Hubble Finds Evidence of Persistent Water Vapor in One Hemisphere of Europa

This photograph of the Jovian moon Europa was taken in June 1997 at a range of 776,700 miles by NASA’s Galileo spacecraft. Slightly smaller than Earth’s moon, Europa has a very smooth surface and the solid ice crust has the appearance of a cracked eggshell. The interior has a global ocean with more water than found on Earth. It could possibly harbor life as we know it. Hubble Space Telescope observations of Europa have revealed the presence of persistent water vapor in its very tenuous atmosphere. Hubble observations, spanning 1999 to 2015, find that water vapor is constantly being replenished throughout one hemisphere of the moon. This is a different finding from Hubble’s 2013 observations that found localized water vapor from geysers venting from its subsurface ocean. This water vapor comes from a different process entirely. Sunlight causes the surface ice to sublimate, transitioning directly into gas. This color composite Galileo view combines violet, green, and infrared images. The view of the moon is shown in natural color (left) and in enhanced color designed to bring out subtle color differences in the surface (right). The bright white and bluish part of Europa’s surface is composed mostly of water ice, with very few non-ice materials. Long, dark lines are fractures in the crust, some of which are more than 1,850 miles long. The Galileo mission ended on Sept. 21, 2003, when the spacecraft was intentionally commanded to dive into Jupiter’s atmosphere, where it was destroyed. However, to this day scientists continue to study the data it collected. The Jet Propulsion Laboratory (JPL) in Pasadena, California managed the Galileo mission for NASA’s Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech). This image and other images and data received from Galileo are posted on the Galileo mission home page. Background information and educational context are also available for the images. (Credits: NASA, NASA-JPL, University of Arizona)

GREENBELT, Md. (NASA PR) — NASA’s Hubble Space Telescope observations of Jupiter’s icy moon Europa have revealed the presence of persistent water vapor – but, mysteriously, only in one hemisphere.