ARRL

ARRL Satellite Bulletin ARLS014 (1998)

SB SPACE @ ARL $ARLS014
ARLS014 New amateur satellite package launched

ZCZC AS14  
QST de W1AW  
Space Bulletin 014  ARLS014
From ARRL Headquarters  
Newington, CT  October 27, 1998
To all radio amateurs

SB SPACE ARL ARLS014
ARLS014 New amateur satellite package launched

SEDSAT-1, Amateur Radio's newest satellite, launched successfully
October 24 from Cape Canaveral.  However, after fewer than two dozen
orbits around Earth, reports indicated problems with the
spacecraft's batteries and solar panels.  SEDSAT-1 was fabricated by
students at the University of Alabama-Huntsville.  It was boosted
into space by the same Delta II rocket that carried the Deep Space
One probe.  The package contains a Mode L digital store-and-forward
transponder and a Mode A analog transponder.

Chris Lewicki, KC7NYV, of the University of Arizona Student
Satellite Project, reported earlier today that telemetry from
SEDSAT-1 indicated the spacecraft's power had dropped to zero at one
point and the satellite reset itself.  Intermittent telemetry
suggests the batteries are not storing their specified 8 Ah.
Lewicki said the satellite went quiet halfway through a pass over
Tucson on orbit 27, indicating it had gone into its ''power cycle''
mode.  Lewicki said in this state, the satellite notices that it is
in extremely low power conditions and waits 10 hours until
attempting to transmit again.

The solar panels appear to be producing as much power as expected,
but Lewicki said they are ''slow to react when exiting an eclipse
period,'' so charging does not start until at least 10 minutes into a
daylight cycle.

As a result of the power cycling, images of the satellite's
deployment from the booster were lost.

Lewicki is seeking monitors to listen and decode telemetry for
periods when the spacecraft is nearing the end of its day cycle and
entering eclipse.  The downlink is 437.91 MHz, 9600 baud FSK (with
adjustment for Doppler shift).  A telemetry program is available at
the SEDSAT Web site, http://www.seds.org/sedsat/tracking.

''To use it, you must put your TNC in KISS mode and must set the
appropriate COM port parameters,'' Lewicki said.  Current two-line
Keplerian elements also are available at the SEDSAT Web site.

E-mail telemetry reports including the orbit number, your
latitude/longitude, UTC, and brief description of hardware used to
telemetry@seds.org.

Lewicki said nothing was heard from the spacecraft in Phoenix at
1200 UTC October 26, nor was it heard in London on a later orbital
pass.

SEDSAT coordinator Mark Maier, KF4YGR, at the University of
Alabama-Huntsville said the satellite's initial telemetry was
nominal except that power numbers were below prediction on earlier
orbits.  He said the satellite's orbit ''processes out of North
America for fairly long periods''-a half a day or more at a time.

For more information, visit the SEDSAT Web site at
http://www.seds.org/sedsat/.

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