Comments by "H. de Jong" (@h.dejong2531) on "Voyager 1 and 2 Detected Something Beyond the Edge of Our Solar System" video.

  1. Yes, they're shutting down instruments to stay within the available power.
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  2. Have a look at the APL Interstellar Mission proposal.
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  3.  @g.g.hochstetler2286  I disagree. Building a model is a lot more difficult if you don't have data to go on.
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  4. The Voyagers don't have instruments that are useful for that. The cameras were fine for the planetary encounters, but not suitable for finding very faint objects. The camera platforms were switched off in 1989, and these days, there's not enough power left to operate them.
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  5. Space is really empty. Those Star Trek scenes with the Enterprise picking its way through a boulder field are very unrealistic. At Voyager's location, the average density is 1 atom per cm3.
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  6. The camera is a Vidicon tube (analog TV camera). Its output is digitized. Voyager's transmitter produces 12 W of RF. This is sent through an antenna with 48 dBi gain. NASA uses the Deep Space Network to receive these signals. This has large dish antennas (34 m diameter, 74 dB gain) in 3 stations: Goldstone, USA, Madrid and Canberra. These antennas are equipped with receivers that are cooled to around 4 K, to reduce their noise to the absolute minimum. Signal power at the end of the chain is around -150 dBm, with a receiver that can pick up signals down to -170 dBm. Voyager has a star tracker: this tracks the position of the Sun and a bright star, that gives the attitude of the probe. It uses thrusters to change the attitude: these can aim the probe to an accuracy of less than 1 degree.
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  7. No. For the heliosphere, the Voyagers provided the first data - anything before that was theoretical; Voyager was the first chance we had to validate and refine the model. For our climate, we have enormous amounts of data, with more being added every day. And we have the option to validate these models against e.g. historical data. So the uncertainty in climate models is a lot smaller than that of our heliopause models before Voyager.
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  8. That generator costs $100 million and runs on Plutonium. That's why it's not available at Home Depot.
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  9. No. They're moving at a speed of 17 km/s. To brake from that speed to 0 and head back into the inner solar system would take thousands of tons of fuel .
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  10. It's surprisingly difficult to build anything faster. APL is working on an interstellar mission proposal, and they have trouble coming up with a design that's twice as fast as the Voyagers. We have some ideas on how to improve the longevity, but the main limit remains RTG lifetime.
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  11. Space is really empty. The average density is 1 atom per cm3. Even in the asteroid belt, the chance of hitting an asteroid when you cross the belt is less than 1 in a billion.
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  12. It's a combination of careful design (choosing the best components, adding redundancy) and luck (both Voyagers have been running on their backup transmitters for decades now, as their primary transmitters failed early in the mission).
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  13. There's a big difference between the heliosphere model (for which the Voyagers were the first to provide data) and climate models (for which we have mountains of data).
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  14. It's more complicated than that. 1. survivorship bias. Many of those devices failed, we remember the few that lasted a long time. 2. consumers voted with their wallets: they overwhelmingly chose to buy cheaper appliances, i.e. lower quality.
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  15. Congress only wanted a limited mission, so Voyager was sold as a Jupiter-Saturn mission first. The engineers kept in mind they'd also like to visit Uranus and Neptune so they built the spacecraft to last. After the Saturn encounters, the value of the mission was evident enough that mission extensions were granted.
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  16. It's hard to build an accurate model if you have no data. For the heliosphere, the Voyagers were the first to give us measurements at all.
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  17. There are 2 definitions for the extent of our solar system: 1. the region in which our sun's gravity is dominant. This stretches halfway to the next star, and includes the Oort cloud. 2. The region in which our sun's electromagnetic and particle radiation is dominant. This ends at the heliopause.
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  18. The info is about 20 hours old. That's the travel time for the signal. Space is really empty. Those Star Trek scenes with the Enterprise picking its way through a boulder field are very unrealistic. At JWST's destination, the average density is 1 atom per cm3.
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  19. The electronics and fuel in the Voyagers are kept warm by heaters. The spacecraft bus is covered in insulation, so little heat is lost to space. The Voyagers do get hit on occasion by micrometeoroids. The electronics are well-protected inside, so these hits mostly punch tiny holes in the large antenna.
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  20. Their onboard transmitter produces 12 W of RF power. We continue to be able to receive this by having giant dish antennas to receive Voyager's signals, with the best receiver electronics money can buy ($100 million each, the receiver is cooled to cryogenic temperatures to reduce noise). At these distances, communication is slow: Voyager sends data at 160 bits/s.
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  21.  @alexbrewer3675  The camera left on the moon was installed on the lunar rover. It was controlled from Earth, by Ed Fendell in Mission Control. He worked out when to send the commands, to compensate for the time delay in sending the commands to the moon. It took 3 tries to get this right: on Apollo 15 and 16, the LM soon left the filed of view of the camera. On Apollo 17, he got the timing right and we have a splendid view of the ascent. The lunar rover had a direct radio link to Earth (using the large dish antenna on the rover) which carried the TV signal in one direction, and remote control signals in the other.
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  22. The planetary science community just recommended a Uranus orbiter as the next large mission, so you may get your wish.
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  23. The camera system is not optimized for faint objects: it has too much noise, so it's unlikely it'd be useful for finding planets.
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  24. They use radioisotope thermal generators: Pu-238 decays and produces heat, Peltier elements convert this to electricity.
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  25. Oort cloud objects are small, with enormous gaps between them - you could fit Pluto's orbit in those gaps. The average density is estimated at 1 atom per cm3.
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  26. Before the Voyager missions, we had no idea where the heliopause was. Some estimates put it at 40 AU. And we were lucky that the Grand Tour trajectory pointed more or less towards the bow of the heliosphere.
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  27. Yes. Voyager 1 would be the first to arrive at Jupiter (it was launched on a faster trajectory).
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  28. Space is empty. Very empty: the average density is 1 atom per cm3. Even in the densest part of the solar system (the asteroid belt), the chance of colliding with an object large enough to end the mission is only 1E-9.
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  29. That's not what they're doing. They're switching off instruments to stay within the available power.
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  30. The distances between objects in the Oort cloud is expected to be huge.
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  31. You're comparing apples and oranges. For the heliosphere, the Voyagers were the first to give us measurements at all. For diseases we don't have that problem: we have enormous amounts of data going back centuries. So when a new disease appears, we have models that have been tested already on other diseases, which can be adapted to provide accurate predictions in a short time, which is what happened for Covid.
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  32. 1. Careful design, with lots of redundancy. There have been failures, both Voyagers are using their backup transmitters now. 2. Luck: we're only one failure away from end of mission. They're not sending the information quickly though. NASA uses a giant dish to receive Voyager's signals, with the best receiver electronics money can buy ($100 million each, the receiver is cooled to cryogenic temperatures to reduce noise). At these distances, Voyager sends data at 160 bits/s. Luckily that's enough for the instruments that are still operating.
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  33. Wrong, they didn't switch either of the Voyagers off. They're still working, and we receive data from them every day.
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  34. NASA uses a giant dish (34 m or 70 m diameter) to receive Voyager's signals, builds the best receiver electronics money can buy (cooled to near absolute 0 to reduce noise), and they have a clear line of sight without obstacles between transmitter and receiver. The data rate is very low at these distances: 160 bits/s.
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  35. The black hole is "massive" as in heavy, but it only takes up a tiny area: the supermassive black hole at the center of our solar system fits within Mercury's orbit. And there are millions of stars all around the black hole, so the black hole won't show up in ordinary photos. Only a system like the Event Horizon Telescope has enough resolution to show the black hole.
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  36. The farther away from the sun you get, the larger solar panels have to be to provide enough power. At Voyager's distance, you'd need several tons of solar panels to replace an RTG that weighs 50 kg.
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  37. You're misremembering. They could still communicate, and they still had people from the original team operating the computers. They were looking for young programmers who could be added to the team to learn from the original team.
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  38. Cost. NASA had seen its budget cut by 75% in the early 1970s, and the Voyager mission was scaled back from the original plan (which included 4 spacecraft with more payload than the Voyages).
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  39. Because their primary mission was to visit the same planets. That dictated their trajectory afterwards.
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  40. NASA uses a giant dish (34 m or 70 m diameter) to receive Voyager's signals, with the best receiver electronics money can buy (cooled to near absolute 0 to reduce noise), and they have a clear line of sight without obstacles between transmitter and receiver. The data rate is very low at these distances: 160 bits/s.
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  41. That lid never made it out of our atmosphere: the air resistance on the way up burned it up.
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  42. It's the other way round: They're switching off instruments to stay within the available power of the RTG.
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  43. about 17 km/s, or 61,000 km/h.
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  44. Voyager's transmitter produces 12 W of RF (or 18, but it's usually set to 12 W). This is sent through a 3.6 m dish antenna with 48 dBi gain.  To compensate for the weak signal, NASA uses a giant dish (34 m diameter) to receive Voyager's signals, with the best receiver electronics money can buy (cooled to near absolute 0 to reduce noise), and they have a clear line of sight without obstacles between transmitter and receiver. The data rate is very low at these distances: 160 bits/s.
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  45.  @bastawa  The beam width of the antenna is 0.5º. That's pretty narrow, but the distance is so huge that by the time the signal reaches Earth, that beam is about 300 million km wide. i.e. at the beginning of the mission, Voyager had to be aimed at Earth regularly, to follow it in its orbit. These days, Voyager can stay in the same orientation for months, if not the whole year because our entire orbit fits in that beam.
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  46. The Voyagers use radioisotope thermal generators: Pu-238 decays and produces heat, Peltier elements convert this to electricity. Pu-238 has a half-life of 87.7 years, so the output of the RTG reduces a bit every year. The Voyagers started out with 470 W, they're at about half of that now. You can receive a signal from so far away with careful design of the transmitter and receiver. Dish antennas concentrate the signal into a narrow cone, providing an enormous amount of gain over omnidirectional antennas. You can also build very sensitive receivers by cooling them to cryogenic temperatures (which reduces noise). NASA uses a 34 m dish to receive Voyager's signals. Transmission speed is 160 bits per second. Voyager's transmissions are sent out in a cone 0.5º wide. That isn't much, but by the time it gets to Earth, Earth's entire orbit fits inside that cone. Beyond Earth, you could still receive the signal with ever more elaborate transmitters. At some point, the signal loses coherence and becomes unintelligible, but that takes a long time.
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  47. We don't know if there's an edge: In all directions, we can see galaxies to the edge of our detection ability (about 13 billion lightyears).
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  48. What on Earth are you talking about? In 1969, NASA installed the first computer using integrated circuits in the Apollo CM and LM. It cost millions. In 1981, we (literally, anyone) could buy computers with about the same processing speed and memory capacity for $400. NASA and the DOD made that possible by investing in computer technology when it was expensive. The didn't keep anything away from us; quite the contrary.
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  49. False. We hae independent confirmation that the Voyagers are where NASA says they are.
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  50.  @abstract5249  On several occasions, radio telescopes detected the Voyagers. Febr 21, 2013, National Radio Astronomy Observatory's Very Long Baseline Array (VLBA) and Green Bank Telescope. Repeated in June 2013. November 8, 2018, Parkes radio telescope tracked Voyager 2. In 1989 during the Neptune encounter, the VLA was used to downlink data.
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  51.  @abstract5249  I see you're providing no evidence for your claim.
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  52. Using a single 34-m antenna, we can keep in contact until 2050 (Voyager 1) and 2057 (Voyager 2), if their power supply would last that long. NASA also have the option to receive data with an array of antennas, which could stretch this even further. The Voyager missions will end when there's not enough power left to operate one instrument. Not because we can't communicate with them.  And it's an expensive solution. A repeater near Jupiter, for instance, would orbit along with Jupiter, and would be farther away from the Voyagers than we are for half of Jupiter's 12-year orbit. You'd need 4 repeaters in Jupiter orbit alone for them to be useful. Easily a 4 billion dollar endeavor. Antennas on Earth cost $100M each.
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  53.  @rogerthat487  We're not ignoring anything. We have data from meteorological stations all over the world, for every day of the last ~200 years. Beyond that it gets more sparse, but we have usable data from various sources going back thousands of years. We use this to test and refine our models - not just by comparing to actual weather, but by running tests: start the model at 1900 with the data from that year, and compare the predictions it makes to our historical data for 1901 etc. And we don't just have one model: every research group develops models, These are compared with each other, to see which is the most accurate, and those are used as the start of the next iteration of making models. We've been doing climate modelling since the 1970s, so today's models have decades of testing and refinement behind them, and provide excellent predictions. And even if we ignore the models for a moment: the data itself tells us our climate is changing rapidly. The 1990-2000 decade set records: these 10 years were the warmest we'd ever seen since we started measuring. Then came the 2000-2010 decade, and it was warmer than 1990-2000. Then came 2010-2020 and it was warmer than 2000-2010. The only remaining uncertainty in our models is caused by having to predict human action: if we take climate change seriously and we limit our CO2 emissions, we get one outcome. If nations drag their heels and keep increasing their CO2 output, we get another outcome.
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  54. The point of sending out probes is to gather scientific data. The only way to do that for targets as far away as the heliopause is with a one-way mission.
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  55. No, obviously. They do carry some redundancy (both are using their backup transmitters now, for instance, and the computers are all duplicated).
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  56. That's incorrect. Only one Hubble was built. The NRO didn't need Hubble, they had the KH-11, which uses a mirror similar to Hubble's, with instruments optimized for Earth observation (i.e. very different to Hubble's requirements).
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  57. No, both Voyagers are still operational. There's some garbage data coming from Voyager 1's attitude control system, but that doesn't seem to be impacting operations.
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  58. The team wants to do that, but it's not certain that a mission extension will be granted for that.
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  59. Using a single 34-m antenna, we can keep in contact until 2050 (Voyager 1) and 2057 (Voyager 2), if their power supply would last that long. NASA also have the option to receive data with an array of antennas, which could stretch this even further. The Voyager missions will end when there's not enough power left to operate one instrument. Not because we can't communicate with them.
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  60. yes.
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  61. Don't be ridiculous. Models are being tested all the time. For our climate, for example, we have enormous amounts of data going back centuries, and we can reconstruct more data from indirect sources going back millions of years. Our climate models are tested against this data; that's how we know how accurate these models are.
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  62. That's nonsense. Humans are perfectly capable of building systems that last a long time. We're just mostly too cheap to do it.
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  63. other way round: Interstellar is between stars, intergalactic is between galaxies.
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  64. Pu-238 has a half-life of 87.7 years, so the output of the RTG reduces a bit every year. The Voyagers started out with 470 W, they're at about half of that now.
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  65. It's a phonograph record, not a CD. Instructions for playback are on the cover. Any civilization advanced enough to have spacflight should be able to read those instructions and build a record player.
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  66. The camera systems on the Voyagers were switched off in 1990. They no longer have enough power to run the cameras.
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  67. To bring them back, we'd have had to design a different trajectory that would slingshot them back into the inner solar system from Neptune, and we'd have missed out on 30 years of measurements on the outer solar system and the heliopause.
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  68. APL is working on an interstellar mission proposal. Even using an SLS to launch a Voyager-sized spacecraft, we can only get it to twice Voyager's speed.
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  69. Using a single 34-m antenna, we can keep in contact until 2050 (Voyager 1) and 2057 (Voyager 2), if their power supply would last that long. NASA also have the option to receive data with an array of antennas, which could stretch this even further. This is much cheaper than building relay spacecraft.
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  70.  @invictusfarmer7188  We'll have to invent faster-than-light communications to do that. (yep. Star Trek fan)
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  71. We don't. The Voyagers have a few kgs of fuel left, enough to change their course by a tiny amount. But we have no way to scan the area ahead of the Voyagers for obstacles smaller than, say, Pluto. Luckily space is very empty, so we can get away with that.
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  72. You're comparing apples and oranges. For the heliosphere, the Voyagers were the first to give us measurements at all. For our climate we don't have that problem: we have enormous amounts of data going back centuries, and we can reconstruct more data from indirect sources going back millions of years. There was a time when our climate models weren't very good: back in the 1960 when this science was in its infancy. These days, the models are accurate, and consistently make correct predictions.
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  73. What do you mean? The trajectory of both probes has not changed since their last planetary encounter in the 1980s: they're going in a straight line.
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  74. We did that in 2017, using radio telescopes. Some of the telemetry being sent back by Voyager 1 is off: the data sent by the attitude control system (i.e. which direction it's pointing in) is corrupt. The rest of the data is still correct. NASA's in contact with the Voyagers every day, and that contact includes accurately measuring the location of both spacecraft. So we know they're still where they're supposed to be. We can still receive signals from V1, indicating that the attitude is still correct. That makes it very unlikely the problem is caused by anything outside the spacecraft.
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  75.  @STOICZZZ  JWST would see the Voyagers as a single pixel at most, that's not enough to get information useful for troubleshooting the attitude data problem.
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  76. There are models and models. For our model of the heliosphere, the Voyagers are providing the first in-situ measurements. So we basically knew going in our model was going to be incomplete and have large error bars. For may processes here on Earth we have much better models, based on mountains of data, that have been tested by making predictions and seeing if they are accurate. The errors in those models are going to be tiny, which gives us confidence to use them for further predictions.
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  77. Easily. Photons don't need to interact with anything to travel - in fact they travel better in a vacuum. If radio waves couldn't travel through a vacuum, we wouldn't get sunlight on Earth.
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  78. Yes. They were numbered that way because Voyager 1 would be the first to reach Jupiter.
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  79.  @pathtooptimalhealth  They were named before the launch, the launch dates are set far in advance.
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  80. No. Two years ago, there was a period when we couldn't send commands to Voyager 2 because the only antenna that could do that was being upgraded. We're still in daily contact with both Voyagers.
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  81. You're watching the wrong videos. We launched several dedicated missions to study asteroids.
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  82. We can, we just had other priorities.
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  83. Science starts with observations. Scientists try to find an explanation for those observations, this becomes a model. The model is tested using more observations or experiments. When the model holds up and makes accurate predictions, it becomes a theory. The word 'theory' has a specific meaning here: it's not the colloquial opposite of 'practice'; a scientific theory is a model that has been shown to be accurate in a wide range of circumstances, and the best way we currently have to explain how things work. Scientists are very aware of the gaps in our theories, and are careful not to mix up conjectures and proven theories. The press consistently gets this wrong and ascribes far more confidence than the scientists themselves feel.
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  84. Using a single 34-m antenna, we can keep in contact until 2050 (Voyager 1) and 2057 (Voyager 2), if their power supply would last that long. NASA also have the option to receive data with an array of antennas, which could stretch this even further. The Voyager missions will end when there's not enough power left to operate one instrument. Not because we can't communicate with them. And it's an expensive solution. A repeater near Jupiter, for instance, would orbit along with Jupiter, and would be farther away from the Voyagers than we are for half of Jupiter's 12-year orbit. You'd need 4 repeaters in Jupiter orbit alone for them to be useful. Easily a 4 billion dollar endeavor. Antennas on Earth cost $100M each.
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  85. That's a ridiculous conclusion to draw. Scientists are very aware of the limitations of their knowledge.
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  86.  @bradandrews777  You're confusing popular journalism with science. In scientific papers, scientists are very careful to indicate how certain they are of their hypotheses.
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  87. Space exploration has a huge ROI, growing the economy to make more money available for fixing the planet. Satellites are an essential tool for monitoring the planet (land use, climate, pollution).
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  88. They were numbered in order of arrival at Jupiter. Voyager 2 was launched first, but had a slower trajectory than Voyager 1.
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  89. They use Pu-238, which has a half-life of 87.7 years, so the output of the RTG reduces a bit every year. The Voyagers started out with 470 W, they're at about half of that now. Pretty soon, not enough power will be available to run one science instrument.
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  90. After the Voyagers, we switched to long-term missions to single planets: Galileo, Juno and Cassini examined Jupiter and Saturn for years, answering the questions raised by the Voyager missions. A mission to Uranus is being developed right now.
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  91. You're wrong, all Voyager data is accessible.
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  92.  @eriknelson2559  The Voyagers have enough propellant to last another 2 decades. They're running out of Pu-238, not hydrazine. Adding another RTG would weigh a lot more than 1 kg.
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  93. Modeling is an essential part of science. Science starts with observations. Scientists try to find an explanation for those observations, this becomes a model. The model is tested using more observations or experiments. When the model holds up and makes accurate predictions, it becomes a theory. The word 'theory' has a specific meaning here: it's not the colloquial opposite of 'practice'; a scientific theory is a model that has been shown to be accurate in a wide range of circumstances, and the best way we currently have to explain how things work. In this case, we had no prior in-situ observations, so we built a model based on the physics we knew to be involved and what Earth-based observations we had.
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  94. You misinterpreted the news. They didn't need to wake one up. In 2020, NASA replaced the transmitter on the only antenna that can send new commands to Voyager 2. During that time, we kept receiving data from Voyager 2 every day, we just couldn't send new commands.
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  95. In principle yes, but the distances between objects in the Oort cloud is expected to be huge. So the chance of an impact is low.
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  96. to get miles, divide the number of km by 1.6.
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  97. Yes.
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  98. Voyager 2 was aimed to fly by Neptune's moon Triton, which meant the trajectory would go out of the ecliptic.
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  99. Depends on how you define it. The heliopause is the end of the region where the Sun's electromagnetic and particle influence is dominant, but the Sun's gravity is dominant in a much larger area.
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  100. They're doing both. They've switched off heaters, and they're planning to operate instruments intermittently when that becomes necessary.
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  101. They're slowly decelerating (the Sun's gravity slows them down gradually, but they have enough speed to escape our solar system).
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  102. yes.
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  103. The Voyager missions are real. Anyone claiming otherwise is neither unbiased nor objective.
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  104. It's surprisingly difficult. APL is working on an interstellar mission proposal, and they have trouble coming up with a design that's twice as fast as the Voyagers.
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  105. Those JPL documents were written long after the launch (2002), so they reflect the status then. The video gets it right: at launch, only a Jupiter-Saturn mission was approved.
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  106. That's really unlikely. Only one system is sending spurious data (the attitude control system), all the other data remains normal.
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  107. We'd find lots of empty space.
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  108. NASA uses a giant dish (34 m or 70 m diameter) to receive Voyager's signals, builds the best receiver electronics money can buy (cooled to near absolute 0 to reduce noise) and they have a clear line of sight without obstacles between transmitter and receiver. The data rate is very low at these distances: 160 bits/s.
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  109. They were switched off because after Neptune, there was nothing for the cameras to look at. And the amount of available power was getting smaller, so switching off the camera platform meant they could keep using the other instruments.
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  110. The trajectories were dictated by the planetary encounters. Voyager 1 did a flyby of Saturn's moon Titan, which set the exit trajectory. Voyager 2 flew by Neptune's moon Triton.
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  111. The 'Pale Blue Dot' image shows Earth as a single pixel. We can identify that pixel as Earth only because we know where the planets were at that moment, and we know Voyager's orientation.
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  112. The Bible tells us to take care of Earth. Our behavior which causes climate change is not 'taking care of Earth'.
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  113. That "kit" was a hoax. $250 gets you a starter motor and no batteries.
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  114. No. They're moving away from us at a huge speed (17 km/s), it would require several Saturn Vs worth of fuel to brake to 0 and accelerate in the other direction.
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  115. That's nonsense. Building equipment that lasts a long time is a skill that's been generally available to anyone for a long time. When it comes to spacecraft, there were specifics we had to learn: our first spacecraft didn't last a year. Our first probes into deep space predate the Voyagers by 20 years, so the Voyagers were built on a lot of experience. Heck, we even built Pioneer 10 and 11 specifically to measure what the environment around the outer planets was like so we could design the Voyagers properly - and it's a good thing we did, the radiation environment around Jupiter's a lot worse than we expected so the Voyagers had to be built to keep functioning in this environment. Then there's the timeline: Congress approved money for a 5-year mission instead of the Grand Tour that was requested, and the team building the spacecraft went ahead and built the probes to last as long as possible anyway, knowing that successful Jupiter and Saturn encounters would increase the chance of getting a mission extension. They were never designed for 5 years only. As for 'last even that much longer if not outlive Earth' - it's easy to do that with an inert object. We don't have interstellar travel.
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  116. The power source for the Voyagers costs $100 million for 470 W, and contains Plutonium. Nobody's going to use that in cars or phones.
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  117.  @gilee4481  In those days there was a certain amount of optimism about peaceful uses of nuclear power. They were quickly superseded by Li-iodide batteries. Pu-238 is safe as long as it's contained, but very toxic if spread around. A cremation of someone with a Pu-238 pacemaker implanted would be a major disaster. And that's a pacemaker: an expensive medical device used in small numbers, on people who are under regular medical care. Seeing how careless people are with their phones, I wound't want a Pu battery anywhere near that.
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  118.  @gilee4481  Cars? A Pu battery that weighs 500 kg (about the weight of the 100 kWh battery in a Tesla) produces.... 4 Kw. That's enough for a top speed of 50 km/h. And you forgot to address the cost: nuclear fuel processing (Pu-238 doesn't occur in nature, it has to be produced in a nuclear reactor, after which you have to separate it from other reaction products) is expensive.
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  119. As long as they don't cut the RTG open, they'll be fine. The entire decay chain of Pu-238 only produces Alpha particles, which are stopped by a sheet of paper.
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  120. Wifi is designed to be short range, because the shorter the range, the more wifi hotspots you can install without them interfering with each other, and the more users you can serve. Radio waves don't travel well through solid obstacles, so each wall between you and the hotspot reduces your signal. The same goes for cell phones. NASA uses a giant dish antenna to receive Voyager's signals, builds the best receiver electronics money can buy ($100 million each, the receiver is cooled to cryogenic temperatures to reduce noise), and they have a clear line of sight without obstacles between transmitter and receiver. At these distances, communication is slow: Voyager sends data at 160 bits/s.
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  121. Yes. Pioneer 10 was launched in that direction .Unfortunately that spacecraft is long out of power.
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  122. That's incorrect. We still talk to both every day.
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  123. The drawback is the price tag: $100M.
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  124. No, it's a graphical representation of measurements.
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  125. Their trajectories were dictated by the planetary encounters. The 'grand tour' alignment meant both probes would be going in similar directions. But Voyager 1 went 'up' relative to our ecliptic plane, and Voyager 2 went 'down'.
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  126. Do not vote for any Republicans in November. They continue to support a would-be dictator who has no respect for the election process.
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  127. It's molecules moving very fast. It's not inaccurate to call that wind even if there are only very few molecules (1/cm3).
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  128. There are instructions on the cover. Anyone who has figured out spaceflight can figure out how to play a record that has visible wave patterns.
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  129. Depends on how you define it. The heliopause is the end of the region where the Sun's electromagnetic and particle influence is dominant, but the Sun's gravity is dominant in a much larger area.
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  130. No. Voyager 1 is sending some spurious telemetry from one system (AACS).
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  131. There's only one star in our solar system: the Sun. It will take tens of thousands of years before either Voyager gets anywhere near another star. I suspect you're talking about asteroids or space debris instead: space is empty. The gaps between objects are huge, so the chance of hitting anything is astronomically low.
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  132. no, but the Voyagers aren't powered by chemical batteries. They use radioisotope thermal generators: Pu-238 decays and produces heat, Peltier elements convert this to electricity. Pu-238 has a half-life of 87.7 years, so the output of the RTG reduces a bit every year. The Voyagers started out with 470 W, they're at about half of that now.
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  133. There is a proposal to do that: the APL Interstellar mission. It turns out to be really difficult to make a spacecraft faster than the Voyagers: the APL proposal requires a launch on an SLS, and its speed is 7 AU/year, only twice as fast as Voyager.
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  134. Space is really empty.
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  135. The sun's gravity is dominant in a much larger area than that: roughly halfway to the next star, so 2 lightyears or so.
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  136. No, the EU model didn't predict the heliopause.
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  137. That's a load of nonsense. Planet-size objects are easy to detect from any of the 800 astronomical observatories on Earth, plus the thousands of amateur astronomers. NASA is in no position to keep this kind of information secret.
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  138. The Moon missions ended because they were expensive. It took 5% of the Federal budget for a decade to get to the Moon. After Apollo, NASA's budget was slashed to 1/5 of what it was. So NASA concentrated on cheaper efforts: a reusable spacecraft (Space Shuttle), and learning how to live in space for longer periods (via the ISS).
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  139. No, they didn't shut down. Both remain operational.
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  140.  @jimmytaylor1570  yeah, there was a story in the news recently that headlined 'NASA is shutting down the Voyagers'. That headline was misleading. That "shut down" process will take years. NASA is going to keep the spacecraft running for as long as possible. They'll monitor the available power (which slowly reduces, at about 4 W/year) and switch off instruments to stay within that limit. Occasionally, they find a way to keep the instruments running for longer than expected: two years ago the engineers switched off the heater for the cosmic-ray detector, which had been crucial in determining the heliopause transit. Everyone expected the instrument to die, but it kept working. This, and variability in the rate of decay of the RTG makes it difficult to predict exaxtly when the Voyagers will run out of power to run the last remaining instrument. The current best guess is 'about 2025'.
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  141. That would mean it'd take a lot longer to get to the heliopause.
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  142.  @joeydepalmer4457  Up and down are relative to some reference. Astronomers use Earth as their reference. So 'up' is the direction our North pole points to.
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  143.  @joeydepalmer4457  Yes, it could be. These names are arbitrary. Once the first people started using 'north' and 'south' we were all stuck with whatever they chose.
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  144. Yes, those are taken into account.
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  145.  @henkvisser9741  The instruments are pretty simple. They detect magnetic fields, and various types of radiation. The 'unexpected' happens when the measurements are different to what the physics model predicted, but it's still measuring something well-known and well-tested before launch. The Voyagers also have onboard checks to make sure the computers haven't been corrupted.
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  146. No. The EU 'theory' posits that every interaction in the universe is driven by electromagnetism instead of gravity. That has been disproven. The existence of EM interactions in our solar system does not mean the EU theory is correct.
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  147.  @rogerthat487  That's climate denier propaganda not supported by data.
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  148. No. They don't carry enough fuel to do that: they're leaving the solar system at a speed of 17 km/s. You would need several Saturn V rockets to brake from 17 km/s to 0 and then accelerate in the other direction.
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  149. No, the density is far too low to harvest usable energy from them.
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  150. You're comparing apples and oranges. For the heliosphere, the Voyagers were the first to give us measurements at all. For our climate we don't have that problem: we have enormous amounts of data going back centuries, and we can reconstruct more data from indirect sources going back millions of years. We can use that data to verify our models. There was a time when our climate models weren't very good: back in the 1960 when this science was in its infancy. These days, the models are accurate, and consistently make correct predictions.
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  151. Voyager 1 would be the first one to reach Jupiter.
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  152. Yes and no. Temperature is a property of matter. There's almost no matter in space, so space itself doesn't have a temperature. If you have a spacecraft in space, the only way for it to get warmer or colder is through radiation. Anything near Earth that's exposed to direct sunlight warms up to about 120 ºC. Anything in shadow can get very cold (JWST manages 40 K in the shadow of its sunshade).
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  153. As you get farther out from the sun, your solar panels provide less power. At their current distance, solar panels provide 1/14400 the power they do here on Earth.
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  154. Cell service is short-range radio, with a tiny antenna and a $3 receiver in your phone. The cell system is built deliberately to have short range, because the shorter the range, the more cell towers you can install without them interfering with each other, and the more users you can serve. Radio waves don't travel well through solid obstacles, so each wall between you and the cell tower reduces your signal. NASA uses a giant dish to receive Voyager's signals, builds the best receiver electronics money can buy ($100 million each, the receiver is cooled to cryogenic temperatures to reduce noise), and they have a clear line of sight without obstacles between transmitter and receiver. At these distances, communication is slow: Voyager sends data at 160 bits/s.
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  155. it wouldn't be centuries, it'd be 100,000 years.
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  156. They use radioisotope thermal generators: Pu-238 decays and produces heat, Peltier elements convert this to electricity. Pu-238 has a half-life of 87.7 years, so the output of the RTG reduces a bit every year. The Voyagers started out with 470 W, they're at about half of that now. They cost about $100 million a piece to produce, because you have to process highly radioactive material to get the Pu-238.
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  157.  @randycooper3940  Sure, large-scale development would make RTGs cheaper, but they'd need to be about a million times cheaper to be cost-competitive with our current grid. I don't see that happening.  RTGs are also really inefficient: The Voyager RTGs convert about 5% of the heat from the Pu-238 into usable power. And producing Pu-238 adds another step of inefficiency. For use on Earth, you're much better off with a nuclear reactor, which gets closer to 50% efficiency. Distributed nuclear power isn't going to happen. A Pu-238 RTG is safe under normal circumstances (it only produces alpha radiation, which is stopped by the casing), but an accident would spread toxic, radioactive Pu-238.
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  158. The Voyagers can't land, so any species that can find and access one of the Voyagers has mastered spaceflight, figuring out how to play a record is a far simpler problem than spaceflight so we're confident they could solve that puzzle. Sound and light are pretty universal.
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  159. Voyager took 45 years to travel to a point still within our solar system. We don't have the technology yet to travel to other stars in a reasonable time.
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  160. above and below the ecliptic plane.
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  161. Because nothing like that exists.
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  162. No. The density was higher than expected, but not by enough to account for the missing mass.
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  163. Cell service is short-range radio, with a tiny antenna and a $3 receiver in your phone. The cell system is built deliberately to have short range, because the shorter the range, the more cell towers you can install without them interfering with each other, and the more users you can serve. Radio waves don't travel well through solid obstacles, so each wall between you and the cell tower reduces your signal. NASA uses a giant dish to receive Voyager's signals, builds the best receiver electronics money can buy ($100 million each, the receiver is cooled to cryogenic temperatures to reduce noise), and they have a clear line of sight without obstacles between transmitter and receiver. At these distances, communication is slow: Voyager sends data at 160 bits/s. It takes about 20 hours for radio signals from Voyager to reach Earth.
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  164. No. Our climate models are excellent, and have been shown to accurately predict events again and again. In 2000, we tallied the average temperatures for 1990-2000 and it turned out that decade was the hottest decade since temperature measurements began. In 2010, we did that again and the 2000-2010 turned out to have been even warmer. In 2020, we did that again and the 2010-2020 decade turned out to have been even warmer. This validated our models, again, showing a strong correlation between humans producing excess CO2 and our planet getting warmer. So anthropogenic global warming is not "rhetoric", it's data. Plain for all to see. We're warming up the planet. The only people still denying that are shills for the fossil fuel industry and the people hoodwinked by them.
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  165. Kilometers tell 97% of the world's population everything. Miles are for laggards.
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  166. That channel pushes pseudoscience.
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  167. not so much "now" as "over the past 10 years". They're measuring the heliopause, where the Sun's electromagnetic influence ends and the interstellar medium begins.
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  168. there's no way to do that. They'd need several Saturn V's worth of fuel to reverse course.
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  169. Yes, there are proposals to use magnetic fields to protect long-duration human missions.
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  170. Cell service is short-range radio, with a tiny antenna and a $3 receiver in your phone. The cell system is built deliberately to have short range, because the shorter the range, the more cell towers you can install without them interfering with each other, and the more users you can serve. Radio waves don't travel well through solid obstacles, so each wall between you and the cell tower reduces your signal. NASA uses a giant dish to receive Voyager's signals, builds the best receiver electronics money can buy ($100 million each, the receiver is cooled to cryogenic temperatures to reduce noise), and they have a clear line of sight without obstacles between transmitter and receiver. At these distances, communication is slow: Voyager sends data at 160 bits/s. And they still get interference on occasion (rain is a problem, for example).
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  171. No, NASA hasn't decided that at all. They're going to keep the spacecraft running for as long as possible. They'll monitor the available power (which slowly reduces, at about 4 W/year) and switch off instruments to stay within that limit. Occasionally, they find a way to keep the instruments running for longer than expected: two years ago the engineers switched off the heater for the cosmic-ray detector, which had been crucial in determining the heliopause transit. Everyone expected the instrument to die, but it kept working. This, and variability in the rate of decay of the RTG makes it difficult to predict exaxtly when the Voyagers will run out of power to run the last remaining instrument. The current best guess is 'about 2025'.
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  172. That's incorrect. LaCroix is a charlatan peddling nonsense.
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  173. You're comparing apples and oranges. For the heliosphere, the Voyagers were the first to give us measurements at all. For our climate we don't have that problem: we have enormous amounts of data going back centuries, and we can reconstruct more data from indirect sources going back millions of years. There was a time when our climate models weren't very good: back in the 1960 when this science was in its infancy. These days, the models are accurate, and consistently make correct predictions.
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  174. The EU hypeothesis has been disproven. It's junk.
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  175. Space is empty.
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  176. The Voyagers haven't stopped reporting back quite yet.
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  177. No, it includes instructions on how to play the record. Building a record player should not be difficult for a civilization that has mastered spaceflight.
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  178. We have much larger antennas here on Earth than on JWST. NASA uses 34-m antennas to contact Voyager, JWST has an antenna about 1 m wide.
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  179. No.
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  180. You're comparing apples and oranges. For the heliosphere, the Voyagers were the first to give us measurements at all. For our climate we don't have that problem: we have enormous amounts of data going back centuries, and we can reconstruct more data from indirect sources going back millions of years. There was a time when our climate models weren't very good: back in the 1960 when this science was in its infancy. These days, the models are accurate, and consistently make correct predictions.
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  181. They use radio. This was invented around 1900. Cell phones use radio. The only new requirement for cell phones was the ability to have multiple calls going on without them interfering with each other.
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  182. No. For the heliosphere, the Voyagers provided the first data - anything before that was theoretical; Voyager was the first chance we had to validate and refine the model. For our climate, we have enormous amounts of data, with more being added every day. And we have the option to validate these models against e.g. historical data. So the uncertainty in climate models is a lot smaller than that of our heliopause models before Voyager.
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  183. They're commonly used to describe directions relative to the ecliptic.
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  184. No, from Neptune.
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  185. The only problem is that the atmosphere will melt your spacecraft.
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  186. The Voyagers detected the heliopause (the edge of the area where the solar wind is the main contribution to the environment). The location of the heliopause and the shape of the heliosphere were unknown until then. The shape is still being debated because we only have 2 data points.
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  187.  @hisgreasiness  Yes, sounds about right.
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  188. No. They use radioisotope thermal generators: Pu-238 decays and produces heat, Peltier elements convert this to electricity.
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  189. North and South in the solar system are relative to the ecliptic plane.
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  190. NASA isn't upset at the Voyagers. The Voyager 1 data anomaly has been solved: The AACS had started sending its telemetry data through an onboard computer known to have stopped working years ago, and the computer corrupted the information. Switching back to the correct computer solved the problem.
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  191. Voyager 1 was the first to arrive at Jupiter.
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  192. yes. Voyager 1 would be the first one to reach Jupiter.
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  193. They use radioisotope thermal generators: Pu-238 decays and produces heat, Peltier elements convert this to electricity. Pu-238 has a half-life of 87.7 years, so the output of the RTG reduces a bit every year. The Voyagers started out with 470 W, they're at about half of that now. In a few years, there won't be enough power left to drive the radio transmitter. That will end the mission.
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  194. That's a load of nonsense. There is no "planet x".
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  195. No. It's pretty simple to transmit data at long distances. NASA uses a giant dish (34 m or 70 m diameter) to receive Voyager's signals, builds the best receiver electronics money can buy (cooled to near absolute 0 to reduce noise), and they have a clear line of sight without obstacles between transmitter and receiver.
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  196. The Voyagers won't get anywhere near another star for the next 100,000 years or so. Plenty of time to invent better weapons.
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  197.  @bobsmoot2392  What would aliens be doing in the empty space between star systems? You underestimate how big space is.
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  198.  @bobsmoot2392  The golden records' primary function was to inspire humanity.
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  199.  @bobsmoot2392  The main goal of the records was to inspire humanity and get some PR for the Voyager project.
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  200. that's because water, unlike gas, is not compressible.
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  201. There was nothing left to look at. The Voyager cameras were built for the planetary encounters, and wouldn't work well for astronomical observations (not enough light available).
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  202. Yes.
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  203. The Voyagers use radioisotope thermal generators: Pu-238 decays and produces heat, Peltier elements convert this to electricity. Pu-238 has a half-life of 87.7 years, so the output of the RTG reduces a bit every year. The Voyagers started out with 470 W, they're at about half of that now. This is unsuitable for use in phones.
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  204. They were numbered in order of arrival at Jupiter.
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  205. We already know there's no dead twin. Full-sky surveys from Earth have ruled that out, with much better instruments than the Voyagers carry.
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  206. The first images the Voyagers took a few days after launch are of Earth and the Moon. It seemed fitting that the last images the Voyagers took would be a family portrait of the solar system, including Earth. Not because those images had any scientific value, but because they have emotional value.
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  207. With the information on the plaque that covers the records, building a record player is easy.
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  208. Don't be silly. We know what goes on out that far because we sent spacecraft (the Voyagers) to measure the environment.
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  209. here on Earth? No, they've long since been replaced. They're still running some of the original software in emulation, IIRC.
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  210. Not really. New Horizons is not going to last longer than the Voyagers and was optimized for the Pluto encounter, not examining the heliosphere. There's a proposal from APL for an interstellar mission, their focus is on making it a lot faster than the Voyagers.
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  211. That's incorrect. The Voyagers have no batteries, so there's no low-powered mode they can use. The 'once every 24 hours' is correct, but that comms session lasts 8 hours. During that transmission, they're relaying live sensor data - this data can't be stored on board any more.
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  212.  @RandyJames22  Not really. The trajectory design was determined entirely by the position of the 4 gas giants, and the flybys the team wanted to do (Voyager 1 visited Titan at Saturn, which meant its trajectory would go upwards out of the ecliptic plane, voyager 2 visited Triton at Neptune, aiming its trajectory downwards).
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  213. No. They were launched at a high enough speed to escape from the solar system, so they'll keep going.
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  214. We don't have one.
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  215. They swapped them at the last moment because problems were found in what ended up as Voyager 1. The numbering reflected which spacecraft arrived at Jupiter first.
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  216. less than 1 kg.
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  217. The electronics are kept warm by heaters.
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  218. No. It'll take tens of thousands of years before they get anywhere near another star, and even then they'll pass that star at a distance of more than 1 lightyear. The Voyagers will run out of electrical power in the next 5 years. They won't be able to send anything after that.
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  219. Yes.
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  220. You're comparing apples and oranges. For the heliosphere, the Voyagers were the first to give us measurements at all. For our climate we don't have that problem: we have enormous amounts of data going back centuries, and we can reconstruct more data from indirect sources going back millions of years. There was a time when our climate models weren't very good: back in the 1960 when this science was in its infancy. These days, the models are accurate, and consistently make correct predictions.
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  221. After the Voyagers, NASA switched to missions that would examine one planet in detail. Galileo, Juno and Cassini were built to answer questions raised by the Voyager data. These are expensive missions, so we can't do very many of them.
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  222. By then the power supply will be dead, so they won't measure anything.
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  223. They numbered them that way because Voyager 1 would be the first to arrive at Jupiter.
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  224. We can do that because we know exactly where the Voyagers are. If we didn't, we'd never find them again.
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  225. In Earth orbit, the standard speed is about 17000 mph. for interplanetary missions, speeds vary depending on destination: anything heading towards the Sun is accelerated by the Sun's gravity, anything heading outwards gets slower the further away it gets. What makes the Voyagers special is that they have reached escape velocity from the sun. Only 5 spacecraft have done that so far (Pioneer 10/11, Voyager 1/2, New Horizons), and Voyager 1 is the fastest of those.
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  226. yep.
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  227. For the heliosphere, the Voyagers were the first to give us measurements at all. We have much better data to go on for most areas of science.
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  228. The heliosphere is defined as the region where the Sun's electromagnetic influence is dominant. The Voyagers left that area a few years ago. They won't leave the area where the Sun is gravitationally dominant for 50,000 more years.
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  229. The Voyagers don't use batteries. They use radioisotope thermal generators: Pu-238 decays and produces heat, Peltier elements convert this to electricity. Pu-238 has a half-life of 87.7 years, so the output of the RTG reduces a bit every year. The Voyagers started out with 470 W, they're at about half of that now.
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  230. APL is working on an interstellar mission proposal. These missions are difficult to get funded: they're expensive, and it takes decades to get results.
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  231. It shields against any radiation in the form of a particle with an electric charge (ions of radioactive isotopes, loose protons, etc) . Those are deflected by magnetic fields.
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  232.  @macsnafu  If we could see magnetic fields, I suspect we'd see huge bubbles around each star (their heliospheres). And charged particles streaming out from every star (solar wind). And those streams would interact with each other in between the heliospheres.
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  233. We're perfectly capable of building durable devices. It just costs more money than we're generally willing to spend. Hell, we perfected the art long before the Voyagers: we have machines and infrastructure 100 years old that's still in daily use.
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  234. You're comparing apples and oranges. For the heliosphere, the Voyagers were the first to give us measurements at all. For most models we don't have that problem: we have lots of data to test the model with, and we add more data every day, so models can be improved quickly.
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  235. No. That coal plant is much more efficient than any car engine, so it uses less fuel to charge your Tesla than you would use in your car. That reduces your CO2 emissions even if you get your power from coal.
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  236. The video is correct: Voyager 2 was launched first. The numbering was swapped because Voyager 1 would be the first one to reach Jupiter.
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  237. The heliopause is the edge of the heliosphere. The heliosphere is the area in which our sun's influence is dominant. The heliopause is where the sun's influence reduces. Outside the heliosphere, the interstellar medium is dominant.
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  238. No. The AACS was sending its data to the wrong computer (a failed unit) for processing. Once they switched back to the working backup computer, the AACS data returned to normal.
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  239. Wrong, we still get data from them every day.
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  240. Voyager has the same problem. When it rains at the DSN station they use to receive Voyager's signal, the S/N ratio takes a nose dive. They have about 20 dB of margin, but there's still occasional loss of signal.
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  241. That's not what happened. Congress approved money for a 5-year mission instead of the Grand Tour that was requested, and the team building the spacecraft went ahead and built the probes to last as long as possible anyway, knowing that successful Jupiter and Saturn encounters would increase the chance of getting a mission extension.
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  242. yep. And Earth has its own energy shield.
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