Pioneer space probes slow down beyond Pluto.

[anomalies]

Space probes feel cosmic tug of bizarre forces

Robin McKie, science editor
Sunday September 12, 2004
The Observer

Something strange is tugging at America's oldest spacecraft. As the Pioneer 10 and 11 probes head towards distant stars, scientists have discovered that the craft - launched more than 30 years ago - appear to be in the grip of a mysterious force that is holding them back as they sweep out of the solar system.

Some researchers say unseen 'dark matter' may permeate the universe and that this is affecting the Pioneers' passage. Others say flaws in our understanding of the laws of gravity best explain the crafts' wayward behaviour.


the rest of the story (http://www.guardian.co.uk/space/article/0,14493,1302721,00.html)

[QJones]

Forgive my ignorance .. how reputable is the Guardian?

This story is quite fascinating, showing how little we know about extra-system details.

[Planetwatcher]

I think it somewhat goes without saying that the probes will tend to slow down the farther they go, and it doesn't in itself mean that dark matter is involved.

The probes are basicly still coosting from the last manuver, either a burn or gravity assist.
Contrary to what many believe, space is not a vaccum devoid of all matter, there is small amounts of matter spread out, and there is dust in both the Kupier Belt, as well as the Orrt Cloud. This matter and dust causes resistence against the moving object, and can contribute to it's slowing down.

Take into account the probes have been traveling for over 30 years. While Newton's Laws state that objects in motion tend to stay in motion, it doesn't say that motion is absolute but that it tends to continue moving in the same direction and speed, until something changes it, but such objects won't continue forever.
Eventually the probes would come to rest without the help of anything else.

Also keep in mind the probes are still subject to gravity from other objects, and there are plenty of other objects, including the Sun, and all the planets excerting small amounts of gravity, all of which from the probes vantage point would try to pull it back to the Sun, or at least slow it down over time.

Finally, it may well be that there is dark matter involved as well. It's not out of the question, but not likely the total reason either.

[Richard0802]

Hi all,

I was following this thread at: OTHER STORIES \ Unknown Force affects Probes

It sounds interesting.

[Wouter]

I also think dark matter has the upper hand here. I have no idea what else it could be. The laws of gravity should be understood fairly good by now, atleast since Einstein. We should be able to have pointed out objects that could influence the path of the Pioneer probes. Did the Voyager probe experience the same thing??

By the way, Planetwatcher: That's Kuiperbelt and Oort-cloud. Two names of dutch astronomers. Yes - Huygens (Cassini-Huygens probe) also was a dutch astronomer. Furthermore, the exact first law of Newton states "An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force." :)

[anomalies]

So far, in my experience, The Guardian has been fairly reputable (a UK site). It is Pravda (from Russia) that has proven to hoax or not check out the persons making claims in their articles.

I have also seen this story elsewhere.

[anomalies]

Originally posted by Planetwatcher@Sep 17 2004, 08:29 AM
I think it somewhat goes without saying that the probes will tend to slow down the farther they go, and it doesn't in itself mean that dark matter is involved.

The probes are basicly still coosting from the last manuver, either a burn or gravity assist.
Contrary to what many believe, space is not a vaccum devoid of all matter, there is small amounts of matter spread out, and there is dust in both the Kupier Belt, as well as the Orrt Cloud. This matter and dust causes resistence against the moving object, and can contribute to it's slowing down.

Take into account the probes have been traveling for over 30 years. While Newton's Laws state that objects in motion tend to stay in motion, it doesn't say that motion is absolute but that it tends to continue moving in the same direction and speed, until something changes it, but such objects won't continue forever.
Eventually the probes would come to rest without the help of anything else.

Also keep in mind the probes are still subject to gravity from other objects, and there are plenty of other objects, including the Sun, and all the planets excerting small amounts of gravity, all of which from the probes vantage point would try to pull it back to the Sun, or at least slow it down over time.

Finally, it may well be that there is dark matter involved as well. It's not out of the question, but not likely the total reason either.


Planetwatcher - you are assuming that inertia is acting on the Pioneer probes. It isn't. (Inertia = the resistance an object has to a change in its state of motion.) That isn't the case for the probes. The gravity of the Sun has been taken into account - the probes are slowing down because of nothing we now know in science and physics to account for it!

Dark matter - ah. Now you're thinking! Something we do not understand may be having an affect on the probes. I hear they may send up another bunch of probes to check this situation out. I hope so.

[Tom2Mars]

I would tend to agree with Planetwatcher on the possibility that a large amount of standard dust and comets in the Oort cloud and stuff could add up to enough gravtational drag.

As I have read about it, "dark matter" isn't the regular "stuff".

[Planetwatcher]

Thank you Tom. I am more and more thinking it is regular, but perhaps more dense dust. From what little I know about dark matter, it would likely have a much greater effect, but it can't be ruled out either.

[GOURDHEAD]

As these probes move further from the center of mass of the solar system, the mass contributing to the retarding gravitational attraction increases proportional to the third power of the radius as the gavitational force is decreasing proportional to the square of the radius. The coefficient of mass increase is a variable getting smaller as the distance from the mass center gets larger. Could this be part of the effect being observed?

[antoniseb]

Originally posted by GOURDHEAD@Sep 21 2004, 01:45 PM
the mass contributing to the retarding gravitational attraction increases proportional to the third power of the radius as the gavitational force is decreasing proportional to the square of the radius.
Hi Gourdhead, Where did this third power of the radius thing come from? I don't recall actually seeing a statement about the scale of the effect as a function of distance. This could be an important clue.

[Richard0802]

A very good question Gourhead, that I am not qualified to answer. However this cannot be ruled out. NASA took possession of a new super computer August, and no doubt this formula can be entered into to it to find out.

Just in passing, NASA has dedicated its new Altix supercomputer 'KC' to the memory of India-born astronaut Kalpana Chawla. Chawla was one of the seven-crew members aboard the Space Shuttle Columbia, which disintegrated midair in February last year. :rolleyes:

Perhaps we could contact NASA and ask them Gourhead?

[Richard0802]

Quote:

“The orbit reconstruction from the Doppler tracking data of the hyperbolic trajectory away from the Sun of the Pioneers shows an anomalous deceleration of both spacecraft of the order of 10-9 m/second 2. The Doppler blieshift is present in the data from both craft of approximately 1.1 x 10-8 Hz/s corresponding to an apparent deceleration of the spacecraft of approximately 8 x 10-10 m/second squared.”

Andreas Rathke
ESA Concepts team (DG-X) Noowlwijk, The Netherlands.

Try putting this data into your calculation Gourhead, perhaps it will help to support your concept. The (-9), (2) and (-10) are subscript figures. :huh:

[QJones]

The idea of more probes is certainly a good one. Hopefully they could be sent with enough speed to get some type of meaningful data in a meaningful time period.

If there is something directly outside our solar system that's messing with our "strong" knowledge of fundamental gravity, I think we owe it to ourselves to learn about it.

The ramifications for astronomy science would be extreme.

[Tom2Mars]

Gourdhead, re-
Could this be part of the effect being observed?

Now I wish I hadn't skipped over the Chapter on calculating the gravitational effects of different types of spheres on a mass in Morris Kline's book, 'Calculus, An Intuitive and Physical Approach" And, a solar system isn't exactly a normal everyday uniform sphere...thanks for the observation!

[openmind]

I’ve just registered to post a reply to this thread. Just by chance I read a possible (although exotic) explanation for the probes slowing down.

I'm busy reading my way through Mark McCutcheon's "The Final Theory" for the second time (trying to assess where his theory could be wrong) and just last night read his explanation for the slowing down of the deep space probes.

For those who haven't read his book, check out The Final Theory (http://www.thefinaltheory.com). His website is a bit dodgy, but his book is really interesting.

Anyway, the short version of his theory is that all matter is expanding by a constant rate. This includes all atoms, you and me, planets, orbital rings, etc. We can't see this expansion because our instruments (rulers, etc) expand as well. The only manifestation that we can detect is gravity. He suggests that gravity isn't a force, but rather the effect of matter expanding, and filling up space between objects.

Anyway, to the specifics of the voyager probe slowing down:

All motion is merely relative. While the probe is within the solar system, and the various planets' orbits (which are expanding at the same speed - otherwise we'd see changes over time), the probe is moving from the sun at a faster rate then the various orbits are. The orbits are moving from the sun to match the expansion in size of the sun – otherwise the orbits would shrink over time. But once the probe is past Pluto, it's relative speed is no longer increased by relative increases in speed provided by "gravity assist manoeuvres" (which are explained as well), and so essentially, the probe is travelling at a constant speed, while the orbits of the solar system are increasing in their expansion speed and effectively slowly overtaking the probe.

I know this sounds extremely out of whack. I've tried to explain in a few paragraphs what the author explained over a few chapters. And reading over this post, I know I have failed dismally to do his theory justice. While I'm not affiliated with the author at all, I do highly recommend his book. I have failed to find serious comments or reviews by scientists who have read his book - most comments tend to be defensive and emotional posted by people who have only read a few pages of the website - which I admit is not the best. I bought the book and half expected to find out he’s a complete nut – but his argument is compelling.

The book slowly explains the theory in easy to understand steps, and covers many areas of physics (gravity, magnetism, electricity, duality of light, structure of atoms, sub-atomic particles, etc). The cause of the voyager probe slowing down is only one of many explanations in the book to mysteries that current science can't explain - and what's got me interested is I can't find holes in the logic behind it. I’m the first to admit that I’m not a scientist and am not qualified to review any science text. However, I excelled in high school physics and am logical and generally quite sceptical of new theories that claim as much as this theory does. But I’ll say it again – I just can’t fault this guy’s logic. He’s either a genius, or completely wrong – but in a subtle way.

If anyone can point me in the direction of a good review by a scientist who’s read the book, I’d really appreciate it!

[shamus123]

I just read a review by D.A. White. Check it out http://www.dpedtech.com/FTreview.pdf