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Science (non-SETI) :
The Voyagers
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Lynn Send message Joined: 20 Nov 00 Posts: 14162 Credit: 79,603,650 RAC: 123 |
Thanks for the update Lynn L. One wounders now if NASA had wished that they you're welcome, Nick. NASA, most likely would now think differently. |
Lint trap Send message Joined: 30 May 03 Posts: 871 Credit: 28,092,319 RAC: 0 |
Thanks for the update Lynn L. One wounders now if NASA had wished that they From the memory of an Old Fart, IIRC, there was quite a bit of controversy over the planned RTG power plants. Putting a nuclear reactor, using U-238, on a rocket wasn't looked upon by the public as the best idea in the world at the time. U-238 has a long half-life of almost ~4.5 billion years, so, the fear was that if anything went wrong during launch or until the craft reached escape velocity, there was a chance of a major environmental impact. I believe NASA did well to get what they got. Lt edited... |
tullio Send message Joined: 9 Apr 04 Posts: 8797 Credit: 2,930,782 RAC: 1 |
AFAIK U-238 is not fissile, only fertile. Natural Uranium has a small percentage of U-235 (0.7 %) which enables it to be used in a reactor having heavy water as moderator, like in Canada's CANDU (Canada Deuterium Uranium). Tullio |
Gary Charpentier Send message Joined: 25 Dec 00 Posts: 30640 Credit: 53,134,872 RAC: 32 |
The material in the modified SNAP-19's on Voyager is Pu238. Half life about 87 years. However the thermocouples are decaying faster. |
Lint trap Send message Joined: 30 May 03 Posts: 871 Credit: 28,092,319 RAC: 0 |
The material in the modified SNAP-19's on Voyager is Pu238. Half life about 87 years. However the thermocouples are decaying faster. Thanks for the corrections! Lt |
Gordon Lowe Send message Joined: 5 Nov 00 Posts: 12094 Credit: 6,317,865 RAC: 0 |
Just watched a new interesting documentary about these fascinating Voyagers. 40 years ago they were launched. The mind is a weird and mysterious place |
Gordon Lowe Send message Joined: 5 Nov 00 Posts: 12094 Credit: 6,317,865 RAC: 0 |
Just watched a new interesting documentary about these fascinating Voyagers. http://www.npr.org/sections/13.7/2017/08/23/545484098/to-infinity-and-beyond-celebrating-40-years-of-the-voyager-mission This is the show I just watched: http://www.pbs.org/the-farthest/home/ The mind is a weird and mysterious place |
janneseti Send message Joined: 14 Oct 09 Posts: 14106 Credit: 655,366 RAC: 0 |
If Voyager were to travel to Proxima Centauri, at this rate, it would take over 73,000 years to arrive. That's a long time! |
janneseti Send message Joined: 14 Oct 09 Posts: 14106 Credit: 655,366 RAC: 0 |
NASA revealed the winning #MessageToVoyager and beamed it into space. https://youtu.be/5VzVyYbPbJY |
Gordon Lowe Send message Joined: 5 Nov 00 Posts: 12094 Credit: 6,317,865 RAC: 0 |
Thanks to Carl Sagan for persuading the Voyager team to turn the camera back toward Earth for the famous pale blue dot picture. :~) The mind is a weird and mysterious place |
Gordon Lowe Send message Joined: 5 Nov 00 Posts: 12094 Credit: 6,317,865 RAC: 0 |
NASA revealed the winning #MessageToVoyager and beamed it into space. I love that William Shatner was alive to take part in this! The mind is a weird and mysterious place |
Gordon Lowe Send message Joined: 5 Nov 00 Posts: 12094 Credit: 6,317,865 RAC: 0 |
Nice article about the Golden Records aboard the Voyagers: https://www.newyorker.com/tech/elements/voyager-golden-record-40th-anniversary-timothy-ferris The mind is a weird and mysterious place |
Gordon Lowe Send message Joined: 5 Nov 00 Posts: 12094 Credit: 6,317,865 RAC: 0 |
Thrusters fired! The mind is a weird and mysterious place |
Gordon Lowe Send message Joined: 5 Nov 00 Posts: 12094 Credit: 6,317,865 RAC: 0 |
I loved the Viking mission to Mars, and it communicated back to earth for a long time, all things considering it was a planetary lander, but the Voyager mission is so beyond anything the earth ever has sent out into space, I really love hearing about it still being alive out there. The fact that it can still receive and process physically functional commands is truly amazing to me. I wish I was on the staff of it's control center so I could celebrate with them. :~) The mind is a weird and mysterious place |
tullio Send message Joined: 9 Apr 04 Posts: 8797 Credit: 2,930,782 RAC: 1 |
The computers of the Voyagers have programs written in an outdated assembler language, according to NASA, and maybe NASA had problems finding programmers who knew that assembler. Having worked with theZilog Z80 assembler, maybe I can start a new career. We used eight inch floppies,, 20 MByte Winchester disks and 10 Mbyte tapes, on which we made daily incremental backups. Tullio |
moomin Send message Joined: 21 Oct 17 Posts: 6204 Credit: 38,420 RAC: 0 |
The computers of the Voyagers have programs written in an outdated assembler language, according to NASA, and maybe NASA had problems finding programmers who knew that assembler. Having worked with theZilog Z80 assembler, maybe I can start a new career. We used eight inch floppies,, 20 MByte Winchester disks and 10 Mbyte tapes, on which we made daily incremental backups. Perhaps the computers of the Voyagers are not even coded with assembler language. The Apollo moonlanders where not. Just hard coded machine language. https://history.nasa.gov/computers/Ch6-2.html The computers aboard the Voyager probes each have 69.63 kilobytes of memory, total. That’s about enough to store one average internet jpeg file. The probes’ scientific data is encoded on old-fashioned digital 8-track tape machines rather than whatever solid state drive your high-end laptop is currently using. Once it's been transmitted to Earth, the spacecraft have to write over old data in order to have enough room for new observations. The Voyager machines are capable of executing about 81,000 instructions per second. The smart phone that is likely sitting in your pocket is probably about 7,500 times faster than that. They transmit their data back to Earth at 160 bits per second. A slow dial-up connection can deliver at least 20,000 bits per second. |
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