Washington, July 27th
Astronomers first discovered evidence of water vapor in the atmosphere of Jupiter’s moon Ganymede with NASA’s Hubble Space Telescope.
This water vapor is formed when the ice from the lunar surface sublimes – so it turns from solid to gas. The findings are published in the journal Nature Astronomy.
Previous research has provided circumstantial evidence that Ganymede, the largest moon in the Solar System, contains more water than all of the earth’s oceans.
However, the temperatures there are so cold that the water on the surface is a frozen solid. The Ganymede Ocean would inhabit about 100 miles below the crust; therefore, water vapor would not represent the evaporation of this ocean. To find this evidence of water vapor, astronomers re-examined Hubble’s observations from the past two decades.
The team, led by Lorenz Roth of the Royal Institute of Technology KTH in Stockholm, Sweden, analyzed combined data from two instruments: the 2018 Hubble Space Spectrograph and archival images from the Space Telescope Imaging Spectrograph (STIS) between 1998 and 2010.
They found that there was almost no atomic oxygen in Ganymede’s atmosphere.
Ganymede’s surface temperature varies greatly during the day and around noon near the equator it can become warm enough for the ice surface to release (or sublimate) a few small amounts of water molecules.
“So far, only molecular oxygen has been observed,” Roth explained. “This occurs when charged particles erode the ice surface. The water vapor we have now measured originates from ice sublimation caused by the thermal leakage of water vapor from warm ice regions,” Roth added.
The finding adds anticipation to the upcoming JUICE European Space Agency mission, which means JUpiter ICy moons Explorer. JUICE is expected to be launched in 2022 and arrival on Jupiter in 2029. It will observe Jupiter and its three largest moons in detail for at least three years, with particular emphasis on Ganymede as a planetary body and potential habitat.
Currently, NASA’s Juno mission has looked closely at Ganymede and recently released new images of the icy moon. Since 2016, Juno has been studying Jupiter and its environment, also known as the Jovian system. IANS