TAG | Pioneer Anomaly partially explained with heat |
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| by William Atkins | |
| Monday, 05 May 2008 | |
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Page 1 of 3 Sir Isaac Newton described the gravitational force that a body exerts on another body as related to the primary body’s mass. Gravity exerted by a massive body, it turns out, exerts less force on another body as that body gets further away from it. The gravitational force decreases according to the inverse square of the distance between the two bodies. Albert Einstein later added to the laws obeyed by gravity in his theory of relativity. However, the Pioneer Anomaly (or Pioneer Effect) doesn’t seem to quite fit in with these accepted laws of gravity by Newton and Einstein. Specifically, the Pioneer Anomaly is the observed but long-time unexplained deviation from the expected trajectories of the two NASA spacecraft, Pioneer 10 and Pioneer 11, along with other spacecraft as they travel on courses in the outer reaches of our solar system. Pioneer 10 and 11 are on a course that will soon take them outside of our solar system. They are slowing down as they move further away from the Sun because of the gravitational attraction of the Sun on the two tiny objects. However, they are slowing down faster than would be expected when considering all of the known sources that would have an effect on them. Specifically, when all known physical forces acting on the spacecraft are taken into consideration by scientists, a small force remains. Astronomers describe it as a constant sunward acceleration. Its magnitude is 8.74 x 10-10 meters per square seconds, plus or minus 1.33 x 10-10 meters per square second. Thus, each and every year their speed decreases by a little bit and Pioneer 10 and 11 travel about 3,000 miles (5,000 kilometers) less distance per year than they should travel according to the laws of physics. So far, over thirty years of traveling has caused the two spacecraft to be about 248,500 miles (400,000 kilometers) closer to the Sun than they should be--according to the Pioneer Anomaly. An explanation to the troubling mystery has been searched for since 1980, when John Anderson and colleagues at NASA’s Jet Propulsion Laboratory (Pasadena, California, United States) began looking for a valid explanation for the Pioneer Anomaly. Possible explanations have included observation errors, unidentified source(s) of force on the spacecraft, dark matter, drag from interplanetary materials, gas leaks from the spacecraft themselves, radiation pressure from the Sun, and a theoretical deviation to the force of gravity at very low accelerations. However, a logical explanation to any of these supposed explanations could not be given by scientists. Thus, astronomers now have the troubling thought that the laws of physics, which we think rule the functioning of the Universe, might be incorrect with regards to our understanding of them. Some time ago, The Planetary Society came in with funding for the Pioneer Anomaly. And, Slava Turyshev, of the Jet Propulsion Laboratory, gave of his time to try to explain the mystery. Please read on |
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