Scientists tracking the distant probe (now some 11 billion kilometres from Earth), say that the probe’s speed, presently 43,400km/h, is being reduced by the force by almost 10km/h per century. Not much but entirely noticeable and worthy enough that scientists, like Dr Duncan Steel of Salford University, is speculating this cosmic tug could question whether we know enough about gravity, the universe and everything. [Telegraph]
IIRC, the original problem was that there were 2 probes, and that one of them showed a slowing of speed. Then, later, the second one showed some slowing.
There are about 20 billion ‘things’ in space around these probes that could affect their speed.
One micro-asteroid hitting the probe could cause a change in speed. A change in the density of background hydrogen could cause it. Gravitational influences from objects we can’t even see, might cause it.
Saying the Sun has some ‘other’ kind of ‘force’ that is pulling these probes ‘backward’, seems almost ludicrous.
More likely is that it is something else, and we don’t have the equipment on board the probe that would sense ‘what’ and ‘where’ the something else is.
From comments on Gizmodo:
http://www.newtonphysics.on.ca/anomalous/index.html
“Published: 12:01AM GMT 10 Feb 2002”
“This article is from 2002. In the 8 years since this article was first published, scientists have discovered that Pioneer is colliding with space dust in the Kuiper belt, which slows it down.”
http://gizmodo.com/5642007/a-mysterious-force-is-pulling-pioneer-10-back-toward-the-sun
I would assume our own galaxy likely affects the crafts direction and speed to some degree.
or maybe their calculations are wrong.
“say that the probe’s speed, presently 43,400km/h, is being reduced by the force by almost 10km/h per century”
Maybe the speedometer needs calibration.