New earth-based images prepare for Juno’s encounter with Jupiter’s Great Red Spot

Posted by pt91 at Jul 03, 2017 09:56 AM |
University of Leicester space scientist involved in new images from Jupiter

Issued by University of Leicester Press Office on 30 June 2017

A University of Leicester space scientist has been involved in new Jupiter imagery from two telescopes in Hawaii that is providing context for upcoming close-ups of the Great Red Spot by NASA's Juno spacecraft.

Dr Leigh Fletcher from the University’s Department of Physics and Astronomy is part of the collaborative team supporting the Juno mission with Earth-based observations. The University of Leicester is also home to the only formal UK science lead for the Juno mission.

Dr Fletcher said: “In just a few days’ time, on 11 July 2017, NASA’s Juno spacecraft will perform the closest-ever views of the swirling maelstrom known as Jupiter’s Great Red Spot. It was always hoped that the pre-planned polar orbit and close perijove passes would take the spacecraft over the storm, but the slow and somewhat unpredictable westward motion of the gigantic vortex meant that a little luck would be required. That luck comes in on Perijove 7, and we’ll be rewarded by breathtaking views – so close that the vortex will stretch from jovian horizon to jovian horizon.

“In preparation for that encounter, myself and others have been collaborating on an Earth-based support campaign, capturing multi-wavelength views of the jovian atmosphere to provide spatial, temporal and spectral context for Juno’s close-in encounters. These images show the Great Red Spot as it was just a few weeks ago, and prepare us for Juno’s close-in views.”

High-resolution thermal imaging of Jupiter by the COoled Mid-Infrared Camera and Spectrometer (COMICS) mounted on the Subaru Telescope on Maunakea is providing information that extends and enhances the information that the Juno mission is gathering in its unprecedented mission to probe that planet's interior and deep atmospheric structure together with details of the magnetosphere and its auroral interactions with the planet.

“The Subaru observations of Jupiter so far this year have been timed to coordinate with the greatest benefit to Juno mission”, said Glenn Orton, PI for the portion of the Keck Telescope exchange time with the Subaru Telescope and coordinator for Earth-based observations supporting the Juno project at JPL.

"During our May 2017 observations that provided real-time support for Juno's sixth perijove, we obtained images and spectra of the Great Red Spot and its surroundings. Our observations showed that the Great Red Spot, the largest known vortex in the solar system, had a cold and cloudy interior increasing toward its center, with a periphery that was warmer and clearer. This implied that winds were upwelling more vigorously toward its center and subsiding on the periphery. A region to its northwest was unusually turbulent and chaotic, with bands that were cold and cloudy, alternating with bands that were warm and clear bands (Figure 1). This region is where air heading east toward the Great Red Spot flows around it to the north, where it encounters a stream of air flowing over it from the east,” adds Orton. “This information will allow us to determine the three-dimensional structure of winds that are otherwise only tracked in two dimensions using cloud features in reflected sunlight."

"A wide variety of filters installed in COMICS is advantageous in sensing Jupiter's temperatures in its upper troposphere and in its stratosphere," noted co-investigator and Subaru Telescope staff astronomer Takuya Fujiyoshi.

Juno has now made five close-up passes of Jupiter's atmosphere, the first of which was on August 27, 2016 and the latest (the sixth) on May 19 of 2017. Each of these close passes has provided Juno's science team with unexpected surprises, and the Juno science return has benefitted from a coordinated campaign of Earth-based support. This campaign includes observations from spacecraft near or orbiting the Earth, covering X-ray through visible wavelengths and ground-based observatories covering near-infrared through radio wavelengths.

Another set of supporting observations that were simultaneous with the Subaru observations were made by the Gemini North telescope's NIRI instrument, which imaged Jupiter in the near-infrared, measuring reflected sunlight from cloud and haze particle in Jupiter's upper troposphere and lower stratosphere ‒ levels generally higher in Jupiter's  atmosphere  than  most  of  the  Subaru  measurements,  providing  complementary  information.  “Wide coverage of wavelength available from the telescopes on Maunakea is thus advantageous for the study,” Fujiyoshi says.

The NASA Juno spacecraft was launched in August 2011 and began orbiting Jupiter in early July 2016. A primary goal  of  the  mission  is  to  improve  our  understanding  of  Jupiter  ‒  from  its  atmospheric  properties,  to  our understanding of how Jupiter and other planets in the outer Solar System formed. Subaru's mid-infrared imaging and spectroscopy with COMICS are particularly useful to Juno's instrument, by providing information about the temperature  field  and  the  distribution  of  ammonia,  a  condensate  in  Jupiter  similar  to  water  in  the  Earth's atmosphere. These serve as boundary conditions for the distribution of ammonia at this level and much deeper in Jupiter's atmosphere.

In the full campaign of Earth-based support, the Subaru observations provide the highest spatial resolution of Jupiter's thermal output due to the 8-meter size of its primary mirror. For the images of Jupiter's Great Red Spot in May 2017, COMICS could resolve features close to the 1,000-km resolution of Juno's MWR experiment.

"The Subaru Telescope provided the highest spatial resolution of heating in Jupiter's stratosphere from auroral-related processes," notes co-PI Yasumasa Kasaba of Tohoku University, Japan, who was the PI of collaborative telescope time granted directly by Subaru Telescope. He also notes, "This heating will be studied and compared with auroral phenomena in the ultraviolet and near-infrared observed by Juno and other ground-based facilities, as well as the Hubble Space Telescope and JAXA Hisaki UV/EUV space telescope with Tohoku University's Haleakala telescope and many others."

A full list observatories active in the Juno support observations and details of their observations is given in this page.

Besides Fletcher, Orton, Kasaba, and Fujiyoshi, the collaborative observing team included James Sinclair, Anna Payne (JPL); Joshua Fernandes (California State University, Long Beach); Patrick Irwin (University  of  Oxford);  Padma  Yanamandra-Fisher  (Space  Science  Institute);  Takao  Sato  (JAXA);  Davide  Grassi (IAPS/INAF); Shohei Aoki (IASB, Belgium); Tomoki Kimura (RIKEN); Chihiro Tao, Takeshi Kuroda (NICT); Takeshi Sakanoi, Hajime Kita, Hiromu Nakagawa (Tohoku University); Hideo Sagawa (Kyoto Sangyo University), and Joana Bulger (Subaru Telescope).

For more information contact Dr Leigh Fletcher at


NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Juno mission for the principal investigator, Scott Bolton, of Southwest  Research Institute  in  San  Antonio.  The  Juno  mission  is  part  of  the  New  Frontiers Program  managed  by  NASA's  Marshall  Space  Flight  Center  in  Huntsville,  Alabama,  for  the  Science  Mission Directorate.  Lockheed Martin  Space  Systems,  Denver,  built  the  spacecraft.  JPL is  a  division  of  Caltech  in Pasadena, California.

More information on the Juno mission is available at:

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