Gravity Science (Juno)

Gravity Science is an experiment and instrument set aboard the Juno Jupiter orbiter, designed to monitor Jupiter's gravity. Juno's Gravity Science experiment is intended to mapping Jupiter's gravitational field, which allows the interior of Jupiter to be better understood. The Gravity Science experiment uses special hardware on Juno, and also on Earth. GS uses the high-gain K-band and X-band communication system and communication systems on Earth of the Deep Space Network as well as special communication hardware on Juno called KaTS, or Ka-Band Translator System. These components work together to detect minute changes in radio frequency, see Doppler shift, thus detecting the spacecraft's velocity over time. The KaTS box was funded by the Italian Space Agency and overseen by a professor at University La Sapienza in Rome. KaTS detects signals coming from the DSN on Earth, and then sends reply in a very precise way, that ultimately allows the velocity of Juno to hopefully be determined to within 0.001 milimeters per second. The spacecraft receives a tone signal on the Ka-band but then replies using the X-band radio.

As the spacecraft traverses the space near Jupiter, the planet, and even variations in the planets interior cause a variation in Juno velocity. The Gravity Science experiment measures these velocity changes using a combination of hardware on Earth and the Spacecraft, which in turn allows the affect of Gravity to be measured, and thus mass variations in Jupiter's interior.

Communication signals:

Juno launched in 2011 and arrived at Jupiter orbit in July 2016.

The GS was planned out to be used on orbits 4, orbit 9, and orbits 10 through 32. When GS operates it must point its antenna at Earth, and its is not operated simultaneously with the Microwave Radiometer instrument on Juno.

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