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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.
http://xkcd.com/54/
Low on gas!
*** Don't be dull.***
I know it is unscientific of me, but I hate it when the answer is so much less interesting than the mystery. Not because I dislike seeing a mystery solved but because when the answer is mundane it just means we have to look else where for the really earth shaking discoveries. Hopefully some day in my life time we will make some truly earth shaking discovery. I remain optimistic.
If the tail lights hadn't burned out.
Contribute to civilization: ari.aynrand.org/donate
Damn, I always thought it was the Invisible Pink Unicorn just fucking with us. Now, science has me questioning my blind faith. Curse you science!!! ::shakes fist::
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.
Thanks to the data backup preservation efforts of a NASA Ames Research engineer...
Maybe in the future, the design of probes should be such that the emanation of energy creates a micro-sail. Maybe it won't matter given the heliosheath, but all other things being equal, I'd prefer its own forces to accelerate it, rather than hinder it.
According to roman_mir it's the unions' fault.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
... has it's original programming scrambled and begins to evolve on it's own.
Sent from my ENIAC
Ever seen U.S. Navy fatigues? They're blue. Stick out like a blue thumb. Might as well wear a bullseye on your back, head, and chest. No wonder the Japs sunk their battleships.
My money is on interstellar photo radar.
Tomorrow is another day...
Don't want to get a double fine from the Vogons...
the truth is out there
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.
When I click the link on my android phone, it redirects to the mobile site, from there back to the normal site, again to the mobile site and on and on, until my browser barfs out. Nice. Engineering at its best.
Say out loud: I'm an Aspie and I'm somewhat proud, I guess. Uh. Can I write an email in all caps instead? Hm...
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.
http://xkcd.com/559/
and it's too fsking long and full of facts.
....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
And brake lights actually don't brake, but accelerate ...
http://www.icr.org/article/3472/
Was there not a /. article a half a year ago that blamed heat for the slowdown?
Also worst summery ever, it needs to actually mention what this new theory is.
Troll is not a replacement for I disagree.
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
My high school physics teacher would like me to point out: There is no such thing as 'decelerating'.
There is accelerating in a positive direction on some respective axis, and accelerating in a negative direction on an axis, but none can be logically called decelerating as it is not somehow un-accelerating, just changing direction.
If the only way you can accept an assertion is by faith, then you are conceding that it can't be taken on its own merits
Hope it wasn't aliens.
It was, aliens fucked over the carbinator.
Expansion of the universe
Not so much "NASA" in the whole but individual research groups which change and disband with time. Private individuals pretty experience the same with childhood photographs and videos.
Some of the original moon landing video tapes were lost, recycled or decayed. For the 40th anniversary they digitally restored copies from the public. These "restored" ones were better than the originals from analog days. But there is always the nagging hint some future scientific discovery may compromised by lacking the originals.
Detailed modeling of the radiation leak hypothesis.
From the article:
It's too bad climate scientists can't seem to manage to understand this.
Quote: "Three decades after its discovery, we can now say there is no exotic cause for the Pioneer anomaly: The puzzling deceleration was produced by the asymmetric radiation of waste heat created onboard the spacecraft."
My skimming skills are getting better the older I get. I want the answer, then if it's interesting I'll go for the details.
Those mountains of data are more like molehill's by today's standards.
Hi everyone,
Contrary to what is being reported here, this story is not a dupe. This story, which I, for one, found very well written, recounts the whole saga of determining whether thermal recoil asymmetry could account for the Pioneer anomaly. It is based on the latest publication on the topic, which is dated June 2012 and is still behind a paywall at PRL.
Basically, previous report on thermal recoil where interesting in theory but insufficiently conclusive, because they were consistent with a constant deceleration over time. This did not make sense, because the thermal output of the radioisotope power generators decays over time, and so should the recoil.
The authors of the study found moldy old tapes under a stair at JPL, which after significant data forensic efforts essentially doubled the amount of telemetry available. With this new data together and with help from JPL data fanatics, retired engineers and pre-CAD old blueprints, the authors were able to model and estimate the recoil orientation and variable intensity over time,. They found that within statistical uncertainty the more precise telemetry data is indeed consistent with thermal recoil, when all other effects are correctly accounted for.
They also say that the Pioneer probes now constitute one the most precise test of GRT available in our solar system.
Huge kudos to the people who made this possible.
BTW, the really truly fine article in IEEE Spectrum is written by the very same people who did the astronomy, math, physics, forensics, modeling and astrogation work, over the course of several years. Instead of whining that the article was a little too long, true geeks among us can only wonder at the dedication and professionalism these guys showed all the way through, not to mention the amazing display of science.
I am more than impressed. Well done !
With this newly explained phenomenon, how long until these spacecraft lose their forward acceleration completely... then head approximately back again, albeit much slower and on a course dependent on the actual heat radiation characteristics, and gravity wells it encounters along the way...?
If (ever so infinitesimally possible) it was a direct vector back, how long would it take to arrive?
I must admit the thought of our space going pilgrims reversing course after an eon or two and returning home after many more is reassuring somehow.
___
To those gibbering about the length of the article and its writing style -- blow it out your backsides, to think our time is worth reading *that* tripe.
<blink>down the rabbit hole</blink>
This disparity has been reported regarding other long-term flights with different thermal designs. I am glad this is documented but it can join the 140 other Pioneer Anomaly theories that are available at ArXIV.or A few of which claim to "prove" that this one is incorrect.
A good experiment that tested this theory would be a good idea. What about measuring the speed of the current flight to Pluto? We might actually have science.
All the "explanations" astronogers offer for the "pioneer anomaly" are feeble at best. Wal Thornhill et al have published a reasonable and testable explanation for the "anomalous" acceleration of the probes. It is not "anomalous" if you can explain it.
Its a good article and written to show how old data was made readable and anaylsed. This is why the tax records and law records written on animal skins circa 1200~1700 AD (The Rolls) are still useful as being readable today held in care of senior law officer The Master of The Rolls in England than recent 1960s/70s records held electronically and now unreadable due to no available machines to read and formats not preserved or changed.
Similar records on stone/clay in Middle Eastand paper in China allow us to back calulate atronomical events.
Brilliant for historians/scientists/engineers as part of their learning: do experiment AND keep a hard copy of raw data as well.
Regards Eion MacDonald
Hint: My goal while reading the article wasn't what you think it was.
Sent from my ENIAC