A strange speck of light appeared recently in the night sky. A UFO? An asteroid headed for Earth? Nope--it's just the 33-year-old third stage of the Saturn V rocket that hurled Apollo 12 to the moon back in November 1969. After circling the sun for decades, it has apparently been recaptured by Earth's gravity, and there's a fair chance it will slam into the moon sometime next year.
The new dot in the sky was discovered on 3 September by Arizona-based amateur astronomer Bill Yeung. Using a semiprofessional telescope, Yeung has already found hundreds of asteroids, and he dutifully reported his new discovery to the Minor Planet Center of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. Surprisingly, initial calculations showed that it loops in an irregular, elongated orbit around Earth with a period of about 7 weeks. Based on the object's appearance and calculations of the path it must have followed through space for the past 3 decades, astronomers are fairly certain it is the Saturn V rocket stage. Radar studies with ground-based telescopes in California and Puerto Rico, now being planned, should nail this down by providing information about the object's surface properties.
The empty rocket stage was probably recaptured by Earth's gravity in April, says Paul Chodas of NASA's Jet Propulsion Laboratory in Pasadena, California, when it happened to enter a region known as the L1 Lagrange point. This area, some 1.5 million kilometers away from Earth in the direction of the sun, is a gravitational no man's land, where it's easy for any object with the right velocity to cross the border between the sun's and Earth's tug. A similar trip, made in the opposite direction, probably put the rocket stage in a solar orbit in the first place, as it was discarded by NASA in an elongated Earth orbit in late 1969.
What will the rocket stage do next? Lacking enough observations, astronomers can't yet say for sure. It could sneak through a Lagrange point again, Chodas says, and resume its solar orbit; but there's a 20% chance that it will hit the moon in 2003, most likely on its invisible far side. And there's a 3% chance that the rocket stage will burn up in Earth's atmosphere sometime in the next 10 years, cleansing the solar system of at least one piece of space junk.
)
)
)
)
)
)
)
)
)
)
)
