|Asunto:||[dxcolombia] SuitSat-1 Battery Voltage May Be on Downward Slide |
|Fecha:||Miercoles, 22 de Febrero, 2006 08:59:39 (-0500)|
|Autor:||oscar eduardo reyes salazar <hk6pro @.......com>
SuitSat-1 Battery Voltage May Be on Downward Slide
NEWINGTON, CT, Feb 17, 2006--Now heading into its third week of operation,
SuitSat-1 continues to put out a faint signal on 145.990 MHz. While hearing
the spacesuit-satellite's telemetry and voice messages can be difficult even
for the best-equipped stations, recent as-yet-unconfirmed reports suggest
that SuitSat-1's battery voltage could be entering a death spiral. ARRL
Member Richard Crow, N2SPI, in New York, has been tracking the satellite's
battery voltage, nominally 28 V. While it had been dropping incrementally,
Crow has noticed a "noticeable acceleration" in the past day or so. While
conceding that he's "going out on a limb" because SuitSat-1's signal was
noisy on its last pass over his QTH, Crow believes he heard the voice
telemetry announce 18.3 V, a precipitous drop from earlier orbits.
A chart plotting SuitSat-1's current vs voltage. [Lou McFadin, W5DID,
"If this is so, the battery voltage may have dropped another 6.9 volts in
only 8 hours," he commented. "If so, the battery voltage is dropping like a
rock." ARRL member AJ Farmer, AJ3U, has posted the reports on his Web site
and invites others. Crow says he won't add the still-questionable reading to
his table until the battery voltage is verified or corroborated.
ARISS Issues Call for Telemetry Reports
Not taking any chances, however, SuitSat-1's sponsor--the Amateur Radio on
the International Space Station (ARISS) program--issued an urgent call for
appropriately equipped Earth stations to make every effort to copy
SuitSat-1's voice telemetry reports. ARISS US Hardware Manager Lou McFadin,
W5DID, who was directly involved in the construction of the SuitSat-1
package, says he and others on his team have been following the voltage
reports with great interest.
"Your efforts to gather the telemetry data are very much appreciated and
will contribute to further success should we get the opportunity to build a
second SuitSat," McFadin said today. "The power system is designed to
squeeze every drop of power out of the batteries that is possible." Post
telemetry reports or recordings to SuitSat@...
Deployed from the International Space Station on February 3, SuitSat-1
already has outlasted its initially predicted one-week active life.
Backdropped by the blackness of space and Earth's horizon, SuitSat-1 begins
its first orbit around Earth. The suit will enter the atmosphere and burn up
in a few weeks. [NASA Photo]
Plotting Current vs Voltage
McFadin explained (see chart) that SuitSat-1's battery current will rise as
its battery voltage drops. "That is the power system's attempt to keep the
transmitter voltage at 12 V," he noted. "As the battery voltage nears 12 V,
the regulator will no longer be able to maintain 12 V output. At a battery
voltage below 9 V all transmissions will cease."
He says that while SuitSat-1's computer will continue to operate down to 3
V, the transmitter will shut down and SuitSat-1 will appear dead. "I expect
this drop-off to occur very rapidly," McFadin added. "We really appreciate
the dedication and true amateur spirit of all those who have helped us
monitor this unique and interesting experiment."
Extremely low transmitter output power has been one explanation for
SuitSat-1's faint signal. AMSAT-NA calculations last weekend suggested that
SuitSat-1's transmitter is likely putting out between 1 and 10 mW instead of
the 500 mW it was supposed to produce.
Prior to launch, ISS Expedition 12 Flight Engineer Valery Tokarev prepares
SuitSat-1's Amateur Radio payload. Tokarev later released SuitSat-1 into
space during a February 3 space walk. [NASA Photo]
Its puny signal aside, the novel SuitSat-1 Amateur Radio transmit-only
spacesuit turned satellite has been heard around the globe since its launch
by the International Space Station crew. ARRL ARISS Program Manager Rosalie
White, K1STO, said last weekend brought reports from teachers who've
integrated SuitSat-1 monitoring into their classroom lessons.
"Thank you to the SuitSat team for the opportunity to have students involved
in such an exciting space project," teacher Neil Carleton, VE3NCE, at R.
Tait McKenzie Public School in Almonte, Ontario, said. "It's been a week of
adventure, and I'm happy to report on the involvement of my class as part of
our grade 6 science studies of space. My students and I look forward to
learning more about SuitSat in the weeks to come."
ARISS to Recognize Last Telemetry Report
SuitSat-1's transmission order is: DTMF tone, CW ID, SSTV image, 30 seconds
of silence, voice identification, mission time, temperature and battery
voltage. The voice messages, telemetry and SSTV image are being sent on a
nine-minute repeating cycle.
ARISS International Chairman Frank Bauer, KA3HDO, said the SuitSat team
plans to provide special recognition to the person who copies the last
SuitSat telemetry, and in particular the mission time and battery voltage.
AMSAT-NA has designated SuitSat-1 as AMSAT-OSCAR 54 (AO-54). By week's end,
SuitSat-1 had completed more than 200 orbits of Earth.
More information on the SuitSat-1 project, including QSL information, is
available on the AMSAT Web site and on the SuitSat Web site.
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