You might think that living half a billion miles from the sun wouldn’t be a place we call home. But planetary astronomers are eager to explore Europe for life. Slightly smaller than Earth’s moon, Europa rotates wildly Jupiter. The icy surface of the moon never gets hotter than minus 260 degrees Fahrenheit F. The temperature is so cold that water ice is as hard as rocks.
However, under the solid icy crust, there may be a global ocean with more water than on Earth. And where there is water, there can be life. Like a leaky garden hose, the ocean spews water vapor into space from geysers penetrating cracks in the surface, as first photographed by Hubble Space Telescope in 2013.
The latest development comes from archival Hubble observations from 1999 to 2015, which found that water vapor is constantly replenished throughout the entire lunar hemisphere. This is a bit ambiguous. However, the atmosphere is only a billionth of the surface pressure of the Earth’s atmosphere.
Water vapor was not directly seen, but the spectroscopic ultraviolet signature of the oxygen was measured by Hubble. Oxygen is a component of water. Unlike geysers, this water vapor does not come from Europe, but sunlight makes surface ice sublime. A similar atmosphere of water vapor was recently found on the Jovian Ganymede moon.
Europe is very exciting as a potential home and target for life NASAEurope Clipper and Jupiter Ice Explorer (JUICE) from the European Space Agency – launch planned within a decade.
This image of Jovian moon Europa was taken in June 1997 at a distance of 776,700 miles by NASA’s Galileo spacecraft. Slightly smaller than Earth’s moon, Europa has a very smooth surface and the hard, icy crust has the appearance of broken eggshells. The interior contains a global ocean with more water than that on Earth. It can include life as we know it. Hubble Space Telescope observations of Europe revealed persistent water vapor in its extremely weak atmosphere. Hubble observations, spanning from 1999 to 2015, found that water vapor is constantly replenished throughout the lunar hemisphere. This is a different finding from the 2013 Hubble observations that found localized water vapor from geysers spewed from the underground ocean. This water vapor comes from an entirely different process. Sunlight causes surface ice to become sublime, and it turns directly into gas. This Galileo composite color display combines violet, green, and infrared images. The image of the moon is displayed in natural colors (left) and enhanced colors designed to highlight subtle color differences on the surface (right). The white and bluish portion of Europa’s surface consists mainly of water ice, with very few non-ice materials. The long, dark streaks are fractures of the crust, some over 1,850 miles long. Galileo’s mission ended on September 21, 2003, when the spacecraft was deliberately ordered to dive into Jupiter’s atmosphere, where it was destroyed. However, scientists to this day continue to study the data they 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 operational division of the California Institute of Technology (Caltech). This photograph, images and other data from Galileo is posted on the Galileo Expedition home page. Background information and educational context for images are also available. Credit: NASA, NASA-JPL, University of Arizona
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.
Europa harbors a vast ocean under its icy surface, which can provide favorable conditions for life. The discovery advances astronomers’ understanding of the icy moons’ atmosphere structure and helps lay the foundation for planned scientific missions for the Jupiter system, in part, to explore whether an environment half a billion miles from the sun could support life.
Previous observations of water vapor in Europe have been linked to plumes erupting on ice, as photographed by Hubble in 2013. They are similar to hot springs on Earth, but extend over 60 miles in height. They produce transient points of water vapor in the lunar atmosphere, which are only a billionth of the surface pressure of Earth’s atmosphere.
However, the new results show similar amounts of water vapor spread over an area larger than Europa in the Hubble observations from 1999 to 2015. This indicates a long-term presence of a water vapor atmosphere only in Europa’s back hemisphere – the part of the Moon that is always opposite The direction of its movement along its orbit. The cause of the asymmetry between the anterior and posterior hemispheres is not fully understood.
The discovery was built on a new analysis of images and spectra from the Hubble archives, using a technique that recently led to the discovery of water vapor in the atmosphere of Jupiter’s moon Ganymede by Lorenz Roth of the Royal Institute of Technology, Space and Plasma Physics. , Sweden.
“The observations of water vapor in Ganymede and across Europe advance our understanding of icy moon atmospheres,” Roth said. “However, the discovery of abundant precipitate water in Europe is a little more surprising than the discovery at Ganymede, because Europa’s surface temperatures are lower than Ganymede’s.”
Europa reflects more sunlight than Ganymede, making the surface 60 degrees Fahrenheit cooler than Ganymede. The highest daytime temperature in Europe is 250 degrees Fahrenheit. Even at lower temperatures, the new observations indicate that water ice sublimates—that is, it transforms directly from a solid to vapor without a liquid phase—from Europa’s surface, just as it does at Ganymede.
To make the discovery, Roth investigated Hubble data sets, selecting ultraviolet observations from Europe from 1999, 2012, 2014, and 2015, when the moon was in different orbital positions. All of these observations were captured using the Space Telescope Imaging Spectroradiometer (STIS). STIS ultraviolet observations allowed Roth to determine the abundance of oxygen – a component of water – in Europe’s atmosphere, and by interpreting the intensity of the emission at different wavelengths, he was able to infer the presence of water vapor.
This discovery paves the way for further studies of Europe with future investigations, including NASA’s Europa Clipper mission and the European Space Agency’s (ESA) Jupiter Icy Moons Explorer (JUICE). Understanding the formation and evolution of Jupiter and its moons also helps astronomers gain insight into Jupiter-like planets around other stars.
These results have been published in the journal Geophysical Survey Schemes.
Reference: “A Stable H.2Europe’s Late Hemisphere Atmosphere from HST Images’ by Lorenz Roth, Sep 13, 2021 Available Geophysical Survey Schemes.
doi: 10.1029/2021GL094289
The Hubble Space Telescope is an international collaborative project between NASA and the European Space Agency (ESA). The telescope is operated by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Consortium of Universities for Research in Astronomy in Washington, DC
