New findings from NASA’s Juno spacecraft have revealed the presence of mineral salts and organic compounds on Ganymede, Jupiter’s largest moon. This discovery sheds light on the moon’s origin and the composition of its underground sea.
Infrared Data Uncovers Hidden Treasures
In June 2021, Juno completed a flyby of Ganymede, passing just 650 miles above its surface. During this mission, infrared data was collected, providing valuable insights into Ganymede’s composition.
Salts and Organics Found in Unique Locations
Scott Bolton, Juno’s principal investigator, noted that the highest concentration of salts and organics was found in both dark and bright regions of Ganymede’s surface, particularly at latitudes protected by the moon’s magnetic field. Ganymede is the only moon in our solar system known to possess a magnetic field, and this discovery suggests a connection to a deep ocean brine.
Ganymede’s Unique Features
Ganymede stands out among Jupiter’s approximately 79 moons due to its remarkable characteristics:
1. Impressive Size
Ganymede boasts a diameter of 3,273 miles (5,268 kilometers), making it the largest moon in our solar system and even larger than Mercury and Pluto.
2. Intriguing Atmosphere and Subsurface Sea
The moon possesses an atmosphere, an internal dynamo, and a subterranean sea hidden beneath layers of ice and a frosty surface. This subsurface ocean may contain more water than all of Earth’s oceans, lying roughly 100 miles (160 kilometers) beneath the icy exterior. NASA’s Galileo spacecraft first detected this hidden ocean during the 1990s.
3. Escaping Water Vapor
In July 2021, data from the Hubble Space Telescope revealed that ice on Ganymede’s surface was transitioning directly into water vapor and escaping into space.
4. Evidence of a Massive Collision
Researchers discovered in May 2022 that Ganymede’s surface features, such as craters, grooves, and patterns, might have resulted from a colossal collision with an object as large as 90 miles (150 kilometers) wide.
Exploring Ganymede’s Mysteries
The European Space Agency’s Jupiter Icy Moons Explorer (JUICE) mission, with a budget of $1.7 billion, embarked on its journey in April with the goal of entering orbit around Ganymede for a nine-month period starting in late 2034. This historic mission aims to become the first spacecraft to orbit any moon beyond Earth.
Before reaching Ganymede, JUICE will conduct flybys of Europa, Callisto, and Ganymede, gaining insights into these celestial bodies. By studying Ganymede up close, planetary scientists hope to gain a deeper understanding of other distant moons and dwarf planets in our solar system and beyond.
Observing Ganymede from Earth
For those interested in observing Ganymede, it’s currently an ideal time. Jupiter and its moons are in opposition, with Earth situated precisely between the Sun and Jupiter. This celestial alignment makes Jupiter and its moons exceptionally bright and close to Earth.
Grab a pair of binoculars, look to the east at dusk, and you should be able to spot at least three of Jupiter’s four Galilean moons: Ganymede, Europa, Callisto, and Io. Keep in mind that the next opposition of Jupiter will occur on December 7, 2024.
