Is there a Water or not?

NASA's Cassini Discovers Potential Liquid Water on Enceladus

03.09.06

NASA's Cassini spacecraft may have found evidence of liquid water reservoirs that erupt in Yellowstone-like geysers on Saturn's moon Enceladus. The rare occurrence of liquid water so near the surface raises many new questions about the mysterious moon.

Image right: Plumes of icy material extend above the southern polar region of Saturn’s moon Enceladus as imaged by the Cassini spacecraft in February 2005. The monochrome view is presented along with a color-coded version on the right. The latter reveals a fainter and much more extended plume component.
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"We realize that this is a radical conclusion -- that we may have evidence for liquid water within a body so small and so cold," said Dr. Carolyn Porco, Cassini imaging team leader at Space Science Institute, Boulder, Colo. "However, if we are right, we have significantly broadened the diversity of solar system environments where we might possibly have conditions suitable for living organisms."

High-resolution Cassini images show icy jets and towering plumes ejecting large quantities of particles at high speed. Scientists examined several models to explain the process. They ruled out the idea that the particles are produced by or blown off the moon's surface by vapor created when warm water ice converts to a gas. Instead, scientists have found evidence for a much more exciting possibility -- the jets might be erupting from near-surface pockets of liquid water above 0 degrees Celsius (32 degrees Fahrenheit), like cold versions of the Old Faithful geyser in Yellowstone.

Mission scientists report these and other Enceladus findings in this week's issue of Science.

"We previously knew of at most three places where active volcanism exists: Jupiter's moon Io, Earth, and possibly Neptune's moon Triton. Cassini changed all that, making Enceladus the latest member of this very exclusive club, and one of the most exciting places in the solar system," said Dr. John Spencer, Cassini scientist, Southwest Research Institute, Boulder, Colo.

"Other moons in the solar system have liquid-water oceans covered by kilometers of icy crust," said Dr. Andrew Ingersoll, imaging team member and atmospheric scientist at the California Institute of Technology, Pasadena, Calif. "What's different here is that pockets of liquid water may be no more than tens of meters below the surface."

Other unexplained oddities now make sense. "As Cassini approached Saturn, we discovered that the Saturnian system is filled with oxygen atoms. At the time we had no idea where the oxygen was coming from," said Dr. Candy Hansen, Cassini scientist at NASA's Jet Propulsion Laboratory in Pasadena. "Now we know that Enceladus is spewing out water molecules, which break down into oxygen and hydrogen."

Scientists are also seeing variability at Enceladus. "Even when Cassini is not flying close to Enceladus, we can detect that the plume's activity has been changing through its varying effects on the soup of electrically-charged particles that flow past the moon," said Dr. Geraint H. Jones, Cassini scientist, magnetospheric imaging instrument, Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany.

Scientists still have many questions. Why is Enceladus currently so active? Are other sites on Enceladus active? Might this activity have been continuous enough over the moon's history for life to have had a chance to take hold in the moon's interior?

"Our search for liquid water has taken a new turn. The type of evidence for liquid water on Enceladus is very different from what we've seen at Jupiter's moon Europa. On Europa the evidence from surface geological features points to an internal ocean. On Enceladus the evidence is direct observation of water vapor venting from sources close to the surface," said Dr. Peter Thomas, Cassini imaging scientist, Cornell University, Ithaca, N.Y.

In the spring of 2008, scientists will get another chance to look at Enceladus when Cassini flies within 350 kilometers (approximately 220 miles), but much work remains after Cassini's four-year prime mission is over.

"There's no question that, along with the moon Titan, Enceladus should be a very high priority for us. Saturn has given us two exciting worlds to explore," said Dr. Jonathan Lunine, Cassini interdisciplinary scientist, University of Arizona, Tucson, Ariz.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the Caltech, manages the mission for NASA's Science Mission Directorate. The Cassini orbiter was designed, developed and assembled at JPL.

Liquid Flowing on Saturn's Giant Moon: Titan

Flowing Liquids on Titan

01.08.07

This synthetic aperture radar image was obtained by the Cassini spacecraft on its pass by Titan's south pole on Dec. 20, 2007. This image is centered near 76.5 south, 32.5 west and covers an area of 620 kilometers by 270 kilometers (385 miles by 170 miles).

Abundant evidence for flowing liquids is seen in this image, from sinuous, wide river channels to shorter, more chaotic drainage patterns. The extremely dissected, rugged terrain in the southern portion of the image has been very eroded by flowing liquids, probably from a combination of methane rainstorms and sapping (subsurface methane rising to erode the surface). The broad valleys seen in the southern portion of the image are particularly intriguing, as they appear to be flat-floored, filled with smooth material, and in places have sharply defined, relatively straight sides. Valleys such as this can be formed by tectonic processes, such as rifting, or by erosional processes, caused by flowing liquid or ice.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

Kibo Module is Now Attached!

Crews Continue Work on Kibo


Image above: A view of Mission Specialists Mike Fossum and Ron Garan as they conduct the second spacewalk of the STS-124 mission. Photo credit: NASA TV

The assembly of the Japan Aerospace Exploration Agency's Kibo laboratory continues today as the STS-124 and Expedition 17 crew members move the logistics module to its fixed position atop the newly installed experiment module.

Mission Specialists Akihiko Hoshide and Garrett Reisman will prepare Kibo’s Japanese Logistics Module (JLM) for removal from its interim location on the Harmony node by removing electrical jumper cables from the vestibule between the two modules and depressurizing the passageway.

Then, with Mission Specialist Karen Nyberg and Flight Engineer Greg Chamitoff at the controls, the International Space Station’s Canadarm2 will unberth the JLM from the top berthing port on the Harmony node and maneuver it for installation to its permanent home atop Kibo’s Japanese Pressurized Module (JPM). Leak checks and pressurization of the JLM and vestibule will follow.

The crew also will activate the Japanese robotic arm located at the forward end cone of the JPM.

In addition, the crew members will participate in several media interviews.

The Phoenix Has Landed...

PASADENA, Calif. -- NASA's Phoenix spacecraft landed in the northern polar region of Mars today to begin three months of examining a site chosen for its likelihood of having frozen water within reach of the lander's robotic arm.

Radio signals received at 4:53:44 p.m. Pacific Time (7:53:44 p.m. Eastern Time) confirmed the Phoenix Mars Lander had survived its difficult final descent and touchdown 15 minutes earlier. The signals took that long to travel from Mars to Earth at the speed of light.

Mission team members at NASA's Jet Propulsion Laboratory, Pasadena, Calif.; Lockheed Martin Space Systems, Denver; and the University of Arizona, Tucson, cheered confirmation of the landing and eagerly awaited further information from Phoenix later tonight.

Among those in the JPL control room was NASA Administrator Michael Griffin, who noted this was the first successful Mars landing without airbags since Viking 2 in 1976.

"For the first time in 32 years, and only the third time in history, a JPL team has carried out a soft landing on Mars," Griffin said. "I couldn't be happier to be here to witness this incredible achievement."

Team members celebrate Phoenix landing on Mars.
Larger view During its 422-million-mile flight from Earth to Mars after launching on Aug. 4, 2007, Phoenix relied on electricity from solar panels during the spacecraft's cruise stage. The cruise stage was jettisoned seven minutes before the lander, encased in a protective shell, entered the Martian atmosphere. Batteries provide electricity until the lander's own pair of solar arrays spread open.

"We've passed the hardest part and we're breathing again, but we still need to see that Phoenix has opened its solar arrays and begun generating power," said JPL's Barry Goldstein, the Phoenix project manager. If all goes well, engineers will learn the status of the solar arrays between 7 and 7:30 p.m. Pacific Time (10 and 10:30 p.m. Eastern Time) from a Phoenix transmission relayed via NASA's Mars Odyssey orbiter.

The team will also be watching for the Sunday night transmission to confirm that masts for the stereo camera and the weather station have swung to their vertical positions.

"What a thrilling landing! But the team is waiting impatiently for the next set of signals that will verify a healthy spacecraft," said Peter Smith of the University of Arizona, principal investigator for the Phoenix mission. "I can hardly contain my enthusiasm. The first landed images of the Martian polar terrain will set the stage for our mission."

Another critical deployment will be the first use of the 7.7-foot-long robotic arm on Phoenix, which will not be attempted for at least two days. Researchers will use the arm during future weeks to get samples of soil and ice into laboratory instruments on the lander deck.

The signal confirming that Phoenix had survived touchdown was relayed via Mars Odyssey and received on Earth at the Goldstone, Calif., antenna station of NASA's Deep Space Network.

Phoenix uses hardware from a spacecraft built for a 2001 launch that was canceled in response to the loss of a similar Mars spacecraft during a 1999 landing attempt. Researchers who proposed the Phoenix mission in 2002 saw the unused spacecraft as a resource for pursuing a new science opportunity. Earlier in 2002, Mars Odyssey discovered that plentiful water ice lies just beneath the surface throughout much of high-latitude Mars. NASA chose the Phoenix proposal over 24 other proposals to become the first endeavor in the Mars Scout program of competitively selected missions.

The Phoenix mission is led by Smith at the University of Arizona with project management at JPL and development partnership at Lockheed Martin, Denver. International contributions come from the Canadian Space Agency; the University of Neuchatel, Switzerland; the universities of Copenhagen and Aarhus, Denmark; Max Planck Institute, Germany; and the Finnish Meteorological Institute.