It seems that Pioneer 10 and Pioneer 11, which are 86 and 57 AUs from the sun, respectively, are traveling more slowly than expected.
(An AU is an “astronomical unit”, the distance from our sun to our planet. Therefore, Pioneer 10 is 86 times as far from the sun as the Earth is. You may think it’s a long way down the road to the chemist, but that’s peanuts to this.)
They call this phenomena ‘the Pioneer Anomaly’ and they don’t know if it’s due to leaking propellant, some heretofore-unknown physics, or if maybe it’s just Bush’s fault.
However, a nearly eight-year study of those possible causes amounted to “no smoking gun,’ said Slava Turyshev, one of the researchers on that study and the ESA proposal from JPL.
Scientists also have looked into “just about everything we can think of,’ Nieto said.
What really puzzles scientists, Turyshev said, is that the anomaly is constant with respect to time and distance from about 1 1/2 billion miles away from the sun to about 6 1/2 billion miles out. The anomalous behavior has been observed in other deep space vehicles such as Voyager and Ullyses.
Nieto said interest in determining the root of the Pioneer problem “is growing in the ether.’
Here are some additional theories from MO, in no particular order (other than they start out bad and get worse):
- Increased magnetic activity on Earth is affecting the probes’ velocity
- They’re just plain tired
- They are nearing the edge of the turtle that holds up everything on his back
- This is actually the way George Lucas intended them to fly all along, but the technology just wasn’t available back then
- NASA engineers forgot to unhook the giant bungee cord that connected the probes to the launch pads
- Uranus sucks
- Reduced NASA funding is hurting mileage
- Dan Rather: “This is the same speed they’ve always been traveling”
- It’s gotta be the shoes
- In Space, No One Can Hear You Lose Steam
For info on the current stats of the Pioneer and Voyager probes, check out Heavens Above’s ‘Spacecraft escaping the Solar System’ page. (hat tip to Fred)