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Remembering Pioneer 10
Daniel Goldman writes "Twenty one years ago today, Pioneer 10 became the first spacecraft to leave our solar system, by crossing the orbit of Neptune (which was then the farthest planet from the Sun). Pioneer 10 was the first spacecraft to enter the asteroid belt, the ring of giant rocks beyond Mars. It survived and zoomed on to Jupiter in late 1973, where it became the first spacecraft to take close-up photographs of the storms on the giant planet's surface. After Jupiter, it kept going, collecting data on the particles and radiation it encountered. More info about Pioneer 10 at Wikipedia."
No, they meant that Pluto has an eccentric orbit, which crosses the orbit of Neptune. Between 1979 and 1999, Pluto was the 8th planet from the sun, and Neptune the 9th.
The edge of the solar system is the heliopause. Pioneer 10 has not gotten close to that. The honor of the first man-made object to leave the solar system belongs to Voyager 1, launched over 25 years ago.
For those looking for a more in depth study of the pioneer missions to the outer planets, this book published in the late 70's (now fully online) is truly a hidden gem from NASA's site. It details every last design aspect of the spacecraft in extremely high detail. We've certianly come a long way in ~30 years from grainy washed out Pioneer photopolarimeter images to super high resolution ultrasharp CCD images from Cassini.
- "Hear that?! The percolations are imminent! Cease your ingress!"
... first spacecraft to enter the asteroid belt, the ring of giant rocks beyond Mars. It survived ...
Contrary to nearly every science fiction chase scene, the asteroid belt in orbit around our star is hardly what anyone would call dense. It "survived"? Heck, it'd have to try pretty hard to hit a rock out there!
Pioneer was supposed to die after reaching the outer planets, but it died in late 2003.
Pioneer 10 is not really dead, it is just so far away we can no longer hear it.
Regardless of how you define it, the farthest planet from the sun has not changed in the last 21 years.
Putting aside the debate over the 10th planet, the farthest planet does in fact change over time. There are times when Neptune is the farthest planet from the Sun, and there are other times when Pluto is the farthest planet from the Sun. So in fact the farthest planet from the Sun HAS CHANGED in the last 21 years.
Why this is the case is left as an excercise for the reader...
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www.moneybythenumbers.com
There was recently a conference about thee er/]
Pioneer Anomaly and the conference webpage
has links to various attempts of explanation.
[http://www.zarm.uni-bremen.de/Pion
As far as I know, there is no consensus if the
anomaly has a trivial explanation
(gas leaking from satellite, dust in the
solar system etc.) or if something non-trivial is happening, such as a quantum garvity effect,
dark matter etc.
No, red shift is only indirectly related to distance from source. What matters is the velocity of the source when the light left relative to our velocity now. Red shift occurs when the source was moving away from us. It's similar to the zeeeouuuu sound cars make when they drive past you - when they are going away, they sound lower pitched.
Given this, and the observation that more distant objects tend to be more red-shifted (to which you refer), we conclude that "the universe is expanding."
> Hi - why can't NASA try to use some nearer spacecratt
> (Cassini, Mars Express etc.) to communicate with Pioneer 10?
Because they really aren't that much closer, nor do they have sifficiently good antennas or receivers for the frequencies used for Pioneer 10 downlink.
I would have to do some research, but I think the previous post referring to inadequate D/L signal strength as the cause of loss of communications is incorrect. I believe the prevailing theory is that the Radioisotope Thermal Generator (RTG ) used as a power supply can no longer provide enough power to trun on the transmitter. Once they miss a few passes, the pointing drifts off, then you are shafted.