Data, Dogma, and Truth Too Detailed to Matter (most of the time)

There are so many lessons in this story it is hard to know where to start. First, don't throw away data. Second, scientists do question their own dogma and in fact get rather excited about it. Third, Click and Clack (Car Talk) glossed their answer to a question the other day (sort of) ... it turns out that running the heater in your convertible does affect the entire planet. A little.

Pioneer 10 and 11 left the the main part of our solar system a long time ago. As they headed on their journey to other worlds, they seemed to slow down in comparison to predictions of their actual rate of movement. This slowing has become known as the Pioneer Anomaly.

One of the most intriguing mysteries in physics is the "Pioneer anomaly," the slowing down of two spacecraft by an unknown force. NASA launched Pioneer 10 and 11 in 1972 and 1973, respectively, and the craft returned stunning images of Jupiter and Saturn. But as both spacecraft continued their voyages at speeds of roughly 27,000 miles per hour, astronomer John Anderson of the Jet Propulsion Laboratory in Pasadena, Calif., noticed anomalies in telemetry data dating from as far back as 1980. With continued analysis, researchers determined that the spacecraft had been slowing down at a constant rate: each year they fell 8,000 miles short of their calculated positions. The strange behavior sparked several theories, but the lack of data made culling the ideas difficult. Now a proposal to analyze telemetry from the early years could literally point toward the correct explanation.
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The hypotheses that have been floated to explain this are of two types: Intrinsic and cosmic. The intrinsic hypotheses suggest that there is a gas leak or some other mechanical thing going on that changes the rate of the space crafts' movement. The cosmic hypotheses suggest that gravity works slightly differently than Einstein's model demands, and that this effect is very small but shows up in this particular case.

In the mean time, piles of data were sent back from Pioneer 10 and 11, used for various purposes, then slated for deletion because it was taking up too much space. However, Slava Turyshev, one of the discoverers of the Pioneer Anomaly wanted to analyze the data, and eventually, the Planetary Society raised the funds to save the data for Slava Turyshev and computer programmer Viktor Toth to play around with.

Now a large team of researchers is analyzing the data. They have created a model of all the systems on the space craft, and by analyzing exactly what was sent back, they are able to model the heat distribution from the Plutonium power source through various parts of the machinery on each probe in very fine detail. The idea is that the movement of heat around in the space craft changes the dynamics of its movement and could thus explain the anomaly.

So far the model accounts for about 30 percent of the observed anomaly for Pioneer 10 up to a distance of 10 astronomical units (approximately 1.5 billion kilometers) from the Sun, Turyshev reported. The group still has to extend the model to other distances and to Pioneer 11. The full verdict may not be in for some time. "I'm trying to ensure we apply every relevant piece of information," Turyshev says. "It is likely that the thermal explanation will explain part of the anomaly," he says, but exactly how much is up for grabs.
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Now it is a waiting game as the team analyses the rest of the data. There is a distinct possibility that this very detailed model will not explain the slowdown in its entirely, which would leave open the possibility of a change in the gravitational model.

That's all very cool and interesting. So, how does this serve as a multi-plex lesson?

First, the data that were going to be thrown away may turn out to be useful, minimally, to refine the mechanical modeling and thus engineering of satellites, spacecraft, and so on. Don't throw away data! Second, nowhere in this story do you hear people denigrating, belittling, or even expelling scientists who are suggesting that a change in the dogma may be afoot. Einstein's gravitational theory is dogma in physics, and physicists are always questioning it. Darwinian evolution is dogma in biology and biologists are always questioning it. This crap about how we expel people who don't blindly accept the dogma is, well, crap. Finally, we have Click and Clack. Being MIT trained engineers, they gave a very good answer: No, when you are driving around in the convertible with the heat on, that heat was originally going to go out the exhaust pipe, and you are just redirecting it. But they also noted that technically, there would be small changes in something because you are moving around energy in some way. It turns out, though, that Click and Clack failed to mention that the movement of heat to different parts of the convertible than otherwise might happen could result in the long term trajectory of the convertible changing. A little.