The tensest moment in spaceflight: Docking with a 100-ton space station while orbiting Earth at five miles per second.
- By Thomas D. Jones
- Air & Space magazine, May 2006
(Page 6 of 6)
We moved on to the Russian-built Service Module for a quick safety briefing and tour; then our hosts returned with us to Atlantis. Over the next few hours we inventoried and turned over to Shep’s crew a half-dozen suitcase-size bags of priority cargo. Included was a locker full of fresh foods and snacks, a welcome break from the freeze-dried, canned, and thermo-stabilized fare they had been eating for more than three months. Four hours after boarding the ISS we were back in Atlantis, closing the hatch to prepare for our spacewalk the next day.
Taco and Roman sent air whistling overboard through the airlock depress valve, lowering the cabin pressure to 10.2 pounds per square inch. The reduction from sea-level pressure would bring down the nitrogen content of our blood, reducing our chances of getting the bends and shortening the time we’d spend the next morning in our spacesuits, preparing for our first spacewalk, or extravehicular activity (EVA). To further lower our blood nitrogen levels, Beamer and I donned portable breathing masks to begin flushing that unwanted gas from our lungs. Looking like a couple of wayward scuba divers, we breathed pure oxygen while readying the EVA tools. We quickly located nearly every item on the checklist, but three critical electrical components, called loopbacks, were missing.
For months we had trained underwater to install these soda-can-size plugs on the lab’s hull, where they would shunt electrical power or data to the proper circuits. These had to be in place for lab activation after EVA 1. We searched our lockers again for the loopbacks, and Marsha checked her inventory sheets. No loopbacks, but she did find several listed items called “1553 bus terminators.”
No doubt at some point in our training we had been exposed to the proper technical name for the loopbacks, but none of us had ever used that term. We quickly realized that “1553 bus terminators” probably referred to the missing parts. A call to Houston confirmed our fears: The lost components had been packed in one of the cargo bags we had just transferred to the station. They were now on the wrong side of a sealed hatch.
The pressure differential between the two vehicles prevented us from simply opening hatches and grabbing the parts. My first thought was that we would have to repressurize either our cabin or the station’s docking tunnel, wasting precious breathing gas in the process. I had just made the call to Houston admitting our mistake when Sergei made a suggestion. Because the loopbacks were only the size of a six-pack, he could place them in the foot-wide vestibule between the orbiter and station hatches; it would take just a few liters of air to equalize the pressure there, making it safe for us to retrieve them.
Sergei’s solution soon had us back in business. As I grabbed the loopbacks from the vestibule, I met his gaze through the porthole in the Russian-built station hatch. He returned my nod and wave of thanks with an easy smile. The irony of having a former Communist rescue our first spacewalk from an embarrassing foul-up wasn’t lost on me, a former Cold Warrior who’d spent my Air Force days flying B-52 bombers. This partnership might yet work.