Slashdot Mirror
New Theory About the Source of Pioneer Space Probe Deceleration
First time accepted submitter deathcow writes "After forty years, a fresh perspective on old Pioneer data leads to new conclusions as to why the Pioneer probes are decelerating. Many theories to the slowing probes have persisted over the years — was it gravity? some type of unforeseen radiation? dark matter? Thanks to the data backup preservation efforts of a NASA Ames Research engineer, mountains of old telemetry data were still available for studying this curious anomaly."
It's thermal recall force from heat generated by components on Pioneer.
The article is way too long but here's the essential paragraph:
"we estimated the magnitude of the thermal recoil force at different times over the course of the Pioneer missions. After matching the model to the Pioneers’ temperature and electrical readings, we found that the spacecraft did experience a sizable thermal recoil force, corresponding to an excess of about 60 W even after 20 years in deep space. The magnitude of the force was still tiny by Earth standards—about the same as the backward push your car experiences in reaction to the photons spit out by its high-beam headlights. The team found that a good half of the force came from heat from the RTGs (radioisotope thermoelectric generators), which bounced off the back of the spacecraft antenna. The other half came from electrical heat from circuitry in the heart of the spacecraft"
There, you may resume.
Sent from my ENIAC
I hate Spectrum. Not because they have bad articles, but because they never have anything that I haven't already been reading about for the past months, or even years.
Hint to editors. If you ever get a submission with a link to Spectrum, chances are very high that Slashdot has covered it before.
Warning: Opinions known to be heavily biased.
Not so new of a theory, and already discussed here at Slashdot:
http://science.slashdot.org/story/11/07/26/0135234/heat-most-likely-cause-of-pioneer-anomaly
Everything from clouds of dark matter, weird gravitational effects, alien tampering and exotic new physics have all been blamed for the 'Pioneer Anomaly' — the tiny, inexplicable sun-ward acceleration acting on the veteran Pioneer deep space probes. However, evidence is mounting for a more mundane explanation. Yes, it's the emission of heat from the spacecrafts' onboard radioisotope thermoelectric generators (RTGs), slowly nudging the Pioneers off course, that looks like the most likely culprit. It's unlikely that this new finding will completely silence advocates of more exotic explanations, however.
Better known as 318230.
The design of these spacecrafts is simply amazing. No wonder the US was the technological marvel of the world at the time. Considering the tools that were available then and the thought that was put into the effects of space on the motion, is mind boggling. Not to mention a power source that will last 88 years and the fact that they are still going and communicating while using a 1 bit camera to create fantastic pictures. I am humbled. The technology that was created and developed as a side effect of this monumental tasks is what made the US a technology giant. We need more of this positive vision and less of the negative sabre rattling.
They were able obtain a longer history of telemetry data by getting it from some guy's laptop hard and finding some mag tapes under a staircase, and they reverse engineered hard-copy blueprints with the help of retired TRW engineers into modern CAD & FEA, and determined that the RTGs were bouncing thermal energy off the dish, creating recoil -- about the same amount as a car's headlights throwing photons forwards push the car backwards.
How was this not interesting? Less energy than is put out by your headlights on your car was actually slowing down a multi-tonne spacecraft zipping through space at over 36,000 miles per second! While its not groundbreaking, it definitely is interesting science, and its frigging SPACE man!
Higgs Boson was discovered and proved to be real. They might even have found a previously undetected particle as well!
Dark matter was proven to exist and the mystery of why the universe is expanding faster and faster was solved!
A private company went into space!
A man jumped from the edge of space and landed safely while anyone on the planet who cared to watch did so!
What the heck do you want, Science to prove God Exists and invite him over for freaking tea?!?
How can you be so jaded?
My money is on interstellar photo radar.
Tomorrow is another day...
Your attention span just... never mind, he wandered off.
This is science kid, leave it for people who can read a full paragraph without needing a red bull. For once the article tells the complete story instead of being some butchered blog summary of a blog summary of a tweet of a snippet and the kiddies are up in arms because they actually have to use the reading skills they never mastered.
MMO Quests are like orgasms:
You may solo them, I prefer them in a group.
If you don't feel like reading the very long and mostly unrelated story, here is the gist: "The puzzling deceleration was produced by the asymmetric radiation of waste heat created onboard the spacecraft. Read more to find out why we believe this." Seems like an awfully long article just to relate that bit of info imo.
....the entire mission cost -all the years in total - for Pioneer 10 was approximately $350 million (2001) USD. (It'll reach Aldebaran in about 2 million years.)
That's a little bit under a single week of NASA's budget this year. ($19bill) ...or about 4 hours of the Defense budget ($677 bill) ...or about an hour of the Social Security+Medicare budgets ($1.92 trillion).
-Styopa
It's thermal recall force from heat generated by components on Pioneer.
Right. and the headline is a little misleading, it's a "new" explanation only if you weren't following; since it was announced in late 2010. The "anomaly" is solved.
Popular Science article about Toth and Turyshev's work here: http://www.popsci.com/pioneeranomaly
More detailed calculations supporting the explanation:
Phys Rev Letters paper by Toth and Turyshev here: http://prl.aps.org/abstract/PRL/v108/i24/e241101
ArXIV paper confirming the work with more details: http://arxiv.org/abs/1103.5222v1
JPL press release: http://www.jpl.nasa.gov/news/news.php?release=2012-209&cid=release_2012-209&msource=12209
Centauri Dreams article: http://www.centauri-dreams.org/?p=23720
Still, it's a nice article to read about how the work is done.
http://www.geoffreylandis.com