Nuclear Propelled Probes to study the Pioneer Anomaly

[John Jacobus <crispy_bird@YAHOO.COM>]

The original is at

http://www.nature.com/news/2004/041115/full/041115-16.html

---------------------------------

Published online: 19 November 2004; |

doi:10.1038/news041115-16 



Following in Pioneer's footsteps

Philip Ball 



Calls grow for a mission to find out why old space

probes are slowing down. 

 

Does the puzzling behaviour of the Pioneer spacecraft

at the edge of the solar system reveal new laws of

physics? Space scientists are calling for a deep-space

mission to find out. Even if there is no revolutionary

physics involved, they say that results could be vital

for engineers designing future deep-space probes.



Pioneer 10 and 11 were launched in 1972 to explore

Jupiter and Saturn. After their studies there were

done, they continued on towards the edge of the Solar

System.



But since around 1980, when they passed beyond the

orbit of Uranus, the radio signals that they send back

to Earth have been shifted to progressively shorter

wavelengths.



This implies that the spacecraft are decelerating very

slightly on their outward journey. But no one knows

why this is happening.



It could just be some unforeseen effect generated

onboard the probes themselves, by leakage of gaseous

fuel from the thrusters, for example.



 "ESA has tried to bring fundamental physics into the

mainstream of space science."  David Southwood

Director of the European Space Agency's scientific

programme 

   

 

But if it is not, then this deceleration (dubbed the

Pioneer anomaly) might point to a gap in our

understanding of the fundamental principles of

physics. It could reveal the influence of a new force,

or perhaps a new kind of matter.



That would be a revolutionary finding. But even the

more mundane explanation of an onboard instrumental

effect would be very important, says Slava Turyshev of

NASA's Jet Propulsion Laboratory in Pasadena,

California, because it would force space engineers to

rethink their methods for very precise navigation in

space.



Stalking course



Sending a mission after the Pioneer craft would allow

scientists to confirm whether the Pioneer anomaly is

real, and to rule out some of the technological

explanations. Turyshev and his colleagues outline

their plan in a preprint on the Arxiv server1.



The mission would need to have very accurate

navigation, and instruments that could detect the tiny

deceleration and potential causes such as leaking gas.

And to get an answer in the next couple of decades

would take a fast-travelling probe, one faster than

the Cassini spacecraft currently orbiting Saturn. That

planet is only half as far away as Uranus, but it

still took Cassini seven years to reach its

destination.



Instead of relying on conventional rocket fuel, the

craft might use the faster propulsion systems being

investigated by NASA and the European Space Agency

(ESA), which involve nuclear power.



The first of these craft is likely to be NASA's

Jupiter Icy Moons Orbiter, scheduled to launch around

2015. But the researchers say that none of the

currently proposed missions could probe the Pioneer

anomaly as they stand, because they will not have

sufficiently accurate navigation or instruments.



So the researchers are arguing for a spacecraft that

draws on the lessons learnt from the Pioneer missions,

in which various accidents of design have made it

possible to track the spacecraft's movement very

closely.



"It could be developed in five years and flown early

in the next decade," they say.



Getting there



Although Turyshev would prefer a dedicated craft, he

admits that adding instrumentation to missions already

planned might be a more realistic option, which could

cost as little as US$70 million. "I believe that an

add-on package will definitely fly in one of the next

missions," he says. 



David Southwood, director of the ESA's scientific

programme, confirms that the Pioneer anomaly is

thought to be important in Europe. "ESA has tried to

bring fundamental physics into the mainstream of space

science," he says.



Both Pioneer spacecraft are now too far away for their

weakening communications systems to make further

contact with Earth. Pioneer 10 was last heard from in

early 2003, and is now over 12 billion kilometres

away. It is heading for the giant red star Aldebaran

in the Taurus constellation, but it won't get there

for another 2 million years.



References

Turyshev S. G., Nieto M. M. & Anderson J. D. Arxiv,

Preprint www.arxiv.org/abs/gr-qc/0409117 (2004).



  © 2004 Nature Publishing Group | Privacy policy 



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-- John

John Jacobus, MS

Certified Health Physicist

e-mail:  crispy_bird@yahoo.com



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