James Webb Space Telescope to study Jupiter’s Great Red Spot
When NASA’s James Webb Space Telescope (JWST) launches in May 2020, one of its first targets is expected to be Jupiter’s Great Red Spot, a large storm believed to have been active on the giant planet for more than 350 years.
A joint project of NASA, the European Space Agency and the Canadian Space Agency, JWST is expected to be the most complex space telescope ever built. Using its infrared capability, it is expected to return data that could build on previous observations of the storm by smaller observatories and by the Hubble Space Telescope in visible light.
Planetary observation is one of JWST’s mission goals, along with direct imaging of exoplanets and novas, studying star formation and witnessing the formation of the universe’s earliest galaxies.
University of Leicester researcher Leigh Fletcher, lead scientist for JWST’s Great Red Spot observations, along with his science team, is expected to create multi-spectral maps of the Great Red Spot using the telescope’s mid-infrared instrument (MIRI). The researchers are part of a larger group that aims to use JWST to study various Solar System planets.
MIRI is expected to analyze the large storm’s thermal, chemical, and cloud structures, specifically focusing on observations between five and seven micrometers—wavelengths in which the planet has never been observed. These wavelengths, which cannot be detected from Earth even with the most powerful telescopes, may enable scientists to see the large storm’s chemical byproducts, which could yield clues to its composition, according to NASA.
“Webb’s infrared sensitivity provides a wonderful complement to Hubble visible-wavelength studies of the Great Red Spot,” said interdisciplinary JWST scientist Heidi Hammel, executive vice president of the Association of Universities for Research in Astronomy, in a NASA news release. “Hubble images have revealed striking changes in the size of the Great Red Spot over the mission’s multi-decade-long lifetime.”
According to NASA, the researchers hope infrared observations will provide insight into the Great Red Spot’s unique color, which some scientists believe is produced by the interaction of solar radiation with chemicals, including sulfur, nitrogen, and phosphorus, originating deep within the storm and brought to its upper layers by atmospheric currents.
“We’ll be looking for signatures of any chemical compounds that are unique to the [Great Red Spot]…which could be responsible for the red chromophores,” Fletcher said. “If we don’t see any unexpected chemistry or aerosol signatures…then the mystery of that red color remains unresolved.”
According to NASA, chromophores are the parts of molecules that give them their colors.
JWST could potentially solve another mystery, specifically the unexplained heat of Jupiter’s upper atmosphere in the vicinity of the Great Red Spot. According to NASA, one theory is that heat is generated in the storm’s interior and is transported from there to the planet’s upper atmosphere. Specifically, Fletcher wants to test a proposed theory that attributes heat within the Great Red Spot to colliding gravity waves and sound waves produced by the storm.
“Any waves produced by the vigorous convective activity within the storm must pass through the stratosphere before they reach the ionosphere and thermosphere,” Fletcher said. “So if they really do exist and are responsible for heating Jupiter’s outer layers, hopefully, we’ll see evidence for their passage in our data. These particular observations will reveal the storm’s vertical structure, which will be an important constraint for numerical simulations of Jovian meteorology. If those simulations can help explain what Webb observes in the infrared, then we’ll be a step closer to understanding how these gigantic maelstroms live for so long.”
Located 22 degrees south of the giant planet’s equator, the Great Red Spot has been continually monitored since 1830. Scientists are uncertain as to whether it is the same storm spotted by astronomer Robert Hooke in 1664 and by Giovanni Cassini the following year.
Although Hubble data has shown the storm’s size has been shrinking for a while, scientists do not believe it is going to die any time soon.
Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.