Space probes feel cosmic tug of bizarre forces - Guardian

[nacnud]

<font color="yellow"><b>Space probes feel cosmic tug of bizarre forces</b><br /><br />Robin McKie, science editor<br />Sunday September 12, 2004<br />The Observer<br /><br />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.<br /><br />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.<br /><br />As a result, scientists are to press a European Space Agency (Esa) meeting, called Cosmic Visions, in Paris this week for backing for a mission that would follow the Pioneers and pinpoint the cause of their erratic movements… </font>a target="_blank" href=http://education.guardian.co.uk/higher/sciences/story/0,12243,1302857,00.html>more<br /><br />I have heard about this before and I'm glad someone is taking a look at it. I didn't realise before that is appears to be affecting both probes which seems to rule out some of the more mundane explanations. I wonder if the Voyagers are similarly affected?<br />

 

[najab]

Very interesting....if gravity follows anything other than an inverse square law, the bonfire of burning astronomy texts will be visible from space!

 

[nacnud]

You'll have to prise my copy of Ohanian out of my cold dead hands first, even if it is wrong that thing cost me an arm and a leg <img src="/images/icons/smile.gif" />.<br /><br />Still if gravity is greater at larger distances than previously thought, as suggested by these observations it would nicely fit in with the galaxy rotation problem where the outer parts of the galaxy seem to be rotating too fast to be gravitationally bound without invoking large amount of dark matter.<br />

 

[aaron38]

If the force of gravity did increase with distance, and with distant galaxys being so far away, wouldn't that be a brake on the expansion of the universe, checking the acceleration?

 

[nacnud]

Yeah it would, but at the moment it seems that the opposite is true and that at very long ranges there is a sort of anti gravity effect, its all getting a little odd out there <img src="/images/icons/smile.gif" />

 

[thalion]

Bravo. If this is a real effect, it's definitely worth investigating, especially if it would involve a reconstruction of cosmology.

 

[mikejz]

This has been written about before. The Voyager probes are 3-axis stablised, where as the Pioneers were spin-stablised--is makes them more adept at sensing the force without interference from an active stablisation system.

 

[nacnud]

Ah I didn't realise the Voyagers were thrust stabilised, thanks for the info.

 

[mikejz]

I'm not 100% sure on the details, but I do remember reading that Voyagers thrusters do not allow for a messurement of the effects of whatever this is.