Astronomy Now Online
Home Magazine Sky Chart Resources Store


Top Stories


Generations of stars pose for family portrait

...a stunning new Spitzer image reveals the family portrait of a star-forming inferno...

read more

The interplanetary mapping maverick

...in an exclusive interview to coincide with the September issue of Astronomy Now, the Planetary Science Institute's Dr Robert Gaskell discusses his innovative mapping technique that is bringing the diverse surfaces of the Solar System to life...

read more

XMM discovers monster galaxy cluster

...XMM has uncovered the most massive cluster ever seen in the distant Universe...

read more



Spaceflight Now +



Subscribe to Spaceflight Now Plus for access to our extensive video collections!
How do I sign up?
Video archive

STS-120 day 2 highlights

Flight Day 2 of Discovery's mission focused on heat shield inspections. This movie shows the day's highlights.

 Play

STS-120 day 1 highlights

The highlights from shuttle Discovery's launch day are packaged into this movie.

 Play

STS-118: Highlights

The STS-118 crew, including Barbara Morgan, narrates its mission highlights film and answers questions in this post-flight presentation.

 Full presentation
 Mission film

STS-120: Rollout to pad

Space shuttle Discovery rolls out of the Vehicle Assembly Building and travels to launch pad 39A for its STS-120 mission.

 Play

Dawn leaves Earth

NASA's Dawn space probe launches aboard a Delta 2-Heavy rocket from Cape Canaveral to explore two worlds in the asteroid belt.

 Full coverage

Dawn: Launch preview

These briefings preview the launch and science objectives of NASA's Dawn asteroid orbiter.

 Launch | Science

Become a subscriber
More video



Cassini pinpoints source of Enceladus jets
BY DR EMILY BALDWIN
ASTRONOMY NOW

Posted: August 28, 2008

Thanks to an amazing new array of photographs of Saturn’s geologically active moon Enceladus, Cassini has pinpointed precisely the source of the icy jets seen erupting from the surface in previous fly-bys.

Map of the south polar region of Enceladus showing the correlation between jet sources identified in Cassini imaging data (and correlating to the roman numeral identification of the new images) and hot spots on the surface. Image: NASA/JPL/Space Science Institute.

Carefully targeted pictures uncover exquisite details in the
prominent south polar tiger stripe fractures from which the jets of icy particles, water vapour and traces of organics emanate. The photographs – captured as Cassini sped past the moon at a staggering 64,000 kilometres per hour – show the fractures are about 300 metres deep, with V-shaped inner walls. The outer flanks of several of the fractures show vast deposits of fine material, while large blocks of ice, tens of metres in size, litter the terrain surrounding the larger fractures.

"There appears to have been extensive fallout of icy particles to the ground, along some of the fractures, even in areas that lie between two jet source locations, though any immediate effects of presently active jets are subtle," says Carolyn Porco, Cassini imaging team leader.

Four source locations for the jets in tiger stripes Baghdad Sulcus, Cairo Sulcus and Damascus Sulcus are circled in this image and superimposed on the new high resolution imagery of Enceladus. Roman numerals correspond to locations indicated on the map above. Image: NASA/JPL/Space Science Institute.

Scientists are now focusing their efforts on the nature and intensity of the jetting process and its effects on the surrounding terrain. This information, coupled with observations by Cassini's other instruments, may answer the question of whether reservoirs of liquid water exist beneath the surface.

"This is the mother lode for us," says Carolyn Porco, Cassini imaging team leader. "[The images show] a place that may ultimately reveal just exactly what kind of environment, habitable or not, we have within this tortured little moon."

Combined with broader images showing the whole region, the new high-resolution snapshots provide critical documentation for understanding what may be powering the activity on Enceladus, and for the first time, planetary scientists are beginning to understand how freshly erupted surface deposits differ from older deposits. One current idea suggests that once warm vapour rises from underground to the cold surface through narrow channels, the icy particles may condense and seal off an active vent. Fresh jets may then appear elsewhere along the same fracture. The latest set of images clearly show evidence for the eruptions moving up and down the lengths of the tiger stripes over geologic time.

Related Stories

Aug 13  Enceladus images dazzling success read more

Aug 12  Cassini swoops past Enceladus read more

Jun 02  Cassini primed for extended tour of Saturn read more

May 21  Cassini maps of Saturn’s moons... read more

Mar 27  Cassini tastes organic material... read more

Mar 14  Cassini flyby success read more

Mar 11  Cassini to dive into water plume... read more

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.
 GET YOUR COPY

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.
 GET YOUR COPY

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!
 GET YOUR COPY


HOME | NEWS ARCHIVE | MAGAZINE | SOLAR SYSTEM | SKY CHART | RESOURCES | STORE | SPACEFLIGHT NOW

© 2014 Pole Star Publications Ltd.