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Pioneer Anomaly Solved By 1970s Computer Graphics
Frans Faase updated us on a Pioneer Mystery we've been following for many years: something is tugging Pioneer 10 & 11. A few years ago a theory surfaced but now "A new computer model of the way heat is emitted by various parts of the Pioneer spacecraft, and reflected off others, finally solves one of the biggest mysteries in astrophysics. Previous calculations have only estimated the effect of reflections. A computer modeling technique called Phong shading was used to work out exactly how the the emitted heat is reflected (PDF) and in which direction it ends up traveling. Taking into account the reflections on the antenna seem to make the anomaly disappear."
The technique for Phong Shading was introduced in 1973 as an improvement to Gouraud Shading, but was too computationally intensive to be used for graphics back then. This is no longer the case.
How does it feel to be a liar with pants constantly on fire?
Oh, well. It was fun while it lasted.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
While a mundane explanation has always seemed most likely, why is is "good to know" that an exciting new discovery isn't going to happen?
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
No, clearly this is part of the great conspiracy known as NASA! They're hiding something, I tell you! It's the aliens, the same ones that helped them fake the moon landing! So yeah, this "finding" has to be part of the great cover-up. It couldn't be simply the laws of physics.
(this is the commenter's physician: a sedative has been administered, and he's been returned to his padded cell)
I am officially gone from
everybody knows that. A much better aproximation to real life surfaces are the Oren–Nayar or Cook-Torrance models of the family of BRDFs.
Experiments and other stuff
So it seems, the mystery ain't a mystery after all...
That tends to happen when you solve them.
Instead why don't they solve the radiosity equation at a 1 mm^2 resolution? That should be feasible with today's computing power, and indisputably give the correct answer.
Its that feeling you got in 8th grade algebra when you did all the work and your answer matched the one in the back of the book.
Have gnu, will travel.
Right, well, heat is energy, which as Einstein showed, is mass. So, figure out the net "heat emitted" vector and you've got your opposite reaction thingy right there.
Radiated heat exerts a force also. It is related to radiation pressure, http://en.wikipedia.org/wiki/Radiation_pressure, but kind of in reverse in a Newton's Third Law kind of way.
I feel sorry for people that don't drink, because when they get up in the morning, that's as good as they're gonna feel
Because focus can now be placed elsewhere instead of continuing to investigate a red herring.
While it is sometimes disappointing that unknown effects don't always turn out to be from unknown causes, having the exciting new discoveries come from the basis of fact rather than imagination is the main difference between actual science versus everything else that claims to be science.
... from Slava Turyshev which describes what they did to model the craft and show that heat could be the culprit.
http://www.planetary.org/programs/projects/pioneer_anomaly/update_20080519.html
Intron: the portion of DNA which expresses nothing useful.
So it seems, the mystery ain't a mystery after all...
That tends to happen when you solve them.
and like usual, the butler did it!
GLaDOS for President 2016! "Well here we are again. It's always such a pleasure." -- GLaDOS, 2011
Fucking Phong Shading. How does it work?
<xml><I><am><so><damn>Web 2.0</damn></so></am></I></xml>
So it seems, the mystery ain't a mystery after all...
That tends to happen when you solve them.
and like usual, the butler did it!
Ah, ha. But, who is the Butler?
When I first saw the splash paragraph I was expecting a Commodore PET was figuring into this somehow.
A feeling of having made the same mistake before: Deja Foobar
Sadly, unless it's one of the big unsolved problems or it takes a PhD to even understand the problem it's probably been solved before. We had a math book that so barely mentioned perfect numbers, I spent a lot of time reaching a result that I felt was "new". Eventually it turns out I had recreated a proof that Euler did in the 18th century. At least it wasn't the Greek, every time you feel bright then you learn someone already figured this out 2000 years ago.
Live today, because you never know what tomorrow brings
The important part is not the mass, but the momentum. Total momentum is conserved, therefore to accelerate (i.e. to increase your momentum) you'll have to emit something carrying the momentum difference (because in space, there's nothing else you could transfer your momentum to). One way is just to throw some matter out, which then of course has backwards momentum, thus giving you forward momentum (remember, the sum must be zero). But radiation also has momentum, therefore you can also emit radiation backwards. Indeed, if only looking at the energy needed, the best propulsion method would be to send a strong laser beam out of your ship, because light has the least energy for a given momentum (according to Einstein, E^2 = (mc^2)^2 + (pc)^2, and for light, m=0).
The Tao of math: The numbers you can count are not the real numbers.
Clearly the true test was to see which students were smart enough to simply copy the answer from the the back of the book in the first place. It's a strategy that serves me well to this day. Now, if only I could find where I put the answer booklet for members of congress...
Scientists point out problems, engineers fix them
altslashdot.org: The future of slashdot.
Janus is pulling them!
(just finished Pulling Ice. I'm sorry.)
Trolling is a art,
Then again, it took almost 30 years for the change in momentum to be measurable, so don't expect any guest appearances on Top Gear.
No folly is more costly than the folly of intolerant idealism. - Winston Churchill
Now, if only I could find where I put the answer booklet for members of congress...
It's in your wallet.
Faster! Faster! Faster would be better!
Radiosity being a 90s computer graphics term for calculation how radiation (heat and light) hit surfaces and are absorbed or re-emitted by them. It came from earlier studies on this not relating to computer graphics.
You can render your radiosity results using phong shading or other shading techniques.
http://lkml.org/lkml/2005/8/20/95
I'm not sure how this become the "biggest mystery in astrophysics." Maybe to the ADD addled tech crowd and other casual people who were using it as code for "hey, maybe aliens." It was like a "god of the gaps" argument. Well, "alien of the gaps."
Occam's razor, use it.
To futher clarify ColdWetDog's answer.
The answer booklet is gray/green hand has a picture of a dead president, or a Founding Father on it.
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
Ah, ha. But, who is the Butler?
The radar dish
The force that blew the Big Bang continues to accelerate.
eh? The WORST thing is light, because light has so very little momentum for so much energy. Using light in collimated beam, it takes 300MW per newton (0.2 lbs) of thrust. or if you reflect the light off of ship from external source, 150 MW per newton. For photonic rocket thrust equals power divided by C, it's a bitch.
Photons may not have mass, but they do carry momentum, and that's what counts.
Until you found out that the answers in the back of the book were also wrong. Darn interns.
So Radar was the butler too. That actually makes sense. Now to get hawkeye and pierce to openthe still.
i thought once I was found, but it was only a dream.
It's always in the last place you looked.
I drank what? -- Socrates
Jeeves???
Nothing here... So... SHOOO!!!
Real men know how to butle themselves.
I drank what? -- Socrates
Well and every crackpot trying to overturn all of modern physics/cosmology without understanding it first. The number of times I've heard the Pioneer Anomaly brought up as evidence that modern physics was fundamentally broken and the Scientific Clergy refused to admit it is... very large. I think I've even heard EU morons claiming that their plasma cosmology explained the Pioneer Anomaly.
Of course nobody who latched on to the anomaly will be satisfied by this explanation. So it goes...
The enemies of Democracy are
Notice how in that sentence he was talking about the Greeks.
The enemies of Democracy are
For you maybe. For me however, the connection between the Queen and Congress wasn't immediately obvious....
Don't be so limiting. Politicians also take credit cards, bullion, golf trips, Interns, chickens.... I guess I'll just stop here.
Faster! Faster! Faster would be better!
Exactly. Photons have the worst case energy/momentum ratio. The advantage of photon drives is not energy efficiency (because they're completely the opposite), it's that you don't need reaction mass.
So if you only need minute amounts of thrust, and have some long-lasting but light-weight source of energy (like an RTG), you can thrust basically forever.
The enemies of Democracy are
Also, it's just plain cool when applied math explains away the mysteries of the world. To my perspective as a layperson, it's incredible how many layers of ingenuity piled up to enable someone to explore and explain some odd phenomenon bouncing off a craft hurtling through space.
Imagine how well you'd model this using monte-carlo techniques / ray tracing.
Poorly when compared to Cook-Torrence, Blinn or Oren-Nayar.
That "thrust basically forever" is good if source is external, then we're talking about solar sails or laser boosting reflectors. But for onboard source it's terrible thing, running a reactor onboard one would be better off using ion thruster, a little fuel with high momentum per particle. The only time photonic propulsion would give massive thrust is with matter-antimatter annihilation, if one could figure out how to reflect gamma rays from one end of the reaction chamber
I RTFA, but didn't find the results of their calculation. The old method yielded 67% of the effect, but they didn't say what the new method resulted in (other than get the "right" answer). Also I'd want to know error bars. Does the new answer +/- error bars overlap with the detected phenomena within the error bars of it's value?
When I was 10, while drying the dishes, I realized that the water wasn't actually going away; was just changing position/form. From this, I realized that energy was the same way (thinking about sunshine and how the photons get absorbed/radiated as heat, etc). And then, a few years later, found out someone else had already figured out this thermo dynamics stuff. Decided then and there I'd stop wasting time with this brain thing and devote my life to viewing porn.
Chickens...[*shudder*] I wish you'd stopped one element earlier.
When our name is on the back of your car, we're behind you all the way!
It's just global warming (for a tiny globe) :)
Great minds think alike; fools seldom differ.
Well, yeah...
Once you find it, why would you keep looking? Ergo, the place you found it is *always* going to be the last place you looked.
MCSE? No, sir...I don't do Windows. Yes, I am an idealist. What's your point?
Yes, he said "at least it wasn't the Greeks", because of how often he finds out that something he thought was novel was discovered by them. Which would be 2000 years ago. Merely 300 years ago is better. Thus "at least it wasn't the Greeks".
Got it now?
The enemies of Democracy are
Hey, you did the work from scratch and that's what counts.
A successful API design takes a mixture of software design and pedagogy.
An ion engine needs a source of energy and reaction mass. It's a very efficient use of reaction mass, but nevertheless. So for the same energy source, you can thrust longer with a photon drive.
Massive thrust is not the point of a photonic drive because they suck at it. Ion drives aren't great at thrust either, but they do have more. So it depends on the particular application which one would be better, though I think for most things we're doing in the near term ion drives are better.
The enemies of Democracy are
http://en.wikipedia.org/wiki/Radiometer/
Of course nobody who latched on to the anomaly will be satisfied by this explanation. So it goes...
Not so. Since I heard about it, I've allowed the possibility that Newtonian/relativistic physics may have some inaccuracies at very large scales, or that something about space was unknown.
Now this calculation offers a much simpler explanation, so I'll count it as far more likely to be true. I'd previously assumed those writing the papers would have accounted for it.
But until we have a Grand Unified Theory, or at least a provable theory of gravity that works at quantum scales, I'm not going to place any 300-year bets that our current understanding of physics is Correct(tm). Useful tools, definitely, but any higher level of Belief is religious in nature.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
Pretty hard to fit any of those, except for credit cards, into your wallet.
How *do* you fit an intern in there, anyways?
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
http://www.eclipse-chasers.com/tseAllias.html
Pretty hard to fit any of those, except for credit cards, into your wallet. How *do* you fit an intern in there, anyways?
You tell them to get in there and make it their problem to find a way.
Live today, because you never know what tomorrow brings
People like that will latch onto anything, it's like the people that take a tiny gap in some evolutionary chain and blow it up as a huge missing link, evolution is bunk and creationism is truth. They'll just pick something else and it'll go on, just like they've retconned that the earth is round and orbits the sun, not flat and the center of the universe. It doesn't matter how far science comes, someone will always manage to shoehorn in their religion.
Live today, because you never know what tomorrow brings
The WORST thing is light, because light has so very little momentum for so much energy.
Unless of course the light is free. The solar constant is about 1 kW/m**2, so solar sails get 1 N per 150,000 m**2, or a circle of about 250 m diameter.
Blasphemy is a human right. Blasphemophobia kills.
Not so. Since I heard about it, I've allowed the possibility that Newtonian/relativistic physics may have some inaccuracies at very large scales,
"Allowed" is what most physicists have done, though the most likely scenario was always considered to be that there was a mundane explanation. "Latched on to" is what crackpots have done, and will continue to do. Because they're trying to overturn all of physics, and "some inaccuracies" still means the existing theory is pretty good and predicts a great many things correctly. But they want to somehow undo all of that with one unexplained thing that the theory doesn't predict.
I'm not going to place any 300-year bets that our current understanding of physics is Correct(tm).
You and every scientist in existence, since they know it isn't Correct(tm) already. Why did you think that was even relevant to bring up? Do you think there is, or for some reason that I was creating, a false dichotomy between idiots trying to overturn physics without understanding it, and current theory being indubitably correct?
The enemies of Democracy are
Occam's Razor is useful for making determinations about what is true among several possible explanations.
It is not, however, useful for helping you come up with the explanations in the first place. As was needed here.
Do you think there is, or for some reason that I was creating, a false dichotomy between idiots trying to overturn physics without understanding it, and current theory being indubitably correct?
I suspect "latched on to" is the point of confusion. I had put the Pioneer Anomaly into the "this needs explaining" category - and something I wasn't willing to let go of for the sake of mathematical purity. From your response, I think your usage meant, "this proves all of physics is wrong." So, it seems we're in agreement, just a difference in usage of an idiom.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
They should be able to model the entire space craft including original heat source(s), other structures acting as thermal masses, reflectors, absorbers, and radiators, and apply known material properties for how each photon should behave statistically.
...and include all the damage, dust, pitting, and corrosion incurred over more than a decade in space, and how that will affect absorbtion/reflection. Do you happen to have any accurate models for that? Of course, an alternative is to use a model that gets us into the 'good enough' category...oh, wait!
Sure I'm paranoid, but am I paranoid enough?
Oh it goes farther than that my friend, it goes back to the OSS covering up the fact that there are Nazis on the moon!
In all seriousness while I'm glad they solved that niggler you can understand why some would have latched onto a "the math don't work" hypothesis, and that is because....well at the incredible sizes of great and small we are talking about in space the math doesn't work which is why we have no grand unified theory yet.
So while I'm glad we don't have a red herring steering us away I bet on our way to the grand unified theory we will have more than one "holy shit!" moment where we find out the way we think things work is full of shit. We are like Archimedes trying to figure out the universe with a hole and a stick. The one thing I'm sure of is there is a hell of a lot we just don't know yet.
ACs don't waste your time replying, your posts are never seen by me.
From your response, I think your usage meant, "this proves all of physics is wrong."
My response, and the very first sentence of my first post. :P
But I'm glad we understand each other now.
The enemies of Democracy are
Does the new answer +/- error bars overlap with the detected phenomena within the error bars of it's value?
If you read the paper itself, there's a graph on page 10 showing exactly that. The error bars on the measured size of the effect overlap almost completely with the error bars on this new calculation.
Direct thermal radiation off the front of the craft explains most of the effect. The "Pioneer anomaly" vanishes completely once you factor in radiation reflected off the antenna dish. It still warrants some more investigation and more papers pinning it down better, but in my opinion this issue can now be pretty solidly categorized as resolved.
-
- - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
Yeah, it's not very exciting, no big theory of physics disproven, no shiny new theory neede to explain this phenomenon. Yet, if you consider the options listed:
1 and 2 are actually pretty far fetched, and when the effect was detected, number 3 was estimated to be not quite enough. Yet someone though "Those estimates aren't quite good enough", and tried a really simple model that I'd wager a great deal many people here have some experience with, put it to use in a novel way, and it worked.
This was an a triumph of the standing on the shoulders of giants maxim, and I love it.
Your malicious disregard for basic communication makes me want to side with Hairyfeet on principle alone.
Also, you should know that I am a little embarrassed that I took the time to 6 posts in the thread you linked. The fact that you seem to have an encyclopedic knowledge of every post you've ever made here leads me to believe you take the goal of winning at internet way to seriously.
Most certainly not. Jeeves was a gentleman's gentleman, a valet, not a butler.
Comes in handy when trolls like Hairyfeet screwup & troll me,
But probably not too helpful in talking to people.
APK, who are you? I apologize for my ignorance, but I'm not certain who you are and why people would seek to defame you. You should know that your anonymous postings and disjointed writing style make you seem less "persecuted intellectual" and more "schizophrenic homeless dude under a bridge".
He is a known troll and malware writer who follows around and trollbombs anyone who points out that even simple math shows his "invention" doesn't work.
There is a reason why everyone abandoned HOSTS files in the late 90s, and that is because they slow your PC down while giving NO protection from malware. it is simple math really, you have a large (estimates at 1.5 million+) dynamically shifting target, where sites become infected, cleaned, reinfected, thousands by the day, sometimes thousands by the hour, yet this loon is convinced that a static HOSTS file will magically protect you from malware.
Sadly this person is also a paranoid schizophrenic with a serious persecution complex who will follow you around, sometimes for months on end, so he can "trollbomb" any posts you place while calling anyone who doesn't join his AC sockpuppet army a "shill post" or a sockpuppet, while quoting from people that frankly wouldn't piss on him if he was on fire like Bruce Perens, and then quotes them in completely unrelated matters to boot.
So don't be surprised if Crazy Petey follows you around for a few days friend, you dared to say something that goes against his "I'm a leet hacker that everyone fears!" delusion, just as I have been followed off and on for months, with everyone that points out what a batshit loonie Petey is being accused of being part of some vast super HB Gary sockpuppet army controlled by me and the Illuminati. I used to think the guy was just a Twitter style troll, now sadly I think he seriously needs some help. It is a shame nobody can track this guy down and do an intervention, as just from his writing style you can tell he is coming off the rails.
ACs don't waste your time replying, your posts are never seen by me.
Hi, I like your sig, new friend.
I feel fantastic, and I'm still alive.
Well, I admit I am disappointed. If they've explained it, they've explained it. But it woulda been cool if physics had had to changeâ¦
i'd hit it so hard, if you pulled me out you'd be the king of britain [bash.org]
http://www.facebook.com/topic.php?uid=254000146591&topic=16411
That is a copy of this site that seems to have gone offline recently:
http://www.suppressedscience.net/
Suppressed? :-) At the very least by marketplace forces? :-(
See also:
http://replay.waybackmachine.org/20090308132014/http://suppressedscience.net/physics.html
http://replay.waybackmachine.org/20090309114648/http://suppressedscience.net/
Stuff I wrote building on those ideas:
http://www.pdfernhout.net/to-james-randi-on-skepticism-about-mainstream-science.html
A 21st century issue: the irony of technologies of abundance in the hands of those still thinking in terms of scarcity.
(this is the commenter's physician: a sedative has been administered, and he's been returned to his padded cell)
Can I please use that as a signature?
Well, I might have a way, but it only works on a semi spherical planet in a vacuum.
I don't remember Pong having any shading, just a black screen with white rectangles!!!!
Sure enough, the cow costume was hanging up next to the superhero outfit and sailors uniform. (S,Spud)
Aw crap! I was hoping the anomaly might point to a new physical effect that could be used to make warp drive or something
Wow, man somebody is on the ball at Wikipedia. Inertia is one of my favorite topics and somebody has already corrected this entry which used to say:
http://en.wikipedia.org/wiki/Inertia
Source of Inertia
There is no single accepted theory that explains the source of Inertia. Various efforts by notable physicists such as Ernst Mach (see Mach's principle), Albert Einstein, D Sciama, and Bernard Haisch have all run into significant criticisms from more recent theorists. A review is given by Vesselin Petkov (2009)[12].
For a recent treatment of the issue see C. Johan Masreliez (2006)[13]. Masreliez has published more on inertia related issues that may also have a say in solving the Pioneer anomaly.
That's great, even to Mars it only goes to somewhat less than half that power, but by Jupiter it's less than 1/25th....can you see the problem?
Sure, knock yourself out. Legally, consider it public domain.
I am officially gone from
Mars is actually 1/4 the force per unit area (inverse square law and all that) but a bit of simple simulation shows that solar sails are probably practical out to Jupiter, where there is still sufficient sunlight to manage orbital insertion without much difficulty.
So yeah, I see the problem, and unlike you I've actually done to modelling to understand the limitations quantitatively, rather than just waving my hands about it.
Although you're still better than the clown who responded above, who doesn't know what the solar constant is.
Blasphemy is a human right. Blasphemophobia kills.
Really: THE solar constant. That's what it's called.
A bit of modelling shows that solar sails are likely to be practical out to the orbit of Jupiter, as anyone who has actually studied the problem knows.
Blasphemy is a human right. Blasphemophobia kills.