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What techniques have been employed for the Juno spacecraft to successfully transmit data packets back to Earth once she's in a polar orbit around Jupiter? Jupiter is a strong source of radio wavelength interference, at the same time it is of course also rather large distance away from the Earth (currently roughly 5.135 AU).

   Juno

    An artist's concept of Juno at Jupiter (Source: Wikimedia Commons)

Please describe Juno's communication subsystem, its predicted efficacy, and any techniques in place to thwart against possible radio wavelength interference, direct line of sight occlusion, transmission carrier waves intersecting with Jupiter's enormous magnetosphere, and other possible reasons for loss of transmission, regardless the source. What levels of data redundancy will be in place (package repetition, multiple carrier wavelengths, e.t.c.), how will data transmissions be encoded (error detection and correction algorithms used), at what rate and orbital position will they be transmitted to help assure the success of this mission critical subsystem component?

If possible, please compare the predicted data transmission failure rates for Juno with observed failure rates from previous missions to Jupiter, what lessons have we learned by then and learned to build around them with Juno, making her more data transmission error resilient.

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This paper describes the Juno telecomm system in detail.

It is a standard deep-space X-band system with a 2.5 m high-gain antenna, a 25 W traveling-wave tube amplifier, and concatenated convolutional and Reed-Solomon or Turbo 1/6 rate error-correcting codes. It will get 18,000 bits per second down to a 34-m antenna on Earth at maximum range (6.459 AU) at a $10^{-6}$ bit error rate.

Most of the noise in the transmission comes from space plasma between Jupiter and Earth, and Earth's atmosphere. Not from Jupiter. Jupiter is noisy in the MHz frequencies, but not in the GHz frequencies.

What is done to assure data integrity is forward error correction. Normally a Turbo code is used, and the rate is chosen to assure less than a $10^{-6}$ bit error rate, with 3 db of margin. For data that doesn't make it due to unexpected interference, e.g. a storm over Canberra or some such, that data can be retransmitted on another pass.

This is just standard procedure for all deep-space direct-to-Earth communication. There's nothing special for Jupiter, once you plug in the range.

The only lesson learned I know of from Galileo might be to not use a deployable high-gain antenna again.

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