A recent flyby of Jupiter by NASA’s Juno spacecraft has led to the discovery of a new cyclone on the south pole of the planet. The 22nd flyby took place on November 3 soaring 3,500 kilometres above the cloud top of the gas giant. The discovery happened when the mission team was working to save the solar-powered spacecraft from Jupiter’s shadow, which could have been its end.
Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio. “We realized that the orbit was going to carry Juno into Jupiter’s shadow, which could have grave consequences because we’re solar powered. No sunlight means no power, so there was real risk we might freeze to death.”
While trying to figure out how to conserve the energy of the spacecraft, the engineers decided to make the Juno jump Jupiter’s shadow.
When Juno first arrived at Jupiter in July 2016, it discovered giant cyclones encircling the planet’s poles — nine in the north and six in the south — each nearly as wide as the continental US.
Scientists were not sure whether these cyclones were like their Earthly siblings — a transient phenomenon, taking only weeks to develop and then ebb — or had permanent fixtures? However, the system seemed stable as none of the six storms (five windstorms swirling in a pentagonal pattern around a central storm at the south pole) showed signs of yielding to allow other cyclones to join in.
“It almost appeared like the polar cyclones were part of a private club that seemed to resist new members,” said Bolton. Then, during Juno’s 22nd science pass, a new, smaller cyclone churned to life and joined the fray, NASA said in its statement.
“Data from Juno’s Jovian Infrared Auroral Mapper [JIRAM] instrument indicates we went from a pentagon of cyclones surrounding one at the centre to a hexagonal arrangement,” said Alessandro Mura, a Juno co-investigator at the National Institute for Astrophysics in Rome.
The new cyclone is about the size of Texas, which is smaller in stature than its six more established cyclonic brothers, Mura said adding that JIRAM data from future flybys could show the cyclone growing to the same size as the other cyclones.
“These cyclones are new weather phenomena that have not been seen or predicted before,” said Cheng Li, a Juno scientist from the University of California, Berkeley. “Nature is revealing new physics regarding fluid motions and how giant planet atmospheres work. We are beginning to grasp it through observations and computer simulations. Future Juno flybys will help us further refine our understanding by revealing how the cyclones evolve over time.”