Mysteriously, five spacecraft that flew past the Earth have each displayed unexpected anomalies in their motions, SPACE.com reports. In five of the six flybys, the scientists have confirmed anomalies.
“I am feeling both humble and perplexed by this,” said Anderson, who is now working as a retiree. “There is something very strange going on with spacecraft motions. We have no convincing explanation for either the Pioneer anomaly or the flyby anomaly.”
In the one probe the researchers did not confirm a noticeable anomaly with, MESSENGER, the spacecraft approached the Earth at about latitude 31 degrees north and receded from the Earth at about latitude 32 degrees south. “This near-perfect symmetry about the equator seemed to result in a very small velocity change, in contrast to the five other flybys,” Anderson explained — so small no anomaly could be confirmed.
The five other flybys involved flights whose incoming and outgoing trajectories were asymmetrical with each other in terms of their orientation with Earth’s equator. The fact this effect seems most evident with flybys most asymmetrical with respect to Earth’s equator “suggests that the anomaly is related to Earth’s rotation,” Anderson said.
As to whether these new anomalies are linked with the Pioneer anomaly, “I would be very surprised if we have discovered two independent spacecraft anomalies,” Anderson told SPACE.com. “I suspect they are connected, but I really do not know.”
“Another thing in common between the Pioneer and these flybys is what you would call an unbound orbit around a central body,” Anderson said. “For instance, the Pioneers are flying out of the solar system — they’re not bound to their central body, the sun. For the other flybys, the Earth is the central body. These kinds of orbits just don’t occur very often in nature — it could be when you get into an unbound orbit around a central body, something goes on that’s not in our standard models.”
The researchers are now collaborating with German colleagues to search for possible anomalies in the Rosetta probe’s second flyby of the Earth on November 13.
“We should continue to monitor spacecraft during Earth flybys. We should look carefully at newly recovered Pioneer data for more evidence of the Pioneer anomaly,” Anderson added. “We should think about launching a dedicated mission on an escape trajectory from the solar system, just to look for anomalies in its motion.”
