ARLA/CLUSTER: NASA convida radioamadores a transmitir mensagens para a nave Juno em 28 MHz

[Luís Garcia Filipe]

Pois, mas não se trata da ISS, é outra coisa.

E com um desafio bem estimulante hehehe

73,

CS7AEL


2013/9/5 Carlos Fonseca <ct1gfqgrupos  gmail.com>

> Aos que se choram de nao conseguirem chamar a iss, aproveitem esta
> oportunidade pata depois nao dizerem que nao avisaram......
>
> 73's de CT1GFQ
> REP#1406
> SKCC#466C
>
> Cump.
> Carlos Fonseca
>
> (Email enviado via plataforma movél).
> No dia 5 de Set de 2013 13:04, "João Costa &gt; CT1FBF" <ct1fbf  gmail.com>
> escreveu:
>
>> Radio hams to say 'HI' to Juno on 10m
>>
>> NASA's Juno mission is inviting amateur radio operators around the
>> world to transmit a coordinated message on the 28 MHz band to the Juno
>> spacecraft
>>
>> NASA's Juno spacecraft will fly past Earth on October 9, 2013 to
>> receive a gravity assist from our planet, putting it on course for
>> Jupiter.
>>
>> To celebrate this event, the Juno mission is inviting amateur radio
>> operators around the world to say "HI" to Juno in a coordinated Morse
>> Code message. Juno's radio and plasma wave experiment, called Waves,
>> should be able to detect the message if enough people participate.
>>
>> Juno will have a better chance of detecting the signal from many
>> operators if the signal is spread out across the spectrum. The Juno
>> Waves instrument is a broadband receiver, and the detector being used
>> for this event has a band width of 1 MHz. It is better for detection
>> of the signal to have a broadband signal coming in.
>>
>> For this experiment, we would like to ask those participating to
>> spread out in frequency across the 10 meter band. We have supplied a
>> table of suggested frequencies between 28 and 29 MHz, based on the
>> last letter of your call. When the HFR receiver is tuned to 28MHz, the
>> center frequency is 28.5 MHz. A 50 kHz high pass filter limits low
>> frequencies hitting the detector, so the frequency table excludes 28.5
>> MHz ±50 kHz. The natural signals we expect to measure at Jupiter will
>> consist of a large number of discrete tones, so spreading the signals
>> out in this manner is a good approximation to the signals we expect to
>> detect. But at Jupiter, we don't expect to be able to decode CW in our
>> telemetry!
>>
>> The 28 MHz band was chosen for this experiment for several reasons.
>> The Waves instrument is sensitive to radio signals in all amateur
>> bands below 40 MHz, but experience with the University of Iowa
>> instruments on the Galileo and Cassini earth flybys shows significant
>> shielding by the ionosphere at lower frequencies. As sad as it sounds,
>> we hope for lousy band conditions on October 9, so an appreciable
>> fraction of the radiated energy escapes the ionosphere into space, and
>> is not refracted back down to the ground somewhere else on the planet.
>>
>> Juno's antenna consists of a pair of tapered 2.8 meter long titanium
>> tubes, deployed from the bottom deck of the spacecraft under the +X
>> solar array and magnetometer boom. A high impedance radiation
>> resistant preamp sits at the base of the antenna and buffers the
>> signals from 50 Hz to 45 MHz. The elements are deployed with an
>> opening angle of about 120 degrees. Ten meters is above the resonant
>> frequency of the antenna and NEC analysis indicates a lobe generally
>> along the spin axis of the spacecraft. This will be good for detection
>> on the inbound part of closest approach to Earth.
>>
>> The Waves instrument uses four receivers to cover the frequency range
>> of 50 Hz to 41 MHz. Signals up to 3 MHz are bandpass filtered, sampled
>> by A/D converters and FFT processed into spectra using a custom FFT
>> processor developed by The University of Iowa under a grant from the
>> Iowa Space Grant Consortium.
>>
>> Please join in, and help spread the word to fellow amateur radio
>> enthusiasts!
>>
>> NASA - Say "HI" to Juno!
>> http://www.jpl.nasa.gov/hijuno/
>> See How do I participate ? for the frequency list.
>>
>>
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>>
>>
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-- 
Cumprimentos;

Luís Filipe Garcia S.
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