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

[Carlos Fonseca]

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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