Stanford's 46-meter breaking old Weaksignal Distance record.
Date: Mon, 15 Nov 1999 07:19:08 -0800
Reply-To: John L. Callas
Sender: MARS-NET
From: "John L. Callas"
Subject: SUCCESS! Stanford Successfully Detects Mars Relay Beacon
Comments: To: Thomas.E.Thorpe@jpl.nasa.gov, Richard.A.Cook@jpl.nasa.gov,
The Stanford 46-meter Antenna successfully detected the 1-watt MGS Mars
Relay Beacon from Mars during at test of the system on 1999-11-03 and
1999-11-04. Initially, the results of the experiment failed to
indicate a signal detection above background, although telemetry from
on board the MGS spacecraft indicated the Mars Relay was operating
nominally. A small timing error, discovered after the test in the
Doppler compensation data used by Stanford to track the expected
received frequency of the signal returning from Mars, prevented the
signal from being resolved in the collected data. However, the effects
from the Doppler timing error were exactly characterized and the data
were reprocessed to remove the effects of the small timing error. When
that reprocessing was perform the Mars Relay signal became clearly and
unambiguously resolved in the Stanford data at the expected signal
strength. Furthermore, the Stanford Antenna with its sensitivity
observed the Mars Relay mode transition from the continuous wave (CW)
mode to the FM modulated subcarrier mode during the test.
Additionally, Stanford was able to discern the effects of the
obscuration of the Mars Relay signal in line of sight to the Earth by
the motion of the MGS solar panels during each orbit. These successful
detection results by Stanford independently confirm the fully
functioning operation of the Mars Relay and its ready status to support
Mars landed operations beginning on 1999-12-03. The Stanford tests
were conducted by Dr. Ivan Linscott of Stanford, Dr. John Callas of
JPL, and Dr. Michael Cousins of SRI International.
As an additional note, this detection by Stanford sets a new World
record (Solar System record) for the distance an UHF signal has been
transmitted and received, 230 million kilometers, and the first ever
detection of an UHF signal from Mars. The previous record of 50
million kilometers was also held by the Stanford 46-meter Antenna.
Sincerely,
John Callas
John L. Callas Jet Propulsion Laboratory
1-818-354-9088 (Office) Mail Stop 169-327
1-818-354-1004 (Fax) 4800 Oak Grove Drive
John.L.Callas@jpl.nasa.gov Pasadena, California 91109
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