A Supercut Astrum Episode Covering the Voyager Mission.Discover our full back catalogue of hundreds of videos on YouTube: https://www.youtube.com/@astrumspaceFor early access videos, bonus content, and to support the channel, join us on Patreon: https://astrumspace.info/4ayJJuZ
Chapter 1: What was the Voyager mission's goal?
In 1977, two pioneers embarked on what might be one of the most epic feats of exploration ever undertaken. Their goal? To unravel the cosmic mysteries surrounding the solar system and our place in it.
Not only did they provide us with some of the first and best imagery of our solar system's outer planets, but they continued to send us incredible new information about our universe from interstellar space, some 47 years and 24 billion kilometers later. The Voyager 1 and 2 probes are more than just instruments and circuitry. They are a symbol of humanity at its best.
Curious, audacious, ambitious and resilient. Voyager didn't just capture dazzling photos of our gas giants and their moons. It captured the hearts and minds of generations back home on Earth. These are the probes that have gone the furthest that any human object has travelled. They are trailblazers and groundbreakers.
It is their unique opportunity and their peril to travel beyond the reach of humanity, to capture images of things we have never seen before so close up, nor have we seen since. When I look back, I realise how little we actually knew about the solar system before Voyager, says Voyager mission project scientist Edward Stone.
Chapter 2: How did Voyager change our understanding of the solar system?
We discovered things we didn't know were there to be discovered, time after time. So, are you curious to see what they learned? I'm Alex McColgan and you're watching Astrum, and in today's Supercut we'll cover everything you might ever want to know about the Voyager missions, from the probes themselves, their grand tour, to their impending tragic finale.
It's one of life's little ironies that it is not new, cutting-edge technology that is advancing our understanding most at the edge of our solar system, but old machines. They have an onboard computer with less memory than the one inside your car's key fob. To this day, they are still using 8-track magnetic tape from the 1970s, which makes them older than many of you sitting here watching this.
This is the conundrum of deep space exploration, where vast distances and extremely long travel times can mean that technology is antiquated by the time it has reached the most ambitious targets. Of course, Voyager 1 and 2 were not initially meant to travel all the way to interstellar space.
They were instead built for a five-year mission to explore Jupiter and Saturn and their larger moons, which was only possible thanks to a rare, once every 176 years planetary alignment However, after completing all of its initial objectives on Jupiter and Saturn, the Voyager mission team added flybys of Uranus and Neptune to one of the probe's objectives.
Later, these two were completed, so NASA announced the start of the even more ambitious Voyager interstellar mission, with the purpose of exploring the outer limits of the sun's sphere of influence and beyond.
This final journey would take both probes off the ecliptic to unexplored parts of the solar system, such as the termination shock and the denser and hotter heliosheath, before finally crossing the heliopause into interstellar space. But how did these incredible machines manage to accomplish so much beyond the scope of their original mission?
It all comes down to that old, but incredibly effective technology. NASA scientists made a number of forward-thinking design choices that allowed the probes to far exceed their initial objectives. To put it simply, they were built different. Here's how. Let's start with one of the most consequential decisions – the fuel source.
Each probe is equipped with a long-lasting radioisotope thermoelectric generator, which converts heat from the decaying Plutonium-238 isotope into electric power. These generators were capable of producing 157 watts of electrical power upon takeoff, about enough to power a laptop and maybe charge a mobile phone too. This might not sound like much, but was more than Voyager needed.
While a radioisotope generator meant that power production was in constant decline, it would half in strength every 87.7 years, it would still be enough power to keep the essentials on the probes running until at least 2025. this long-term fuel capacity was no accident. You see, when the Voyagers launched in 1977, NASA faced a unique opportunity.
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Chapter 3: What technology powered the Voyager probes?
There are many unknowns in a mission of this magnitude. To get to Jupiter, both Voyagers would have to pass through the asteroid belt. Scientists once believed that this region would shred apart any spacecraft that tried to pass through it. However, Pioneers 10 and 11 had previously been able to pass through the asteroid belt, which emboldened Voyager's team to repeat the stunt.
However, failure would have meant disaster before the probes had even reached their first target. Luckily, both probes made it through the asteroid belt unscathed, and we now know that it is mostly empty space thanks to them.
Even with all these successes, and with the probes performing far better than their engineers could possibly have hoped for, as the two spacecraft travelled through the vastness between the planets, it was still at least one more hurdle to cross. What would happen to the probes in the extremely cold temperatures of interstellar space?
NASA installed multiple heaters to keep the machinery operational, Nonetheless, as the probe's power waned, NASA had to turn off some of their heaters to conserve energy. When the cosmic ray detector's heater was turned off two years ago, its temperature plummeted by 70 degrees Celsius. Needless to say, sending a repair team 23 billion kilometres into space isn't an option.
So, everyone thought the instrument would break, but it continued to run smoothly. The fact that the probes have operated so well for 45 years is a testament to their resilience and engineering. But with all this technology, what did they see? Let's go back to the beginning and follow the path they blazed across our solar system.
On the 20th of August 1977, NASA launched the Voyager 2 space probe from Cape Canaveral, Florida. Its partner in crime, Voyager 1, was launched two weeks later on the 5th of September. Even though both probes were Jupiter-bound, Voyager 1 was set on a shorter, faster trajectory, so taking off second made sense. It overtook Voyager 2 on the 15th of December 1977, and exited the asteroid belt first.
Together, this dynamic duo were set to take a dazzling parade of pictures that were absolutely revolutionary at the time. But don't take my word for it. Let's jump in and you'll see for yourself. 13 days after launch, Voyager 1 sent this photo back to Earth. The first of tens of thousands it would send back over the next 5 years.
Taken 11.6 million kilometres from Earth, it's a sentimental place to start our journey. It might remind you of the Earthrise photo taken by the Apollo 11 crew from the moon just 8 years prior. We can see our blue marble and its moon in the distance.
I don't know about you, but I find this photo so hauntingly beautiful, especially knowing how far this probe had travelled and how much it's seen since then. But we've got a long way to go, so let's move on. It would be almost two years before Voyager 1 finally makes its approach to its first target, Jupiter. Not bad, considering it's 714 million kilometres away.
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Chapter 4: What discoveries did Voyager make about Jupiter?
Instead of precise data explaining exactly what Voyager 1's thrusters are doing and what orientation it believes itself to be at, you get long strings of zeros or 377s. The information does not make sense. It suggests that Voyager is doing things and pointing directions that it cannot be. You quickly check your computer again.
Yes, you did just receive a signal from Voyager 1, so its antenna must be pointing towards you, the same as it always has. It cannot be pointing in the strange directions it is claiming, or you would not be getting a signal at all. And not only are you receiving the signal, but it's at the exact same strength too, so it has definitely not changed direction.
And ping, onto your computer comes Voyager 1's latest science data. Strangely enough, this is all normal. While over the years Voyager 1 has had to turn off 5 of its 11 pieces of scientific equipment, and a further 2 have stopped working due to general degradation, the remaining 4 continued to take readings about the interstellar medium, magnetic fields, and cosmic rays.
Nothing here is garbled in any way. You check the other systems. Voyager 1's power supplies are a little low, but that's to be expected. The plutonium oxide that fills its three generators have a half-life of 87 years, but Voyager 1 has been travelling for 45 now. It's no wonder the efficiency has started to decline. In fact, the experts believe that Voyager 1 will not last past 2025.
But that's some time away, it does not explain what is happening now. After checking its other systems, it is just one that is behaving strangely, the AACS, the Attitude, Articulation and Control system. This computer is one of three on Voyager 1, and remember, its job is to make sure the spacecraft's large 3-metre antenna continues to point towards Earth.
This AACS has stopped sending coherent data. You lean back, puzzled. The situation is not as bad as you might have thought, but it is troubling. It's kind of like receiving post from a postman who says hello to you every morning, only for some reason he starts speaking another language one day. The packages he delivers are still the same, and they've arrived at the same address.
It's just the words the man speaks make no sense to you anymore. To further compound the strangeness, Voyager 1 doesn't think that anything is wrong with it at all. The spacecraft comes equipped with emergency safe mode settings that it can go into if it detects that anything is not working the way it ought to be.
Essentially, these involve powering down until scientists can figure out what's wrong with it, and these have not activated. So, Voyager 1 believes that all its systems are working the way they should be. The data is given, the scene is set. This was the question that NASA engineers faced in mid-2022.
A single fault like this might not seem like a big deal, but it hints at something potentially wrong with further systems. And if that is true, it might spell an end to the whole mission. Voyager 1 is, by now... 23.8 billion kilometres away from you. Your solution will have to be made via deduction, alongside careful 22-hour each-way questions and answers with the faulty spacecraft.
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Chapter 5: How did Voyager enhance our knowledge of Saturn?
By evaluating the rest of the systems and finding them normal, you can rule out some of the more unusual explanations. No, this probably is not the work of aliens trying to mess with you. Although NASA scientists were open to the idea of the Voyager probes maybe one day being picked up by alien life,
As evidenced by the golden disks installed on the probes filled with messages about us for aliens to read if ever they stumbled across it, this was more of a symbolic gesture. Besides, it seems that this would be a strange way for aliens to communicate with us. And no, the laws of physics have not broken down.
Voyager 1 has not entered a wormhole that is skewing where it thinks it is while still somehow getting the signal back to you. Given that the scientific data all appears to be providing normal readouts, it's much more likely that the problem lies with the AACS itself.
For four months, scientists and engineers gently prod and examine Voyager 1, testing theory after theory and trying to come up with a solution that fixes things without causing any further damage in the process. they could switch over to a backup system. It would not be the first time they'd started using a new computer on Voyager 1 after the old one stopped working.
Voyager 1 is built with redundancies. This isn't even the first AACS computer that's been used. A previous one became defective a while ago. They also contemplate just leaving things be. After all, the science data is still coming in. Would it be the end of the world if Voyager 1 simply carried on speaking garbled messages? Perhaps this could be the new normal.
Except it implies that a deeper problem is being overlooked. Can you figure out what was going wrong? If you can, perhaps NASA should look into hiring you. It turns out that in the intense, radiation-filled environment of interstellar space, something had made Voyager decide to start using that older, broken AACS computer to send data back to Earth.
Because of the faults in this computer, the data had become corrupted, resulting in the strange numbers. So actually, in this case, the fix was easy. All NASA had to do to fix it was to ask Voyager to start using the right computer again. Once Voyager 1 did that, the problem was resolved. Well, I say easy. And I say resolved.
It still took a couple of months for Voyager 1 to start behaving normally again. And even then, in November 2023, another of Voyager's onboard computers, this time the flight data subsystem, underwent a similar problem and became unable to send home usable science and engineering data. It took until June 2024 until that problem was fully resolved. Voyager 1 is an old ship now.
As it continues to travel through interstellar space, it may encounter more and more faults. In July 2023, a routine series of commands sent to Voyager 2 caused the probe to orient its antenna two degrees away from Earth. This seemingly small divergence was enough that over the massive distances involved, NASA completely lost the ability to talk to Voyager 2, or hear back from the probe.
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