And the poll winner is…

Tethered Satellite, by one vote over working with the Russkies. Guess I should write about that one anyway, on another day.

Tethered Satellite was a joint project between NASA and the Italian Space Agency, Agenzia Spaziale Italiana. I was involved with the tether testing when I was a co-op student, which led to the choice of a copper conducting wire coated with Teflon, surrounded by Kevlar strength fibers and a Nomex overweave. This is what got me hooked on materials testing – from that point on, I picked classes that I thought would help in a future career at NASA and hung on through the weedout courses.

Skip forward to early 1992. One problem with the original coating on the satellite was that it wasn’t all that conductive in vacuum. When they had run the required tests, the paint had only been in vacuum for a few hours, so everything looked fine. What I heard was that someone left the coating in the vacuum chamber over the Christmas holidays and came back to find it nearly insulative. Houston, we have a problem.

One of the smarter coatings experts said that he could make a conductive coating that would work. We must not delay the shuttle launch. So they shipped the Tethered Satellite backup panels to us, we stripped off the old paint, applied the new paint, while running the qualification and acceptance tests at the same time. This meant manufacturing fixtures to hold the panels so paint could be applied evenly, because there was no time to ship them from Italy. This meant making sure the coating was indeed conductive in vacuum by testing in a simulated plasma environment, same as if it were in low Earth orbit, moving through the Earth’s magnetic field. It also meant all the other tests to make sure it would hold up in space – thermal cycling, atomic oxygen, ultraviolet radiation. It also couldn’t be a menace to the astronauts or to other experiments in the Space Shuttle, so there were flammability and outgassing tests. It had to be at least close in optical properties to the old coating, or we’d have had to re-run the thermal models.

We had eight days to do all that and not delay the launch. We did it in seven.

I was one of the wimps and only worked 16-hour days. (Mr. RFH remembers calling me and asking me if he was going to see me that day, and my reply was, “Only if you stay up until midnight.”) There were some people (the coating expert was one) that didn’t go home that week but caught a catnap here and there.

I can’t remember anything else quite like that effort, everyone working together for a common goal, and one of the very few times a daily meeting was necessary and productive.

We were so proud to see that fly, only to have the tether mechanism jam with the satellite only 853 ft. out. Dang it.

6 thoughts on “And the poll winner is…”

  1. David Brin wrote about that project, and then had the tether act as the McGffin in his short story “Tank Farm Dynamo” (first published in 1983), in his “River of Time” collection.

  2. Roamy, thanks for the back story. I remember being bummed when the cable jammed, and did not know about the saga behind the launch.
    Did you corner the tether pulley team in a dark cube-farm later?

    I guess if you knew it would absolutely work, it wouldn’t need research.

    1. One other good story about that time – they were late putting the panels in the oven for bake-out, so when I showed up to do the inspection, I found myself with an hour to kill. Couldn’t sleep, couldn’t go home, couldn’t write any more reports until I had more data, and, well, idle hands are the devil’s tools. My co-worker Swamp Heathen #1 had eight 5 x 10 drawer tackle boxes arrayed in his office with all kinds of electronic and mechanical parts, each drawer numbered horizontally 1-5, 6-10, all the way to 400. He had a computer list of drawer numbers to GSA part numbers.

      I used to stare at that setup and wonder, does he really go by the numbers, or does he just know that spade lugs are second one over, four drawers down? I killed that hour rearranging the whole set-up, all 400 drawers, to where the numbers went vertically, 1-10, 11-20, etc.

      He walked into my office the next day and said, “You have 24 hours to put it back.”
      “How’d you know it was me and not [branch prankster]?”
      “[Prankster] would have just mixed them all up. You were methodical.”

      So I put them back.

  3. Roamy, you know that there are two fairly large spools of the tether still in the store room.

  4. We were so proud to see that fly, only to have the tether mechanism jam with the satellite only 853 ft. out. Dang it.

    I used stronger words, I was really curious to see how much power this thing would develop. Were there any results at all?

    1. There were some results from that flight, but more from the reflight two years later, though that mission generated so much more power than expected, the tether burned through. That time, it was deployed out to 19.7 km (20.7 km was planned). The science instruments on the satellite did send data for several days until the batteries ran out. The tether dynamics folks said they learned a lot about skip-rope and pendulum motion and gravity-gradient stabilization.

      I had another experiment on that first TSS flight, so when I went to KSC to pick it up, I was allowed to go in the clean room and inspect the TSS paint job. The conductive coating used an epoxy binder, which was definitely for just short exposures. A two-week mission was fine, but I wouldn’t fly it for more than a year. That led to development of more durable conductive coatings.

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