THE MOST AMAZING YEAR IN SPACE, EVER (2017), PART 5: Voyager 1 Aces Another Test

Voyager 1: (almost) never say die

As you read this, the first human-made artifact to enter interstellar space is receding from us at a speed of 10.6 miles per second (50 times the speed of sound at sea-level on Earth). It is currently (the morning of March 16, 2018) about 141 times farther from the Sun than the (average) distance of Earth from the Sun. Impeded only by clouds of gas that are tenuous in our region of the galaxy, it should keep up this rate of speed for millennia. That sounds fast, but at astronomical scales it’s barely crawling—17,500 years to cover one light-year. Since it will probably not completely escape the Sun’s gravity until two light-years out, it won’t “really” exit the Solar System for another 35,000 years or so. For the finer points of what constitutes “interstellar space” check out: https://scitechdaily.com/new-data-confirms-voyager-1-interstellar-space/

(You may not be too surprised, if you went to that link, that the determination of Voyager 1’s official interstellar status depended partly on the readings of the “tsunami waves” that have smacked Voyager three times as a result of Coronal Mass Ejections from the Sun.  CMEs are those random ejections of solar plasma that pose a serious threat to our increasingly electrified way of life here on Earth, as discussed in my earlier post  https://www.markheinickewrites.com/2017/11/04/uncertainty-part-two-when-comes-the-big-shock/ . )

Voyager 1 has been on its way since 1977, and has performed flawlessly up to this day.  You can follow its current  progress at this NASA site, where you can also see an illustration of this fabulous machine:
https://voyager.jpl.nasa.gov/mission/status/

After 42 years, Voyager 1 is still reporting daily back from the void, even though the radio signals now take 19+ hours to get here.  (A round trip, sending  a signal from Earth to Voyager and  getting a reply back is 39 hours.) Since the signal from the spacecraft originates with the power of a refrigerator light bulb, 13 billion miles away, the techniques for receiving the signal are almost as amazing as the spacecraft itself.  Reading the infinitesimal signal depends on the Deep Space Network, a combination of radio telescopes at three terrestrial locations—California, Spain, and Australia, capable of monitoring signals from any and all interplanetary (and now interstellar) spacecraft operating in multiple missions. For more on the Deep Space Network, see history of the DSN.

Voyager gets a new attitude

The big news for Voyager 1 in 2017 was the re-activation of “trajectory correction maneuver (TCM)” thrusters, that had been asleep for 37 years.  The TCM thrusters’ original task was to adjust the spacecraft’s trajectory as it peregrinated among planets of the Solar System.  Having done that to perfection, they were now to be re-purposed to help orient Voyager 1 to aim its signal back at Earth—that is, to adjust its “attitude.”  This addressed the problem posed by the degradation of the original attitude thrusters (identical in design, but with a more subtle function) over recent years.

With the possibility of getting data from the spacecraft for another ten years(!), and with the attitude thrusters flagging, NASA engineers went to the bench. That involved digging up 40-year-old computer code written in assembly language (the primitive instructions upon which more intuitively comprehensible modern computer languages are built) to bring the TCM thrusters out of dormancy and test their capability to take over attitude control from their sputtering mates on the other side of the spacecraft.

After massaging the old code, engineers sent the  new instructions to the retreating Voyager 1. . . and held their breath for 39 hours to hear back for test results.  (Yes, among other major accomplishments, NASA engineers, using a sophisticated relay system, are able to hold their collective breath for 39 hours. )

We now know, of course, that Voyager passed the test with flying colors  (although Voyager’s colors are uninspiring, the flying part is pretty much settled), and the engineers were able to breath a gargantuan  collective sigh of relief.   (Followed, we may assume, by a gargantuan keg party, during which off-color thruster jokes, with references to various items of hardware and software, were exchanged.)

The same technique is expected to work for Voyager 2, now fast approaching its own passage into interstellar space, headed in the opposite direction from Voyager 1.  Neither of them can be expected to come within a light year of another star for tens of thousands of years.

For a more detailed account of the thruster conversion drama, go to:
Voyager thrusters respond to wake-up call

If that is not all astoundingly, inexpressibly, dumbfoundingly, awesomely  amazing, then tell me what is.

Levity aside, there are some Big Questions to be asked about the deeper meaning of the Voyager missions . . . 

Galactic emissaries making a cosmic connection: the golden records

If you are inclined to anthropomorphize about a spacecraft—as even the most hard-nosed engineers involved with the space program are wont to do—it’s haunting to envision Voyager 1 sailing through a medium where the density of matter is less than 1/10,000,000,000,000,000,000 that of the density of our atmosphere at sea level, and the temperature is 10 or 20 degrees Kelvin above absolute zero (-253 Celsius; a temperature at which methane is solid).  It’s cold and empty beyond description.

The Star Trek intro, “to boldly go where no man has gone before,” is associated with a fictional spaceship half a mile long with a crew of hundreds.  The expression rings a more poignant note when you consider the reality of a fragile machine, weighing less than a compact car, traversing the immensities.   Will Voyager 1 or 2 ever be found by another intelligent race capable of understanding its origins and purpose? The likelihood is smaller than that of an arrow, shot randomly out over a desert, hitting some particularly sagacious ant scurrying about on its own affairs. And yet . . .

What if some intelligent aliens were one day to snare one of the Voyagers on its lonesome journey? They would be blessed with an intriguing treasure: a golden record.  Each Voyager carries with it a message from humanity in the form of a record—similar in concept to a vinyl record but etched in gold—consisting of an hour-and-a-half of world music and greetings in 55 different languages.  The “cover art” illustrates how the record can be played. We can assume that aliens clever enough to capture the spacecraft without breaking it, will also be clever enough to figure out how to decipher the record. Another bit of cosmic connection.

Comedian Steve Martin, having heard that the golden records bore, in addition to Mozart, Chuck Berry’s “Johnny B. Goode,” quipped that the aliens’ message back to Earth would be “send us more Chuck Berry!”  

Steve Martin’s joke is a jab at high culture, but there’s a deeper point: we really have only a faint idea of what other intelligent species will find pleasure in. It’s a dreary thought that they might take no pleasure in music. But if there’s one thing we can count on: any aliens (biological, mechanical, or a synthesis) capable of figuring out the golden records, will be endowed with a high degree of curiosity—the very trait that fundamentally drives the space program. So they might very well find Chuck Berry as worthy of study as Mozart.

(An aside on curiosity: for long term survival on astronomical time scales, curiosity may be more important than intelligence—although in my mind it’s hard to separate the two.  All living things possess some degree of curiosity, a highly adaptive trait if you want to get from point A to point B. An especially avid curiosity seems to flow naturally from a human kind of intelligence, and efforts to satisfy an avid curiosity pushes one to get smarter, as a group evolutionary trend as well as an individual one. Progress is not all about solving problems—it’s as much about discovering which problems are worth solving. )

Mars, shmars – getting priorities straight

At least, curiosity has driven the space program in the past.  Nowadays the impetus for space exploration has taken a more utilitarian turn: colonizing the moon for the purpose of mining it, mining asteroids, and, most dramatically, colonizing Mars (Elon Musk’s vision) to escape apocalyptic ruination of civilization by war, ecological collapse, or a paroxysm of volcanic super-eruptions.  (As for the most lethal thing that could happen, the arrival of a gamma-ray burst from a relatively close star that would set terrestrial life back billions of years, being on Mars or a moon of Saturn would be of no help; the entire Solar System would get blasted.)

A manned Mars mission will be hugely expensive, upwards of half of a trillion dollars just to get a few people there (and maybe back).  By contrast, NASA has pegged the total cost of the Voyager mission(Voyagers 1 & 2) at $865 million over 40 years—8 cents per American adult per year.

The most important utilitarian mission of the space program, gathering satellite observations of what’s going on here on our planet’s surface, has little sex appeal, but dollar for dollar, in the end will pay off far more handsomely than sending a few people to die on another world.

Don’t get me wrong: the laws of nature dictate that the very long-term survival of the human race require that we leave Earth eventually.  But, given all the challenges we face over the next several decades—achieving ecological sustainability and a modicum of peace, warding off pandemics, and coping with the potentially existential threat of artificial intelligence—given all that, creating a Mars colony sounds like more of an Elon Musk ego trip than a serious effort to save our species.  We have at least tens of thousand of years to undertake the colonization of other planets, moons, and solar systems.  What’s the hurry?

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Addendum: how to view a partial eclipse

To wrap up THE MOST AMAZING YEAR IN SPACE, EVER series, I insert here, as another trace of a cosmic connection,  an image of an instrument

constructed by my friend and fellow blog reader Charlotte Armstrong, to observe indirectly last summer’s eclipse, which was only partial in Maryland. That’s the crescent Sun, as she observed it, at the far end of the viewer. Pretty cool, eh? I thought so, too.

 

================== FOOTNOTES FOLLOW===============

* You may have heard that per NASA, Voyager 1 will make a “rendezvous” (within 1.5 light years) with Star AC +79 3888 in about 40,000 years.  Star  AC +79 3888  is now 17.9 light years distant.  So how can Voyager, at a speed of 17,500 years to cover one light year, get so close to it in 40,000 years?  You heard correctly. The trick is that the star is itself hurtling towards Voyager at a sprightly clip of 2,500 Earth years per light-year.  To arrange the meeting, NASA connected with InterstellarMatch.com at a special astronomers’ discount (good until March 40,000).  Fear not that Voyager 1 will get burned, however—its speed and trajectory will keep it from getting sucked in by AC +79 3888’s gravity. It’s just a celestial flirtation—the ultimate in speed dating.