River and Delta Found on Titan

River on Titan
River and Delta on Saturn’s Moon Titan (click to enlarge)
Image Credit: NASA / JPL-Caltech / ASI

NASA and JPL released this image of a 400 kilometer long river system on Titan. The image was taken on 26 September 2012 by the Cassini spacecraft (in orbit around Saturn) during its 87th flyby of Titan.

The image is oriented with North to the right. The river system flows into the Ligeia Mare, one of three oceans in the northern hemisphere of Titan.

The river is black in appearance, which denotes a smooth surface. Therefore, scientists think that the river is filled with liquid Methane and Ethane along its entire distance.

Saturn Plasma and Enceladus Plumes

Plumes from the South Pole of Enceladus
Image Credit: NASA / JPL / Space Science Institute

Plumes of water and other gases from Enceladus, one of Saturn’s large moons, is now thought to be the source of the dusty plasma circling Saturn. The gases react with the magnetic field of Saturn, stripping electrons from the atoms and molecules. In addition, nano-particles are formed mixed in the plasma. The new results (“Charged nanograins in the Enceladus plume“) have been published in this month’s Journal of Geophysical Research Space Physics:

There have been three Cassini encounters with the south-pole eruptive plume of Enceladus for which the Cassini Plasma Spectrometer (CAPS) had viewing in the spacecraft ram direction. In each case, CAPS detected a cold dense population of heavy charged particles having mass-to-charge (m/q) ratios up to the maximum detectable by CAPS (∼104 amu/e). These particles are interpreted as singly charged nanometer-sized water-ice grains. Although they are detected with both negative and positive net charges, the former greatly outnumber the latter, at least in the m/q range accessible to CAPS. On the most distant available encounter (E3, March 2008) we derive a net (negative) charge density of up to ∼2600 e/cm3 for nanograins, far exceeding the ambient plasma number density, but less than the net (positive) charge density inferred from the RPWS Langmuir probe data during the same plume encounter. Comparison of the CAPS data from the three available encounters is consistent with the idea that the nanograins leave the surface vents largely uncharged, but become increasingly negatively charged by plasma electron impact as they move farther from the satellite. These nanograins provide a potentially potent source of magnetospheric plasma and E-ring material.

Saturn F-Ring Mystery

Saturn F-Ring
Cassini Images an Object Puncturing the F-Ring of Saturn
Image Credit: NASA / JPL-Caltech / SSI / QMUL

Cassini has imaged small objects puncturing the F-ring of Saturn, leaving behind trails of debris that scientists have termed ‘mini-jets’.

Having chanced upon this phenomenon, Carl Murray, a Cassini imaging team member based at Queen Mary University of London, England and others searched through 20,000 images during the seven years Cassini has been at Saturn, and culled some 500 that show these wispy streaks.

Now the imaging team thinks they have the story. Prometheus is a large object in the dynamic F-ring, and its long axis is almost 150 kilometers. It is known to create channels, ripples and snowballs in the F ring, as shown in this video collage. Although a lot of the debris from these collisions dissipate, some of the 1 kilometer sized snowballs persist. They occupy orbits that take them above and below the F-ring, and collide with other particles in the ring at slow relative speeds, around 2 meters per second. These collisions drag glittering ice particles out of the ring, creating the 50 to 150 kilometer long ‘mini-jets’.

Cassini Tasting The Jets of Enceladus

Imagined Encounter of Cassini with the Plumes of Enceladus
Image Credit: NASA / JPL-Caltech / UCLA

The spacecraft Cassini will make a second pass today through the jets spraying from the south pole of Enceladus, one of Saturn’s moons. Less than three weeks ago, Cassini made a similar pass through the jets (27 March). Combined with a previous pass on 1 October, these three passes should allow the ion and neutral mass spectrometer to determine the three dimensional structure of the jets and how they change over time.

This flyby will occur at an altitude of 74 kilometers (46 miles), the same as the March flyby. The plumes are composed of jets of water ice and vapor, and organic compounds emanating from the south polar region. Other measurements of the plumes include the plasma spectrometer and composite infrared spectrometer.

20 Percent Budget Cut for NASA Planetary Science

Money for the Senate Launch System (SLS) has siphoned off funding for the things that NASA does best – Planetary Science Missions. Examples of these over the past three decades include:

  • Viking I and II Mars Landers looked for life in 1976
  • Galileo was launched in 1989 and plunged into Jupiter’s crushing atmosphere on September of 2003 to protect the possible ocean on the moon Europa.
  • The Ulysses Solar Polar Explorer was launched in 1990 and ceased operation in 2009
  • Mars Global Surveyor photographed Mars from 1997 through 2006.
  • MESSENGER was launched in 2004 and arrived in orbit around Mercury in March 0f 2011 after three flybys.
  • The Cassini-Huygens Mission to Saturn arrived in 2004 to Study Saturn and the moon Titan. Exploration continues.
  • Phoenix Mars Lander explored the Martian Polar Region in 2008

The money has been saved for the SLS and building rockets, the things for which NASA is worst:

  • X-33 Venture Star – 1996 to 2001 – 1.2 Billion – Canceled
  • DC-X Delta Clipper – 1991 to 1995 – Transferred to NASA – 1996 -Canceled
  • Constellation and Ares I – 2005 to 2010 – 10 Billion – Canceled

Cassini Captures Rhea at Saturn

Rhea is an Icy Satellite of Saturn.
Image Credit: NASA / JPL-Caltech / SSI

NASA and JPL released this image of the icy moon Rhea, taken on 10 March 2012. The spacecraft Cassini took these and 30 other photographs from an altitude of about 42,000 kilometers (26,000 miles).

All of Cassini’s raw images can be seen at http://saturn.jpl.nasa.gov/photos/raw/.

Below are two views from the flyby.

Closeup of Rhea.
Image Credit: NASA / JPL-Caltech / SSI

Rhea Surface and Craters.
Image Credit: NASA / JPL-Caltech / SSI

Thar’ She Blows

Four Vents at the South Pole of Enceladus
Image Credit: NASA/JPL/Space Science Institute.

Four plumes of water ice can be seen in this image of Enceladus, a 504 kilometer wide moon of Saturn. The image was taken by the Cassini spacecraft at a distance of 617,000 kilometers last December and was just released. The Sun is behind Enceladus and backlights the plumes spewing into space. The moon itself is brightly lit from sunlight reflecting off of Saturn.

Tidal forces created by Saturn stretch and compress the moon’s interior, creating four “tiger stripes” that stretch several hundred kilometers across the south pole. The jets, located along the 500 meter deep stripes, are composed of water vapor and ice, methane, carbon dioxide, and nitrogen.