Who, better than the bride of Jupiter, to show us what’s hidden in the gas giant of our solar system. Thanks to the instruments on board the Juno probe, we now know how Jupiter ‘s atmosphere develops in 3D. From the famous red spot, to the vortices at the poles, Juno, the largest planet in the Solar System, never ceases to amaze. Let’s see what has been discovered, how and what has been the Italian contribution.
The phenomena of Jupiter ‘s atmosphere reconstructed through Juno ‘s probe data
The main characteristic that makes cyclones interesting is their extreme stability underlined by the Italian instrument JIRAM (Jovian InfraRed Auroral Mapper): basically, a vortex in a central position tends to repel like a spring the others that surround its perimeter. In fact, the tendency of cyclones is precisely to reach the pole, if the central cyclone formation was not present. There are 6 for the South Pole (with a central one) and 9 for the North Pole (with a central one).
Jupiter Juno ‘s probe new discoveries: the case of the Red Spot
Who hasn’t noticed in photos of Jupiter the famous ellipse-shaped spot that sits below the planet’s equator? It is an anticyclonic storm. For the first time, it was possible to measure the depth of the Red Spot. Estimated at about 500 km below the planet’s cloud tops. Thanks to Juno’s July 2019 flyby in the vicinity of the famous anticyclone, it was possible to obtain the measurement of the gravitational footprint of the mass enclosed in the spot itself.
The protagonist of the study was one of our compatriots: Marzia Parisi, a scientist at JPL. Although the probe had a speed of about 209,000 km / h. The team was able to detect a variation of that speed during the passage over the Blur of 0.01 millimeters per second, a consequence of gravitational perturbation. A sensational result considering the sensitivity of the instruments needed to detect such a variation.
Once again, Italy is the protagonist. Thanks to KaT (Ka-Band Translator), a Ka-band sensitive instrument developed by ASI and Thale Alenia Space. It exploits the Doppler effect of the signal, related precisely to the speed of the probe. Measuring the frequency variation it is possible to trace the desired speed values. Adding the precision of tracking of the Deep Space Network, more than 650 million kilometers away, we succeeded in the enterprise.
“The precision required to obtain the gravity of the Great Red Spot during the July 2019 flyby is astounding. Being able to integrate MWR’s discovery about depth, gives us great confidence that future gravity experiments on Jupiter will yield equally intriguing results.
Marzia Parisi, JPL scientist.
Fences and zones: similarities with the Earth?
Another detail definitely more evident from the photos: is the subdivision of Jupiter into darker belts (shades of red) and lighter areas (shades of white). The separation is guaranteed by rushing streams that blow in the direction East – West but with opposite directions. However, it remains to be fully understood the mechanism: by which the belts are brighter in the infrared than the areas up to a certain level. Then the opposite happens.
As on our Planet, Jupiter appears to have motions similar to Earth’s Ferrel cells. The difference lies in the very different number. For the Earth there is one per hemisphere, Jupiter has 8, but 30 times larger! Thanks to another instrument on board Juno, the MWR (Microwave Radiometer), it has followed the trace of ammonia molecules. That has allowed us to define the geometry of the cells. Another key achievement of the Juno probe that is paving the way for an accurate knowledge of Jupiter’s atmosphere. And not only.
