(CBS NEWS) -- NASA's Cassini spacecraft is poised to snap a dramatic portrait of
Earth Friday, capturing a mosaic showing humanity's home in space as a
pinprick of light just to one side of Saturn's spectacular rings.
in Saturn's shadow as it loops behind the ringed world, Cassini's
cameras will take a series of photos that will be assembled into a
mosaic spanning the width of the gigantic ring system and, in the
process, capturing distant Earth and its moon some 898 million miles
A similar mosaic was assembled in 2006, but the picture was
set up for research and did not show the planet and its rings in
natural color. This time around, Cassini will capture a view intended
from the start for public consumption, one that will show Saturn and
Earth as they would appear to an astronaut looking on from Saturn's far
At Saturn's enormous distance, the crescent Earth, with
most of North America illuminated by the sun, will span a single pixel
and will appear as a pinpoint of light in the depths of space. The view
will be similar to the 2006 image and reminiscent of a shot by the
Voyager 1 probe in 1990 from the edge of the solar system.
The Voyager photo was taken at the request of Carl Sagan, who marveled at the "pale blue dot" that was Earth.
Porco, leader of Cassini's imaging team at the Space Science Institute
in Boulder, Colo., worked with Sagan on the Voyager image and hopes
Friday's picture will spark a similar moment of wonder for a much
broader segment of the population.
She wants people to step outside and wave at Cassini and to "think
about where we are, think about life on planet Earth, how incredibly
marvelous it is, think about your own existence, just have a moment of
cosmic self awareness."
"I just thought it would be a fantastic
moment, a fantastic opportunity, if we could do it again, do it right,
make sure the pictures are the correct camera settings, correct filters,
all that stuff, do it right and let everybody know in advance so this
could become a kind of interplanetary salute between robot and maker."
with the globe-spanning mosaic, Cassini also will zoom in on Earth with
it's narrow-angle camera. While the spacecraft is simply too far away
to capture any detail -- "we're still going to be a pale blue dot,"
Porco said -- the image should show both the planet and its moon,
separated by about 20 pixels.
"The moon, you know, is very much
fainter than the Earth so probably we'll have to boost its brightness,"
Porco said. "But we should, in the narrow angle camera, be able to see
"I'm really hoping it's kind of a knock-your-socks-off picture with the diffuse rings in it, Saturn and so on," she said.
will snap its pictures during a 15-minute period starting at 5:27 p.m.
EDT (GMT-4). Friday. The narrow-angle view of Earth and moon is expected
to be released within days of the photo session, but Porco said the
full mosaic will take six weeks or so to downlink, process and assemble.
managed by the Jet Propulsion Laboratory in Pasadena, Calif., braked
into orbit around Saturn on July 1, 2004. It completed its original
four-year mission in 2008 and a two-year extension in 2010. It currently
is flying through a second mission extension and scientists hope to
continue collecting data through 2017.
During an ever-changing series of orbits around Saturn, Cassini has
chalked up a near flawless performance, dropping off a European Space
Agency probe that landed on the surface of the moon Titan and studying
the enigmatic planet and its rings in exhaustive detail with
state-of-the-art cameras and instruments.
The 2006 picture of
Saturn, one of the spacecraft's most popular images, was taken while
Cassini was behind the planet as part of a science campaign and the
camera settings were adjusted accordingly. While Earth is visible in the
picture, Saturn appears in hues that do not mirror what the eye would
"It was not taken with the idea of making it a picture that
would be good for public consumption," Porco said. "That was basically
just because we were so busy when we first got into orbit, for those
first two or three or four years. ... The quality of the image is just
not very good.
"More than anything else, I really felt it was a
wasted opportunity. If people had known in advance their picture was
going to be taken, it would have been a tremendous opportunity for
people to be high fiving all over the planet and for announcing to the
world, you know, look how far we have come in the exploration of our
solar system, we have a robot in orbit around Saturn now that is going
to take our picture."
Porco never gave up hopes for a second
opportunity. Three years ago, she and her staff began studying Cassini's
planned trajectory to look for potential photo opportunities, occasions
when the spacecraft would be in eclipse behind Saturn and out of the
glare of direct sunlight.
As it turned out, July 19 was a good choice, one that did not
interfere with normal science operations, and NASA began publicizing the
encounter last month, launching a "Wave at Saturn" campaign on its web site.
I'm too starry eyed about all this, but I know this -- when I went
around giving talks about Cassini and I end my talk on that September
2006 picture, it's a picture that draws gasps from people," Porco said.
of how cynical people are, they look at that and they see Saturn and
its rings in a way they've never seen them before, and then they see
Earth in the distance. It just gets people. So I was just trying to tap
into that, that powerful recognition that moves people, only do it this
time in advance."
A passionate advocate of space exploration, Porco set up two web competitions on her Diamond Sky Productions
site, inviting the public to submit music and photos that capture the
moment of the cosmic encounter. A second website, called "The Day the Earth Smiled," provides additional details.
plans to digitize the winning entries and beam them into deep space
through a radio telescope as "kind of a long-distance call to our fellow
The message follows earlier one-way calls to
the cosmos, starting with a message developed by astrophysicist Frank
Drake and Sagan that was transmitted toward a globular star cluster in
1974 as a demonstration of the capability.
NASA's Pioneer and
Voyage probes, all four now departing the solar system, were equipped
with messages intended for any aliens who might encounter them in the
remote future. Porco began her career with the Voyager project and
worked with Sagan to pull off the 1990 Voyager 1 portrait.
I'm intending to do with this is make it a serious message a la the
previous Drake and Sagan efforts, instruct the recipients of this
message how to even read it, and encode important information about us,
our planet and so on," Porco said of her "Message to the Milky Way."
contest, called Earth Beheld, asks the public to "contribute one image
that best represents planet Earth and could be understandable to an
The other contest -- A Musical
Celebration -- asks for compositions capturing the "spirit and
significance of The Day the Earth Smiled."
"I hope, at the
appropriate time, regardless where or on which side of the planet you
are, that you stop what you're doing, go outside, gather together with
friends and family, contemplate the utter isolation of our world in the
never-ending blackness of space," she wrote on her web site.
then, by all means, rejoice! Hoot and holler, twist and shout, raise a
glass, make a toast, dance beneath the diamond sky with one hand waving
free, or celebrate in silence. Whatever it takes. But be sure to smile,
knowing that others around the world are smiling too, in the sheer joy
of simply being alive on a pale blue dot."