Ranging and Pioneer

The position of Pioneer was calculated from Doppler information. Ranging
was not available. Can anyone explain why ranging could not be used? Is
this just a limit on available technology, or is there a more
fundamental reason?


Regards

--
Charles Francis
substitute charles for NotI to email

Oh No wrote:
The position of Pioneer was calculated from Doppler information. Ranging
was not available. Can anyone explain why ranging could not be used? Is
this just a limit on available technology, or is there a more
fundamental reason?

gr-qc/0104064

Spud

Thus spake Spud

Oh No wrote:
The position of Pioneer was calculated from Doppler information. Ranging
was not available. Can anyone explain why ranging could not be used? Is
this just a limit on available technology, or is there a more
fundamental reason?

gr-qc/0104064

Many thanks. If I understand Anderson correctly it is merely an
engineering constraint. With a (perhaps greatly) amplified signal it
should be possible to reduce integration times to achieve correlation so
that the signal can be returned without a substantial range delay.
Anyway that is the basis on which I am working at the moment.

But I am not an engineer, and I was hoping this might be confirmed. My
arguments would take quite a different form if this was a fundamental
constraint.




Regards

--
Charles Francis
substitute charles for NotI to email

Oh No wrote:

Thus spake Spud

Oh No wrote:
The position of Pioneer was calculated from Doppler information. Ranging
was not available. Can anyone explain why ranging could not be used? Is
this just a limit on available technology, or is there a more
fundamental reason?

gr-qc/0104064

Many thanks. If I understand Anderson correctly it is merely an
engineering constraint. With a (perhaps greatly) amplified signal it
should be possible to reduce integration times to achieve correlation so
that the signal can be returned without a substantial range delay.
Anyway that is the basis on which I am working at the moment.

But I am not an engineer, and I was hoping this might be confirmed. My
arguments would take quite a different form if this was a fundamental
constraint.

http://arxiv.org/abs/gr-qc/0205059
Pioneer anomaly
http://arXiv.org/abs/gr-qc/0307042
Rationalized Pioneer anomaly
http://arXiv.org/abs/gr-qc/9810085
Believable rationalized Pioneer anomaly
http://arXiv.org/abs/gr-qc/gr-qc/0310088
Believable Pioneer anomaly updated
http://www.arxiv.org/abs/gr-qc/0411020
Pioneer anomaly
http://arXiv.org/abs/physics/0502123
Commentary on Pioneer anomaly minutia
http://arXiv.org/abs/gr-qc/0506139
http://math.ucr.edu/home/baez/open.questions.html

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz3.pdf

Oh No wrote:

The position of Pioneer was calculated from Doppler information. Ranging
was not available. Can anyone explain why ranging could not be used? Is
this just a limit on available technology, or is there a more
fundamental reason?


Regards


Here is an extreme case
in terms of Beta Pictoris
at many light years distance

arXiv:astro-ph/0601244 v1 11 Jan 2006

Dynamic motions are inferred from
atomic molecular quantum transitions.

The time (frequency) of such transitions are assumed the same
there and here
from which observed differences in frequencies
are related to dynamic motions.

The problem is the same as you identify.
How does one "range" the motions of Asteroid size objects
(which do not have quantum transitions) in Beta Pictoris
other than observing the gross newtonian gravity motions of the system
as a whole.

The problem could be solved if only a radar signal could be sent,
reflected for obtaining active ranging information.

Such a procedure is performed with the earth's moon
which is aided by a corner reflector positioned there.
Moon position is ranged from earth within centimeters.

Could such a ranging procedure be conducted
on a Pioneer size object at 10 AU.
If so, then a dedicated spacecraft mission would not be necessary.
One would only have track various objects
of Pioneer size and smaller that are at 10 AU.
(area to mass ratio may be a very important parameter)

Such questions are important.
It could be the reason that our solar system is essentially dust free
at 5 billion years old
and Beta Pictoris has lots of dust at ~10 million years old.

Richard

Oh No wrote:
The position of Pioneer was calculated from Doppler information. Ranging
was not available. Can anyone explain why ranging could not be used? Is
this just a limit on available technology, or is there a more
fundamental reason?

Interesting

astro-ph/0501626

Spud

In article .com, Spud writes:

Oh No wrote:
The position of Pioneer was calculated from Doppler information. Ranging
was not available. Can anyone explain why ranging could not be used? Is
this just a limit on available technology, or is there a more
fundamental reason?

gr-qc/0104064

Spud

Just wanted to ask something about this. In order to measure Doppler
shift, you need to measure frequency accurately right? And in order to
measure frequency accurately you have to have an accurate clock.

I founded an IRC network (Newnet Internet Relay Chat). We had a problem
with servers being out of sync, clocks didn't agree.

Part of our network was using national institute of standards and
technologies NIST time server, others were using a time server at Nasa.

The root of the problem turned out that NASA's time server was about
five seconds off of NIST's.

Now I thought NIST was supposed to be THE gold standard, which would
mean that NASA's clock is off. And if NASA's clock isn't accurate, then by
extension neither is the precise measure of frequency and thus Doppler shift.

So I can't help but wonder while we're re-writing the laws of
cosmology on the basis of the unexpected Doppler shift of Pioneer I and II,
if we might be really doing so on the basis of an incorrectly calibrated
clock at NASA.

--
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In article , Nanook wrote:
Part of our network was using national institute of standards and
technologies NIST time server, others were using a time server at Nasa.

The root of the problem turned out that NASA's time server was about
five seconds off of NIST's.

Now I thought NIST was supposed to be THE gold standard, which would
mean that NASA's clock is off. And if NASA's clock isn't accurate, then by
extension neither is the precise measure of frequency and thus Doppler shift.

I was under the impression that the "gold standard" for time is a
collaborative thing between a number of national and international time
services, not tied to any one machine or even site.
A five *second* difference between clocks that are meant to be accurate
to microseconds per year/ millennium (I can't remember which) I don't think is
credible. More credible would be that your network topology either had some
sort of horrible delay-inducing asymmetric loop in it to one of the time
sources, or that you were asking the wrong questions of one of the machines.
E.g., getting time according to UTC from one machine, but something corrected
to local noon from the other (that would give time differences of up to several
minutes a day, if I remember my horology correctly, but variable at different
times of the year).

--
Aidan Karley, FGS
Aberdeen, Scotland
Written at Tue, 11 Jul 2006 03:13 +0100, but posted later.

In article , Nanook
wrote:

The root of the problem turned out that NASA's time server was about
five seconds off of NIST's.

Now I thought NIST was supposed to be THE gold standard, which would
mean that NASA's clock is off. And if NASA's clock isn't accurate, then by
extension neither is the precise measure of frequency and thus Doppler shift.


NASA is a big organization. They don't have 'a clock'.

Are the timeservers you were using supposed to be public timeservers?
What stratum are they? If you are setting up a large IRC network, you
shouldn't be hitting high level time servers. Get one of your machines
to be the only one to contact a good server (or some other source like
a cheap GPS clock) and have others contact that machine.

Anyway, when I got to my current job, I pointed my NTP client at
time.where.I.work , which worked as an NTP server. When I noticed that
the time on my computer was way off, I tracked down the owner of that
machine. He didn't know his computer's NTP server port was active, he
just had a desktop computer named 'time' and a laptop named 'space'.

So anyway, it is unlikely that the Pioneer anomaly is due to an
inaccurate NTP server.

--
David M. Palmer (formerly @clark.net, @ematic.com)

In article , David M. Palmer
wrote:
So anyway, it is unlikely that the Pioneer anomaly is due to an
inaccurate NTP server.

Doesn't the Pioneer anomaly predate the development of NTP
anyway?

--
Aidan Karley, FGS
Aberdeen, Scotland
Written at Wed, 12 Jul 2006 09:30 +0100, but posted later.