31Oct2012

 Carl Sagan – The Pale Blue Dot.

The Pale Blue Dot is a photograph of planet Earth taken in 1990 by the Voyager 1 spacecraft from a record distance of about 6 billion kilometers (3.7 billion miles) from Earth.

It is part of the solar system Family Portrait series of images. In the photograph, Earth is shown as a tiny dot (0.12 pixel in size) against the vastness of space. The Voyager 1 spacecraft, which had completed its primary mission and was leaving the Solar System, was commanded by NASA to turn its camera around and to take a photograph of Earth across a great expanse of space, at the request of Carl Sagan.

The Followers:

“This is why I love astronomy Carl Sagan wrote this about the photo taken by Voyager of Earth 22 years ago this month. This was the last picture taken by Voyager at a distance of 4 billion miles away.It makes you think of everything that was, is, and will be. All those wars over pointless crap fought over stuff most people don’t remember.” [Youtube Post]

“The more I watch this the more I appreciate the genius that was Carl Sagan. We are part of something bigger than ourselves. We are part of the universe in all of its beauty and complexity down to the simplest microorganism. It matters how we treat each other.” [Quote from a fan]

The Story:

It’s now the 22nd anniversary of a special photograph. It’s a very dramatic photo, even though, at first glance, it’s mostly dark and seems to show nothing at all. But if you look closely, you can see a tiny speck of light. That speck is the Earth, seen from very, very, very far away.

Two decades ago, Candice Hansen-Koharcheck became the first person to ever see that speck, sitting in front of a computer at NASA’s Jet Propulsion Lab in California. “I was all alone, actually, that afternoon, in my office,” she recalls.

http://1.bp.blogspot.com/-WVLSoN4MedY/UIVxeT-_-yI/AAAAAAAAAQU/jqzi8QqHRNs/s640/Pale+blue+dot+1.jpg

Taken in 1990 by NASA's Voyager 1 spacecraft, the "pale blue dot" photo shows what our planet looks like from 4 billion miles away. Earth is the tiny speck of light indicated by the arrow and enlarged in the upper left-hand corner. The pale streak over Earth is an artifact of sunlight scattering in the camera's optics

Her office was dark. The window shades were drawn. She was searching through a database of images sent home by the Voyager 1 spacecraft, which at the time was nearly 4 billion miles away. “I knew the data was coming back,” she says, “and I wanted to see how it had turned out.”

Finally, she found it. “It was just a little dot, about two pixels big, three pixels big,” she says. “So not very large.” But this was the Earth — seen as no human had ever seen it before.

What’s more, an accidental reflection off the spacecraft made it look as though the tiny speck was being lit up by a glowing beam of light. “You know, I still get chills down my back,” says Hansen-Koharcheck. “Because here was our planet, bathed in this ray of light, and it just looked incredibly special.”

And yet, if you weren’t searching for it, that special little speck would be almost invisible. The Apollo astronauts had taken photos that showed the Earth as a big blue marble, swirling with clouds and continents. But this picture showed the smallness of Earth in the vastness of space.

A New Perspective On The Planet

The late astronomer Carl Sagan eloquently tried to express how he felt about this photo in his book Pale Blue Dot:

Part of Image:Planetary society.jpg Original c...

"Founding of the Planetary Society Carl Sagan, " (Photo credit: Wikipedia)

“Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every ‘superstar,’ every ‘supreme leader,’ every saint and sinner in the history of our species lived there — on a mote of dust suspended in a sunbeam.”

Robert Poole, a historian at the University of Cumbria in the United Kingdom who wrote a book on images of Earth from space called Earthrise: How Man First Saw the Earth, says this particular photo shows what an extraterrestrial might see as it approached our solar system.

“This is not our view. We’ve managed to go out and get the view that somebody else might have, whereas the early Apollo pictures of the blue marble were our own view of Earth,” Poole says. “Like most people, I saw it in the newspaper not long after it was taken and kind of intellectually I thought, ‘This is amazing!’ “

A Photo That Almost Didn’t Happen

Pictures like this are still few and far between. They are not exactly easy to take. In fact, we almost didn’t get this one. Sagan lobbied for it early in the Voyager 1 mission. But others objected that taking it might fry the spacecraft’s camera. That’s because the Earth is so close to our extremely bright sun. “There was a reluctance to take any kind of risk when we would point back towards the sun; we didn’t want to accidentally damage the cameras in any way,” says Hansen-Koharcheck.

“Oh, there was a lot of debate as to what its value would be,” recalls Edward Stone, who was — and still is — the chief scientist for the Voyager mission. “It was not a scientific image. It was really, I think, an image to sort of declare that here, for the first time we could take such an image, and second of all it provided a new perspective of Earth and its place in our solar neighborhood.”

But the idea was shelved for years, as Voyager 1 flew through the solar system and did its science, sending images back from Saturn and Jupiter. In 1989, the mission was winding down — some staff was going to leave. And Sagan made a last-minute request to please, please, take this unique photo before the opportunity disappeared forever.

The decision went to the top levels of NASA “because it was going to extend the mission in terms of imaging capability for an additional six months or so and that of course did cost money,” explains Stone.

“I did get a visit from Carl Sagan. We talked about a lot of things. And somewhere in that conversation he mentioned this idea,” recalls the then-head of NASA, retired Vice Adm. Richard Truly. “I thought, heck, with Voyager so far away, if it could turn around and take a picture of the different planets including the Earth, that that would really be cool. And so I was a great advocate of it, although I can’t take any credit for it.”

In 1990, late on Feb. 13 — or on Valentine’s Day, in the time zone used by the Voyager 1 team — the spacecraft turned its cameras to Earth.

A Relatively Tiny Object In The Vastness Of Space

Later, the image was released to the world to great fanfare. But it never really captured the popular imagination like the famous Apollo images.

Voyager Saturn Labeled Moons“I think it was hard — it’s still hard — to get really your head around the fact that our solar system is so immense, compared to Earth,” says Stone.

To get the full impact of this photo, Stone says, you really have to see it up on a wall, as part of large panorama that Voyager 1 took of the solar system’s distant planets.

NASA’s Jet Propulsion Lab used to have just such a display with the full mosaic of photos posted up in an auditorium, says Hansen-Koharcheck. “And to show the whole thing it covered, oh, I don’t know, 12 or 14 feet,” she says — of mostly empty black space, with just a few pinpricks of light showing the planets. One of them was labeled Earth.

“One of the guys that took care of that display told me one time that he was forever having to replace that picture,” says Hansen-Koharcheck, “because people would come up to look at it and they would always touch the Earth.”

Voyager 1 is now about three times farther away than it was 20 years ago, says Stone. The spacecraft still routinely phones home, although its cameras no longer take photos. But if it could send back another picture, the little dot that is Earth would look even fainter and even smaller

  Source: NPR

 

6 Fascinating Facts About Space Probe Voyager 1

http://www.history.com/news/wp-content/uploads/2012/08/voyager-i.jpg

When Voyager 1 blasted off from Earth on September 5, 1977, it was designed to last for five years. Today, on its 35th anniversary, the space probe continues to communicate with NASA as it approaches the heliopause—the boundary between our solar system and interstellar space. The farthest man made object from Earth, Voyager 1 may keep exploring space for another 10 or 20 years before its power runs out. Meanwhile, check out these cool facts about the spacecraft and its mission.

1. Voyager 1 has an identical twin.
In the early 1970s, the National Aeronautics and Space Administration (NASA) developed a mission called Voyager to make a “grand tour” of Jupiter and Saturn—and possibly Uranus and Neptune if all went well. The agency planned to launch a pair of unmanned spacecraft on different trajectories to thoroughly study the planets from multiple angles. Voyager 1 and Voyager 2 are identical in construction. Each weighs around 1,500 pounds. Each is equipped to conduct 10 specific experiments, ranging from taking pictures to measuring atmospheric plasma concentrations. Each contains about 65,000 individual parts. (Some of those components represent technology that might seem laughable now but was cutting-edge at the time, such as a digital eight-track recorder.) When they were launched in 1977, the Voyagers were designed for a five-year lifespan, but both have outlived that projection by 30 years.

2. Voyager 1 actually launched after Voyager 2.
NASA launched Voyager 1 on September 5, 1977, 16 days after the launch of Voyager 2. Why this reversal in order? The Voyager mission was designed to take advantage of a rare configuration of the solar system’s giant planets, Jupiter, Saturn, Uranus and Neptune. In this arrangement, which occurs roughly once every 175 years, the giants lined up in a way that would allow the probes to harness each planet’s gravitational forces to “swing” from one to the next with minimal self-propulsion. To accomplish this feat, the probes were launched on different trajectories. Voyager 2′s so-called slow trajectory would enable it to potentially visit all four giant planets, while Voyager 1′s faster trajectory would get it to Jupiter and Saturn before it headed into deep space. Voyager 1′s course allowed it to overtake Voyager 2 in the Asteroid Belt and gain the lead position in the mission. So, while Voyager 1 launched second, NASA knew all along it would take first place in the race to deep space, and they named it accordingly.

3. NASA engineers considered more than 10,000 possible trajectories for the Voyager mission.
Because of the complexity of using a “gravity assist” technique to propel Voyager 1 from Jupiter to Saturn and then on to interstellar space during its exploratory mission, NASA engineers considered thousands of potential trajectories for the probe. The engineers needed to chart a precise course that would take Voyager close to the planets but not so close that the next leg of the journey was compromised. Ultimately, NASA engineers chose a route for Voyager 1 that would ensure the completion of its primary mission to study the two giant planets before propelling it toward interstellar space. Thirty-five years later, it’s safe to say they chose well.

4. Any extraterrestrials who encounter Voyager 1 will need to figure out an ancient Earth technology called the “record player.”
In order to offer a sense of Earth’s culture to any spacefarers encountered by Voyager 1, NASA included a 12-inch gold-plated audiovisual disc on the craft. Dubbed the Golden Record, this disc contains a variety of content that was chosen by a committee chaired by the late scientist Carl Sagan. The disc includes photos and drawings, spoken greetings in many languages, music and Earth sounds. For the convenience of any alien life forms that discover the Golden Disc, NASA included a cartridge and needle for playback. However, the extraterrestrials will first have to figure out how to build a record player and speaker. Including that technology aboard Voyager 1 would have added too much weight and bulk.

5. It currently takes approximately 16 hours and 38 minutes to receive communications from Voyager 1.
With Voyager 1 positioned nearly 12 billion miles from Earth, according to NASA’s official live odometer, it takes over 16 hours for scientists to receive data from the probe—or for the spacecraft to receive signals from Earth. Voyager continues to send a steady stream of information to NASA scientists, including data on the direction of gravitational fields around it and the speed of surrounding solar winds. The solar wind speed has been registering as zero for some time now, indicating Voyager 1 is at the very fringe of the solar system where the sun’s energy blow-by doesn’t reach. Scientists believe the defining parameter confirming the probe’s move into interstellar space, however, will be a shift in surrounding magnetic fields from an east-west orientation to north-south. At that moment, which could occur any day now, Voyager 1 will pierce the veil of deep space.

6. In its final act of photography, Voyager 1 snapped the only existing portrait of our solar system.
Not long after Voyager 1′s encounter with Saturn in 1980, NASA engineers turned off the craft’s cameras to conserve energy. For nearly a decade, the probe quietly flew toward deep space. But as it approached the edge of the solar system, NASA engineers on February 14, 1990, instructed Voyager to turn its cameras back on and take a last look over its shoulder at the planets. In a series of 60 images, Voyager 1 returned the only “family portrait” of our solar system, including the sun, Venus, Earth, Jupiter, Saturn and Uranus. The photo mosaic depicts Earth as a small, pale blue dot afloat in the vastness of space. The photos were the last Voyager 1 ever took; its cameras were again turned off to maintain maximal energy reserves as the craft prepared to become the first man made object to reach interstellar space. Source: History In The Headlines

Graham Dixon says:

great article – places everything in perspective

Graham Dixon says:

great article – puts everything in perspective

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