Responder a este mensaje

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, 
Graphic]


"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]


Educational Value

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.

_________________________________________________________________
MSN Amor: busca tu ½ naranja http://latam.msn.com/amor/


-~--------------------------------------------------------------------~-

-~--------------------------------------------------------------------~-
         Compra o vende de manera diferente en www.egrupos.net