RE: smap 15-003A/40376

From: Ted Molczan via Seesat-l <>
Date: Sun, 7 Jan 2018 13:03:11 -0500
Tristan Cools wrote:

> My first satellite observation of 2018 today at 16:56UTC: 2015-03A/40376 or
> the NASA satellite Smap is tumbling with a period of about 1s.  No
> chronograph with me.
> The satellite was already a failure almost 6 months after launch, it had a
> large dish antenna.  I wonder, with a tumble like that why it hasn't been
> torn of in the meantime...

I suspect that the regular variation in brightness is due to the satellite's rotating antenna:

"The L-band SAR and radiometer share a 6-m mesh deployable offset-fed reflector antenna that rotates at 13 to 14.6 rpm
to provide high spatial resolution with a 1000 km measurement swath that enables global coverage every 2-3 days..."

SMAP Antenna Beam Footprint:

The L-band radar failed in July 2015, but the radiometer continued to operate, presumably still fed by the rotating

Ted Molczan

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Received on Sun Jan 07 2018 - 12:03:58 UTC

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