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Episode 149: STS-72 - Endeavour’s Hitchhiker (SFU, OAST-Flyer)

Table of Contents

On STS-72 we’re going to deploy one spacecraft but retrieve two! We’ll also test out some new EVA techniques, bid farewell to a frequent flyer, and spin Koichi Wakata around until he stops smiling.

Episode Audio>

Episode Audio #


Photos #

The crew of STS-72 pose for a group photo on the flight deck.
Leroy Chiao and Dan Barry shake hands in their spacesuits.
The shuttle’s robot arm manipulates and object in the payload bay. The Earth is seen in the background.
Space Shuttle Endeavour touches down in a night landing.

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Transcript #

NOTE: This transcript was made by me just copying and pasting the script that I read to make the podcast. I often tweak the phrasing on the fly and then forget to update the script, so this is not guaranteed to align perfectly with the episode audio, but it should be pretty close. Also, since these are really only intended to be read by myself, I might use some funky punctuation to help remind myself how I want a sentence to flow, so don’t look to these as a grammar reference. If you notice any egregious transcription errors or notes to myself that I neglected to remove, feel free to let me know and I’ll fix it.

Hello, and welcome to The Space Above Us. Episode 149, Space Shuttle flight 74, STS-72: Endeavour’s Hitchhiker

Before we get started, I wanted to mention something that I just recently learned. When I create this podcast, I upload it to a hosting service that then distributes it to a number of different destinations. These destinations include Apple Podcasts, Spotify, Google Podcasts, YouTube, Stitcher, and of course, the RSS feed on the show’s website, I chose a bunch of different destinations in an effort to make it easier for people to listen to the show wherever they typically listen to podcasts. The thing I recently learned is that apparently, some of these destinations are inserting ads in between episodes or even directly into the show itself. So I want to say definitively that there are no advertisements on this show. If you’re hearing them, I’m not getting a dime from them and you’re getting a subpar version of the podcast. If you’re hearing ads, I’d appreciate if you could give me a heads up by emailing me at with information about where you’re listening and how the ads are being injected. I’d also strongly suggest using a dedicated podcast playing app and subscribing directly to the RSS feed rather than going through a middleman. This is an important issue to me, so I’m 100% willing to play tech support on this one, so if you’re unsure how to get started using a dedicated podcast app, shoot me an email and I’d be happy to walk you through it. If you’ve been putting up with ads with the idea that you’re supporting the show, I appreciate it, but what you actually need to do is go to the show’s patreon, or donate directly on the show’s website You’re also more than welcome to just enjoy the show completely for free, with no advertisements, the way it was meant to be heard.

OK with that out of the way.. Last time, we talked about the third space shuttle rendezvous mission to the Russian space station Mir. In an effort to make things a little easier and a little safer during subsequent shuttle dockings, we delivered a pressurized docking module, which now resides on the end of the Kristall module. The docking module added a little extra length to Kristall, provided the clearance required to maneuver the orbiter in close proximity to the various solar arrays and antennas sicking out of Mir. We also delivered some science equipment, a new guitar, and a whole bunch of ice cream.

For today’s mission, instead of dropping something off, we’ll be picking something up. To explain, we need to roll the clock back by around ten months and roll the globe over around 8000 miles west to the Tanegashima Space Center in Japan. Perched atop an H-II rocket was the Space Flyer Unit, a new research satellite poised to begin its long duration mission. The spacecraft was built and operated by the National Space Development Agency of Japan, or NASDA, which was the predecessor to today’s Japan Aerospace Exploration Agency, or JAXA. After its successful ride uphill, the Space Flyer Unit, or SFU, embarked on a nearly year-long mission to study plasma in space, electric propulsion, and the effects of the low earth orbit environment on a high voltage solar array. It also used its lofty vantage point to study the heavens using an infrared telescope while also keeping an eye on the impact of microgravity on some material science and biology experiments.

The Space Flyer Unit is pretty cool, but it comes with a catch. If Japanese scientists wanted to study the samples after their lengthy stay on orbit, they would need a little help. That’s because among its 3600 kilograms of mass you’d find solar arrays, propulsion systems, communications, science payloads, and so on.. but no heat shield. Hmm.. if only there were some other vehicle out there with the capability of plucking a poor defenseless science spacecraft out of its orbit and returning it safely to the Earth.. .. .. let’s meet the crew.

Commanding the flight was Brian Duffy, who we last saw flying as pilot on another satellite retrieval mission, STS-57. On that flight, the satellite in question was the European-made EURECA spacecraft. So between that flight and this, it makes me think Duffy is attempting to build his own international space station by just capturing a bunch of international satellites and sticking them together in his backyard. This is his third of three flights.

Joining Duffy at the front of the flight deck was today’s pilot, Brent Jett. Brent Jett was born on October 5th, 1958 in Pontiac, Michigan but calls Ft. Lauderdale, Florida home. He picked up a Bachelor’s in Aerospace Engineering form the US Naval Academy and later a Master’s in Aeronautical Engineering from the US Naval Postgraduate School. In between, he learned how to fly the F-14 Tomcat, soaring through the skies all over the world. After earning his Master’s, he graduated from the Navy Test Pilot School and tested a number of different aircraft for the Navy. He was back to flying F-14s when NASA came calling in 1992 and this is his first of four flights.

Behind Jett we find Mission Specialist 1, Leroy Chiao. We saw Chiao not too long ago on STS-65, the IML-2 flight. But since I just talked about IML-Man one episode ago, I’m not going to bring it up again. Except.. oops. Anyway, this is Chiao’s second of four flights.

Sitting behind the pilot crew and helping them out as flight engineer was Mission Specialist 2, Winston Scott. Winston Scott was born on August 6th, 1950 in Miami, Florida. Scott plays the trumpet and earned a Bachelor’s degree in music from Florida State University. After that he did what most people with a degree in music do and joined the Navy to learn how to fly, spending four years flying helicopters in anti-submarine patrols. He went back to school to pick up a Master’s in Aeronautical Engineering with Avionics and then returned to the sky, this time flying jets. After working his way through a variety of jet aircraft including the TA-4J-Skyhawk, the F-14 Tomcat, the F/A-18 Hornet, and the A-7 Corsair, he was selected as an astronaut in 1992, and this is his first of two flights.

Moving downstairs we find Mission Specialist 3, Koichi Wakata. Koichi Wakata was both in 1963 in Saitama, Japan. He earned a Bachelor’s degree in Aeronautical Engineering, a Master’s in Applied Mechanics, and a Doctorate in Aerospace Engineering, all from Kyushu University, though that doctorate will come a few years after this flight. After he earned his Master’s, he went to work at Japan Airlines as an aircraft structural engineer in Narita. In 1992 he was selected to become a mission specialist, representing the National Space Development Agency of Japan. So while Wakata wasn’t the first Japanese person to fly on the shuttle, the fact that he’s flying as a full blown mission specialist is pretty significant, and once again reminds us of the looming space station era. This is Wakata’s first flight, with two more shuttle flights and a Soyuz flight to come. And actually, at the time of this recording, Koichi Wakata is still an active astronaut. He is currently slated to fly on the SpaceX Crew-5 mission to the International Space Station in 2022.

And rounding out the crew we find Mission Specialist 4 Dan Barry. Daniel Barry was born on December 30th, 1953 in Norwalk, Connecticut but he’d say he’s from South Hadley, Massachusetts. He earned a Bachelor’s degree in Electrical Engineering from Cornell University, a Master’s and Doctorate in Electrical-Engineering-and-Computer-Science from Princeton, and a doctorate in Medicine from the University of Miami. After earning his MD, he did an internship and residency in Physical Medicine and Rehabilitation at the University of Michigan, becoming a professor in the same topic as well as in Bioengineering. His research included biological signal processing, including acoustic and electrical signals from muscles. He was selected as an astronaut in 1992 and this is his first of three flights. Oh, and in 2005 he was on the reality TV show Survivor and was voted out on day 15. Bummer.

One thing I wanted to mention that won’t really play well on an audio-only medium like this is the mission patch for STS-72. Ever since Gemini 5, the crews of US spaceflights have collaborated with artists to design a patch that captures the spirit of their upcoming mission. What I like about this mission patch is.. it’s recursive. That is, the patch shows a scene outside Space Shuttle Endeavour, with the SFU nearby and a crew member out on an EVA. And what’s that on the EVA crew member’s arm? Well.. it’s the STS-72 mission patch! If you look very closely you’ll see a scene outside Space Shuttle Endeavour with the SFU nearby and a crew member out on an EVA. And what’s that on the EVA crew member’s arm? It’s the STS-72 mission patch! If you–wait.. we better stop here or we’ll just keep going forever.

Thanks to the specific constraints imposed by this ground-up rendezvous mission, the launch was scheduled for the middle of the night, at 4:18 am on January 11th, 1996. One nice thing about such an early time of day is that you typically don’t have to worry too much about the weather since the Florida sun hasn’t had a chance to churn up the atmosphere. And sure enough, for the most part the countdown went nice and smoothly. Some minor communications issues at Mission Control in Houston popped up and were resolved, and then the liftoff was pushed back a few minutes so Endeavour wouldn’t be diving right in front of a passing piece of space debris. The total delays only added up to 23 minutes out of the 50 minute long launch window though, so we’re ready to go. On January 11th, 1996, at 4:41 AM Eastern Standard Time, Endeavour lifted off for the tenth time and the US human spaceflight program kicked off its 35th year of flight operations.

Ascent went smoothly which meant that Commander Duffy and Pilot Jett could dive right into the first of several maneuvers required to perform the upcoming rendezvous with the Space Flyer Unit. Just like the first time Endeavour flew, this would be a hybrid rendezvous. After the successful shuttle launch, the SFU lowered its orbit and moved into a control box, which is basically a general region in orbit that the two spacecraft would meet. These hybrid rendezvous are a little complicated since we’ve got two maneuvering spacecraft, but they also allowed the SFU to stay higher for longer and should save on propellant.

What didn’t help the propellant margins was something that happened on flight day two. Folks tracking such things on the ground noticed that Endeavour would be getting uncomfortably close to another object in orbit, necessitating a 1.2 meter per second burn to get out of the way. What’s kind of funny about this is that one source calls this object out as the now-dead stealthy satellite Misty, which we maybe deployed back on STS-36. Well, whatever it was, it was in the way, so Endeavour slightly tweaked its orbit to get around it.

Other than the risk mitigation maneuver imposed by maybe-Misty, the far field rendezvous proceeded smoothly and on Flight Day 3 it was time to move in for the final approach. Just like on Mir, we’ll be moving up from below, using an R-bar approach. Once Endeavour got close enough, Commander Duffy took over with manual control while Mission Specialist Chiao operated the handheld laser rangefinder and Mission Specialist Wakata stood ready with the robotic arm. Once the orbiter was within around 45 meters, Duffy slowed his approach and began stationkeeping. Seemingly floating above the orbiter was the Space Flyer Unit, a round spacecraft about 4.7 meters across and 3 meters tall, flanked by two solar arrays that when combined were around 24 meters long. Since the SFU had limited onboard battery power, ground controllers in Japan had waited until the last second to retract the wide solar arrays on either side of the spacecraft. The shuttle crew watched as the solar arrays retracted, and waited for word that they had successfully been latched into place.. word that never came. In fact, controllers on the ground were unable to confirm that the solar arrays were secure, which made it too dangerous to try to bring them back to Earth in the back of the shuttle. No problem though, Japanese engineers had planned for this problem. After rotating to the proper attitude, the SFU ejected one solar array backwards in orbit, then rotated 180 degrees and sent the second array after the first. It was important to eject these backwards since it would lower their orbit and not create more space debris for future missions to dodge.

With SFU running on internal power, the clock was now running, but there were no other issues. Duffy brought Endeavour in close, Wakata grappled the spacecraft, and lowered it down into the payload bay. A small dedicated robot arm called the Remote Operated Electrical Umbilical swung into place and connected to the SFU, which would now receive power from the orbiter.

The capture was delayed by an hour and a half while the solar array situation was sorted out, but all things considered the capture went very smoothly. The SFU had one last twist for the crew, however. Due to a problem with the heating system in the spacecraft, the SFU began to get too cold. This imposed new attitude constraints on Endeavour, which now had to stay pointed in a direction that maintained the SFU at the proper temperature. Not a huge deal, but it did mean that folks down in Houston had to scramble to replan parts of an EVA that was scheduled for later in the flight.

The SFU had been designed to fly at least one more time, but this is the last time we’re going to see it. I’m just guessing but I’d speculate that the higher priority ISS construction missions pushed the possibility of a second shuttle SFU retrieval into the great dustbin of hypothetical unflown shuttle flights. If you’re ever in Tokyo, you can visit the Space Flyer Unit at the National Museum of Nature and Science.

The next day, with one free-flying satellite recovered, it was time to deploy another. Once again, the reusable SPARTAN spacecraft built by the Goddard Space Flight Center would be going on a field day. Mission Specialist Koichi Wakata again operated the controls of the Canadarm to first grapple the little spacecraft, raise it up out of the payload bay, and release it. After it did a little wiggle to show that it was working, Pilot Brent Jett blipped a few upward-facing thrusters and Endeavour carefully backed away.

When he was asked about it in a 2011 oral history, Mission Specialist Leroy Chiao said “I’m not even sure what its mission was. But then three days later we came back and grappled it and brought it back home. I’m trying to remember what it did.” Clearly it made an impression on Chiao since not only could he not recall the spacecraft’s purpose, but they actually came back for it in two days, not three. Let’s see if we can help Chiao out.

This flight of the SPARTAN platform was called the OAST-Flyer, with OAST standing for Office of Aeronautics and Space Technology, which was the organization sponsoring the onboard experiments. Actually, the office had been renamed from the Office of Aeronautics and Space Technology to the Office of Aeronautics, Exploration and Technology and then to the Office of Advanced Concepts and Technology and then to its current name, the Office of Space Access and Technology. Though don’t think too hard about that one because later on in 1996 the whole thing was dissolved anyway, with its responsibilities moving to other groups within NASA. Somehow the original acronym stuck through all of that, so OAST-Flyer it is.

On board were four experiments which each sought to answer some technological questions that would make it easier to design future spacecraft. First was the Return Flux Experiment. This is yet another experiment seeking to better understand how objects in low orbit interact with the atmosphere. In a perfect vacuum, if a tiny speck of dust or dirt were to fall off a spacecraft, it would go drifting off into space forever and there’d be no problem. In low Earth orbit, however, that dirt would soon encounter some extremely thin gas and get pushed back towards the spacecraft. This was called “molecular backscattering” or “return flux”. If the dirt came back and landed on a sensitive instrument or on the lens of a camera, over time that could present a serious problem. So the Return Flux Experiment would be seeking to understand this problem by actually releasing some known particles and then taking a look at the condition of the spacecraft when it got back.

Next was an experiment with an acronym I’m going to pronounce as GADACS, which is great because it’s actually a multi-level acronym. GADACS stood for the GPS Attitude Determination and Control Experiment, with GPS of course being short for the Global Positioning System. And if you’re wondering where the S at the end of GADACS came from in the phrase “GPS Attitude Determination and Control Experiment”, I’m right there with you. Anyway, this experiment would essentially do what it said on the box. It would be collecting signals from GPS satellites in medium earth orbits, carefully processing them, and not only determining the position and velocity of the OAST-Flyer, but also its orientation in space. I believe the way they do this is through the use of multiple GPS receivers, which would get slightly different timing. I had to kind of chuckle when I read that the hope here with this new GPS-based system was to replace other attitude determination instruments, such as star trackers, gyroscopes, and magnetometers. Well, I can tell you that as I write this it’s December 2021, OSAM-1 isn’t scheduled to launch for a few more years, and we have star trackers and gyros. So I’m guessing this didn’t work out quite as hoped. Even if that’s true, though, this experiment made a notable contribution by making OAST-Flyer the first ever spacecraft to use GPS for its navigation.

Next up is the Solar Exposure to Laser Ordnance Device, or SELODE. You’d think that with such high energies and such low margins for error, the last thing in space that you’d want is an explosion, but actually satellites have tons of pyrotechnic devices. For instance, you might want to keep an antenna firmly folded up and attached to the side of the spacecraft during launch and initial checkout, and then release it so it can extend. Rather than something tricky like a motor, you can set up a spring that is trying to push the appendage where it needs to go, and an explosive bolt to keep it in place until the time is right. Then with one simple electric pulse you can trigger the bolt to fire and you’re good to go.

The concern here was with that one simple electric pulse. With stuff like charged particles from solar wind, plasma from flying through the upper atmosphere, and building up a charge with solar arrays, space is a complicated electrical environment. One stray zap of static electricity and oops, your pyrotechnic device kicked off early. So with that in mind, this experiment was trying some new devices that relied on a pulse of laser light instead of electricity. It should be a lot more stable and less error-prone, but came with its own challenges. Specifically, SELODE wanted to see how a laser-activated pyrotechnic charge might react to concentrated sunlight while in space. So we’ve got lasers, explosives, and space. Sounds like a pretty cool experiment to me.

And finally, the Spartan Packet Radio Experiment, which was provided by the Amateur Radio Association at the University of Maryland. This would be using packet radio techniques enjoyed by ham radio operators to send out GPS information from the satellite. It would also be relaying the position of stations on the ground. As someone who has recently started playing around with FT8, this just sounds to me like just a good excuse to get some QSOs through a cool shuttle-deployed satellite, but who can blame them. In a sort of funny twist, this amateur radio experiment marks the first time that there’s been any sort of signal or communication from a SPARTAN payload during flight. Mission controllers wouldn’t be relying on it to downlink science data or for operations, but for the first time they could at least keep an eye on it. Neat.

While OAST-Flyer was off doing its thing, the crew’s attention would next turn to the first of two EVAs. These were the latest in a series of spacewalks seeking to develop tools and techniques that would be helpful when building the International Space Station, while also making sure that plenty of astronauts had some experience working outside. There are some pretty good personal details on this EVA thanks to a 2011 oral history with the EVA lead for this flight, Mission Specialist Leroy Chiao. Chiao will be heading outside for both spacewalks, while Dan Barry and Winston Scott will have to share and each get one. Apparently, Barry was originally going to get both, but in an effort to further spread the experience, the second EVA was given to Scott.

I can’t imagine this was super popular with Dan Barry, because in a surprising peek behind the curtain, Chiao recalled some conflict with Barry about how the EVAs were planned. First, Barry thought that despite this being his first flight and Chiao’s second, he should be in charge of the spacewalks. He actually explicitly told Chiao this, creating some friction. I’m not exactly sure why, maybe because Chiao was around seven years younger, but who can say.

That friction actually became somewhat of a problem at times during training. As Chiao tells it, Barry was a bit of a perfectionist and had trouble accepting the fact that while the EVA training in the neutral buoyancy pool was a high fidelity simulation, it wasn’t perfect. Certain allowances had to be made in order to get through the training in a timely manner. The important part wasn’t perfectly replicating the planned spacewalk in the pool, it was learning enough that it could be done perfectly in space.

I brought this up not to dunk on Dan Barry, who actually sounds like a pretty incredible guy. But rather, I brought it up because I think a lot of what we hear about space history tends to gloss over disagreements and interpersonal friction. For the most part, that’s actually probably a good thing. As long as the mission’s getting done, at some point that’s just gossip. But I thought it was cool to have this little reminder, yet again, that astronauts are people too, and just like everyone else they sometimes rub their coworkers the wrong way. But since these are all smart, professional people who are highly motivated to get the job done, they found a way to work through it, become a cohesive crew, focus on their mission, and get it done. And that’s pretty cool.

Whatever friction existed between Chiao and Barry in the pool had been set aside a long time ago, and on flight day 5 it was time to do it for real. Chiao commented that when he first emerged from the airlock, quote “I was prepared for an awesome view but I didn’t expect to really get what I got, which was a big 3D perspective because of all the peripheral vision effects coming in.” And in fact, the flight surgeon can back up Chiao’s initial reaction to sticking his head out into the void. He was later told that at the moment he opened the door on the first EVA, his heart rate skyrocketed.. and I can’t blame him!

The first task was assembling a portable work platform creatively named the Portable Work Platform, or PWP. This was the latest iteration of something we’ve seen come in handy a few times now. Once assembled and attached to the end of the robot arm, the PWP provided an EVA crew member with a stable place to stand as well as some structure to hold tools and equipment as they’re being moved around. This latest version allowed the foot restraint to swivel side to side, providing the spacewalker with a little extra flexibility. It also could grab onto an ORU, an Orbital Replacement Unit, which is a big bulky standardized box that was being developed for easy servicing of equipment outside the ISS.

Chiao and Barry also tested out something called a rigid umbilical. On the ISS there would be a need to get various wires and fluid conduits from point A to point B outside the station. The rigid umbilical hoped to make that easier. Think of a long thin box made out of a metal latticework, and inside the box are some electrical cables and flexible pipes. That’s basically what we’re talking about here. On this EVA there would be no live electrical connections or actual fluid moving through the conduits, but it gave the crew a chance to try moving and unfolding the 110 kilogram structure, as well as connecting the cables and pipes inside. One of the main findings was that in space the cables and plastic sheathing could get very cold, making them very stiff and difficult to manipulate. So it would be important to keep the diameter of these cables a small as necessary and to include some extra slack. But they also reported that the spacing of the connectors, which had been placed with bulky spacesuit gloves in mind, was perfect.

Before we head back inside, I want to read an extended quote from an interview with Dan Barry. He said: “At the end of my first spacewalk on STS-72, I had the rare experience of seeing stars while out on EVA. We had a task at the very end of the spacewalk to test the lights on our helmets. To get the best test, we did something never done before during a spacewalk; we turned off all of the orbiter’s lights, which are so bright that they prevent spacewalkers from seeing the stars. Our helmet lights worked fine - I could see and work without difficulty. After the test I turned ff the lights, and suddenly it was so black I couldn’t see my hand. I waited for my eyes to adjust and was rewarded by millions of stars, faint at first but eventually turning into brilliant points. Still, they didn’t cast enough total light even to see myself. Right at the end I flashed my helmet lights a few times, just in case anyone was watching.”

Well, if someone out there was watching, they would have noted that the first EVA lasted for 6 hours, and 9 minutes.

While Chiao and Barry flexed their sore fingers, time marched on and on flight day 6 it was time to retrieve OAST-Flyer. The final approach went exceedingly smoothly, though it is worth noting that the spacecraft was several dozen kilometers away from where it was expected to be. Preliminary investigation suggested that the Return Flux experiment may have imparted more thrust than expected, requiring an overly aggressive response from the attitude control thrusters, which in the real world are never perfectly balanced, so a little sideways thrust is bound to build up. No matter, though, since the STS-72 crew had no trouble tracking it down.

Commander Duffy even let Pilot Jett get some time at the controls during proximity operations. Jett said “Endeavour flies extremely well. It’s very stable. It flies even better than the simulators.” After 46 hours of flying on its own, Koichi Wakata reached out with the RMS and retrieved the little spacecraft before safely parking it back in the payload bay. The only hiccup was that the amateur radio experiment shut down around 17 hours into the flight. That’s a bummer but since it wasn’t one of the main experiments, it’s not the end of the world. And with that, STS-72 chalked up the unusual combination of one spacecraft deployment and two spacecraft retrievals.

The next day, on flight day 7, it was time to head outside again. Leroy Chiao would again be taking the role of EV1 while Winston Scott would be heading out as EV2. Much of this EVA overlapped with the previous one, but with a few differences. Scott slipped his feet into a foot restraint that had some load-sending instruments attached to it. He then sort of wiggled back and forth, repeatedly leaning way back before swinging forward. This way engineers on the ground would have a good idea of what sorts of forces a spacewalker could impart to their restraints. Makes me think of Ox van Hoften wrestling the satellite on STS-51i as his feet strained to break off the restraint.

Scott also took some time to basically just quietly stand around in the dark as part of an evaluation of further upgrades to the thermal controls on the extravehicular mobility units. The new heaters got a thumbs up from Scott, who experienced no discomfort.

Both Chiao and Scott did some more work with cables and umbilicals, connecting them to an instrumented plate that measured what sorts of forces were being put on the connections. They also tested out the Body Restraint Tether that we saw a few missions back. This device held onto the structure, thus freeing a crew member’s hands to focus on the task at hand. It didn’t provide the same support as the portable foot restraints, but was a heck of a lot easier to move around and set up, so would be more appropriate for a bunch of simpler tasks.

They also both tried out the Electronic Cuff Checklist, which has actually flown several times at this point, but never quite seems to work right. This was basically a small screen that could potentially replace a printed EVA checklist. It had the benefit of lighting up in the dark and it would be easy to update during the flight. Well, in theory. One of them got stuck in an invalid configuration after being updated and that was the end of that ECC. Both crew members thought the idea was sound, but the actual implementation was lacking, especially in direct sunlight. Considering I’ve never heard of these devices, I don’t think they made the cut. Though these days, I wonder if maybe they’d work well with some e-paper, similar to an e-book reader.

The 6 hour and 53 minute EVA ended without incident, though later inspection the ground turned up some alarming news. Both crew members had small cuts in the outermost layer of their gloves. This layer was related to thermal control and there was no danger of the gloves depressurizing, but who could say what a deeper cut would have done. The incident prompted an investigation into what unexpected sharp object caused the cuts as well as new policies for controlling sharp surfaces in the payload bay. The main culprit in the official mission report was some of the connectors in the task plate being used to measure cable forces, but it required deeper investigations to be sure. Yet another reminder that in space the smallest thing will get you..

In his oral history, Chiao was asked if he found that the training in the pool was sufficient for getting the job done on orbit. He said the training was totally different than the real thing but totally sufficient. To paraphrase, the pool allows a crew member to get the spatial aspect of the EVA into their muscle memory. They learn where they’ll be and when, and where their crewmate will be at the same time. They learn where the tools are, when they can take a break, and they can smooth out any awkward sequences of events. And this was maybe the disconnect that lead to Dan Barry’s dissatisfaction with the training before his first flight. The goal isn’t really to perfectly emulate the space environment. Nothing on Earth can do that, literally. But with some clever training, you can get close enough that the last little leap is manageable on the fly. As long as you know what the limits are, it’s totally different, but totally sufficient.

With the primary objectives of the mission over, this is the part of the mission where the post-flight presentation invariably turns to goofing off. They played with their food, they tossed things around the middeck, and eventually began tossing each other round, doing long somersaults in the weightless environment. Koichi Wakata said “We could also experience how our body reacts to different kinds of motion in microgravity. As you can see, my smile decreases as the spin goes on.” There was also a note in the mission report that made me laugh. Talking about an incident where a camera began to eat its tape, it said quote “The fourth camcorder began making crunching sounds when operating.”

The crew also made a few nods to both Mission Specialist Koichi Wakata, as well as the Japanese spacecraft currently strapped into the payload bay. They brought a microgravity-friendly version of the ancient board game Go to play during downtime. Winston Scott, a black belt and karate expert, demonstrated some moves down on the middeck. It was remarkable seeing how stable his body was once he snapped into a position. And with the successful end of the mission in sight, Wakata filled in the second eye of a Japanese daruma doll, the first one being filled in when the challenging task began.

While they didn’t really impact the crew experience, I want to briefly mention some of the payloads in the far back of the payload bay. The Shuttle Laser Altimeter seemed to be a carbon copy of the LITE experiment we saw back on STS-64, firing laser pulses at the ground in an effort to measure the altitude of large swaths of the earth. The Thermal Energy Storage experiment repeatedly heated and cooled some fluoride salts, studying how empty spaces, or voids, in the salts formed and moved around during repeated thermal cycles. And FLEXBEAM.. flexed a beam. Really it imparted a vibration onto some aluminum beams to see how long it would take them to stop without any efforts to damp it. This isn’t really related to the experiment itself but there was something sort of weird about this payload. In the official mission press kit, in mid-sentence, really in mid-word, it suddenly switches to talking about the Shuttle Laser Altimeter again for a few sentences. I think someone in the press office had a little copy/paste accident.

But really I wanted to mention these payloads because making its eighth and final flight into space was the Shuttle Solar Backscatter Ultraviolet experiment, or SSBUV. This little payload has been flying with us since 1989, and sought to provide an independent and highly calibrated set of data about how ultraviolet light interacted with the atmosphere. By flying over the same places at the same time as earth observation science satellites, SSBUV ensured that the data they collected was accurate and could be counted on. After this flight, its contribution to science was now complete.

And so was this mission! With no weather issues delaying the deorbit, Endeavour cruised through an uneventful reentry to a night landing at the Shuttle Landing Facility. Duffy pointed out that if you watch the replay of the landing, after the orbiter was on the ground, you could see him steering the nose back and forth. he explained that he was trying to find the center line, but since the runway lights were almost two miles back, it was pretty dark where he was. And since commanders liked to judge each other by how perfect their landings were, quote “It’s real important that you stop on the center line. Most important part of the mission.”

Endeavour came to a stop at an unknown distance from the center line, concluding the 8 day, 22 hour, zero minute, and 45 second mission, with two spacecraft safely carried home in the back of the payload bay, and another 13 hours of EVA experience under NASA’s belt.

Next time.. it’s the 150th episode of The Space Above Us, so let’s do something special! We’ll take a brief break from the world of human spaceflight and celebrate the long-anticipated arrival of the Galileo spacecraft at Jupiter. Scientists had been waiting for this moment for years, but the mission was just getting started. Let’s find out if it was worth the wait.

Ad Astra, catch you on the next pass