Preliminaries

IN THIS STORY I’m going to talk a lot about NASA,^* but when I say “NASA did this” and “NASA did that,” I don’t mean all of NASA; I just mean that part of NASA associated with the shuttle.

To remind you about the shuttle, the large central part is the tank, which holds the fuel: liquid oxygen is at the top, and liquid hydrogen is in the main part. The engines which burn that fuel are at the back end of the orbiter, which goes into space. The crew sits in the front of the orbiter; behind them is the cargo bay.

During the launch, two solid-fuel rockets boost the shuttle for a few minutes before they separate and fall back into the sea. The tank separates from the orbiter a few minutes later—much higher in the atmosphere—and breaks up as it falls back to earth.

The solid rocket boosters are made in sections. There are two types of joints to hold the sections together: the permanent “factory joints” are sealed at the Morton Thiokol factory in Utah; the temporary “field joints” are sealed before each flight—“in the field”—at the Kennedy Space Center in Florida.

FIGURE 1. The space shuttle Challenger. The fuel tank, flanked by two solid-fuel rocket boosters, is attached to the orbiter, whose main engines burn liquid hydrogen and liquid oxygen. (© NASA.)

FIGURE 2. Locations and close-up views of booster-rocket field joints.