Reason Behind the Slowing of Pioneer 10 and 11 is Solved

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**Easy E**

http://www.space.com/16648-pioneer-anomaly-spacecraft-mystery-solved.html

Scientists have finally cracked a decades-old spaceflight riddle, figuring out why NASA's Pioneer 10 and 11 probes began to slow mysteriously as they sped far from the sun.

The cause of the so-called "Pioneer Anomaly," it turns out, is heat coming from the electrical current flowing through the probes' instrument and power systems. This heat pushed back on the spacecraft, causing them to decelerate slightly, according to a new study.

"The effect is something like when you're driving a car and the photons from your headlights are pushing you backward," lead author Slava Turyshev, of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., said in a statement. "It is very subtle."

Decelerating spacecraft

Pioneer 10 and Pioneer 11 launched in 1972 and 1973, respectively. They were the first spacecraft to fly through the main asteroid belt, and the first to study Jupiter up-close. The probes kept on cruising after their Jupiter encounters, speeding toward Saturn and beyond. [A Photo Tour of the Planets]

Pioneer 10 and 11 will eventually exit the solar system, but they likely won't be the first to do so. Scientists think the Voyager 1 spacecraft, which is about 11.1 billion miles (17.8 billion kilometers) from Earth, may leave our cosmic neighborhood any day now.

In the early 1980s, mission scientists noticed that the spacecraft were slowing down unexpectedly. But they dismissed this as a transient phenomenon resulting from dribbles of propellant left in the probes' lines, researchers said.

The issue didn't go away, however. In 1998, when Pioneer 10 and 11 were more than 8 billion miles (13 billion km) from the sun, a team of researchers calculated that the spacecraft were declerating at a rate of about 300 inches per day squared (0.9 nanometers per second squared).

The scientists couldn't explain the slight slowdown, so they raised the possibility that some new type of physics that contradicted Albert Einstein's general theory of relativity may be responsible.

There go all those conspiracy theories about Einstein getting it wrong.

**Kanluwen**

So the answer isn't "aliens"?

Dang...

**Mr Nobody**

Kanluwen wrote:
So the answer isn't "aliens"?

Dang...

When it starts returning to earth, then we can say it's aliens.

**juraigamer**

Ha ha, my headlights slowing me down, I'll use that next time I need to stop sooner, just turn on my high beams.

**d-usa**

We should all watch Star Trek The Motion Picture when Voyager leaves the system

**KalashnikovMarine**

d-usa wrote:
We should all watch Star Trek The Motion Picture when Voyager leaves the system

Vger!

That's pretty crazy though, the miniscule heat generated by the satellite is literally slowing it DOWN! That's a combination of insane and awesome.

**d-usa**

KalashnikovMarine wrote:
d-usa wrote:
We should all watch Star Trek The Motion Picture when Voyager leaves the system

Vger!

It's not good-bye, it's see you later

**Steve steveson**

juraigamer wrote:
Ha ha, my headlights slowing me down, I'll use that next time I need to stop sooner, just turn on my high beams.

I thought that was why people keep flashing there lights and beeping there horn behind me when I brake.