Washington: The Hubble Space Telescope’s observations of Jupiter’s icy moon Europa revealed a persistent presence of water vapor, suggesting possible conditions suitable for life, according to NASA.
Hubble is an international collaboration between the US Space Agency and the European Space Agency.
Astronomers at the KTH Royal Institute of Technology, Space and Plasma Physics in Sweden have discovered that Europe has vast oceans beneath its icy surface, but mysteriously, only in one hemisphere.
Previous observations of water vapor on Europa have been linked to blobs erupting through the ice, as photographed by Hubble in 2013. They extend more than 60 miles and produce temporary drops of water vapor in the moon’s atmosphere, which are no more than one millionth of a millionth. surface pressure, NASA says, about Earth’s atmosphere.
The new findings, published in the journal Geophysical Research Letters, show the same amount of water vapor spread over a larger area of Europe in the Hubble observations from 1999 to 2015.
This suggests the existence of a long-term water vapor atmosphere only in the later European hemisphere – the part of the Moon that is always in the opposite direction of its movement along its orbit. The causes of the asymmetry between the anterior and posterior hemispheres are not fully understood.
To make the discovery, Lorenz Roth of KTH investigated the Hubble archive dataset, selecting European ultraviolet observations from 1999, 2012, 2014 and 2015 when the moon was in different orbital positions.
All observations were captured using the Space Telescope Imaging Spectroradiometer (STIS). STIS’s ultraviolet observations allowed Roth to determine the abundance of oxygen – a component of water – in the European atmosphere, and by interpreting the strength of the emission at different wavelengths, he was able to infer the presence of water vapor.
The same technique recently led to the detection of water vapor in the atmosphere of Jupiter’s moon Ganymede.
“Observing water vapor over Ganymede, and on the other side of Europe, advances our understanding of the icy moon’s atmosphere.
“However, the discovery of a steady abundance of water in Europe is a bit more surprising than the discovery on Ganymede because Europa’s surface temperature is lower than that of Ganymede,” Roth said.
Europa reflects more sunlight than Ganymede, making its surface 60 degrees Fahrenheit cooler than Ganymede. The highest daytime temperature in Europe is a freezing 260 degrees Fahrenheit.
However, even at lower temperatures, new observations suggest that water ice sublimates—that is, changes directly from solid to vapor without a liquid phase—from Europa’s surface, as happened on Ganymede, the team said.
The findings help lay the groundwork for a planned scientific mission of the Jovian system, in part, to explore whether an environment half a billion miles from the sun could support life.
(Ean)
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