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starship-design: Fwd: Mystery force tugs distant probes
In a message dated 5/16/01 2:23:59 PM, kgstarks@collins.rockwell.com writes:
>
>http://news.bbc.co.uk/hi/english/sci/tech/newsid_1332000/1332368.stm
>
>
>Tuesday, 15 May, 2001, 15:46 GMT 16:46 UK
> Mystery force tugs
> distant probes
>
> The Pioneer craft are heading towards the stars
> By BBC News Online science editor Dr
> David Whitehouse
>
> An unexplained force is pulling on distant
> spacecraft. Researchers have come to this
> conclusion after a thorough analysis of the
> deep-space probes' trajectories.
>
> It could be just a tiny
> unnoticed effect in the
> spacecraft themselves,
> but scientists warn it
> could also be the first
> hint that modifications
> need to be made to our
> understanding of the
> force of gravity.
>
> "It is almost as if the
> probes are not behaving according to the
> known law of gravity," said Dr John Anderson,
> of the American space agency's (Nasa) Jet
> Propulsion Laboratory, and lead scientist on
> the study.
>
> He said: "We've been working on this problem
> for several years, and we have accounted for
> everything we could think of."
>
> Great detail
>
> The unexplained force appears to be acting on
> four deep-space probes scattered around the
> Solar System.
>
> Pioneer 10 was launched towards the outer
> planets in 1972. It is now well beyond Jupiter
> but still in radio contact with Earth.
>
> By studying the Doppler shift (the "stretching")
> of the radio signals from the probe, scientists
> have been able to calculate how fast the craft
> is travelling. Since 1980, its trajectory has
> been mapped in very great detail.
>
> The puzzle is that Pioneer 10 is slowing more
> quickly than it should.
>
> It was initially suggested that this might be
> due to the force from a tiny gas leak or that it
> was being pulled off course by the gravity of
> an unseen Solar System object.
>
> Unseen body
>
> The mystery deepened further when an
> analysis of the trajectory being followed by its
> sister spacecraft, Pioneer 11, launched in
> 1973, showed that it too was being subjected
> to the same mysterious effect.
>
> But Pioneer 11 is on the opposite side of the
> Solar System from Pioneer 10, about 22 billion
> km (about 14 billion miles) away. This means
> the effect cannot be the gravitational effect
> of some unseen body.
>
> Add to all this hints that the same unexplained
> effect might have been acting on the Galileo
> spacecraft on its journey to Jupiter, and the
> Ulysses spaceprobe that is circling the Sun,
> and you have a Solar System-wide puzzle.
>
> In a report soon to be published in a major
> astronomical journal, Dr Anderson and
> colleagues have carried out an impressive
> study of the state of the Pioneer spacecraft
> and all the tiny forces to which they could be
> subjected.
>
> Planets unaffected
>
> "Our analysis strongly suggests that it is
> difficult to understand how any of these
> mechanisms can explain the magnitude of the
> observed behaviour of the Pioneer anomaly,"
> the team says.
>
> It has been suggested that the spacecraft
> tracking data have shown a deviation in the
> force of gravity that is apparent only across
> vast distances. It has also been pointed out
> that the strength of the effect seems to be
> related to two of the Universe's physical
> constants: the speed of light and the speed of
> the expansion of the Universe.
>
> But others have dismissed this as being too
> fanciful, arguing that if the Pioneer anomaly
> was really indicative of a change in our
> understanding of gravity, then it would be
> apparent in the orbits of the planets around
> the Sun - which it is not.
>
> The effect is as yet unexplained and with all
> four affected probes never to return to Earth
> for analysis, it may well remain that way.
>
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1332000/1332368.stm
Tuesday, 15 May, 2001, 15:46 GMT 16:46 UK
Mystery force tugs
distant probes
The Pioneer craft are heading towards the stars
By BBC News Online science editor Dr
David Whitehouse
An unexplained force is pulling on distant
spacecraft. Researchers have come to this
conclusion after a thorough analysis of the
deep-space probes' trajectories.
It could be just a tiny
unnoticed effect in the
spacecraft themselves,
but scientists warn it
could also be the first
hint that modifications
need to be made to our
understanding of the
force of gravity.
"It is almost as if the
probes are not behaving according to the
known law of gravity," said Dr John Anderson,
of the American space agency's (Nasa) Jet
Propulsion Laboratory, and lead scientist on
the study.
He said: "We've been working on this problem
for several years, and we have accounted for
everything we could think of."
Great detail
The unexplained force appears to be acting on
four deep-space probes scattered around the
Solar System.
Pioneer 10 was launched towards the outer
planets in 1972. It is now well beyond Jupiter
but still in radio contact with Earth.
By studying the Doppler shift (the "stretching")
of the radio signals from the probe, scientists
have been able to calculate how fast the craft
is travelling. Since 1980, its trajectory has
been mapped in very great detail.
The puzzle is that Pioneer 10 is slowing more
quickly than it should.
It was initially suggested that this might be
due to the force from a tiny gas leak or that it
was being pulled off course by the gravity of
an unseen Solar System object.
Unseen body
The mystery deepened further when an
analysis of the trajectory being followed by its
sister spacecraft, Pioneer 11, launched in
1973, showed that it too was being subjected
to the same mysterious effect.
But Pioneer 11 is on the opposite side of the
Solar System from Pioneer 10, about 22 billion
km (about 14 billion miles) away. This means
the effect cannot be the gravitational effect
of some unseen body.
Add to all this hints that the same unexplained
effect might have been acting on the Galileo
spacecraft on its journey to Jupiter, and the
Ulysses spaceprobe that is circling the Sun,
and you have a Solar System-wide puzzle.
In a report soon to be published in a major
astronomical journal, Dr Anderson and
colleagues have carried out an impressive
study of the state of the Pioneer spacecraft
and all the tiny forces to which they could be
subjected.
Planets unaffected
"Our analysis strongly suggests that it is
difficult to understand how any of these
mechanisms can explain the magnitude of the
observed behaviour of the Pioneer anomaly,"
the team says.
It has been suggested that the spacecraft
tracking data have shown a deviation in the
force of gravity that is apparent only across
vast distances. It has also been pointed out
that the strength of the effect seems to be
related to two of the Universe's physical
constants: the speed of light and the speed of
the expansion of the Universe.
But others have dismissed this as being too
fanciful, arguing that if the Pioneer anomaly
was really indicative of a change in our
understanding of gravity, then it would be
apparent in the orbits of the planets around
the Sun - which it is not.
The effect is as yet unexplained and with all
four affected probes never to return to Earth
for analysis, it may well remain that way.