How a single human hair almost stopped a SpaceX launch
How a single human hair almost stopped a SpaceX launch
Engineers quip that FOD is a four-letter phrase, however there’s nothing humorous about extraneous particles and its potential to trigger catastrophe.
The incident occurred round 10:25 a.m. ET on Oct. 5 because the SpaceX web site crew was making ready the Crew Dragon Endurance for launch atop a Falcon 9 rocket. When the 4 Crew-5 astronauts have been already within the capsule and the hatch was closed, a eager eye seen a single human hair within the latch. The hair was labeled FOD — the engineering time period for overseas object particles — requiring motion by the location crew.
The countdown clock had simply handed T-90 minutes, so time was of the essence. The location crew calmly opened up Endurance‘s hatch and eliminated the offending strand. They did one other inspection, totally cleaned the seal space and closed the hatch for the second and last time. A subsequent strain take a look at confirmed the leak.
The entire thing solely took a couple of minutes and it did not have an effect on the launch. Falcon 9 blastoff happened at midday, as scheduled, with Crew 5 astronauts Nicole Aunapu Mann, Josh Casado, Koichi Wakata and Anna Kikina — efficiently reached the Worldwide Area Station the subsequent day.
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That the SpaceX web site crew would take the time to take away not less than one hair earlier than launching the rocket is telling and fully comprehensible. Within the aerospace trade, FOD is outlined as any object that doesn’t belong to a selected location, be it a hatch seal, engine, cockpit or runway. Misplaced particles can harm tools, contribute to suboptimal efficiency of methods, and trigger full failure.
It is a drawback in lots of industries, however for the aerospace trade it’s a drawback that prices $4 billion yearly. respectively to Boeing. NASA manages a BE program on the Kennedy Area Middle, which goals to “decrease the potential for harm or lack of flight tools or damage to personnel because of the lack of gadgets in flight tools, thereby conserving nationwide assets.”
Chatting with me on a video name, Tom Simon, deputy spacecraft supervisor at NASA’s Johnson Area Middle, mentioned, “We’re all educated from day one when coping with flight methods to look at for FOD.” Extraneous objects resembling pencils, paper clips, screwdrivers, hair and mud “could appear minor,” however they’ll, amongst different issues, result in “a seal that slowly leaks overboard,” he mentioned. “After we construct methods, we take it severely,” he added.
As an engineer, FOD is “ingrained in your system,” John Posey, NASA’s lead engineer for Crew Dragon, instructed me on the identical name. It’s “thought of the best threat in coaching packages,” as FOD carries the potential to “shoot down missiles and planes,” he defined.
Simon and Posey could not communicate to particular SpaceX insurance policies and protocols, however they weren’t shocked by the location crew’s actions in eradicating human hair. FOD related to sealing surfaces is a serious concern. Once you’re coping with a sealing floor and it is advisable to present a airtight seal, “you don’t need something urgent in opposition to it,” Posey mentioned. “One thing like hair — relying on its dimension and orientation — can result in a leak path.”
Posey mentioned that in time-sensitive conditions, resembling the ultimate closure of a capsule hatch, the sudden incidence of FOD have to be constructed into the schedule and course of, along with having a contingency plan in place ought to such a state of affairs come up. Web site crews must “step again, take away the merchandise, recheck and even clear the seal, after which transfer ahead with the job you are attempting to do,” Posey mentioned.
It isn’t simply hatches which might be prone to FOD. Launch operators implement processes to cut back the chance of FOD, resembling utilizing covers or shields when operations resembling reducing or sawing have to be carried out close to spacecraft. And, in fact, the operators themselves have to be clear. Propulsion methods wherein gasoline and oxidizers are pumped by high-pressure methods may be affected by FOD, mentioned Posey, who labored on the house shuttle in its last days and “spent 1000’s of hours on propulsion methods, engaged on the ground with technicians to make it possible for every part is ok.”
As Simon defined, the diploma of cleanliness required usually depends upon the character of the challenge or mission itself. Posey mentioned every system wants its personal management plan, with engineers defining acceptable limits and deciding what must be examined.
Clear room protocols for unmanned satellite tv for pc launches are usually minimal, “proper right down to washing arms and placing on gloves,” he mentioned. Crewed missions, nevertheless, are a unique story. “It isn’t simply the avionics system that has to work with crews, you additionally don’t desire issues flying all over,” along with conserving the seals clear, Simon mentioned. As soon as in orbit, microgravity can immediately trigger undetected PVD, together with hair and mud, to drift round. Posey mentioned filtration methods are designed to cope with issues like that, “however you continue to need to stop nuisances,” resembling requiring covers over hatch seals, amongst different measures. And “even the lids should be cleaned and checked for leaks,” he added.
Posey supplied some sage recommendation: “All the time ensure you open the system in a clear room, do solely what it is advisable to do, and take a look at it earlier than you shut it.” And “in the event you see one thing that does not look proper, go in and examine,” as a result of it is a “needed burden,” he mentioned. A second set of eyes would not damage, he added. “FOD will discover a option to get into your system,” Posey mentioned, therefore the time period Good FOD. He instructed of an incident wherein a boot or shoe covers have been immediately present in a shuttle compartment. “It simply slipped off any individual’s leg, and issues like that may be humorous on reflection,” Posey mentioned, however booties, duct tape or anything that does not belong could possibly be a flammability drawback.
Measures to forestall FOD from coming into parts or complicated methods start within the cleanroom, and every cleanroom has its personal cleanliness necessities relying on the challenge. Clear rooms “undergo particular certification and are managed to a sure cleanliness score primarily based on what’s in there,” and gadgets sometimes have to be permitted earlier than being allowed into the clear rooms, Posey mentioned.
Lockers can be found to retailer free gadgets; with tape and sticky flooring coverings, you may repair the gadgets that needs to be within the room; and tethers can catch something that by accident falls. Coveralls, recognized to engineers as “bunny fits,” cowl the legs and arms and often have a hood with a hair web. Beards are lined with beard nets and sneakers are booties.
“Once you’re prepared and every part’s arrange, you undergo the double doorways,” Posey mentioned, the primary of which “shut behind you, and then you definitely go into the clear room.” Within the center chambers of some double doorways, “the air blows round you, sucking in mud and particles,” he defined. Employees will gather any FOD discovered and decide the place it got here from and whether or not extra controls are wanted. Clear rooms are “by no means clear sufficient,” Posey added.
These measures are a further however needed headache. The excellent news is that FOD detection is bettering over time. Cameras at the moment are routinely used to watch nearly each nook of the launch pad, whereas X-rays and CT scans permit us to look inside objects and create 3D photographs of the half’s inside. With these instruments, engineers can “see construct issues” and “detect FODs that would not in any other case be discovered,” Posey mentioned. Improved FOD sniffing capabilities have gotten more and more necessary to the personal sector, particularly within the period of reusable parts.
Human hair discovered contained in the hatch seal might have prompted an issue throughout Crew-5’s flight, however that does not matter. Security and elimination of something that would endanger folks’s lives is necessary. Engineers will proceed to hunt out FOD whatever the inconvenience it could trigger.
extra: remembering Enterprise: a take a look at shuttle that by no means flew into house.
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