pad crew would take the time to take away a single hair upfront of a rocket launch is revealing and completely comprehensible. In the aerospace trade, FOD is outlined as any object that doesn’t belong at a selected location, whether or not that location is a hatch seal, an engine, a cockpit, or the runway. Debris within the fallacious place can harm gear, facilitate the suboptimal efficiency of methods, and set off outright malfunctions.

It’s a problem throughout many industries, however for the aerospace trade, it’s an issue that comes with a $4 billion price ticket annually, according to Boeing. NASA runs a FOD program at Kennedy Space Center, the aim of which is to “minimize the possibility of damage or loss of flight hardware or injury to personnel due to lost items within the flight hardware elements, resulting in preservation of national resources.”

Speaking to me on a video name, Tom Simon, deputy spacecraft supervisor at NASA Johnson Space Center, mentioned, “we’ve all been trained since day one, when dealing with flight systems, to watch out for FOD.” Extraneous gadgets, reminiscent of pencils, paperclips, screwdrivers, hair, and mud, “might seem minor,” however they might, amongst different issues, lead to a “seal that is slowly leaking overboard,” he mentioned. “When we’re building systems, we take it seriously,” he added.

As an engineer, FOD is “ingrained in your system,” John Posey, NASA lead engineer for Crew Dragon, instructed me throughout the identical name. It’s “considered a top risk in training programs,” as FOD carries the potential to “bring down rockets and aircraft,” he defined.

Simon and Posey weren’t capable of converse to SpaceX’s particular insurance policies and protocols, however they weren’t shocked by the pad crew’s actions in eradicating the human hair. FOD associated to the sealing of surfaces is a critical concern. When coping with a sealing floor, and when having to make sure a good seal, “you don’t want something pressing up against it,” Posey mentioned. “Something like hair—depending on its size and orientation—can result in a leak path.”

Posey mentioned that, for time-sensitive conditions like the ultimate closing of a capsule hatch, the sudden look of FOD must be constructed into the timeline and course of, along with having a contingency plan ought to this situation come up. Pad crews ought to “back out, remove the item, re-inspect, and even clean the seal, and then move forward with the job you’re trying to do,” mentioned Posey.

It’s not simply hatches which might be liable to FOD danger. Launch operators implement processes to mitigate FOD danger, reminiscent of utilizing covers or shields when work like chopping or sawing must be accomplished close to spacecraft. And after all, the operators themselves have to be clear. Propulsion methods, wherein fuels and oxidizers are pumped by way of high-pressure methods, might be affected by FOD, mentioned Posey, who labored on the Space Shuttle throughout its last days and “spent thousands of hours on propulsion systems, working on the floor with technicians, to make sure it’s all good.”

As Simon defined, the required diploma of cleanliness usually will depend on the character of the venture or mission itself. Posey mentioned each system wants its personal management plan, with engineers defining acceptable limits and deciding what must be screened.

Clean room protocols for uncrewed satellite tv for pc launches are typically minimal, “to the point of washing hands and putting on gloves,” he mentioned. Missions involving a crew are a distinct story, nonetheless. “With crews, not only does the avionics system have to work, you also don’t want to have things flying all over the place,” along with preserving the seals clear, mentioned Simon. Once in orbit, microgravity can out of the blue trigger unnoticed FOD to drift round, together with hair and mud. Posey mentioned filtration methods are designed to cope with this form of stuff, “but you still want to prevent hassles,” reminiscent of requiring covers over hatch seals, amongst different measures. And “even covers have to be cleaned and checked for leaks,” he added.

Posey provided some sage recommendation: “Always make sure you’re opening a system in a clean room, perform only what you need to do, and do an inspection prior to closing it up.” And “if you see something that doesn’t look right, go in and investigate,” because it’s a “necessary burden,” he mentioned. A second set of eyes received’t harm, he added. “FOD will find a way to get into your system,” mentioned Posey, therefore the time period “Smart FOD.” He recounted an incident wherein a bootie, or a shoe cowl, was out of the blue found within the Shuttle compartment. “It just slipped off someone’s foot, and these types of things can be funny in retrospect,” mentioned Posey, however booties or tape or anything that doesn’t belong is usually a flammability concern.

Measures to forestall FOD from stepping into elements or complicated methods begin within the clear room, and each clear room has its personal cleanliness necessities, relying on the venture. Clean rooms “are specially certified and monitored to a certain cleanliness rating depending on what’s in there,” and gadgets usually have to be accepted earlier than they’re allowed right into a clear room, mentioned Posey.

Lockers can be found to carry free gadgets; tape and sticky flooring pads can safe gadgets that should be within the room; and tethers can catch something that’s by accident dropped. Overalls, identified to engineers as “bunny suits,” cowl legs and arms and often function a hood with a hair web. Beards get lined by beard nets, whereas sneakers get booties.

“Once you’re ready and all geared up, you step through a double door,” mentioned Posey, the primary of which “closes behind you and then you go into the clean room.” In the medium chambers of some double doorways, “air blows all over you, sucking up any dust or debris,” he defined. Staff will accumulate any discovered FOD and examine the place it got here from and whether or not any extra controls are wanted. Clean rooms “are never clean enough,” Posey added.

These measures are an added however obligatory headache. The excellent news is that FOD detection is enhancing over time. Cameras are actually routinely used to watch nearly each nook of a launch pad, whereas X-ray and CT scans can peer inside objects and create 3D pictures of an element’s inside. With these instruments, engineers can “see assembly issues” and “detect FOD that wouldn’t have been found otherwise,” Posey mentioned. An enhanced potential to sniff-out FOD is of accelerating significance to the personal sector, significantly within the period of part reusability.

The human hair discovered contained in the hatch seal might or might not have brought about an issue throughout the Crew-5 flight, however that doesn’t matter. What issues is security and the elimination of something that would put human lives in danger. Engineers will proceed to hunt out FOD, whatever the inconvenience it could trigger.

More: Remembering Enterprise: The Test Shuttle That Never Flew to Space.