Mystery Object Orbits Earth

A puzzling object just discovered in orbit around Earth might be an Apollo rocket on a fantastic journey through the solar system.

Sept. 20, 2002: Something odd is circling our planet. It’s small, perhaps only 60-ft long, and rotates once every minute or so. Amateur astronomer Bill Yeung first spotted the 16th magnitude speck of light on Sept. 3rd in the constellation Pisces. He named it J002E3.

Automated asteroid surveys scan the skies every few weeks, yet there was no sign of Yeung’s object earlier this year. "It must have entered Earth orbit recently," says Paul Chodas of NASA’s Near-Earth Object Program at JPL. "But it doesn’t match any recently-launched spacecraft."

In other words, it’s a mystery.

Above: Andrea Aletti of the Schiaparelli Astronomical Observatory captured this 10-minute exposure of J002E3 gliding among the stars of the constellation Taurus on Sept. 17th. J002E3 rotates or tumbles every minute or so, which causes the brightness variations shown in the picture. [more]

Could it be an alien spaceship? "If it is," says Chodas, "the aliens aren’t good pilots. J002E3 is in a chaotic orbit. It loops around Earth once every 48 days or so, coming as close to our planet as the Moon and ranging as far away as two lunar distances." There’s no evidence that the speck is moving under its own power. The orbit is constantly changing because of gravitational perturbations by the Sun and Moon.

At first Yeung and others thought J002E3 might be a small asteroid–a reasonable guess. The object is as bright as a 30m-wide space rock and it’s moving about as fast as an asteroid should move. Mars and Jupiter have captured asteroid moons before; perhaps Earth had done the same.

[…]

How does J002E3 jump back and forth between a Sun-centered orbit and an Earth-centered orbit? “It moves through the L1-point,” explains Chodas. Also known as “the 1st Lagrangian point,” the L1 point is a location in space 1.5 million km closer to the Sun than Earth. Objects placed there in a circular orbit will move around the Sun in exactly one year–always directly between our planet and the Sun. The Solar and Heliospheric Observatory, for example, is a spacecraft that lives at the L1 point. It enjoys a continuous view of the Sun, 24 hours a day, 365 days per year. Objects closer to Earth than the L1 point are controlled by Earth’s gravity. Objects beyond the L1 point are controlled by the Sun. “When J002E3 came close to the L1 point in April 2002, the object passed throuhgh L1–like a portal–from a Sun-orbit to an Earth-orbit. At some time in the future it might leave Earth-orbit in the same way, back out through the L1 point.”

via Mystery Object Orbits Earth – NASA Science.

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