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Re: Determination of c: Pioneer 10 Speaks.



Here's a useful experimental determination of c for those who have access
to a big-dish high-power well-steered spatially diverse uplink that can
pick out a signal that's 2^-71 watts at 16 baud.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sat, 2 Mar 2002
From Larry Lasher, Pioneer Project Manager
Subject: Pioneer-10 30 Year Launch Anniversary Track

Pioneer-10 was successfully contacted today. Yesterday, about 3pm PST a
200 Kw uplink transmission from Goldstone California, the 70 meter DSN
antenna DSS-14, was sent to Pioneer-10 and 22 hours later in Madrid Spain
at the DSN 70 meter antenna DSS-63 the confirmation of contact was
received. From a distance of 79.7 AU DSS-63 acquired the signal on time at
about -183 dbm. They spent an hour peaking the signal (-178.5 dbm) and
then they were able to lock up telemetry at 16 bps at an SNR of -0.5
db. Tracking continued until the elevation was about 20 degrees but enough
telemetry was received to verify the state of Pioneer-10. Incidentally,
the SETI institute also saw the signal from Arecibo in Puerto Rico. For
years they have used Pioneer-10 as a reference for their investigations.

The spacecraft is still healthy. The power is still sufficient to support
the loads with the bus voltage at about 26 volts (nominal is 28). The
uplink from DSS-14 was received by the spacecraft at -131.7 dbm. The
spacecraft is extremely cold, with many of the temperature readings at the
bottom of their scales. Two commands were sent yesterday from Goldstone
and both were confirmed to have been executed by the spacecraft. One
scientific instrument is still on, the Geiger Tube Telescope, and Dr. James
Van Allen, the PI, will be happy to hear he has some more data to look at.

Thirty years ago the first mission to explore the outer planets,
specifically the planet Jupiter, was launched from KSC. Many of the people
who designed, built and flew the spacecraft have passed on but Pioneer-10
continues. From ARC and the Pioneer Project we send our thanks to the
many people at the DSN (Goldstone and Madrid) and JPL who made it possible
to hear the spacecraft signal again.

Dave Lozier, Pioneer Flight Director
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Brian Whatcott
Altus OK Eureka!

Howdy,

I have a feeling that the value of c was used to determine the 79.7
AU distance to the Pioneer-10. Therefore you can't turn it around
and find c from this data.

Good Luck,
--
Herb Schulz
(herbs@interaccess.com)