Completely Floored


“On the table in the mock-up room, there’s a rather distinctive piece of red triangular grid. What are y’all doing with that?”

I had tagged along on the annual intern and co-op tour of Marshall Space Flight Center, and was visiting the propulsion research facility that has been used for development of the Ares I rocket. The highlight of the tour is full-scale mock-ups of the rocket’s instrument unit and engine housing. The piece of grid in question was on a table in that room. I knew why it was there in the first place, but didn’t know why it was still there.

So I asked the tour guide, and he told me. And hearing the final part of the story was one of those moments that makes me proud just to be associated with NASA.

I knew what the grid was. It’s a piece of flooring from Skylab, or, more accurately, from the Skylab trainer decomposing outside the U.S. Space & Rocket Center here in Huntsville. (Donations to the Skylab Restoration Project can be made to the USSRC.)

The floor, as described in Homesteading Space,was a relic of the development of Skylab. Originally, Skylab was going to be launched as a live, fueled Saturn IB stage. Once it arrived in orbit, astronauts would retrofit it from a live rocket stage into a space station. To expedite that process, engineers looked at what could be done to provide a head-start on the conversion. It was determined that the stage could be launched with floors in place, so long as the floors were a grid pattern than would be allow fuel to pass through it easily.

Eventually, the decision was made to use a Saturn V for the launch instead of the smaller Saturn IB, which meant that Skylab could be launched as a fully ready space station, instead of as a rocket stage. The change meant that the floor was no longer needed for its original purpose, since the stage wouldn’t be fueled. In the meantime, however, a secondary application of the design had been discovered. The obvious problem with floors in microgravity, of course, is that things don’t stay on them. You can’t, nominally, actually stand on the floor. But someone realized that the grid floor lent itself to that nicely. Footwear was designed with a triangular piece that fit into the grid, allowing Skylab crew members to lock themselves into place easily to stand in front of equipment. The original purpose was obsolete, but the secondary purpose was invaluable to the program.

I was touring the Ares I mock-up building years ago, when I saw a piece of the Skylab floor. I asked about it, and was told that Ares engineers were looking at using the design for the new rocket. The human factors engineers were trying to figure out the best way to install equipment in the instrument unit. One of the proposals was to place equipment on a shelf that would be made along the lines of the Skylab floor. The triangular design would be sturdy enough to support the equipment during launch, without wasting precious mass.

Ultimately, however, the idea was rejected in favor of mounting the instruments directly to the interior wall of the ring. So I was a bit surprised to see the floor piece still in the room. And that brings us back to the beginning of this post.

The person I asked, who was leading the tour, was in human factors — designing the equipment with the people who will be using it in mind. Ares I was being designed so that it could be serviced on the launch pad in the event of a problem in order to expedite turnaround time. And that requires that the equipment be designed to be accessible, but also with an eye toward the fact that human beings aren’t perfect and hard hats can catch the edge of instruments or tools can bang against things they’re not supposed to. Someone had the idea of using the Skylab floor design for yet another application — tools carried in to the IU have the potential to hit something or be dropped or cause problems otherwise. But what if tools weren’t necessary? The Skylab floor and footwear allowed astronauts to lock into place and unlock easily, with no tools. If the same concept could be applied to the IU equipment, the need for tools could be reduced and the risks they present reduced correspondingly. The Skylab floor, in this case, wasn’t being used so much as the answer as the question — how can the same thing be accomplished in a way that could be used for Ares.

With Ares I most likely canceled, the odds are that particular application of the Skylab floor design won’t be flying. But the same concept could carry forward into future vehicles.

That said, it’s amazing how one piece of pretty simple design has had four separate applications in the space program over the years; how much inspiration engineers have taken from a repeating triangular pattern. It’s a testament to the creativity in NASA both decades ago and today, and it wouldn’t surprise me at all if future engineers discover even more solutions in those simple triangles.

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