UA Astronomers Discover That Earth's Second Moon Wears Apollo Paint

Lori Stiles
Sept. 18, 2002

Astronomers have the first direct evidence that a newly discovered object orbiting Earth is debris from one of the Apollo moon launches over 30 years ago.

Carl Hergenrother and Robert Whiteley, astronomers at the Lunar and Planetary Laboratory at the University of Arizona, used the Steward Observatory 61-inch telescope near Mount Bigelow in the Santa Catalina Mountains north of Tucson for observations of J002E3.

The mysterious object named J002E3 was discovered in orbit around Earth on Sept. 3 by amateur astronomer Bill Yeung, viewing from a site in southern California. The discovery made news headlines as it could be the only satellite, other than the moon, naturally captured by Earth to enter Earth orbit.

After studying the object's past motion, Paul Chodas of the NASA Jet Propulsion Laboratory (JPL) in Pasadena, Calif., concluded that the object had been orbiting the sun until April of this year, when it was captured by Earth. Researchers have believed that J002E3's small size and unusual orbit suggest the object is no asteroid or other natural object, but a piece of man-made "space junk," possibly a piece of one of the Saturn V rockets that launched American astronauts to the moon during the Apollo program. The JPL news release is on the web at

Hergenrother and Whiteley measured reflected light from the object Sept. 12 and 13. The photometric measurements showed that the object spins once every 63.5 seconds or once every 127 seconds – more observations are needed to pin down the exact time, Hergenrother said. "Such a rapid rate of rotation is not unheard of either for an asteroid or a piece of man-made space junk, but is very consistent with each," he added.

The UA astronomers made their definitive observations with various filters to sample the colors, or spectra, that J002E3 reflects.

"Rather than looking like a known asteroid, the colors were consistent with the spectral properties of an object covered with white Titanium oxide (TiO) paint," Hergenrother said. "The Apollo Saturn S-IVB upper stages were painted with TiO paint," he noted.

Hergenrother and Whiteley checked their observations with some professional colleagues, " a kind of informal 'peer review' just in case we were way off on things," Hergenrother said.

Those key colleagues include Richard Binzel and Andy Rivken of the Massachusetts Institute of Technology. Binzel and Rivken took infrared spectra on the unique object, and those spectra "confirm that J002E3 is a dead ringer for white TiO paint," Hergenrother added.

The object is most likely a S-IVB from either Apollo 8, 10, 11, or 12, with Apollo 12 being most likely, the UA researchers conclude.

"As Bill Yeung said, this is the first recorded observation of any object being captured into a geocentric orbit," Hergenrother said.

"There is also a fairly good chance that J002E3 might crash into the moon at some point. Scientifically, that isn't too important, but it is interesting, " he said.