Category Archives: Europa, Titan, & other deep space sites

Cassini observes odd feature in a Titan sea

NASA’s Cassini probe orbiting Saturn spots a feature on the moon Titan that has changed over time:

Cassini Watches Mysterious Feature Evolve in Titan Sea

NASA’s Cassini spacecraft is monitoring the evolution of a mysterious feature in a large hydrocarbon sea on Saturn’s moon Titan. The feature covers an area of about 100 square miles (260 square kilometers) in Ligeia Mare, one of the largest seas on Titan. It has now been observed twice by Cassini’s radar experiment, but its appearance changed between the two apparitions.

Images of the feature taken during the Cassini flybys are available at photojournal.jpl.nasa.gov/catalog/PIA18430

Mysterious Changing Feature in Ligeia MareThese three images, created from Cassini Synthetic Aperture Radar (SAR) data,
show the appearance and evolution of a mysterious feature in Ligeia Mare,
one of the largest hydrocarbon seas on Saturn’s moon Titan.
Image credit: NASA/JPL-Caltech/ASI/Cornell › Full image and caption

The mysterious feature, which appears bright in radar images against the dark background of the liquid sea, was first spotted during Cassini’s July 2013 Titan flyby. Previous observations showed no sign of bright features in that part of Ligeia Mare. Scientists were perplexed to find the feature had vanished when they looked again, over several months, with low-resolution radar and Cassini’s infrared imager. This led some team members to suggest it might have been a transient feature. But during Cassini’s flyby on August 21, 2014, the feature was again visible, and its appearance had changed during the 11 months since it was last seen.

Scientists on the radar team are confident that the feature is not an artifact, or flaw, in their data, which would have been one of the simplest explanations. They also do not see evidence that its appearance results from evaporation in the sea, as the overall shoreline of Ligeia Mare has not changed noticeably.

The team has suggested the feature could be surface waves, rising bubbles, floating solids, solids suspended just below the surface, or perhaps something more exotic.

The researchers suspect that the appearance of this feature could be related to changing seasons on Titan, as summer draws near in the moon’s northern hemisphere. Monitoring such changes is a major goal for Cassini’s current extended mission.

“Science loves a mystery, and with this enigmatic feature, we have a thrilling example of ongoing change on Titan,” said Stephen Wall, the deputy team lead of Cassini’s radar team, based at NASA’s Jet Propulsion Laboratory in Pasadena, California. “We’re hopeful that we’ll be able to continue watching the changes unfold and gain insights about what’s going on in that alien sea.”

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and ASI, the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about Cassini and its mission, visit:

Videos: New Horizons-Pluto and Voyager-Neptune fly-by discussions

The videos have been posted of the panels in Monday’s two-part NASA event (see earlier posting) about the New Horizons Pluto mission and comparing that probe’s passing the orbit of Neptune with the 25th anniversary of the Voyager 2 fly-by of Neptune.

A panel discussion of the New Horizons project:

Caption:

NASA’s Mission to Pluto was a two part televised science event at NASA headquarters on August 25 – the same date that the agency’s New Horizons spacecraft passed the orbit of Neptune on its way to Pluto and exactly 25 years after the Voyager spacecraft’s encounter with Neptune in 1989. During the first event, entitled NASA’s New Horizons Pluto Mission: Continuing Voyager’s Legacy of Exploration, NASA scientists and officials discussed the two missions.

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Five participants in the Voyager 2 fly-by of  Neptune in 1989 reminisce and compare that event with next year’s New Horizon’s fly by of Pluto:

Caption:

NASA’s Mission to Pluto was a two part televised science event at NASA headquarters on August 25 – the same date that the agency’s New Horizons spacecraft passed the orbit of Neptune on its way to Pluto and exactly 25 years after the Voyager spacecraft’s encounter with Neptune in 1989. During the second event, entitled New Horizons-Voyager Connections: Memories from the Team, several New Horizons science team members gave personal accounts of their work during the Voyager Neptune encounter and discussed their new assignments on the Pluto mission.

An improved view of Triton

Neptune’s moon Triton is far, far away but we got a close up look at it when the Voyager 2 probe passed by in 1989. The Voyager’s imagery of Triton has been enhanced with modern processing techniques:

Voyager Map Details Neptune’s Strange Moon Triton 

August 21, 2014 : NASA’s Voyager 2 spacecraft gave humanity its first close-up look at Neptune and its moon Triton in the summer of 1989. Like an old film, Voyager’s historic footage of Triton has been “restored” and used to construct the best-ever global color map of that strange moon. The map, produced by Paul Schenk, a scientist at the Lunar and Planetary Institute in Houston, has also been used to make a movie recreating that historic Voyager encounter, which took place 25 years ago, on August 25, 1989.

The Voyager 2 spacecraft flew by Triton, a moon of Neptune, in the summer of 1989.

The Voyager 2 spacecraft flew by Triton, a moon of Neptune, in the summer
of 1989. 
Image credit: NASA/JPL-Caltech/Lunar & Planetary Institute.
Full image and caption

The new Triton map has a resolution of 1,970 feet (600 meters) per pixel. The colors have been enhanced to bring out contrast but are a close approximation to Triton’s natural colors. Voyager’s “eyes” saw in colors slightly different from human eyes, and this map was produced using orange, green and blue filter images.

In 1989, most of the northern hemisphere was in darkness and unseen by Voyager. Because of the speed of Voyager’s visit and the slow rotation of Triton, only one hemisphere was seen clearly at close distance. The rest of the surface was either in darkness or seen as blurry markings.

The production of the new Triton map was inspired by anticipation of NASA’s New Horizons encounter with Pluto, coming up a little under a year from now. Among the improvements on the map are updates to the accuracy of feature locations, sharpening of feature details by removing some of the blurring effects of the camera, and improved color processing.

Although Triton is a moon of a planet and Pluto is a dwarf planet, Triton serves as a preview of sorts for the upcoming Pluto encounter. Although both bodies originated in the outer solar system, Triton was captured by Neptune and has undergone a radically different thermal history than Pluto. Tidal heating has likely melted the interior of Triton, producing the volcanoes, fractures and other geological features that Voyager saw on that bitterly cold, icy surface.

Pluto is unlikely to be a copy of Triton, but some of the same types of features may be present. Triton is slightly larger than Pluto, has a very similar internal density and bulk composition, and has the same low-temperature volatiles frozen on its surface. The surface composition of both bodies includes carbon monoxide, carbon dioxide, methane and nitrogen ices.

Voyager also discovered atmospheric plumes on Triton, making it one of the known active bodies in the outer solar system, along with objects such as Jupiter’s moon Io and Saturn’s moon Enceladus. Scientists will be looking at Pluto next year to see if it will join this list. They will also be looking to see how Pluto and Triton compare and contrast, and how their different histories have shaped the surfaces we see.

Although a fast flyby, New Horizons’ Pluto encounter on July 14, 2015, will not be a replay of Voyager but more of a sequel and a reboot, with a new and more technologically advanced spacecraft and, more importantly, a new cast of characters. Those characters are Pluto and its family of five known moons, all of which will be seen up close for the first time next summer.

Triton may not be a perfect preview of coming attractions, but it serves as a prequel to the cosmic blockbuster expected when New Horizons arrives at Pluto next year.

The new Triton map and movie can be found at: www.lpi.usra.edu/icy_moons/

In another historic milestone for the Voyager mission, Aug. 25 also marks the two-year anniversary of Voyager 1 reaching interstellar space.

The Voyager mission is managed by NASA’s Jet Propulsion Laboratory, in Pasadena, California, for NASA’s Science Mission Directorate at NASA Headquarters in Washington. Caltech manages JPL for NASA. The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, manages the New Horizons mission for NASA’s SMD.

For more information about the Lunar and Planetary Institute, visit: ww.lpi.usra.edu

For more information about Voyager, visit:

For more information about New Horizons mission, visit:

 

Cassini spots clouds moving over Titan

The Cassini spacecraft orbiting Saturn has returned images showing clouds moving over the surface of the Moon Titan:

Cassini Tracks Clouds Developing Over a Titan Sea

Clouds on Titan

Cassini scientists noted a decrease in clouds everywhere on Titan
after a large storm in 2010, and expected clouds to return sooner,
based on computer models of Titan’s atmosphere.

NASA’s Cassini spacecraft recently captured images of clouds moving across the northern hydrocarbon seas of Saturn’s moon Titan. This renewed weather activity, considered overdue by researchers, could finally signal the onset of summer storms that atmospheric models have long predicted.

A movie showing the clouds’ movement is available at: www.jpl.nasa.gov/spaceimages/details.php?id=PIA18420

Click here for full animation of PIA18420
Click on the image for the full animation

The Cassini spacecraft obtained the new views in late July, as it receded from Titan after a close flyby. Cassini tracked the system of clouds developing and dissipating over the large methane sea known as Ligeia Mare for more than two days. Measurements of cloud motions indicate wind speeds of around 7 to 10 mph (3 to 4.5 meters per second).

For several years after Cassini’s 2004 arrival in the Saturn system, scientists frequently observed cloud activity near Titan’s south pole, which was experiencing late summer at the time. Clouds continued to be observed as spring came to Titan’s northern hemisphere. But since a huge storm swept across the icy moon’s low latitudes in late 2010, only a few small clouds have been observed anywhere on the icy moon. The lack of cloud activity has surprised researchers, as computer simulations of Titan’s atmospheric circulation predicted that clouds would increase in the north as summer approached, bringing increasingly warm temperatures to the atmosphere there.

“We’re eager to find out if the clouds’ appearance signals the beginning of summer weather patterns, or if it is an isolated occurrence,” said Elizabeth Turtle, a Cassini imaging team associate at the Johns Hopkins University Applied Physics Lab in Laurel, Maryland. “Also, how are the clouds related to the seas? Did Cassini just happen catch them over the seas, or do they form there preferentially?”

A year on Titan lasts about 30 Earth years, with each season lasting about seven years. Observing seasonal changes on Titan will continue to be a major goal for the Cassini mission as summer comes to Titan’s north and the southern latitudes fall into winter darkness.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory (JPL) in Pasadena, California, manages the mission for NASA’s Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the United States, England, France and Germany. The imaging team is based at the Space Science Institute in Boulder, Colorado.

More information about Cassini is available at the following sites:

Video: The Lure of Europa – Featuring Bill Nye and special guests

The Planetary Society organized a special event on Capitol Hill last month to discuss the mysteries of the  Jupiter moon Europa and why there should be a NASA mission there.  The event was unexpectedly popular. Lots of  public visitors to the Capital decided to sit in.  Bill Nye was probably a major reason:  The Lure of Europa – Featuring Bill Nye and special guests

Caption:

Europa is a moon of Jupiter that may have three crucial ingredients for life: liquid water, energy, and nutrients. What, if anything, can be found in the great oceans of Europa? Could NASA look for life? How could we explore affordably? Bill Nye The Science Guy, eminent NASA scientists, and prominent legislators examined just these questions in a public event inside the halls of Congress. This was recorded live on July 15th, 2014.

Recorded by Tushar Dayal.

Speakers (in order of appearance):
* Casey Dreier (Director of Advocacy for The Planetary Society and event emcee)
* Rep. Lamar Smith (Chairman, House Science Committee; Texas 21st District)
* Rep. John Culberson (Texas 7th District)
* Rep. Adam Schiff (California 21st District)
* Dr. Ellen Stofan (Chief Scientist, NASA)
* Dr. Robert Pappalardo (Europa Study Scientist, JPL)
* Bill Nye, The Science Guy (CEO of The Planetary Society)