NASA Space

For the first time, water vapor has been found on Jupiter’s massive moon Ganymede

According to new research, astronomers have discovered traces of water vapor for the first time in the wispy sky of the Jupiter’s moon Ganymede, solar system’s biggest satellite. According to the researchers, the discovery could offer light on similar liquid atmospheres that may shroud other icy bodies that are found in the solar system and beyond.

According to a previous study, Ganymede, which is larger compared to Pluto and Mercury and only slightly smaller than Mars, might hold additional water than all of the oceans of the Earth combined. On the other hand, the Jovian moon is frigid that water that is on its surface has frozen solid. Ganymede’s liquid water would be hidden roughly 100 miles (160 kilometers) under its surface. Previous research revealed that ice on the Ganymede’s surface might go straight from solid to gas, skipping the liquid phase, allowing water vapor to form part of the huge moon’s thin atmosphere. However, the proof of the water has been difficult to come by – until now.

Researchers evaluated old and fresh Ganymede data from the Hubble Space Telescope of the NASA Agency for the new study. Hubble took the first ultraviolet photographs of Ganymede in 1998, including shots of its auroras, which are the huge moon’s equivalents of Earth’s southern and northern lights. Within these auroras, colorful ribbons of the electrified gas served as evidence that Ganymede had a weak magnetic field. The existence of the oxygen molecules, each made up of two oxygen atoms, was suggested by ultraviolet signals observed in these auroral bands, which are created when charged particles damage Ganymede’s frozen surface. However, a few of these UV emissions were not consistent with what one would anticipate from a pure molecular oxygen environment. Previous studies showed that the differences were caused by signals from atomic oxygen or single oxygen atoms.

Researchers used Hubble to assess the amount of atomic oxygen found in the atmosphere of Ganymede as part of a broad observing effort to support NASA’s Juno mission to Jupiter. Surprisingly, they observed very little atomic oxygen, implying that the earlier UV signals must have been caused by something else. The researchers were particularly interested in how Ganymede’s surface temperature varies dramatically throughout the day. This is with highs of approximately minus 190 degrees Fahrenheit at noon at the equator. Its lows are approximately minus 315 degrees Fahrenheit at night.

Ice on Ganymede may grow sufficiently heated to turn directly to vapor in the warmest regions. They discovered that discrepancies in the number of ultraviolet photos from Ganymede nearly match where water in the atmosphere of moon would be anticipated based on its environment. “Water vapor in the atmosphere fits the data quite well,” said main study author Lorenz Roth, who serves as a planetary scientist at the Stockholm’s KTH Royal Institute of Technology.

About the author

Andrzej Kowalski