I was recently contacted by some folks who were interested in – of all things – comments I made in a shuttle press conference some 8 or 10 years ago. These folks were concerned that I and the shuttle team had not treated a specific risk to the space shuttle with enough rigor. Fortunately, I was very familiar with the subject and want to fill in the record on that topic.
The space shuttle was assembled and maintained in the most stringently clean environments practical. Whenever someone entered a shuttle cockpit the full suite of protective clothing was required. I remember that Presidential candidate John Kerry was photographed in the full bunny suit ensemble when he visited KSC and the snarky public comments about how silly he looked helped sink his electoral ambitions. Partially because of that, I would dodge the photographers on those few occasions that I entered a shuttle.
Despite the cleanliness precautions, every time a shuttle got to orbit there was a cloud of debris liberated into the cockpit: dust, screws, washers, bits of cleaning cloth, other fabric, miscellaneous small junk. It was a health hazard to the crew and the filters in the air recirculation system rapidly cleaned out most of it. The crew would install a special device shortly after arriving on orbit, it had an appropriately awful acronym: OCAC. Say that quickly a couple of times. But it worked to help collect all the trash floating in the air. (Orbiter Cabin Air Cleaner).
Whenever a new uncrewed visiting vehicle or new module is plugged into the ISS, the crew must don masks and eye protection when they first open the hatch and go inside. Every new space seems to have its share of floating junk which had to be filtered out, which can take some time.
On one shuttle mission, a crew member lost a religious medal on a short jewelry chain. Despite searching diligently for it both in flight and then during refurbishment on the ground the medal was never found. A couple of flights later, the medal and its chain floated out into the mid deck after having been hidden for months and more than one trip to space and back. Where it had been lodged, undetected for all that time, is a mystery.
In a similar way, starting with STS-1, when the shuttle payload bay doors opened in microgravity every flight, junk was seen floating out: fabric, washers, screws, unidentified parts. This was despite the rather extreme measures taken during pre-flight preparation (and later refurbishment) to keep the bay spotlessly clean. During turnaround operations, folks working in and around the payload bay had to wear those goofy bunny suits and were instructed to always be on the lookout for “FOD” (Foreign Object Debris).
Sometimes we would see junk slowly departing from the shuttle vicinity with our cameras or the crew would report seeing something. Every single sighting was investigated to the best of our ability.
This floating space junk was of concern for a couple of reasons; first, as I have explained before (see https://waynehale.wordpress.com/2019/09/25/oops/) the mechanisms to open, close, and latch the payload bay doors were complex and it was possible something could get in a critical spot and jam one of those critical mechanisms. Second, and related, there was always a concern that some of that junk floating out might be actual parts of the critical mechanisms that weren’t fasted down properly and now, after loosing some screws or bolts, that mechanism might not work when needed to close and latch up everything for re-entry.
Finally, there was the concern about later running into stuff that had become part of the orbital debris cloud in low earth orbit. Not only what the crew saw, or the onboard cameras detected, there was ground tracked debris evidence. Almost every flight the space tracking people would call us up and say that they were tracking something – generally small – in an orbit nearby the shuttle. This was always concerning and especially so after the loss of Columbia. Without a lot of fanfare, we would use all our tools – mostly video cameras onboard the shuttle or on the robot arm – to look all around and see if something critical – like a thermal protection tile – had come off. I can’t tell you how many times we did such an inspection, but my guess is probably 1 of every 3 flights had an incident that resulted in as thorough an inspection as we could make.
Generally, if the tracked items were co-orbiting with the shuttle, the relative velocity was small, and not really a concern for collision damage. But every sighting was a major concern as a possible loss of something critical from onboard.
Of course, for subsequent shuttle flights, coming in a different orbit, collision damage was a real issue. Items lost off the shuttle became part of the orbital debris environment. If the ground tracking folks predicted a close approach we would maneuver, or not (see https://blogs.nasa.gov/waynehalesblog/2009/12/09/post_1260386290939/).
Despite all our efforts to identify most of these space junk sightings, few of them were conclusively identified. Lots of effort was expended and a real level of concern remained over those that were not positively identified. Unfortunately, in those days, tracking of small items in LEO was problematic.
As I started out this post by saying that recently I have been contacted about pictures of junk near the shuttle – taken long ago now. Implied in their contact was that I was cavalier about these issues and did not pay enough attention to them, or that some shadowy figure in the chain of command had told us not to pay any attention to them. I hope this post demonstrates that neither of those conditions were true and the entire team put forward their best efforts to ensure the safety of the crew and vehicle.