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Carl Sagan

The news of a software patch uploaded to the Voyager probes reminded me of a 1980 book telling precisely the story of how their journey began 46 years ago. When said book hit the publishing press, Voyager 1 had just finished its flyby of Saturn, a planet which Voyager 2 was about to survey a few months later. Assisted by gravity slingshots, the latter probe would reach Uranus in 1986 and Neptune in 1989. Both Voyagers would cross the Heliopause decades later, one in 2012, and the other in 2018. Against all odds, they are both beeping back to Earth as you read these lines.

The book in question is “Cosmos”, of course, by the late astronomer Carl Sagan. It is a compendium of history, biology, astronomy, engineering, and social sciences, with breadth and a poetry at each step of the way.

No, there are no extensive tales about computers or programming languages in the pages of “Cosmos”, something the readers of this magazine might be expecting every month. But of course, computers there are, controlling the cameras and governing the ship, constantly keeping an eye on some stars for navigation:

The attitude and articulation control subsystem (AACS) computer manages the tasks involved in stabilization via its interface equipment. For attitude reference, star trackers, star scanners, solar trackers, sun sensors, and planetary limb trackers come into use. Voyager’s AACS uses a sun sensor for yaw and pitch reference, and a star tracker trained continuously on a bright star at right angles to sunpoint for roll reference.

Here are some crunchy details computer fans will surely enjoy:

The Voyager CCS and Viking CCS would ultimately have the same amount of memory (just under 70kB) despite the routines and programs for Voyager being much more complex. In-flight programming allowed for new routines and programs to be uploaded regularly in non-volatile memory and eliminated the need for large amounts of memory to be required onboard.

The original software for the Voyager probes was written using Fortran 5 then ported to Fortran 77, and today there is some porting in C. Low-level, light-weight software is increasingly important as the probes move farther and farther away from Earth and communication becomes slower.

I hope the reader will indulge me in proposing a tangential perspective on “Cosmos”. Because this book is based on an uncanny premise: a perspective on our life as a species seen from space, as if an alien life form had authored it after studying us closely for a while.

The sixth chapter of Cosmos, called “Travelers’ Tales”, tells precisely the story of the Voyager probes. It starts by telling the story of Dutch explorers in the seventeenth century, then the story of renowned scientists and explorers like Galileo, Huygens, Leeuwenhoek, and Zheng He. In this sixth chapter, Sagan describes a logbook, where an imaginary pilot inside the Voyager probes would write down their experience day after day, as they move farther and farther away from planet Earth. Just like seventeenth century travelers using stars to find their way across the oceans, the Voyagers quite literally still do the same.

According to Sagan, we are just “One Voice in the Cosmic Fugue” (chapter 2) living at “The Shores of the Cosmic Ocean” (chapter 1). And when he asked, “Who Speaks for Earth?” (chapter 13) we stayed shamefully silent.

The idea of an “Encyclopædia Galactica” (chapter 12) sent my mind on overdrive. Is there one? Is there a file about us somewhere in it? Jodie Foster’s character, in this clumsy adaptation of yet another book by Carl Sagan, also briefly mentioned it when discussing the incoming signal discovered by SETI. I guess Wikipedia is the closest thing to an Encyclopædia Galactica that I will get to see during my lifetime on this planet.

Sprinkled inside the pages of “Cosmos” there are dozens of gorgeous photos, taken by the onboard cameras of various spacecraft, often processed in “false color” and igniting my mind with the most incredible views of worlds far away. Another famous photograph, understandably not featured in the pages of “Cosmos”, was the one known as “Pale Blue Dot”, taken by Voyager 1 in 1990. This photograph inspired Carl Sagan yet another book.

Cosmos is the first science book I read as a kid. I had watched (needless to say, in absolute awe) the TV series around 1980, but one day, walking around Buenos Aires, I discovered the companion book on display in one of the city’s largest bookstores. I begged my mother to buy me a copy. This book is still with me, almost 40 years later and after three migrations across the Atlantic, and I must have read it a dozen times. It is challenging to put in words the impact that this book has had on me.

As Bruce Lewenstein said in 2002,

Ultimately, books create the culture that we live in. They are elements both of the scientific culture and of our more general culture. By looking at them we can actually see the ways in which science and modern culture are not separate but are — to use a jargon word from the sociology of science — co-produced. Neither science nor society exists without the other one.

As a side effect of my fanaticism for the “Cosmos” TV series, I became obsessed with Vangelis‘ music, and of course, I bought the cassette tape with the official soundtrack, but that is another story. Today, in our age of streaming services, you can listen to it on Spotify.

The Voyager probes have seemingly been there my whole life. Voyager 1 was launched the day after I celebrated my 4th birthday. I watched the TV series on Canal 13 when I was in first grade, more or less at the same time when U2 and Depeche Mode were recording their first albums. I saw Voyager 2’s pictures of Uranus in the pages of the Argentine edition of the “Muy Interesante” magazine as I was heading towards high school. Years later, I read Sagan’s “Dragons of Eden” and “Pale Blue Dot” books while studying physics in college. Carl Sagan passed away shortly before I began a career in software engineering.

Decades later, I got news of the Voyagers crossing the heliopause while I was busy making mobile apps for a living. In 2016, I bought a copy of the re-edition of the Voyager Golden Record on Kickstarter, used by movies such as Star Trek: The Motion Picture (1979) and John Carpenter’s Starman (1984) as a basis for their plots. And now, as I enter my sixth decade on Earth, writing a monthly magazine about computer programming, boom; they show up in the news once again, receiving a remarkable software update, still phoning home every so often.

We are living in a truly remarkable age. Godspeed, Voyagers.

Cover photo by the author.

Continue reading Issue 062: IBM or go back to Issue 063: Space. Did you like this article? Consider subscribing to our newsletter or contributing to the sustainability of this magazine. Thanks!
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