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In 2001, a titanium motor casing from a Delta II ended up in Saudi Arabia. (NASA)

The Things That Fell to Earth

How NASA can predict when space junk will fall in your back yard.

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ON JANUARY 15, 1995, A JAPANESE ROCKET took off from Kagoshima, carrying a Russian-made satellite with German scientific instruments. The mission’s purpose was to test materials processing techniques in microgravity and then return the samples to a landing zone in Australia.

But the launch vehicle swerved off course and headed for the horizon. Ground controllers in Germany listened for radio signals indicating that the satellite had reached a stable orbit, but they heard nothing. Without such confirmation, they eventually concluded it had fallen back to Earth. Searching for the satellite was never considered since it could have ended up almost anywhere, and all involved with the mission assumed that the Russian spacecraft would never be seen again.

As it turned out, the heat-shielded landing capsule ended up in northern Ghana, near the town of Tamale, after the satellite had limped around Earth twice in a lopsided orbit. The capsule’s parachute had opened as planned, and as the craft drifted down, it broadcast homing signals that nobody picked up.

Villagers outside of Tamale witnessed the landing and called the local schoolmaster. It was obvious to him that the vehicle was a spacecraft and, given the Cyrillic characters on its side, probably of Russian origin. The schoolmaster organized a recovery team, who trucked the hardware to a storage room in town. Then he wrote to officials in Accra asking how to contact the satellite’s owners.

Months later, news of the space object reached Geoffrey Perry, an amateur satellite tracker in England, who quickly realized it must be the lost Russian vehicle. He knew whom to call in the German space program, and a few months later, staffers from the German embassy in Ghana showed up in Tamale and asked for their payload. Along with the capsule, the Germans were given a bill for the storage fee, which they grudgingly paid.

Had the Germans known the capsule’s point of reentry into the atmosphere, they could have avoided the storage fee. Eight years later, another team desperately seeking another failed space vehicle knew its point of reentry. Using models that can predict how space objects fall through Earth’s atmosphere, this team was able to pinpoint not merely the continent, the country, and even the county where something had fallen, but the likely pasture.

For weeks, searchers on foot had combed the ground in east Texas, seeking pieces of the space shuttle Columbia, which on February 1, 2003, had broken apart during reentry, killing all seven astronauts aboard. The location of each fragment of the shattered shuttle was carefully documented, and then the parts were transported to a hangar at Kennedy Space Center in Florida, where reconstruction efforts tried to help forensic engineers discover what had gone so terribly wrong.

On March 18, a recovery team was sent to an area that had already been searched; in fact, it had been marked “completed.” This time, though, the team was seeking one particular piece of hardware that had been aboard Columbia. Knowing its size and weight, and the distribution of other pieces already recovered, experts in reentry dynamics had concluded that the 58-pound object—a VCR-size box containing potentially valuable flight data on the doomed mission—would lie in the already-searched area.

Sure enough, on a hillside near Hemphill, Texas, technicians found the Orbiter Experiment Recorder, embedded several inches in the ground. It contained time-tagged measurements that were exactly what investigation teams needed to pinpoint the moment Columbia’s left wing had collapsed, an event that preceded the breakup of the vehicle.

The insights that led to the search team’s discovery had been developed over many years of study at NASA’s Johnson Space Center in Houston, Texas, and an earlier instance of spacecraft disintegration made the shuttle searchers confident that they were on the right track.

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