[Southack]

Acceleration in the opposite direction is also known as deceleration...

[Gamecock]

Acceleration in the opposite direction is also known as deceleration...

Bump until I can drink a couple Hefe-Weizens and think about that....

[GOPJ]

Mix this with "no known life in the universe except us" (after 30 years of looking) and you start coming up with weird conclusions. Computer?

[StormEye]

"Acceleration in the opposite direction is also known as deceleration..."

I'm not referring to deceleration. In referring to a slight acceleration in the direction of motion away from Earth and the solar system. I remember reading about this a few years ago. Maybe as little as two years ago. The people monitoring the Voyagers and the Pioneers said the space craft were speeding away from the the Sun at a faster rate than predicted. And these scientists had no explanation for the phenomenon. Some proposed explanations included:

i) The pressure of sunlight on the vehicles.
ii) Possibly some sort of gas leaking from the space craft slighly accelerating them.
iii) The expansion of space -- thus effecting the measured speed of the space craft.
iv) Measurement errors.
v) Something effecting the radio signals from the space craft.

Now they say the vehicles are inexplicably slowing down. Albeit, very slightly.