NEW YORK — It’s been years since NASA last heard from either of its two Pioneer probes hurtling out of the solar system, but scientists are still debating the source of an odd force pushing against the outbound spacecraft.

Dubbed the Pioneer Anomaly, the unexplained force appears to be acting against NASA’s identical Pioneer 10 and 11 probes, holding them back as they head away from the Sun.

Whether that force stems from the probes themselves, something exotic like dark matter, or some new facet of physics or gravity, remains in doubt.

But a wealth of newly recovered data and telemetry, spanning decades of observations by both Pioneer 10 and 11, may yield the final answer to whether conventional physics or perhaps something new is at work on the two spacecraft. An answer could arise from the new data after about a year of analysis by an international team of researchers.

“I would like to see this story reach its finality,” said Slava Turyshev, an astrophysicist with NASA’s Jet Propulsion Laboratory (JPL) who has spent the last 14 years–some of it on his own time–studying the Pioneer Anomaly. “So if it’s conventional physics, that’s fine and we can all go about our daily business. But if it’s something else, there may be another page.”

He and other fellow devotees discussed the astrophysics oddity late Monday during the Seventh Annual Asimov Debate here at the American Museum of Natural History.

Turyshev’s international team includes researchers from all Pioneer Anomaly camps, with some learning towards a conventional physics explanation while others trend toward the unknown fringe. Still other researchers have their own opinions.

“If I were a betting man, which I am not, I would bet a whole case of cranberry juice that the Pioneer Anomaly will have an ordinary explanation that is within known physics,” said Irwin Shapiro, an astrophysicist at Harvard University unaffiliated with the Pioneer Anomaly research team, during the debate.

Shapiro said that the number of actual instances in which oddities like the Pioneer Anomaly have opened pathways to fundamentally new physics are rare, and that ongoing studies may yet yield a conventional explanation.

Read Tariq Malik’s full article at SPACE.com.