NASA Abandoned A Spacecraft in Orbit for 5 Years. When It Came Home It Surprised Them!

hello it's Scott Manley here in April of 1984 space shuttle Challenger took off carrying an important scientific payload which was supposed to spend about a year in space now as it happened it would spend a little longer than that initially they thought it was going to be recovered in February of 1985 but various delays and problems pushed things back and eventually they were looking at September of 1986 but as we know that didn't happen because in early 1986 this very same space shuttle ended up in small pieces on the bottom of the ocean and so with the space shuttle program grounded there was no way to bring this scientific satellite home and it was abandoned in orbit for almost 6 years and as it turned out this would actually be a good thing for much of the research that was carried out on this spacecraft this was an experiment called the long duration exposure facility and presumably by the end of the mission it was the longer duration exposure facility it was a bus-sized vehicle with a bunch of experiments slapped all over its surface and the idea was these would just be exposed to the rigors of low earth orbit and when they brought them home they would be able to analyze them and determine how materials had changed and being transformed by space flight NASA had been flying stuff into space for decades by this point but they still didn't really understand the long-term effects of low earth orbit while they had sent humans into space these had generally been short missions like a month or so the obviously Skylab was one of the things that remained on orbit for a fairly long time and was regularly visited and it revealed a number of problems with material degradation due to the environment of low earth orbit in the early days of space flight Engineers had a pretty good idea of the things to expect they knew that there would be no atmosphere so liquids would tend to evaporate faster you might have out gassing from certain substances there was higher radiation levels in space spacecraft would be exposed to much more ultraviolet radiation which can cause degradation of certain chemicals and micrometeorites were known to occasionally impact surfaces you know things the size of a grain of sand moving at several kilometers per second could punch holes through things or create tiny craters in hard surfaces but there was another factor that hadn't really been anticipated in the early days of space flight and that is that the Earth's atmosphere doesn't magically stop at 100 kilm just because Theodor Von Carmen you did some math no the the Earth's atmosphere is is fuzzy it continues outwards Getting Thinner and thinner and an orbital altitudes it is a more perfect vacuum than anything that we can make on vacuum Chambers on the Earth but there is still a tenuous atmosphere there the spacecraft are interacting with and one of the important constituents of this atmosphere is atomic oxygen so on the earth we are surrounded by about 20% oxygen it's great especially if you want to set something on fire but in Space the ultraviolet radiation breaks these molecules apart into individual oxygen atoms and they are vastly more reactive those individual oxygen atoms really want to interact and react with anything especially when they come in with velocities of about 5 m per second if you've ever seen an oxyacetylene cutting torch at work realize that most of the cutting is due to the oxygen so the rarified atmosphere wasn't a huge issue on short-term missions but the USA was planning to build a space station space station freedom and they knew that they needed to analyze all the materials that they might use for this to make sure that they could handle being in space for years at a time so yeah the ldef experiment was proposed in the mid 1970s originally it was like a microm meteorite experiment but they realized that they could expand it to the entire environment of low earth orbit and groups from all over NASA indeed groups from all over the world were allowed to submit their experiments where they would be placed on the spacecraft placed in space for exposure to the rigors of the you know low earth orbit and then eventually return to them for postflight analysis this spacecraft was designed to be a 12-sided cylinder you know the kind of thing you get when you have don't have enough polygons to work with uh it had a relatively simple structure and the experiment trays could be bolted into each of these areas and it was actually designed to hold a constant attitude in space it would be vertical with a space Fairing and a an earth facing side and it would also o be aligned using the Earth's magnetic field to hold it pointing the same direction in orbit so there would be a you know a windward side and a l side where you would have much more atmosphere impinging on one side than the other and the stabilization was totally passive they used gravity gradient stabilization to hold it vertically and they used uh magnetic fields to align it with the direction of motion and then they used these special uh motion damper systems which would have magnets inside a fluid like an oil which would generate a drag and then those in turn were surrounded by like a graphite layer so as it rotated the it would slowly damp the rotation and it would ultimately damp down to its desired orientation without spending any power and having this be totally passive meant that yes it could actually survive almost 6 years in space and still be in the correct orientation and that's not to say that the spacecraft was completely passive there was batteries on board to power some experiments uh experiments that recorded the you know vibrations from me micrometeorite impact there were experiments which would have samples that would be exposed for a limited time and then doors would close and that would allow them to understand how perhaps the environment of low earth orbit changes over time and you know time had actually become something of a serious pressure towards the end as they approached recovery they had initially launched it into a 500 km orbit thinking that that would give them enough time but by the time they launched to recover it its orbit was more like 320 km and it was losing hundreds of meters of altitude per day due to atmospheric drag so yes eventually in January of 1990 STS 32 is finally sent up to retrieve it at one point it looked like this was going to be the first space shuttle to fly over Christmas so there is actually a photo the crew took of them in their flight suits wearing like Santa hats and beards but uh yeah unfortunately was delayed so that fell a little flat but they did actually make a special delivery uh taking the sycom satellite up into orbit they had to launch that first obviously because the lde facility was quite substantial and took up a fairly large uh volume in the bay I did find this really cool like early animation of the recovery process I I love the early CGI partly because at the time of course I was using like 8bit computers and this stuff was unheard off in terms of quality but you know you think about it they were interested in how these samples would handle exposure to space and so they had to actually very carefully plan the approach to this so that they weren't firing any of their maneuvering thrusters directly at the hardware and then once they had grappled the spacecraft they wanted to rotate it around and very carefully get photographs of every single angle of this spacecraft because once they were going to take it home it was going to be exposed to to the Earth's atmosphere and that might cause chemical reactions which change the surface or it might cause bits to break off due to the stresses of Entry as it happens on the way in they actually observed like trailing particles that were in formation with it so they were small paint flaks or pieces of film or something that were breaking off and floating around with this object for you know a substantial amount of time and those kind of things can be really problematic in space flight because these particles can light up when they're illuminated by the Sun and they can confuse star trackers this has happened in the past the crew also came up with an extra procedure which uh they thought was a good idea not all the scientists agreed so because they were interested in the effects of atomic oxygen they after capturing the facility they maneuvered the space shuttle so it was basically shielding the facility from the atmosphere right and the idea was they wanted to reduce this effect as they rotated the spacecraft around and got all the different view angles but apparently this meant that they fired the thrusters more than anticipated and this meant slightly more contamination by you know monomethyl hydrogene and all that other wonderful stuff the space shuttle uses so I see some of the papers talking about the analysis describing this as a mistake during recovery another interesting observation by the astronauts was that there were supposed to be these reflectors on the surface they were called bicycle reflectors like the plastic retro reflectors you see on bike wheels and things like like that most of these were no longer reflective because of the damage due to the atomic oxygen so now the shuttle would then spend longer in space than any other at this point firstly they had a whole lot of bioscience experiments that they wanted to do but then because they were Landing with this big heavy payload they wanted the biggest widest Runway possible and so they waved off other opportunities that would have t allowed them to land earlier in favor of Edwards so that they could actually be sure that they could handle this you know big heavy Mass inside the payload Bay they changed the parameters of the wheel touchdown because they the extra mass that would be in there I believe it was the first shuttle with a landing mass of over 100 tons and it had a total Mission duration of 10 days 21 hours after landing the payload was removed from the bay moved to a clean room photographed separated into the experiments which were sent to the various labs and you know for a while there was a possibility if a followup but as it turned out they it only flew once and that's partly because space station plans were changing when it first launched the space station was called Freedom when it landed it was called Alpha and of course Very quickly the US got to put experiments on Mir and the International Space Station became a thing so I bet you're all excited to see just what kind of damage being in low earth orbit can do to a spacecraft well this is a photo of the space facing end of L before flight and this is the photo that Marsha Ivan took immediately as it was placed in the payload Bay and if you put them side by side yeah you can definitely see there are some like foil myar colored sections where it's basically disintegrating peeling off some of the white areas are now brown as if somebody spilled coffee in space but to be clear some of these color changes are because it's different lighting conditions so this is a closeup of the heavy ion capture experiment and yeah they had this myar thermal coding something we see a lot in space flight well you know for long term it just isn't that great uh the polymer would essentially slowly rot under the exposure to the the atmosphere and this would be accelerated if there was a micrometeorite hole the atomic oxygen would rush into this and it would disintegrate it from behind and we see similar effects on this uh system which was supposed to test various types of solar cells and various Coatings so up the top you'll see these things held in place and uh yeah after flight some of them have just completely disintegrated away and if you look at the top right you'll see why it was important that they photographed it after capture because there's a section of one of those things that's just Fallen away as they brought it back into the lab now this photo show shows two scuff plates so these are used to align and secure the payload in the the payload Bay and they come from different parts of the same payload now when they launched they were yellow with black outlines and the reason why they are two different colors is cuz one was on the Leading Edge and one was on the trailing Edge and the one that's light that was on the Leading Edge so it was getting much more of this Atomic oxygen impacting the other side it was on the back end and it didn't so this is like a kind of bleaching action where they would have some composition change in the paint which turned it dark but the atomic oxygen would come in and it would take that material off and so one side would be kept you know brighter color but there was actually like a brown stain that appeared all over it and they spent a lot of time analyzing this to figure out where it came from and their conclusion was that there was like paint used for thermal control on the outside and on the inside and they think that this paint after launch into space it began outgassing these hydrocarbons which hung around and subject to radiation they polymerized they formed this sort of brown organic Gunk that stuck to some of the surfaces and you can see that this stain was strongest around the various ports that carry cables between the interior and the exterior and also incidentally it would tend to not appear on the front side of the spacecraft because of the bleaching action of the atomic oxygen so this brown Gunk sure looks ugly but it could be really critical if it ended up say on optical system so you have to be careful what kind of materials you're using to make sure that they're not off-gassing compounds that could affect your instrumentation they were able to catalog micrometeorite impacts all over the surface and some of these were obviously from space debris and those tended to be on the forward- facing side of the spacecraft but the ones which were coming from behind those had to have come from higher up at higher velocities there were experiments that were able to catalog the number of impacts over time and they showed that they did change in particular after the start of 1986 the number of debris impact events dropped and that it would be consistent with the US stopping almost all their launch activity so look this generated a huge amount of research I have barely scratched the surface and uh as a result it led to a lot of new materials things which were robust to be used in low earth orbit with that Atomic oxygen problem there are huge number of Publications detailing the materials that you can use when you're building a payload to operate on the space station or to operate in low earth orbit for a significant amount of time you'll notice that a lot of spacecraft that go into deep space will have this you know gold file looking myar multi-layer in insulation whereas on the space station that's actually a whole lot less common they cover it with a beta cloth first and then there's the multi-layer insulation underneath so while ldef may have been abandoned in orbit for way longer than it expected it was not forgotten and the research that came out of it transformed Engineering in low earth orbit I'm Scott Manley fly safe [Music]

Channel: Scott Manley

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Length: 15min 17sec (917 seconds)

Published: Mon Apr 29 2024