Tracking Mysterious Space Junk
9 Oct 2002
(Source: Near Earth Object Program Office)
J002E3: An Update
Steve Chesley and Paul Chodas
NASA's Near-Earth Object Program Office
We have new results since our September 19 report on the distant Earth satellite J002E3. Evidence continues to accumulate that J002E3 is the lost S-IVB third stage from the Saturn V rocket used to launch the Apollo 12 lunar landing mission in November 1969.
J002E3 passed into the daytime morning sky around Sept. 24, and a week later amateur astronomers Richard Fredrick and Vance Morgan at Powell Observatory in Kansas recovered the object after it had crossed into the evening sky. However, their measurements did not match the predicted position unless we added a gentle push from solar radiation pressure to our acceleration model. As more observations were reported over the next few days, it became clear, not only that radiation pressure was detectable in the motion of the body, confirming that J002E3 is a man-made object, but also that the size of this acceleration matches very well with what we would expect for an S-IVB.
With the quality of our orbital solution improving, we decided to look to see if this relatively bright object had been detected by other telescopes before its discovery in the first week of September. Indeed, using the SkyMorph online search system, we found a single trail from the fast-moving object on an image taken by the NEAT-Palomar NEO survey on June 16, 2002. After we notified him of the detection, Reiner Stoss of DANEOPS [http://earn.dlr.de/daneops/] immediately measured the precise position for us.
The new precovery data extended the arc of observations from 35 days to 114 days, dramatically improving our ability to determine the past and future paths of this object and to measure the acceleration of solar radiation pressure. At our last report we had only 15 days of observations and there was greater uncertainty about what the future held for J002E3. We were not sure how long it would remain in the Earth's vicinity, although it appeared likely to escape next June. We could not even rule out the possibility of a collision with the Earth or Moon over the the next year. It is now certain that J002E3 will depart the Earth-Moon system in June 2003 and that there is no possibility of an impact for several decades. In the years ahead J002E3 may be recaptured, but the first opportunity for this will not be until the mid-2040s.
Looking into the past, we are still unable to connect the motion of J002E3 with the last know position of the Apollo 12 S-IVB. One reason is that the solar radiation pressure is not constant in time, but rather changes with its position around the sun; to precisely account for this effect we need to know the pole of rotation. Furthermore, if J002E3 is the Apollo 12 S-IVB then that stage spent more than a year in a highly chaotic orbit around the Earth. So far these two factors have combined to prevent us from predicting the position of J002E3 with sufficient precision to definitively link these two objects. Nonetheless, we are hopeful that with continued observations, and with the possibility of additional precovery observations, this link can be conclusively established before J002E3 slips back into solar orbit next summer.