NASA Lunar Reconnaissance Orbiter reception updated: (20/06/2009 21:31:38 +0100)
The LRO was launched flawlessly by NASA on the 18th June 2009 at 5:32pm EDT from Kennedy Space Centre. The launch initially looked like it would be scrubbed due to the close proximity of thunder / anvil clouds, but at the last minute these cleared resulting in a 'green' for the weather. Incidentally, an extremely informative and interesting 'blog' by the LRO mission team can be found at http://lroupdate.blogspot.com/ - this is well worth a read as it contains some excellent technical references.
The following day, 19th June 2009, the S-Band TT&C downlink, nominally transmitting on 2271.200MHz was acquired by amateur stations in the UK, the Czech Republic and the USA, details below;
19th June 2009, 06:09BST - Doppler signal acquired on 2271.191 - possibly LRO's low gain antenna.
19th June 2009, 06:53BST - A nice strong signal with sidebands - typical of TT&C. Minutes before this FFT was captured, the LRO was seen searching for an uplink signal to lock to - presumably this accounts for the lack of Doppler noted in the FFT.
19th June 2009, 11:57BST - Still a decant signal during the LRO cruise phase.
The LRO also has a Ka-Band transmitter centred on 25.650GHz, a down converter for which has been built and tested. The down converter is very simple, it consists of a 'brick' oscillator running at 12.1GHz, which is locked to a 100.833333333MHz GPS locked source. The 12.1GHz is internally doubled to 24.2GHz in the receiver front end module to form the first LO. The incoming 25.650GHz signal is filtered with a low loss band pass filter, mixed with 24.2GHz to result in a 1450MHz IF which is then tuned with the usual receiver / SDR-14 combination to look for signals.
Tuning information for LRO based on its velocity can be found in the Amateur-DSN spreadsheet as per the information below;
|DSN tracking spreadsheet by Paul M0EYT||Info||DSN||Spacecraft TX||Velocity||Doppler corrected||Doppler shift||Tuning Freq|
|Mission Name / JPL Horizons ID||OK ?||Channel||frequency (MHz)||(KM/s)||(MHz)||(KHz)||(MHz)|