Space

December 13, 2013

Hubble Space Telescope sees evidence of water vapor venting off Jovian moon

nasa-hubble
NASA’s Hubble Space Telescope has observed water vapor above the frigid south polar region of Jupiter’s moon Europa, providing the first strong evidence of water plumes erupting off the moon’s surface.

Previous scientific findings from other sources already point to the existence of an ocean located under Europa’s icy crust. Researchers are not yet certain whether the detected water vapor is generated by water plumes erupting on the surface, but they are confident this is the most likely explanation.

Should further observations support the finding, it would make Europa the second moon in the solar system known to have water vapor plumes. The findings were published in the Thursday, Dec. 12, online issue of Science Express, and reported at the meeting of the American Geophysical Union in San Francisco.

“By far the simplest explanation for this water vapor is that it erupted from plumes on the surface of Europa,” said lead author Lorenz Roth of Southwest Research Institute in San Antonio. “If those plumes are connected with the subsurface water ocean we are confident exists under Europa’s crust, then this means that future investigations can directly investigate the chemical makeup of Europa’s potentially habitable environment without drilling through layers of ice. And that is tremendously exciting,”
In 2005, NASA’s Cassini orbiter detected jets of water vapor and dust spewing off the surface of Saturn’s moon Enceladus. Although ice and dust particles subsequently have been found in the Enceladus plumes, only water vapor gases have been measured at Europa so far.

Hubble spectroscopic observations provided the evidence for Europa plumes in December 2012. Time sampling of Europaís aurora emissions measured by Hubble’s imaging spectrograph enabled the researchers to distinguish between features created by charged particles from Jupiter’s magnetic bubble and plumes from Europaís surface, and to also rule out more exotic explanations such as serendipitously observing a rare meteorite impact.

The imaging spectrograph detected faint ultraviolet light from an aurora, powered by Jupiter’s intense magnetic field, near the moon’s south pole. Excited atomic oxygen and hydrogen produce a variable aurora glow and leave a telltale sign that they are products of water molecules being broken apart by electrons along magnetic field lines.

“We pushed Hubble to its limits to see this very faint emission. These could be stealth plumes, because they might be tenuous and difficult to observe in the visible light.” said Joachim Saur of the University of Cologne in Germany. Saur, who is principal investigator of the Hubble observation campaign, co-wrote the paper with Roth.

Roth suggested long cracks on Europa’s surface, known as lineae, might be venting water vapor into space. Cassini has seen similar fissures that host Enceladus’ jets.

Also like Enceladus, the Hubble team found the intensity of the plumes varies with Europa’s orbital position. Active jets have been seen only when Europa is farthest from Jupiter. But the researchers could not detect any sign of venting when Europa is closer to Jupiter.

One explanation for the variability is these lineae experience more stress as gravitational tidal forces push and pull on the moon and open vents at larger distances from Jupiter. The vents are narrowed or closed when the moon is closest to the gas giant planet.

“The apparent plume variability supports a key prediction that Europa should tidally flex by a significant amount if it has a subsurface ocean,” said Kurt Retherford, also of Southwest Research Institute.

Europa’s and Enceladus’ plumes have remarkably similar abundances of water vapor. Because Europa has roughly 12 times more gravitational pull than Enceladus, the vapor, whose temperature is measured at minus 40 degrees Celsius, does not escape into space as it does at Enceladus. Instead, it falls back onto the surface after reaching an altitude of 125 miles, according to the Hubble measurements. This could leave bright surface features near the moon’s south polar region, the researchers hypothesize.

“If confirmed, this new observation once again shows the power of the Hubble Space Telescope to explore and opens a new chapter in our search for potentially habitable environments in our solar system” said John Grunsfeld, an astronaut who participated in Hubble servicing missions and now serves as NASA’s associate administrator for science in Washington. “The effort and risk we took to upgrade and repair Hubble becomes all the more worthwhile when we learn about exciting discoveries like this one from Europa.”

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. The Association of Universities for Research in Astronomy Inc. in Washington operates STScI for NASA.




All of this week's top headlines to your email every Friday.


 
 

 

Headlines July 31, 2015

News: Carter: Military leaders could arm more troops at home – Following the recent fatal shooting of four Marines and a sailor in Tennessee, Defense Secretary Ash Carter is ordering the military services to consider new policies that would enhance security for troops at home, including potentially arming more personnel.   Business: DOD weighs supplier base,...
 
 

News Briefs July 31, 2015

U.S. delivering eight newer F-16 warplanes to Egypt The United States Embassy in Cairo says the U.S. is delivering eight newer F-16 warplanes to Egypt as part of an ongoing military support package. It says in a July 30 statement that the aircraft, of the current Block 52 production variant, will be flown in from...
 
 
Lockheed Martin photograph

Lockheed Martin successfully tests design changes for Orion spacecraft’s fairing separation system

Lockheed Martin photograph A protective panel for Orion’s service module is jettisoned during testing at Lockheed Martin’s Sunnyvale, California facility. This test series evaluated design changes to the spacecraft’s fair...
 

 

Australian company to provide parts for initial production of Triton UAS

Northrop Grumman has awarded the first Australian supplier contract for the U.S. Navy’s MQ-4C Triton unmanned aircraft system initial production lot to Ferra Engineering. Brisbane-based Ferra Engineering will manufacture mechanical sub-assemblies for the first four Triton air vehicles including structural components. “At Northrop Grumman it’s very important to not only develop...
 
 
Boeing photograph

CH-46 ‘Phrog’ makes its last hop

Boeing photograph The CH-46 Sea Knight helicopter commonly known as the “Phrog,” is set to retire and to be flown one last time by Reserve Marine Medium Helicopter Squadron (HMM) 774 on Aug. 1. The CH-46 Sea Knight is a med...
 
 

Insitu awarded LRIP Lot IV RQ-21A Blackjack Systems contract

Under the terms of its latest contract, Insitu will build six RQ-21A Blackjack systems for the U.S. Navy and Marine Corps. The $78-million Small Tactical Unmanned Aircraft Systems Lot IV Low Rate Initial Production contract is the latest event in the program’s progression toward the Initial Operational Test and Evaluation phase.   “This award will...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>