* Astronomy

On July 15, 1972, Pioneer 10 was the first spacecraft to enter the asteroid belt.

Is the solution discovered a "closed form" solution. Did the asymetric force come from a model that had been tested or was the force arrived at by fitting the data. I assume there some fitting of data but how well did the model fit and where are the equations specifying the force for a given heat radiation.

Ed ~ the two post dated 'Dec 16 14:24 2010' and 'Mar 31 17:10 2011' describe the modelling used. Basically, once the thermal radiation pressure forces were accounted for, they could explain the small spacecraft drag.

Anniversary of the Pioneer 10 launch in 1972

Launched on March 2, 1972, Pioneer 10 was the first spacecraft to travel through the asteroid belt, and the first spacecraft to make direct observations and obtain close-up images of Jupiter. Pioneer 10 is now coasting silently through deep space toward the red star Aldebarran, a journey of over 2 million years.

On July 15, 1972, Pioneer 10 was the first spacecraft to enter the asteroid belt, located between the orbits of Mars and Jupiter. Surprisingly, the on-board experiments demonstrated a deficiency of particles below a micrometre (m) in the belt, as compared to the vicinity of the Earth. The density of dust particles between 10100 m did not vary significantly during the trip from the Earth to the outer edge of the belt. Only for particles with a diameter of 100 m to 1.0 mm did the density show an increase, by a factor of three-fold in the region of the belt. No fragments larger than a millimetre were observed in the belt, indicating these are likely rare; certainly much less common than anticipated. As the spacecraft did not collide with any particles of substantial size, it passed safely through the belt, emerging on the other side about February 15, 1973.
Read more