# Pioneer is NOT slowing down!

Quite the busy week for me this week, sorry for lack of posts.. but here’s a question that was sent to me from a fan who’s also studying in school to become an Astrophysicist.. Good luck Brian K ðŸ˜€

There’s a few posts I found on the net that NASA and a few other unrelated agencies that reported that the Pioneer 10 and Pioneer 11 spacecrafts were slowing down. Before I have astrophysicists and Neil deGrasse Tyson come and pimp slap me for stating that the space-crafts are defying the very laws of motion that Newton threw in our faces, know that there ARE logical and real reasons as to why they could be slowing down. The rate at which they initially reported to be slowing down was too fast for the explanations and we began to wonder why. The first reason was the decay of the plutonium on-board supplying power. As it decays, heat builds up and provides a reverse thruster. Someone call Mr. Crusher and tell him to turn off impulse thrusters.

Here’s the thing: They’re not slowing down; everyone claiming they are slowing down needs to understand that we’re not looking at the whole picture. The universe is expanding. It’s expanding very fast, at a rate of about 72 km/s per mega parsec (~3 million light years (cubic measurement, not square footage.. 3D universe, remember?)). When we measure something like the distance of a meteor in our solar system, we don’t need to take into effect the expansion of the universe as it wouldn’t change the final result if we did or did not. The Pioneer spacecrafts are so far away from Earth that we do need to take these numbers into effect, as we all know that the distance between two points that are traveling straight gradually growing apart will forever be a larger distance the farther you get away from the source.

What the hell did you just say Jeff?

Go grab a protractor, or something triangle shaped. Hell, draw one of these:

Take the top of the triangle (whatever point you decide is the top is irrelevant) and draw the lines on either side in a straight line outwards. Continue their current trajectory until you run out of space on your paper. Measure the distance between the lines at two different points. This is what I mean; the farther the lines are away from where the top of the triangle is, the farther the distance between them. If that distance is as far apart as the Earth and Pioneer 10 is for example, we NEED to calculate with the speed of the expansion of the universe in our distance equations to get an accurate reading of it’s current speed/distance from the source. Without that, then we get silly things like people believing that an object in space is slowing down.

Jeff Wilton

Jeff is the founder and owner of Everyday Science Stuff. ESS is a one man operation, with the core belief that all education should be served without crippling debt tuition, without revenue generating ads and without any restrictions of any kind such as paywalls, forced login and account creations, geographical restrictions, and so on.