Mysterious Force Affects Pioneer 10 & 11 Probes

JabbaTheFart writes "The Guardian is writing that 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."

Comments

for the love of god,

[Anonymous Coward]

exactly what was AFFECTED?

Re:for the love of god,

[bilenkey]

It is called Pioneer Anomaly: there is a small but systematic departure from the expected motion of the spacecraft. Both of them move as if they were subject to a new, unknown force pointing towards the Sun. This force imparts the same constant acceleration, of about 10^-7 cm / s^-2. Read more: http://physicsweb.org/article/world/12/1/5 and http://physicsweb.org/article/world/17/9/3.

Re:for the love of god,

[blighter]

So you're saying that some mysterious force beyond the solar system caused these probes?

And here I thought that human engineering and curiousity had caused them and that the mystery force was merely changing their expected behavior!

If the post had read "Mystery Force is effecting a slowdown of Probes" that would be correct.

As written, however, the correct word is "affect".

The force!

[tuxter]

It is also thought that dark matter is at the centre of galaxies Could explain a lot of things, e.g. the expansion/contraction of the universe. Judging by the amount of "tangible" matter in the universe, there is no way to halt the expansion, and it will go on forever. However, if there is dark matter, it could hold enough gravity to halt expansion and force the big crunch. Lots of info on this sort of stuff here

A bit of editing would have helped

[rooijan]

Note to Hemos: The verb is spelled "affect". You know, with an "a". The noun is spelled "effect", but it's the verb needed in the title.

Sorry, don't mean to sound curmudgeonly and grumpy and so forth, but so few people get this right that I can't stand by and let it slide.

I'll put the cantankerous old grouch away now...

Re:A bit of editing would have helped

[tiled_rainbows]

Yes, effect is also a verb. But it's not the verb you're looking for.

Other Slashdot Story (from 3 years ago)

[Maddog Batty]

Bit of an old story this.

Better Article On The Subject

[G Samsonoff]

Link to the Physics Web article: http://physicsweb.org/article/world/17/9/3

Re:Better Article On The Subject

[smithwd]

There was also an article on the subject in The Economist a couple of weeks ago. The Economist story refers to a paper by Chris Duif that looks at other gravitational anomolies. Specifically there is something called the "Allais effect" which describes a measurable change in the force of gravity during solar eclipses. The effect has been experimentally confirmed by a number of observations with different measurement methods - and is also inconsistent with General Relativity. It will be interesting to see what - if anything - comes from the NASA Gravity Probe experiments.

Re:How do they track them?

[applemasker]

The last signals were recieved from Pioneer 10 in early 2003, but telmetry stopped almost a year before. From the Feb. 25, 2003 press release that "pronounced" Pioneer 10 dead:

RELEASE: 03-082HQ PIONEER 10 SPACECRAFT SENDS LAST SIGNAL After more than 30 years, it appears the venerable Pioneer 10 spacecraft has sent its last signal to Earth. Pioneer's last, very weak signal was received on Jan. 22, 2003. NASA engineers report Pioneer 10's radioisotope power source has decayed, and it may not have enough power to send additional transmissions to Earth. NASA's Deep Space Network (DSN) did not detect a signal during the last contact attempt Feb. 7, 2003. The previous three contacts, including the Jan. 22 signal, were very faint with no telemetry received. The last time a Pioneer 10 contact returned telemetry data was April 27, 2002. NASA has no additional contact attempts planned for Pioneer 10.

Re:Radiation pressure

[DrRossi]

It is most certainly not radiation pressure from the RTGs. If you would care to read the original 54 page article gr-qc/0104064 at http://arxiv.org/ you would have noticed that the original authors took serious effort to account for the radiation pressure from the RTGs and could make it in no way large enough to account for the anomaly.

Re:Or...

[Dave_M_26]

If I remember correctly it's by David Brin.

Certainly in his anthology "The River of Time" there was a story called " The Crystal Spheres"

Dust from the kuiper belt is slowing down probes

[madsatod]

I like the following explanation of the anomalous acceleration. No dark matter/20 dimensions/new gravity theory needed here. A small amount of dust in the kuiper-belt that transfers momentum with the probe should be enough to explain the slowdown. Look at: http://www.newtonphysics.on.ca/Anomalous/Accelerat ion.html

What the difference is

[ananiasanom]

To quote from the journal article which I was modded "offtopic" for referring to:

Affect and effect are two different verbs, with related but quite different meanings.

Affect is the more common. To affect something is to alter it, usually but not always in a harmful way.

Effect is less common. To effect something is to cause it to happen. I noticed people starting to use this more commonly about eight years ago. Soon afterwards, people started to use the verb "to effect" instead of the verb "to affect", unaware of the difference in meaning. The difference is so strong that these people often end up saying the opposite of what they mean.

here is a good reference.