Untitled DocumentThat mysterious object discovered in orbit around Earth on September 3 is likely not to hit the Moon. Rather, the suspected Saturn IVB upper stage will swing back into orbit around the Sun, scientists said today.
A study of the path of the object -- dubbed J002E3 -- has led to the new assessment, said Paul Chodas of the NASA Jet Propulsion Laboratory (JPL) in Pasadena, California.
"Our orbit knowledge has improved significantly since last week, and the chances of a lunar impact have now decreased to less than one percent. It now looks like the object will escape from the Earth next year and head back out into solar orbit," Chodas told SPACE.com.
Whatever it is
At first researchers believed that J002E3 might be an asteroid, freshly captured by Earth and entering our planet's orbit. Initial looks at the object concluded that it had been orbiting the Sun until April of this year. At that time, the Earth captured it into an orbit that put it about twice as far away as the Moon.
Tracking and space-debris experts contend the object is likely an Apollo lunar leftover, due to its small size and odd orbit. They're pretty sure it's an old Saturn S-IVB upper stage used to hurl Apollo 12 astronauts to the Moon in late 1969.
Meanwhile, University of Arizona astronomers scanned the object using special telescopic gear, discerning that J002E3's spectra matches that of Titanium oxide. That find supports the belief that what is being tracked is indeed the Apollo Saturn S-IVB rocket stage -- hardware pained with Titanium oxide paint.
Suspect identified
While it was strongly suspected a week ago that J002E3 had been captured by the Earth in April of this year, it was not known how long the object had been orbiting the Sun prior to capture.
Additional observations have now confirmed that the object was indeed captured from a solar orbit earlier this year, and they have also made clear that it escaped the Earth-Moon system in March 1971, report Chodas and Steve Chesley, both of NASA's Near-Earth Object Program Office at JPL.
The timing of the object's escape is consistent with the Chodas and Chesley theory that J002E3 is indeed the Apollo 12 S-IVB third stage, which was left in a distant Earth orbit after it was launched on Nov. 14, 1969 and passed the Moon four days later. Also, brightness of the object suggests it matches up with the rocket's upper stage size.
"We conclude that the Apollo 12 S-IVB stage is the most likely identity of the object," Chodas and Chesley report.
Decreasing chances of impact
In a JPL statement released today, the object's future destinations are detailed.
"Our improved orbital knowledge for J002E3 is also allowing more precise predictions for its future motion," notes the JPL statement.
According to Chodas and Chesley, the likelihood that the object will impact the Moon next year has decreased to less than one percent. This new conclusion follows from the fact that the range of possible motion in 2003 is now more tightly constrained and barely intersects the Moon.
The possibility of collision with the Earth has also decreased, down to well less than one percent. Even if J002E3 should hit our planet, the object is too small to be considered hazardous.
"It now appears likely that the object will escape back into solar orbit in June 2003 after its brief six-orbit visit to our planet. In 30 years time the Earth may once again capture J002E3 for another brief tour around its home planet," the JPL researchers add.
See a JPL animation of the J002E3 being captured into Earth orbit
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