[amsat-bb] Monitoring Marsexpress around Mars

[Klaus Fenger <klaus@xxxxxxxxxx>]

Hello group,

here in Kiel, Northern Germany, we have spent most time during the 
Christmas holidays in front of our computer and receiver to collect some 
results and experience about the Mars Express.
Unfortunalty we couldn't monitor the transfer into a orbit around Mars. 
On the 25th of December we were curious what would happen to the signal 
and doppler shift. But we had to deal with Murphy's law. Our receiving 
system had a malfunction and the only one who could repair it had to 
"join" his family.

But there was the second day:
In time Mars came up and the Mars Express was found. During this monitor 
window we did record the frequencies from 11:30 UTC to 19:55 UTC. These 
plots can be seen under:



http://www.lernnetz-sh.de/satellit/mars/index.htm

Frequenciese were decreasing continously. Around 15:42 UTC we monitored 
an increase of the doppler frequency by 22 kHz which happend again at 
16:38 UTC by 5 kHz. Our first assumption was a failure in our receiving 
system but we couldn't find any.
This increase in doppler shift was again monitored the next day, the 
27th of December, exactly at the same time. This was the proove that 
there was no malfunction in our system.

On the 26th of december Mars Express disappeared behind Mars. This can 
be seen in the waterfall plot on the left hand side. Also the 
degradation of signal caused by the athmosphere can be seen. After 92 
minutes the signal came up again when Mars Express left the Mars shadow 
again.

On the 27th od December we monitored the signal over 9 hours. No 
shadowing by Mars could be seen. This could only mean that we were 
looking vertical to the orbit of Mars Express. This is raising some 
questions:

Is the orbit of Mars Express rotating so that we are looking vertical to 
it on the 27th of December?
Why there is no doppler shift towards higher frequencies?
Has someone any information or details about the orbit of Mars Express?

We only have information about a perigeum of 200 km and an apogeum of 
7000 to 10000 km.

73 de Klaus, DF5DU and the team of DL0SHF


-- 

-------------------------------------------------------------------------
Klaus Fenger

Kiebitzflehr 6
24616 Brokstedt
Germany
Telef: 49 4324 88615
Mobil: 49 171 3149650
 
E-Mail: klaus@fengers.de
 
http://klaus.fengers.de
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