Tuesday, November 12, 2019

Consider Again That Dot

Consider Again That Dot

Portrait of Voyager 1 spacecraft in space. Image Credit: NASA/JPL-Caltech

Launched in September of 1977, Voyager 1 took advantage of a rare alignment of the outer planets of the solar system. Voyager 1’s mission has three major sections. The first was the exploration of Jupiter and Saturn. Next, and currently ongoing, is the exploration of the edge of solar system. Finally, once Voyager runs out of energy and falls silent, it will serve as a silent testament to a race of beings that sent their hopes to the stars.

Following Voyager 1’s close encounter with Saturn November 12, 1980, the planet’s gravity bent Voyager’s trajectory out of the plane of the solar system. It was now the fastest object ever built by humans, and it was on its way to exit the solar system. Voyager was already wildly successful. It had sent back incredible close up pictures of the gas giants Jupiter and Saturn.

The swirling maelstrom of the Great Red Spot.

This is the closest picture of the Great Red Spot taken by Voyager.
Image Credit: NASA / JPL-Caltech / Björn Jónsson CC BY-NC-SA 3.0

The majesty of the fine rings around Saturn.

This image of Saturn and its rings was captured as Voyager departed Saturn following its encounter.
Image Credit: NASA / JPL / color composite by Gordan Ugarkovic CC BY-NC-SA 3.0

It shed light on the moons of these planets, now worlds themselves, and discovered the great variety of moons in our backyard.

Io, a world dotted with huge, active volcanos.

The surface of Io, mottled yellow and white, and spotted with volcanos.
Image Credit: NASA / JPL / Ted Stryk CC BY-NC-SA 3.0

Europa, covered in a thick sheet of ice above an ocean of liquid water.

Europa's surface in half phase, crisscrossed by deep fissures in the ice.
Image Credit: NASA / JPL / Björn Jónsson CC BY-NC-SA 3.0

Titan, cloaked in a hazy, orange atmosphere; the only moon in the solar system to have one.

Titan's surface remains hidden beneath a smooth, orange atmosphere.
Image Credit: NASA / JPL / Gordan Ugarkovic CC BY-NC-SA 3.0

It cannot be overstated just how much the Voyager program contributed to our understanding of the planets. Even today, scientists examine the mountains of data sent back from Voyager, and are still making new discoveries.

There would be no further planets for Voyager 1 after Saturn. At some point, it would not make sense to continue powering its cameras. Nothing in Voyager’s field of view would appear as anything larger than a dot, and the electricity could be better used powering its other detectors, and sending those signals back to scientists on Earth.

Before the cameras were turned off, a group of scientists led by Carl Sagan campaigned for Voyager 1 to turn back and collect a series of images capturing the planets of the solar system one last time. There would be absolutely no science to learn in this Family Portrait; it would be purely sentimental. Sagan’s point of view prevailed over the resistance of others within NASA. On February 14, 1990, Voyager 1 took one last picture of home before it left forever.

Family Portrait of the planets of the solar system taken by Voyager 1. The planet locations are marked in the panorama by the first letter of their names, and an inset shows the detail of each.
Image Credit: NASA / JPL

The image of Earth received the name “Pale Blue Dot” because of the rhetoric used by Carl Sagan in his efforts to describe the subject of the picture. No description of the picture comes close to fully capturing the importance of the photograph besides Sagan’s. The two are forever intertwined. To quote Sagan from his book “Pale Blue Dot”:

The Pale Blue Dot. Earth is roughly in the center of the rightmost sunbeam.
Image Credit: NASA/JPL

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.

The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.

At the time of capture, Voyager 1 was approximately 6 billion kilometers from Earth, more than 40 times the distance from Earth to the Sun. It is the most distant picture of Earth ever taken. NASA estimates that Earth occupies 0.12 pixels of the image. It is easy to misidentify Earth as noise. The light beams are reflections of the Sun occurring within the camera. The picture shows Earth as it is: a delicate point of light in the vast cosmic darkness and lit by a sunbeam.

The Voyager program is one of the grand scientific triumphs of human history. It is the initial reconnaissance of our solar system. It continues to contribute to science even today as the twin Voyager spacecraft enter interstellar space. But this image of the Earth, more than any other single image taken in the Voyager program, is the true gift of Voyager.

At 7pm on February 7, 2020, the Delta College Planetarium will be holding a special event commemorating the thirtieth anniversary of the capturing of the Pale Blue Dot, the end of the first phase of the Voyager missions. We will cover the history of the Voyager missions, and examine how Voyager changed our understanding of the planets.