Spaceflight Now



Spaceflight Now +



Premium video content for our Spaceflight Now Plus subscribers.

Burn ignition!
Mission control erupts in applause as communications from Cassini confirm the orbit insertion burn has begun. (60sec file)
 Play video

Burn completed
Signals from Cassini announce the conclusion of the Saturn orbit insertion burn, confirming the spacecraft has arrived at the ringed planet. (2min 15sec file)
 Play video

Post-arrival briefing
Mission officials hold a post-orbit insertion burn news conference at 1 a.m. EDT July 1 to discuss Cassini's successful arrival at Saturn. (25min 27sec file)
 Play video

Wednesday's status briefing
Cassini's health in the final hours before arrival at Saturn is presented in this status briefing from 12 p.m. EDT on June 30. (33min 09sec file)
 Play video

International cooperation
Officials from the U.S., European and Italian space agencies discuss the international cooperation in the Cassini mission and future exploration projects during this news conference from 2 p.m. EDT June 30. (19min 35sec file)
 Play video

'Ring-side' chat
This informal "ring-side chat" from 5 p.m. EDT June 30 discusses the Cassini mission to Saturn and the future of space exploration. (49min 20sec file)
 Play video

Cassini update
Mission managers and scientists provide an update on the Cassini mission and preview the spacecraft's arrival at Saturn during this news conference from June 29. (51min 58sec file)
 Play video

Phoebe science briefing
Scientists report scientific results from the Cassini spacecraft's close-up examination of Saturn's moon Phoebe. (31min 53sec file)
 Play video

Phoebe flyby preview
This animation shows Cassini during its encounter with the tiny moon Phoebe on the route to Saturn. (42sec file)
 Play video

Cassini preview
The Cassini spacecraft's arrival at Saturn is previewed in this detailed news conference from NASA Headquarters on June 3. (50min 01sec file)
 Play video

Saturn arrival explained
Cassini's make-or-break engine firing to enter orbit around Saturn is explained with graphics and animation. Expert narration is provided by Cassini program manager Robert Mitchell. (3min 33sec file)
 Play video

Cassini mission science
The scientific objectives of the Cassini mission to study the planet Saturn, its rings and moons are explained by Charles Elachi, director of the Jet Propulsion Laboratory. (4min 54sec file)
 Play video

Huygens mission science
After entering orbit around Saturn, the Cassini spacecraft will launch the European Huygens probe to make a parachute landing on the surface of the moon Titan. The scientific objectives of Huygens are explained by probe project manager Jean-Pierre Lebreton. (3min 14sec file)
 Play video

Become a subscriber
More video



NewsAlert



Sign up for our NewsAlert service and have the latest news in astronomy and space e-mailed direct to your desktop.

Enter your e-mail address:

Privacy note: your e-mail address will not be used for any other purpose.



Scientists marvel at photos
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: July 1, 2004

Making gravity visible, close-up images of Saturn's rings shot by NASA's newly arrived Cassini probe revealed an intricate, never-before-seen tapestry of icy particles herded into spiralling density waves by the effects of nearby moons.


One of the images taken by Cassini from orbit of Saturn shows a close-up view of the planet's rings. Credit: NASA/JPL
 
Carolyn Porco, leader of the Cassini camera team, a serious Beatles fan and one of the world's leading authorities on Saturn's ring system, was almost at a loss for words describing her initial impressions of the new vistas opened up by Cassini.

"I don't think you have to be a ring scientist to imagine what last night was like to us," she said of the spacecraft's arrival in Saturn orbit and the initial batch of ring pictures beamed back to Earth early today. "It was beyond description, it was mind blowing, it was every adjective you could think of.

"Even though we've had a long time to think about our images ... I'm surprised at how surprised I am at the beauty and the clarity of these images. They are shocking to me. You are going to see some images now, they were so shocking I thought my team here was playing tricks on me and showing me a simulation of the rings and not the rings themselves. It's just utterly remarkable."

Cassini snapped 61 black-and-white pictures of Saturn's rings early today after completing a 96-minute rocket firing to brake into orbit around the ringed planet. Program manager Bob Mitchell reported this afternoon that engineering data radioed back from Cassini shows the spacecraft survived two ring plane crossings without incident and that all of its myriad subsystems were in good health and operating normally.

Cassini skimmed over the top of the rings as it braked into orbit and shortly after main engine shut down, the spacecraft began carrying out commands to photograph the rings, first from the upper backlit side and then from below, where the thin disk of icy particles was bathed in direct sunlight.

Because of Cassini's enormous velocity - 60,000 mph or so at engine cutoff - its cameras were programmed with shutter speeds of five thousandths of a second to prevent blurring. In the minute required to snap a picture, record the data and be ready for another shot, Cassini moved hundreds of miles, preventing researchers from taking overlapping photos or the multiple images required for color.

But no one was complaining.


One of the images taken by Cassini from orbit of Saturn shows a close-up view of the planet's rings. Credit: NASA/JPL
 
"The Cassini cameras are far more capable than the Voyager cameras were, which is in large part why these images are so spectacular," Porco said. "The other part, of course, is that the spacecraft gives us a very steady platform. This machine, you turn it, you point it and it stays there. It's like a tripod in space. So it allows us to take very sharp images."

Cassini will never again fly so close to the rings and the level of detail the craft's cameras captured was stunning. If there was a central theme to the pictures it was the ubiquitous presence of density waves, regions of alternating brightness and darkness that look like ripples in fine sand. The spacing of the ripples, caused by gravitational interactions with nearby moons, decreases as one moves outward from the planet.

"This is a telltale sign of a density wave, the wavelengths decreases as you go outward and also the amplitude of the wave damps so you see it disappear," Porco said, describing one picture. "These are characteristics ring scientists read like a book to discern what kind of properties the particles have, how densely they're packed and so on. As I said, this is unprecedented resolution for the imaging experiment."

One image showed a density wave thinning out to the right and a so-called bending wave moving to the left across the field of view.

In a bending wave, "it's not the number density of particles that is varying, it is literally the height of the ring plane," Porco said. "You can think of the feature on the right as being like corrugated cardboard where the ring is literally warped and its warped because the moons which are exciting that particular wave excite inclination (tilt) in the particle orbits and the particle orbits get phased in such a way that it forms this pattern, which in fact is a spiral pattern.

"If you followed it around the rings, it would take the spiral form," she said. "These are similar to the spiral arms of spiral galaxies."

Describing a blow up of a density wave image, Porco pointed out strange looking structures that "almost looks like straw. I don't know what this is. We think it's real, we see it in other images. ... So it's not some noise pattern in the image.

"There may be processes going on that make the particles clump on scales that you're seeing here. ... Nonetheless we're seeing something here and I literally don't have a clue. This may be brand new, something no one's ever predicted before."

The picture Porco initially thought was a joke was focused on a gap in the outer A ring known as the Encke division, a narrow void swept out by the tiny moon Pan. Along with showing ultra clear views of spiralling density waves on both sides of the gap, the ring material forming the inner edge had a sharply scalloped appearance. Even to the layman, the picture appeared unusual.


One of the images taken by Cassini from orbit of Saturn shows a close-up view of the planet's rings. Credit: NASA/JPL
 
"It just doesn't look real," Porco marveled. "It's so sharp, the wakes that you see in the interior to the Encke gap, you can see the classic scalloped edges. These are caused by gravitational impulses by Pan - there may be other moons there, we don't know - which force eccentricities in the orbits of the particles on the edge of the gap. With repeated passages of the moon ... it builds up this sinusoidal pattern, this beautiful classic pattern.

"This is like textbook physics, textbook ring physics right there in one image," she said.

At a news conference Porco was asked why the study of Saturn's rings was important.

"This is standard ring lore, that Saturn's rings especially are our closest analogue of the celestial disk system," she began. "Frank Shu, an astrophysicist, said this many years ago: there are two types of bodies in the universe. There are spheres and there are disks. And under certain circumstances, a sphere can collapse down into a disk and that's what will happen if you have a spherical cloud of debris and the particles are colliding, they lose energy but they preserve angular momentum and they all end up in a plane. That's a very common process and its given rise to lots of disk system.

"One is Saturn's rings, one was the solar nebula out of which our solar system and the planets formed. Astronomers now see lots of disks around other stars and even reaching way far out in size to the spiral galaxies, they are another disk system. Common physics applies to all of them.

"So in studying rings, we hope to study processes that go on in disks in general," Porco said. "And so we think we're seeing in Saturn's rings some of the processes that went on in the solar nebula before the planets formed. In fact, we may be seeing some of the processes that actually aided the development of the planets."

If one is interested in "understanding where the solar system came from or how it got here, how the planets were formed, then this is the place to go."

Ed Weiler, an astronomer by training who serves as NASA's associate administrator for space flight, offered another reason to study Saturn and its rings.

"When I was growing up, this kind of stuff was science fiction," he said. "We compete with a lot of things: Game Boys, X-Boxes and Play Stations. This isn't science fiction, we actually did this. We're in orbit around another planet taking these kinds of pictures with an incredible machine. We did this. This isn't animation, this isn't PowerPoint, this is real. I like data, and this is real data.

"So I hope we can excite at least a few more kids in this country to become scientists and engineers. If we can do that, it was worth every penny we spent on it."

Spaceflight Now Plus
Additional coverage for subscribers:
VIDEO: TODAY'S NEWS CONFERENCE ON CASSINI'S FIRST PICTURES QT
VIDEO: RING PICTURES ARE PRESENTED WITH EXPERT NARRATION QT
VIDEO: CASSINI RE-DISCOVERS TINY MOONS ATLAS AND PAN QT
VIDEO: CASSINI BOOMING SOUNDS FROM BOW-SHOCK CROSSING QT

VIDEO: CASSINI BEGINS ENGINE FIRING TO ENTER ORBIT QT
VIDEO: BURN ENDS SUCCESSFULLY TO PUT CASSINI IN ORBIT QT
VIDEO: POST-ARRIVAL NEWS CONFERENCE QT

VIDEO: WEDNESDAY'S 12 P.M. EDT CASSINI STATUS BRIEFING QT
VIDEO: A LOOK AT INTERNATIONAL COOPERATION QT
VIDEO: 'RING-SIDE CHAT' ABOUT SPACE EXPLORATION QT
VIDEO: AN OVERVIEW OF CASSINI'S RADIO SCIENCE QT

VIDEO: TUESDAY'S CASSINI MISSION OVERVIEW BRIEFING QT
VIDEO: CASSINI'S ARRIVAL AT SATURN EXPLAINED QT
VIDEO: SCIENCE OBJECTIVES FOR CASSINI ORBITER QT
VIDEO: HUYGENS LANDER SCIENCE OBJECTIVES QT
SUBSCRIBE NOW

New Station
Crew Patch


Free shipping to U.S. addresses!

The Expedition 38 embroidered crew patch for the International Space Station is now available in our store!
 U.S. STORE
 WORLDWIDE STORE


Columbia Report
A reproduction of the official accident investigation report into the loss of the space shuttle Columbia and its crew of seven.
 Choose your store:
U.S. - U.K. - E.U. - Worldwide

Mars Panorama

DISCOUNTED! This 360 degree image was taken by the Mars Pathfinder, which landed on the Red Planet in July 1997. The Sojourner Rover is visible in the image.
 Choose your store:
U.S.

Apollo 11 Mission Report
Apollo 11 - The NASA Mission Reports Vol. 3 is the first comprehensive study of man's first mission to another world is revealed in all of its startling complexity. Includes DVD!
 Choose your store:
U.S. - U.K. - E.U. - Worldwide

Rocket DVD
If you've ever watched a launch from Kennedy Space Center, Cape Canaveral, Vandenberg Air Force Base or even Kodiak Island Alaska, there's no better way to describe what you witnessed than with this DVD.
 Choose your store:
U.S. - U.K. - E.U. - Worldwide

Apollo 11 special patch
Special collectors' patch marking the 35th anniversary of the historic Apollo 11 moon landing is now available.
 Choose your store:
U.S. - U.K. - E.U. - Worldwide

Inside Apollo mission control
An insider's view of how Apollo flight controllers operated and just what they faced when events were crucial.
 Choose your store:
U.S.

The ultimate Apollo 11 DVD
This exceptional chronicle of the historic Apollo 11 lunar landing mission features new digital transfers of film and television coverage unmatched by any other.
 Choose your store:
U.S. - U.K. - E.U. - Worldwide

Next ISS crew
Own a little piece of history with this official patch for the International Space Station's Expedition 11 crew. We'll ship yours today!
 Choose your store:
U.S.

Ares 1-X Patch
The official embroidered patch for the Ares 1-X rocket test flight, is available for purchase.
 U.S. STORE
 WORLDWIDE STORE

Apollo Collage
This beautiful one piece set features the Apollo program emblem surrounded by the individual mission logos.
 U.S. STORE

Expedition 21
The official embroidered patch for the International Space Station Expedition 21 crew is now available from our stores.
 U.S. STORE
 WORLDWIDE STORE

Hubble Patch
The official embroidered patch for mission STS-125, the space shuttle's last planned service call to the Hubble Space Telescope, is available for purchase.
 U.S. STORE
 WORLDWIDE STORE

INDEX | PLUS | NEWS ARCHIVE | LAUNCH SCHEDULE
ASTRONOMY NOW | STORE

ADVERTISE

© 2014 Spaceflight Now Inc.