"NASA discovers brand new force of nature"

[Zanders]

Quote:

NASA scientists say they may have discovered a new force of nature, after research showed two of their deep space probes were being inexplicably pulled off course.

http://news.ninemsn.com.au/world/796...orce-of-nature

So, does anybody have any ideas what would be causing this, or what this would mean?

[Mister Earl]

It's ten-billionths the power of gravity, so the effect is really tiny. At most, it'll mean harder calculations for interstellar travel trajectories, but since we aren't really doing that anyway, it won't affect much. As to what is causing it? Could be warps in spacetime, dark matter, dark energy, interstellar medium, ect. Too early to be sure yet. I'm personally not so sure it's a new force of nature, but I'm a layman, so my opinion is pretty unfounded.

[rwguinn]

[fundie mode] It the shield god put around the solar system to keep us at home[/fundie mode]

[Capsid]

Klingon tractor beam.

[Cuddles]

Why on Earth is this in the news? The Pioneer anomaly has been known about for at least a couple of decades. The most likely candidate is thought to be simply due to differential heating, and therefore radiation, since the spacecraft aren't spherically symmetric. Other possibilities are effects due to the solar wind, or possibly some kind of magnetic effect from the Sun. After that there's been some speculation about possible modifications to gravity, which seems unlikely but isn't totally implausible since these are really our first tests of gravity on these scales. The possibility of an actual new force is so small as to be pretty much fiction at this point.

[rjh01]

I wonder if the effect could be seen in
- the orbits of the outer planets
- Asteroids and comets in elliptical orbits

Here is another news article about it.
http://www.telegraph.co.uk/science/s...eep-space.html
Sorry Cuddles but

Quote:

Assertions by some scientists that the force is due to a quirk in the Pioneer probes have also been discounted by the discovery that the effect seems to be affecting Galileo and Ulysses, two other space probes still in the solar system. Data from these two probes suggests the force is of the same strength as that found for the Pioneers.

I wonder why this is not observed in the orbits of planets, comets and asteroids?

[DC]

/planet x CT mode

That is because of the gravitational field of the planet X that NASA is denying.

[dasmiller]

Originally Posted by rjh01

I wonder if the effect could be seen in
- the orbits of the outer planets
- Asteroids and comets in elliptical orbits

Here is another news article about it.
http://www.telegraph.co.uk/science/s...eep-space.html
Sorry Cuddles but


I wonder why this is not observed in the orbits of planets, comets and asteroids?

If the force is due to solar pressure (radiation pressure or solar wind), then the effect would be orders-of-magnitude smaller for any rock that's big enough to see at those ranges, simply because of the high surface-to-mass ratio of the satellites. The same would apply if it's due to differential outgassing. Because the numbers are so small and because it's very difficult to measure these effects on the ground, it's notoriously difficult to come up with reliable models for them.

Then there's thruster leakage. If the spacecraft hasn't vented its propusion system, then there's helium leaking through the the thruster valves and actually coming out of the thrusters, producing thrust. It's a very low thrust, of course; they're probably losing maybe 1 cc/year of He. It's certainly fair to question whether we'd see similar effects in all 4 spacecraft, but again, I haven't seen the data. And thruster leakage is another effect that we wouldn't expect to see in asteroids

I know the article says that the authors have discounted those effects. I haven't seen their rationales for that, and maybe once I do, I'll change my mind. Until then, though, I'm betting on the more mundane effects.

ETA: of course, I immediately jumped to the spacecraft-centric possibilities, but I'm also not convinced that we know our solar system's mass distribution well enough to say that the Pioneer Anomaly can't be explained by gravity-as-we-know-it. Again, if I saw the data, I might change my mind.

[Soapy Sam]

Spacetime may be less like a rubber sheet than like a stretch nylon one with fitted corners.

[quarky]

That would be sexier than the old model.

[BenBurch]

Originally Posted by quarky

That would be sexier than the old model.

But less able to deal with "fluids."

[Cuddles]

Originally Posted by rjh01

I wonder why this is not observed in the orbits of planets, comets and asteroids?

Because we know what spacecraft are supposed to be doing. The orbits of planetary bodies are only known through observation, and errors on the measurements of their motion, as well as other important factors such as mass, mean that there are limits on how well we can actually predict anything about them. Spacecraft, on the other hand, are things we built and sent into space. We know everything about them down to the micron, and can calculate exactly where they should be and how they should behave to much greater accuracy. It's therefore possible to notice effects many orders of magnitudes smaller than we can see for the various things in space that we didn't put there ourselves.

[Soapy Sam]

It's not a new force. It's deep space quantum moths, nibbling holes in the rubber sheet.

Are there any serious (non mystery force) contenders for an explanation of the discrepancy?
A preferred "grain" to spacetime for instance?

[MRC_Hans]

Bjarne was right! It's the Space Wind ^[tm]!



.....

Or not.


Hans

[Cuddles]

Originally Posted by Soapy Sam

Are there any serious (non mystery force) contenders for an explanation of the discrepancy?
A preferred "grain" to spacetime for instance?

As I noted above, the preferred contenders generally don't require any changes to physics at all. The explanation generally thought to be most likely is simply the asymmetric shape causing different heating and radiation on different parts of the probes. Other possible explanations involve things like the solar wind, the Sun's magnetosphere, and so on. Things that we don't necessarily understand very well because we've only been able to measure them at a very limited set of points, but which don't require any big changes to the laws of physics, just corrections to how we think specific phenomena behave.

Things like modifications to gravity, new forces, quantised spacetime, and so on, are all things that people love to jump on because they sound all cool and sciency, but they're way down on the list of likely explanations.

[Soapy Sam]

I'm presuming though that the good folk at NASA know all this.
If the effect was on a single craft, such explanations would be top of the list.
Once four are involved, I presume there is a consistency in the effect across all four which rules out such individual variations.
(eg, if all four showed a consistent deceleration radial from the Sun that exceeds solar gravity, it would be hard to explain in those terms, but would seem to imply some equivalent of friction applying to all four and likely to be due to some unexpected property of space rather than of the craft themselves.)

[aleCcowaN]

It looks like such "force" is holding back the expensive thingamajigs. I would expect that solar wind accelerate them a bit. I wonder what's the difference between a strange force ten billionth weaker than gravity way far from the sun and those artifacts bumping into an astray hydrogen atom one each five seconds.

I suppose the answer is not in those Oprah-like articles. Or maybe the answer is here:

Edited by LashL:

Removed image. Rule 10 applies to images as well as text.

[taken without permission from bit_pattern's album]

[dasmiller]

Originally Posted by Soapy Sam

I'm presuming though that the good folk at NASA know all this. If the effect was on a single craft, such explanations would be top of the list.
Once four are involved, I presume there is a consistency in the effect across all four which rules out such individual variations.
(eg, if all four showed a consistent deceleration radial from the Sun that exceeds solar gravity, it would be hard to explain in those terms, but would seem to imply some equivalent of friction applying to all four and likely to be due to some unexpected property of space rather than of the craft themselves.)

But the spacecraft are all built of similar materials, with similar guidelines and similar design principles. And compared to a planet, they're all the same size. Four is a very small sample size, particularly when trying to evaluate a very small effect.

And I'm a little wary of the claim that all four are seeing the same effect at the same magnitude. They're on wildly different trajectories in very different regions, seeing different small discrepancies in their accelerations.

[rjh01]

Originally Posted by Cuddles

Because we know what spacecraft are supposed to be doing. The orbits of planetary bodies are only known through observation, and errors on the measurements of their motion, as well as other important factors such as mass, mean that there are limits on how well we can actually predict anything about them. Spacecraft, on the other hand, are things we built and sent into space. We know everything about them down to the micron, and can calculate exactly where they should be and how they should behave to much greater accuracy. It's therefore possible to notice effects many orders of magnitudes smaller than we can see for the various things in space that we didn't put there ourselves.

This is so far wrong that I can hardly believe it is a serious post.

Even if we knew exactly where a spacecraft was and its velocity soon after launch we would then depend on measurements similar to measurements of the planets to find its current position.

We have only been observing the spacecraft for a decade or so, we have been observing planets for a century or more. We would know the smallest errors in their position by now. I can see only two differences between a planet and a spacecraft

1. Their mass, volume and density.
2. The orbit. Planets are in a stable orbit. Spacecraft are heading out of the solar system.

If the errors in the spacecraft's positions are due to 1 above then the explanation would be due to mundane things. If the errors were due to 2 above then anything is possible. We do not know the orbits of many asteroids that follow an extreme orbit. Comets do follow extreme orbits but they tend to emit particles so any minor errors in their position would be put down to this and not anything else.

[welshdean]

It's the magnets in the LHC.

[BowlOfRed]

Originally Posted by rjh01

Even if we knew exactly where a spacecraft was and its velocity soon after launch we would then depend on measurements similar to measurements of the planets to find its current position.

There is a radio transmitter on the probe, and it is a fairly small object. The planets are much larger objects and don't have stationary transmitters.

Quote:

We have only been observing the spacecraft for a decade or so, we have been observing planets for a century or more. We would know the smallest errors in their position by now.

I would like to know what precision planetary positions are known compared with the probe positions. I'm assuming there's a difference, but I'm not sure where to find that information.

[Iamme]

Originally Posted by welshdean

It's the magnets in the LHC.

Maybe it's flux capacitor went out.

[BenBurch]

Originally Posted by rjh01

This is so far wrong that I can hardly believe it is a serious post.

Even if we knew exactly where a spacecraft was and its velocity soon after launch we would then depend on measurements similar to measurements of the planets to find its current position.

We have only been observing the spacecraft for a decade or so, we have been observing planets for a century or more. We would know the smallest errors in their position by now. I can see only two differences between a planet and a spacecraft

1. Their mass, volume and density.
2. The orbit. Planets are in a stable orbit. Spacecraft are heading out of the solar system.

If the errors in the spacecraft's positions are due to 1 above then the explanation would be due to mundane things. If the errors were due to 2 above then anything is possible. We do not know the orbits of many asteroids that follow an extreme orbit. Comets do follow extreme orbits but they tend to emit particles so any minor errors in their position would be put down to this and not anything else.

Well, now, we know the distance to a spacecraft at any given time by the round-trip light time, and by its internal clock reference.

We can approximate that with planets with radar, but a planet is round and not a good reflector, so the echo is inexact.

For the moon, we did better with the Apollo and Lunokhod laser retro-reflectors, but we still have the issue that the return from them is a few photons and we have some error bars in the timing. But we know the moon really well compared to any of the other bodies in the solar system.

Mars, because of the landers, is second to the moon in the accuracy with which we know its distance and velocity at any time.

We might know the moon's position and velocity better than the position of the Pioneers and Voyagers, but we know their positions and velocities better than we know any of the planets except Mars.

[MattusMaximus]

Didn't we have an extensive thread on this topic a few years back?

[MattusMaximus]

Originally Posted by welshdean

It's the magnets black hole in the LHC.

Fixed that for you

[rjh01]

Originally Posted by BenBurch

Well, now, we know the distance to a spacecraft at any given time by the round-trip light time, and by its internal clock reference.

We can approximate that with planets with radar, but a planet is round and not a good reflector, so the echo is inexact.

For the moon, we did better with the Apollo and Lunokhod laser retro-reflectors, but we still have the issue that the return from them is a few photons and we have some error bars in the timing. But we know the moon really well compared to any of the other bodies in the solar system.

Mars, because of the landers, is second to the moon in the accuracy with which we know its distance and velocity at any time.

We might know the moon's position and velocity better than the position of the Pioneers and Voyagers, but we know their positions and velocities better than we know any of the planets except Mars.

We can work out the distance between us and a planet that has a moon by noting the time the moon goes behind the planet. If the planet is at its closest approach then the light will take a certain time to get to Earth. If the planet is almost on the far side of the sun (but still visible) then the same event will take place a few seconds later, as viewed from Earth, than predicted because it will take light that extra time to get to Earth. We know the speed of light so now we can work out the extra distance between the two planets. In fact this was the first method used to calculate the speed of light. You can also measure the relative size of the planet. So now you should be able to work out its distance. Then you work out the orbit it should have. Then compare that with reality.

Also remember several planets were discovered because the known planets were not in the position they should have been. This then predicted the existence of other planets. We should be able to do similar calculations now even more accurately. If the laws of gravity were wrong we would not be able to get the right answers. We have been observing the planets for many decades, so very small errors should be picked up.

[C_Felix]

Quote:

Pioneer 10 and Pioneer 11, which have been in space for over 40 years, are being steadily pulled towards the sun by an unknown power, according to London’s Telegraph newspaper

The scientists said it could not be gravity or solar radiation, as they decreased over distance.

Being pulled and decreased over distance...Sounds like gravity to me!

[sol invictus]

Originally Posted by rjh01

We can work out the distance between us and a planet that has a moon by noting the time the moon goes behind the planet. If the planet is at its closest approach then the light will take a certain time to get to Earth. If the planet is almost on the far side of the sun (but still visible) then the same event will take place a few seconds later, as viewed from Earth, than predicted because it will take light that extra time to get to Earth. We know the speed of light so now we can work out the extra distance between the two planets. In fact this was the first method used to calculate the speed of light. You can also measure the relative size of the planet. So now you should be able to work out its distance. Then you work out the orbit it should have. Then compare that with reality.

Also remember several planets were discovered because the known planets were not in the position they should have been. This then predicted the existence of other planets. We should be able to do similar calculations now even more accurately. If the laws of gravity were wrong we would not be able to get the right answers. We have been observing the planets for many decades, so very small errors should be picked up.

It's a quantitative question. Yes, we can map the orbits of planets with considerable precision - but that's not where the best limits on modifications of solar-system scale gravity come from. The best limits come from the moon, because of the mirrors astronauts left on it. One can fire a laser at the moon and detect the reflection off the mirror, and so via time delay and/or Doppler shift determine the distance to the moon with extremely high accuracy.

These spacecraft have a similar feature - they send regular radio "pings" back to the earth. As a result their trajectory can be tracked with greater precision than a planet's can be.

[Cuddles]

Originally Posted by Soapy Sam

I'm presuming though that the good folk at NASA know all this.
If the effect was on a single craft, such explanations would be top of the list.
Once four are involved, I presume there is a consistency in the effect across all four which rules out such individual variations.

Yes, NASA do know all that. Which is why they are the ones who give these as the most likely explanations. As Dasmiller says, all the craft are very similar - fairly similar shapes, same RTG power source, same metal components, same size, and so on. If it is something to do with photon pressure, the solar wind, magnetic effects, or whatever, then all the craft would likely be affected in a similar way.

It's possible that other bodies are also affected in similar ways, but there are several problems actually observing that. Firstly, ignoring rjh01's idiocy, we simply don't know the details about any non-manmade bodies anywhere near as accurately. For example, we're not even sure if most asteroids are solid or just loose gravel and dust, so there's really no chance of trying to measure the tiny effects of differential radiation resulting from an asymmetric shape.

Originally Posted by rjh01

This is so far wrong that I can hardly believe it is a serious post.

Everything you say in this post is so hilariously wrong and stupid I really can't imagine why you thought it was a good idea to post it in response to someone who knows far more than you answering a question you asked. Hell, the mere fact that you had to ask the question proves that you're not vaguely competent to argue here. The fact that you're now compelled to argue with someone else who also knows far more than you really is truly bizarre.

One of the more obvious things I will correct though:

Quote:

Also remember several planets were discovered because the known planets were not in the position they should have been.

"Several" does not usually mean "one". Neptune is the only planet that was predicted before it was discovered. It's sometimes thought that Pluto was also predicted, but that was actually pure coincidence. A similar prediction was done for Neptune's orbit that was done for Uranus', which assumed that any deviation would be due to a single planet. Although Pluto was in more or less the right place, it was very quickly realised that it couldn't possible be responsible for the observed deviation since it was so small. We now know that there is actually a whole asteroid belt full of similar bodies, and it is probably the sum of the effect from them that explains Neptune's orbit.

So once again, you really shouldn't insult people right before demonstrating your own utter lack of knowledge on a subject.

[BenBurch]

Originally Posted by rjh01

We can work out the distance between us and a planet that has a moon by noting the time the moon goes behind the planet. If the planet is at its closest approach then the light will take a certain time to get to Earth. If the planet is almost on the far side of the sun (but still visible) then the same event will take place a few seconds later, as viewed from Earth, than predicted because it will take light that extra time to get to Earth. We know the speed of light so now we can work out the extra distance between the two planets. In fact this was the first method used to calculate the speed of light. You can also measure the relative size of the planet. So now you should be able to work out its distance. Then you work out the orbit it should have. Then compare that with reality.

Also remember several planets were discovered because the known planets were not in the position they should have been. This then predicted the existence of other planets. We should be able to do similar calculations now even more accurately. If the laws of gravity were wrong we would not be able to get the right answers. We have been observing the planets for many decades, so very small errors should be picked up.

The error bars on such things are huge in comparison to how we know where a spacecraft is. I've been on an observing team for star occultations, and even with a "point source" there are large error bars.

[BeAChooser]

http://www.dailygalaxy.com/my_weblog...iscovered.html

Quote:

February 26, 2010

"The Spacecraft Flyby Mystery" - Is There a New Physics Waiting to be Discovered?

… snip …

Mysteriously, four spacecraft that flew past the Earth have each displayed unexpected anomalies in their motions. These enigmas join the so-called "Pioneer anomaly" as hints that unexplained forces may appear to act on spacecraft.

…snip …

Jet Propulsion Laboratory astronomer John Anderson and his colleagues — who originally helped uncover the Pioneer anomaly — have studied five deep-space probes — Galileo to Jupiter, the NEAR mission to the asteroid Eros, the Rosetta probe to a comet, Cassini to Saturn, and the MESSENGER craft to Mercury. Each spacecraft flew past the our planet to either gain or lose orbital energy in their quests to reach their eventual targets. (Galileo made two flybys.) In five of the six flybys, the scientists have confirmed anomalies.

… snip …

The one probe that did not confirm an anomaly was MESSENGER, the spacecraft approached the Earth at about latitude 31 degrees north and receded from the Earth at about latitude 32 degrees south.

The five other flybys involved flights whose incoming and outgoing trajectories were asymmetrical with each other in terms of their orientation with Earth's equator, which "suggests that the anomaly is related to Earth's rotation," Anderson told the Times Online.

… snip …

"Another thing in common between the Pioneer and these flybys is what you would call an unbound orbit around a central body," Anderson said. "For instance, the Pioneers are flying out of the solar system — they're not bound to their central body, the sun. For the other flybys, the Earth is the central body.

… snip …

However, in a major disappointment – which had deepened the mystery — the Rosetta spacecraft did not experience the flyby anomaly during this swingby of Earth in 2009, even though the same spacecraft did experience the anomaly when it flew by Earth 2005, but didn’t in 2007.

[DC]

they accidentally hit God who is protecting us, i hope we didn't piss him of

[DeiRenDopa]

Originally Posted by BeAChooser

http://www.dailygalaxy.com/my_weblog...iscovered.html

AFAIK, the 'flyby' anomalies have been pretty much explained now ... and they are quite different from the Pioneer anomaly.

I'll see if I can dig up a paper or three (for accuracy, it's best to go to primary sources, IMHO).

[Soapy Sam]

Oh my Ed!
I just realised.
There's nothing wrong with the spacecraft.

It's us!
Earth is wandering out of it's orbit.

WE'RE DOOMED!

[Bishadi]

is the probe exchanging energy with another source?

[MattusMaximus]

Originally Posted by Bishadi

is the probe exchanging energy with another source?

Yes, at the very least there is an exchange of energy between the probe and the gravitational field of the solar system. Not to mention heating & emission by radiation.

[Bishadi]

are there any math guys on this site?

ie... the suns solar wind and energy (light) is constantly affecting the mass (probe) and then any solar mass (asteroid belts dust, planets etc) are also sharing this exposure to the light.

For example; if you had a cloud of dust in space with no energy, to expose the collective of mass to energy (light) the whole group will be entangled and sharing that exposure.

Look into entanglement.

It is the same reason the arms in the galaxies are moving so fast (galaxy-curve http://en.wikipedia.org/wiki/Galaxy_rotation_curve) by my thinking (shared energy between the bodies increasing the potential (see casimir))

[dasmiller]

Originally Posted by Bishadi

are there any math guys on this site?

I'm one, but this is simply a very complex problem. The individual computations aren't so bad, but since we're looking at a very small discrepancy in the spacecraft's trajectory, we'd need to have a very complete model of the solar system, and that means an awful lot of things that would have to be accurately modeled. It's not something I could crank out in an hour or so.

[MattusMaximus]

Originally Posted by Bishadi

are there any math guys on this site?

Yes. I'm one of them. Do you have some math to share?

Quote:

ie... the suns solar wind and energy (light) is constantly affecting the mass (probe) and then any solar mass (asteroid belts dust, planets etc) are also sharing this exposure to the light.

For example; if you had a cloud of dust in space with no energy, to expose the collective of mass to energy (light) the whole group will be entangled and sharing that exposure.

Look into entanglement.

Ummm, no. Entanglement is a quantum phenomenon, one which works on the atomic & sub-atomic size scales; it doesn't apply to macroscopic objects such as space probes. At least, we have absolutely no reason to believe that it would apply.

Why are you bringing this up? Do you even know what quantum entanglement is? It doesn't seem so; I suggest you look it up.

Quote:

It is the same reason the arms in the galaxies are moving so fast (galaxy-curve http://en.wikipedia.org/wiki/Galaxy_rotation_curve) by my thinking (shared energy between the bodies increasing the potential (see casimir))

No, again. That's called dark matter. I suggest you focus on this section of the link I referenced.

And if you're referring to the Casimir Effect, again that is a quantum phenomenon, one which really only works on very, very small size scales, not on the scale of a galactic disk.

[MattusMaximus]

Originally Posted by dasmiller

I'm one, but this is simply a very complex problem. The individual computations aren't so bad, but since we're looking at a very small discrepancy in the spacecraft's trajectory, we'd need to have a very complete model of the solar system, and that means an awful lot of things that would have to be accurately modeled. It's not something I could crank out in an hour or so.

Actually, no person could do it. Such complex calculations require modern computers, seeing as how you quickly get into the stickiness of the three-body problem and worse, for which there exists no exact solution (thus requiring the computers).