Video Transcript:NASA Journey To The Ringworld

==RINGWORLD==
 A Planetarium Script for JPL / NASA
 
 by Dr. William Gutsch
(Narration Copy -- Flat Screen Update Version -- Late February 2005)
(Alternative narration lines in Metric follow lines in Imperial units.)
Its name is Cassini-Huygens.
On October 15, 1997, it sailed out from the port of Earth
on a seven year,
two billion mile odyssey to the outer solar system.
* * *
It's name is Cassini-Huygens.
On October 15, 1997, it sailed out from the port of Earth
on a seven year,
three billion kilometer odyssey to the outer solar system.
* * *
The size of a school bus
with a total weight of over 12,000 pounds,
and an array of 18 packages of scientific instruments,
Cassini-Huygens represents the combined effort
of scientists and engineers in 18 countries,
and is one of the largest, heaviest,
and most sophisticated interplanetary spacecraft ever launched.
* * *
The size of a school bus
with a total weight of over 5,000 kilograms,
and an array of 18 packages of scientific instruments,
Cassini-Huygens represents the combined effort
of scientists and engineers in 18 countries,
and is one of the largest, heaviest,
and most sophisticated interplanetary spacecraft ever launched.
* * * 
It's destination?…
One of the most intriguing objects in the solar system --
a world of unparalleled beauty and the undisputed "Lord of the Rings" --
Saturn!
For Cassini, the road to Saturn is both long and winding …
… a complex but clever routing
carefully designed to not exceed the limited fuel available and,
at the same time,
take advantage of some extra sightseeing and science along the way.
In what amounts to "going the wrong way first",
Cassini leaves Earth and heads inward, toward the sun
for a rendezvous with our neighbor world, Venus.
But this move is intentional
and only the first step in a calculated series
of what scientists and engineers call "gravity assists".
As it swings close, Venus' gravity is used to tug on Cassini
and change its speed and direction in a very exact way.
For, after a brief engine burn, known as the Deep Space Maneuver,
the spacecraft loops back for a second encounter with Venus.
But the flight path is different this time,
different enough to direct Cassini back toward Earth.
Scientists now use this flight past Earth,
instead of the initial launch from Earth
to toss the spacecraft outward, away from the sun.
And so, Cassini finally sails out …
… across the orbit of Mars …
through the asteroid belt …
and on to giant Jupiter.
During the late 1990s, a spacecraft named Galileo arrived here,
went into orbit around Jupiter,
and provided unprecedented reconnaissance of the planet
and many of its satellites.
Now, in what becomes known as the "Millennium Fly-by",
Cassini adds its cameras and scientific instruments to the effort.
Working in tandem, Cassini and Galileo
map Jupiter's immense magnetic field in three dimensions
as high energy particles, streaming from the distant sun,
buffet the field and continually reshape its outer boundaries.
Some of the particles, along with others from Jupiter's volcanic moon, Io,
are channeled along spiraling paths
down toward the planet's magnetic poles.
There, they collide with Jupiter's upper atmosphere
and set vast regions aglow with shimmering displays
of the Northern and Southern Lights.
In addition, the two spacecraft send back a flood of other data
including dazzling images.
But how do data and images get from spacecraft
such as Cassini
back to scientists hundreds of millions, or even billions, of miles away
on Earth?
* * *
But how do data and images get from spacecraft
such as Cassini
back to scientists hundreds of millions, or even billions, of kilometers away
on Earth?
In California's Mojave Desert, a giant dish shaped antenna
230 feet in diameter stands ready to perform the task..
* * *
In California's Mojave Desert, a giant dish shaped antenna
70 meters in diameter stands ready to perform the task..
* * *
Together with two other sets of super sensitive radio antennas
near Madrid, Spain and Canberra, Australia,
they comprise the components of NASA's Deep Space Network, or DSN.
As the Earth spins in space,
the antennas of one DSN complex after another
are strategically positioned to keep a nearly constant vigil
on a distant spacecraft such as Cassini.
The Deep Space Network provides data on the spacecraft's
speed, and distance.
But its main purpose is to serve as a two way link allowing
scientists and engineers to send instructions to the spacecraft,
and also receive data, including images, from the spacecraft back on Earth.
All this information is sent to Earth
as strings of 1's and 0's "riding the backs" of radio waves
transmitted from Cassini's antennas.
High speed computers at NASA's Jet Propulsion Laboratory
in Pasadena, California are linked to the DSN
and transform these streams of numbers into meaningful information.
In the case of images, numbers become "dots", or "pixels""
in various shades of gray
that are then arranged, row by row, into rectangular pictures.
Three or more such black and white images,
taken through different colored filters,
can then be combined to create an image in color.
And sequences of such images can be strung together to add dramatic,
time-lapse motion to make phenomena like Jupiter's enormous,
dynamic cloud systems come to life.
The task is not dissimilar from what your home computer does in
converting numerical data into pictures you may get
with E-mail or via a TV satellite dish.
But NASA's of the Deep Space Network antennas
are far more sensitive.
They need to be …
for the typical signal transmitted from a spacecraft such as Cassini
is so diluted by the time it reaches Earth,
it can be 20 billion times weaker than the power needed to run
a single digital wristwatch!
The Deep Space Network --plucking "whispers from the sky" and,
over the years, providing a vital link to Cassini …
and NASA's many other "robot explorers" across the solar system.
As winter melts into spring 2001 back on Earth,
Cassini wraps up its brief sojourn at Jupiter.
It has been three years and three months since its launch from Earth.
Now, the final gravity assist from Jupiter is all that is needed
to set the stage for the main event --
Cassini's encounter with Saturn
and its entourage of fascinating satellites.
Mid-June 2004.
Cassini finally reaches the domain of Saturn.
Now … the main work begins.
From this great distance, even traveling at the speed of light,
radio signals to and from the spacecraft
will take nearly three hours to make a round trip journey.
So engineers have "built the spacecraft smart" to largely think for itself
using carefully pre-planned instructions
and contingencies in case of emergencies.
Things are about to start happening so fast,
Cassini will largely be on its own.
19 days before Cassini officially arrives at Saturn,
it encounters the largest of the planet's outer satellites, Phoebe.
The images are wonderfully clear and reveal
what may be a denizen from the far reaches of the outer solar system
that has been captured by Saturn.
Such objects have been described by some as "dirty icebergs".
Indeed, several of Phoebe's craters lend evidence to this scenario
for they show darker, surface material which has slid down
the walls of craters to reveal bright ice underneath.
Cassini races toward its rendezvous with Saturn
drawn by the ringed giant's strong gravitational field.
As Cassini plunges onward, its speed approaches 50,000 miles per hour--
fast enough to fly coast to coast across the United States
in 3 minutes!
* * *
As Cassini plunges onward, its speed approaches 80,000 kilometers per hour,
fast enough to fly coast to coast across the United States
in 3 minutes.
* * *
A moment of truth has arrived --
a "hold your breath moment" upon which
the entire rest of the mission hangs for, at this speed,
Cassini is moving too fast and would simply fly past Saturn.
The spacecraft streaks inward skirting just above the rings
and then …
… for nearly 100 minutes, Cassini's main engine fires in just the right way
to change the spacecraft's speed by 1300 miles per hour
and allow it to drop into orbit around Saturn.
* * *
The spacecraft streaks inward skirting just above the rings
and then …
… for nearly 100 minutes, Cassini's main engine fires in just the right way
to change the spacecraft's speed by nearly 2100 kilometers per hour
and allow the it to drop into orbit around Saturn.
* * *
Cassini's instruments take advantage of this closest approach
to scrutinize the rings and
monitor the innermost regions of the planet's magnetic field.
For the next 6 months,
Cassini completes three carefully executed orbits of Saturn,
as images and other data stream toward Earth.
During these three orbits,
engineers also painstakingly adjust Cassini's speed
and prepare the spacecraft for the next critical part of the mission.
Now, it is time for Cassini's piggybacking Huygens probe
to take center stage.
The product of the European Space Agency,
Huygens' mission is to detach from Cassini,
descend into the atmosphere of Saturn's largest satellite, Titan,
and actually land on its surface.
A final system's check and then …
(Huygens spins up and separates from Cassini as the explosive bolts fire.)
Four hours before Huygens encounters Titan's upper atmosphere,
a wake up call sounds and Huygens' array of instruments come alive.
Larger than the planets Mercury and Pluto,
Titan is one of the most intriguing satellites in the solar system.
It has a substantial atmosphere --
a thick, smoggy shroud of an atmosphere …
but cameras on Cassini begin to see through the haze
to reveal tantalizing light and dark features below.
With Huygens on final approach, the landing zone is narrowed.
Batteries alone will power the probe through the next few critical hours --
the first epic landing on the moon of another planet.
The descent phase has begun as Huygens slams into Titan's upper atmosphere at nearly 14,000 miles per hour!
* * *
The descent phase has begun as Huygens slams into Titan's upper atmosphere at over 22,000 kilometers per hour!
* * *
Over the next three minutes,
temperatures immediately in front of Huygens' heat shield will soar
from 300 degrees below zero to over 21,000 degrees Fahrenheit--
twice the surface temperature of the sun!
In the same three minutes, atmospheric drag also brakes the probe's speed from nearly 14,000 miles per hour to less than 900!
* * *
Over the next three minutes,
temperatures immediately in front of Huygens' heat shield will soar
from nearly 200 degrees below zero Celsius to over 11,000 degrees--
twice the surface temperature of the sun!
In the same three minutes, atmospheric drag also brakes the probe's speed from nearly 22,000 kilometers per hour to less than 1,500!
* * *
At one and a half times the speed of sound, a pilot chute is released
pulling off Huygens' aft cover.
Almost immediately, the probe's main parachute unfurls.
We are 110 miles from the surface.
* * *
We are 175 kilometers from the surface.
* * *
Within 30 seconds, Huygens has slowed to little over half the speed of sound.
The heat shield has done its work and is jettisoned.
For the next 15 minutes, the probe descends under its main chute
as initial scientific measurements begin.
High above, Cassini collects the data transmitted by Huygens
and stands ready to relay it to Earth.
Finally, a smaller drogue chute takes over.
Altitude: 85 miles.
* * *
Altitude: 140 kilometers.
* * *
For the next two and a quarter hours,
as it continues its descent toward the surface,
Huygens' instruments will be busy.
Winds build to 250 miles per hour as Huygens "sniffs" Titan's atmosphere recording its chemical composition.
* * *
Winds build to 450 kilometers per hour as Huygens "sniffs" Titan's atmosphere recording its chemical composition.
* * *
There is abundant nitrogen, as on Earth,
but also a mix of more exotic chemicals
like methane, benzene, and diacetylene.
None the less,
many scientists believe the chemistry of Titan's atmosphere
mimics that of Earth long ago.
If so, Titan may well provide scientists with the equivalent
of a "time machine" to travel back to an era
before life first developed on our world.
Finally, descending through a last layer of cloud, we see the surface --
a close up view of a tiny portion
of the largest unexplored landscape in the solar system.
Our brains struggle to interpret what Huygens eyes reveal.
As Huygens spins beneath its drogue chute
descending from an altitude of 9 down to 5 miles,
a rich mosaic of light and dark areas is stitched together.
* * *
As Huygens spins beneath its drogue chute
descending from an altitude of 14 down to 8 kilometers,
a rich mosaic of light and dark areas is stitched together.
* * *
Soon cameras zero in on an array of intriguing and mystifying features --
… areas of white that may be banks of fog or mist,
… bright spots that may be chains of "islands"
or higher elevation peaks amid a level plain,
… dark regions where springs of liquid methane instead of water
may bubble to the surface,
… and what may well be a coastline of sorts
where rivers and streams of liquid methane flow down hills of ice
to a broad, dark region below.
At last, Huygens comes to rest
with more of a splat than a thud or a splash --
indicative of a surface with the consistency of wet sand.
Its batteries running low,
Huygens still remains active for another few hours
recording a surface temperature near 300 degrees below zero Fahrenheit,
wafts of methane gas on a light breeze,
and a landscape of orange colored chunks of ice under an orange sky.
* * *
Its batteries running low,
Huygens still remains active for another few hours
recording a surface temperature near 180 degrees below zero Celsius,
wafts of methane gas on a light breeze,
and a landscape of orange colored chunks of ice under an orange sky.
* * *
As Huygens' mission draws to a close, that of Cassini has barely begun.
Through at least 2008,
Cassini will tour the Saturnian system.
Many orbits bring it back for a pass by Titan
for now it is Titan's turn to provide gravity assists.
As a result, Cassini will be carefully directed past
many of Saturn's other satellites
while also providing for detailed reconnaissance of Titan itself.
Repeated passes by Titan are also be used to direct the spacecraft
on exotic trips high above Saturn's rings.
In each case, dramatic new vistas and discoveries await us.
Images of Titan taken on successive passages
may be used to make dramatic time-lapse movies to better understand weather systems on this alien world and, perhaps,
better understand weather patterns on our own world as well.
As Cassini passes behind Titan,
scientists will study how radio signals transmitted by the spacecraft
are effected by their passage through the satellite's atmosphere.
Such studies will help us better understand
the composition, density, and pressure of Titan's atmosphere.
Cassini also carries a sophisticated radar that can pierce the clouds
and accurately map portions of Titan's surface.
Already, one such pass has revealed parts of a giant impact crater or basin
over 270 miles across -- roughly the size of Iowa.
* * *
Already, one such pass has revealed parts of a giant impact crater or basin
approximately 440 kilometers across -- roughly the size of Iowa.
* * *
Its floor may be flooded with liquid methane or ethane
making it a shallow, very alien lake.
Another crater some 35 miles across, is surrounded by material
blasted from inside by an ancient asteroid or comet.
* * *
Another crater some 22 miles across, is surround by material
blasted from inside by an ancient asteroid or comet.
* * *
Smaller craters would have also been created in the distant past
but may have been obliterated since then
for Titan is a geologically and meteorologically dynamic world.
Other Saturnian satellites are coming under close study as well.
Cassini's routing calls for several close flights past Enceladus …
… where giant ice volcanoes or geysers
may resurface the landscape and even blast particles far into space
to be captured by and replenish Saturn's outer ring.
Already, close passes have transformed what previously appeared to be smooth plains on Enceladus into a varied landscape.
Here rope-like ridges up to a half mile high suggest places
where water from the interior has escaped and froze on the surface.
Elsewhere, we see a myriad
of large faults, fractures, folds, crevasses, and troughs --
all evidence of a dynamic geological history.
Cassini has also had its first close look at Iapetus,
a satellite with one face as black as asphalt …
and the other as white as newly fallen snow.
Bisecting Iapetus' "dark side",
Cassini has discovered an incredible ridge of ice
that runs over 800 miles along the moon's equator and
contains mountains three times as high as Everest.
* * *
Bisecting Iapetus' "dark side",
Cassini has discovered an incredible ridge of ice
that runs over 1,300 kilometers along the moon's equator and
contains mountains three times as high as Everest.
* * *
Elsewhere on Iapetus, Cassini's cameras capture the aftermath
of a huge landslide that partially obliterates the floor of a giant basin
ringed by walls of ice over 9 miles high.
* * *
Elsewhere on Iapetus, Cassini's cameras capture the aftermath
of a huge landslide that partially obliterates the floor of a giant basin
ringed by walls of ice over 14 kilometers high.
* * *
Later fly-bys of Iapetus will bring us views up to 100 times sharper.
Cassini has also sped past another cratered moon, Dione,
where mysterious white streaks
discovered by the Voyager spacecraft in the early 1980s
are now resolved into vast networks of cliffs of brilliant ice.
In time, Cassini will also scan Rhea,
another world with mysterious white streaks
to see if these also might be cliffs
or offer some other geological surprise.
And, Cassini will fly past Tethys where Ithaca Chasma,
an ice canyon 60 miles wide and up to 3 miles deep,
cracks this moon nearly pole to pole.
* * *
And, Cassini will also fly past Tethys where Ithaca Chasma,
an ice canyon 95 kilometers wide and up to 5 kilometers deep,
cracks this moon nearly pole to pole.
* * *
Past Mimas with a crater so large --
its birth almost shattered this moon to bits.
And …
over potato-shaped Hyperion home to amazing ice cliffs over 6 miles high.
* * *
…over potato-shaped Hyperion home to amazing ice cliffs
over 9 kilometers high.
* * *
And, of course, Saturn itself is also one of Cassini's prime targets.
Cassini is already zeroing in on Saturn's dynamic atmosphere.
In visible light, Saturn frequently displays relatively featureless
belts and bands of butterscotch, beige, and white.
But, in infrared light, Cassini's cameras are unveiling
an exotic tapestry of swirls, scallops, and spots --
telltale signs of a dynamic and turbulent atmosphere
with swirling storms and powerful jet steams.
This is meteorology on a grand scale.
Here a false-color image in the near infrared shows
a giant thunderstorm complex larger than the United States.
Dubbed the "Dragon Storm", it ragged for months.
A time lapse movie made during February and March 2004,
as Cassini coasted toward Saturn,
captures dark storms that sometimes spawn from larger ones …
and great white plumes of clouds
erupting from deep within Saturn's atmosphere.
Cassini is also studying Saturn's magnificent rings
with five times the clarity of previous spacecraft.
The rings are nearly 200,000 miles from edge to edge
yet no more than a hundred feet thick!
* * *
The rings are almost 300,000 miles from edge to edge
yet no more than a 40 meters thick!
* * *
Cassini's camera spy delicate waves, bands, and wakes within some rings
as well as delicate scalloped edges in others. 
Tiny satellites that may be little more than loosely packed piles of rubble
orbit between or just beyond the rings
and produce such cosmic sculpting
using their minute gravitational fields as a tool.
Other tiny moons may yet await discovery,
their existence suggested by the presence of thin rings
recently found in gaps
within broader ring systems.
The closer we look, the more complex Saturn's rings become.
From a distance, the rings look solid.
But, in reality, they are an enormous blizzard
of millions upon millions of pieces of ice that range in size
from grains of sand to boulders larger than a house.
Each races around Saturn in a separate orbit
at speeds up to 50,000 miles per hour.
* * *
Each races around Saturn in a separate orbit
at speeds up to 80,000 kilometers per hour.
* * *
Cassini will focus in on the so called F-ring
that appears to periodically braid and unbraid like a girl's hair.
Other orbits will take Cassini on rare excursions high above the rings.
Such vantage points will allow Cassini
to carefully observe light from selected stars
as it blinks on and off through the intervening rings.
From such periodic tracings, scientists will gather valuable information
on the size distribution of icy chunks and particles within the rings
and how the rings change over time.
While this "Tour Phase" of Cassini's mission is scheduled to last 4 years,
the spacecraft may well remain in good health long thereafter.
If so, the mission may be extended to have a closer look
at new discoveries encountered along the way
or take on a "higher risk assignment"
beyond the scope of the regular mission.
One possibility would be additional close fly-bys of Titan
to improve radar mapping of the surface …
and perhaps ultimately send the spacecraft
on deeper and deeper sojourns through the satellite's atmosphere.
Another plan would have the spacecraft make a higher risk passage
just outside the rings or even through Cassini's Division
to obtain even closer scrutiny of these incredible features …
… or … have Cassini end its life in spectacular fashion
by traveling down into the fascinating atmosphere of Saturn itself.
Exotic worlds lie at our door step.
Now, they are opening to us like never before
and we can only wonder
what new wonders still lie ahead.
And, in the center of it all …
Saturn …
framed by rings of glistening ice.
Thanks to Cassini-Huygens and the dedicated work
of hundreds of scientists and engineers
we are there …
and, the exploration continues.
# # #
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