Why were the Voyager spacecraft numbered “out-of-order”?











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Voyager 2 was launched on August 20, 1977. Sixteen days later, Voyager 1 was launched on September 5, 1977.



Why was the first spacecraft numbered #2 and the second spacecraft numbered #1?





Clarification: One would expect that the first spacecraft to be manufactured would be the first ready for launch. Since that didn't happen, there is more to the story, and that is what this question is about.










share|improve this question




















  • 2




    That still doesn't explain why #2 was launched first.
    – Dr Sheldon
    yesterday






  • 2




    Voyager 1 was started later but used a faster trajectory. From wikipedia "On November 7, 2012, Voyager 2 reached 100 AU from the sun, making it the third human-made object to reach 100 AU. Voyager 1 was 122 AU from the Sun" , "In 2013 Voyager 1 was escaping the solar system at a speed of about 3.6 AU per year, while Voyager 2 was only escaping at 3.3 AU per year.[41] (Each year Voyager 1 increases its lead over Voyager 2) ".
    – Uwe
    yesterday






  • 1




    There is a very good documentary on the Voyager spacecraft called "The Farthest" available on Netflix. I watched it a few nights ago and the numbering was explained there as well.
    – James
    yesterday






  • 1




    While I don't know for sure, I would think that something like the Voyagers would be built in parallel, rather than one after the other.
    – jamesqf
    yesterday






  • 4




    On MER we numbered the builds, but used letters for the launches. So MER-1 was built before MER-2. MER-A would both launch and arrive first, and MER-B would launch and arrive second. We weren't sure which hardware would launch first, and in fact due to how system testing on the two units was laid out, MER-2 became MER-A (Spirit), and MER-1 became MER-B (Opportunity).
    – Mark Adler
    yesterday















up vote
41
down vote

favorite
1












Voyager 2 was launched on August 20, 1977. Sixteen days later, Voyager 1 was launched on September 5, 1977.



Why was the first spacecraft numbered #2 and the second spacecraft numbered #1?





Clarification: One would expect that the first spacecraft to be manufactured would be the first ready for launch. Since that didn't happen, there is more to the story, and that is what this question is about.










share|improve this question




















  • 2




    That still doesn't explain why #2 was launched first.
    – Dr Sheldon
    yesterday






  • 2




    Voyager 1 was started later but used a faster trajectory. From wikipedia "On November 7, 2012, Voyager 2 reached 100 AU from the sun, making it the third human-made object to reach 100 AU. Voyager 1 was 122 AU from the Sun" , "In 2013 Voyager 1 was escaping the solar system at a speed of about 3.6 AU per year, while Voyager 2 was only escaping at 3.3 AU per year.[41] (Each year Voyager 1 increases its lead over Voyager 2) ".
    – Uwe
    yesterday






  • 1




    There is a very good documentary on the Voyager spacecraft called "The Farthest" available on Netflix. I watched it a few nights ago and the numbering was explained there as well.
    – James
    yesterday






  • 1




    While I don't know for sure, I would think that something like the Voyagers would be built in parallel, rather than one after the other.
    – jamesqf
    yesterday






  • 4




    On MER we numbered the builds, but used letters for the launches. So MER-1 was built before MER-2. MER-A would both launch and arrive first, and MER-B would launch and arrive second. We weren't sure which hardware would launch first, and in fact due to how system testing on the two units was laid out, MER-2 became MER-A (Spirit), and MER-1 became MER-B (Opportunity).
    – Mark Adler
    yesterday













up vote
41
down vote

favorite
1









up vote
41
down vote

favorite
1






1





Voyager 2 was launched on August 20, 1977. Sixteen days later, Voyager 1 was launched on September 5, 1977.



Why was the first spacecraft numbered #2 and the second spacecraft numbered #1?





Clarification: One would expect that the first spacecraft to be manufactured would be the first ready for launch. Since that didn't happen, there is more to the story, and that is what this question is about.










share|improve this question















Voyager 2 was launched on August 20, 1977. Sixteen days later, Voyager 1 was launched on September 5, 1977.



Why was the first spacecraft numbered #2 and the second spacecraft numbered #1?





Clarification: One would expect that the first spacecraft to be manufactured would be the first ready for launch. Since that didn't happen, there is more to the story, and that is what this question is about.







voyager






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited yesterday

























asked yesterday









Dr Sheldon

2,014832




2,014832








  • 2




    That still doesn't explain why #2 was launched first.
    – Dr Sheldon
    yesterday






  • 2




    Voyager 1 was started later but used a faster trajectory. From wikipedia "On November 7, 2012, Voyager 2 reached 100 AU from the sun, making it the third human-made object to reach 100 AU. Voyager 1 was 122 AU from the Sun" , "In 2013 Voyager 1 was escaping the solar system at a speed of about 3.6 AU per year, while Voyager 2 was only escaping at 3.3 AU per year.[41] (Each year Voyager 1 increases its lead over Voyager 2) ".
    – Uwe
    yesterday






  • 1




    There is a very good documentary on the Voyager spacecraft called "The Farthest" available on Netflix. I watched it a few nights ago and the numbering was explained there as well.
    – James
    yesterday






  • 1




    While I don't know for sure, I would think that something like the Voyagers would be built in parallel, rather than one after the other.
    – jamesqf
    yesterday






  • 4




    On MER we numbered the builds, but used letters for the launches. So MER-1 was built before MER-2. MER-A would both launch and arrive first, and MER-B would launch and arrive second. We weren't sure which hardware would launch first, and in fact due to how system testing on the two units was laid out, MER-2 became MER-A (Spirit), and MER-1 became MER-B (Opportunity).
    – Mark Adler
    yesterday














  • 2




    That still doesn't explain why #2 was launched first.
    – Dr Sheldon
    yesterday






  • 2




    Voyager 1 was started later but used a faster trajectory. From wikipedia "On November 7, 2012, Voyager 2 reached 100 AU from the sun, making it the third human-made object to reach 100 AU. Voyager 1 was 122 AU from the Sun" , "In 2013 Voyager 1 was escaping the solar system at a speed of about 3.6 AU per year, while Voyager 2 was only escaping at 3.3 AU per year.[41] (Each year Voyager 1 increases its lead over Voyager 2) ".
    – Uwe
    yesterday






  • 1




    There is a very good documentary on the Voyager spacecraft called "The Farthest" available on Netflix. I watched it a few nights ago and the numbering was explained there as well.
    – James
    yesterday






  • 1




    While I don't know for sure, I would think that something like the Voyagers would be built in parallel, rather than one after the other.
    – jamesqf
    yesterday






  • 4




    On MER we numbered the builds, but used letters for the launches. So MER-1 was built before MER-2. MER-A would both launch and arrive first, and MER-B would launch and arrive second. We weren't sure which hardware would launch first, and in fact due to how system testing on the two units was laid out, MER-2 became MER-A (Spirit), and MER-1 became MER-B (Opportunity).
    – Mark Adler
    yesterday








2




2




That still doesn't explain why #2 was launched first.
– Dr Sheldon
yesterday




That still doesn't explain why #2 was launched first.
– Dr Sheldon
yesterday




2




2




Voyager 1 was started later but used a faster trajectory. From wikipedia "On November 7, 2012, Voyager 2 reached 100 AU from the sun, making it the third human-made object to reach 100 AU. Voyager 1 was 122 AU from the Sun" , "In 2013 Voyager 1 was escaping the solar system at a speed of about 3.6 AU per year, while Voyager 2 was only escaping at 3.3 AU per year.[41] (Each year Voyager 1 increases its lead over Voyager 2) ".
– Uwe
yesterday




Voyager 1 was started later but used a faster trajectory. From wikipedia "On November 7, 2012, Voyager 2 reached 100 AU from the sun, making it the third human-made object to reach 100 AU. Voyager 1 was 122 AU from the Sun" , "In 2013 Voyager 1 was escaping the solar system at a speed of about 3.6 AU per year, while Voyager 2 was only escaping at 3.3 AU per year.[41] (Each year Voyager 1 increases its lead over Voyager 2) ".
– Uwe
yesterday




1




1




There is a very good documentary on the Voyager spacecraft called "The Farthest" available on Netflix. I watched it a few nights ago and the numbering was explained there as well.
– James
yesterday




There is a very good documentary on the Voyager spacecraft called "The Farthest" available on Netflix. I watched it a few nights ago and the numbering was explained there as well.
– James
yesterday




1




1




While I don't know for sure, I would think that something like the Voyagers would be built in parallel, rather than one after the other.
– jamesqf
yesterday




While I don't know for sure, I would think that something like the Voyagers would be built in parallel, rather than one after the other.
– jamesqf
yesterday




4




4




On MER we numbered the builds, but used letters for the launches. So MER-1 was built before MER-2. MER-A would both launch and arrive first, and MER-B would launch and arrive second. We weren't sure which hardware would launch first, and in fact due to how system testing on the two units was laid out, MER-2 became MER-A (Spirit), and MER-1 became MER-B (Opportunity).
– Mark Adler
yesterday




On MER we numbered the builds, but used letters for the launches. So MER-1 was built before MER-2. MER-A would both launch and arrive first, and MER-B would launch and arrive second. We weren't sure which hardware would launch first, and in fact due to how system testing on the two units was laid out, MER-2 became MER-A (Spirit), and MER-1 became MER-B (Opportunity).
– Mark Adler
yesterday










1 Answer
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up vote
65
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accepted










Voyager 1 was the first to reach Jupiter and the first to reach Saturn, as it was launched on a "shorter and faster trajectory" (Wikipedia, NASA). So the numbering was chosen to reflect the order of the main part of the mission, not the launches.



I have not found any sources explicitly stating that as the reason, but the arrivals at Jupiter and Saturn received much more publicity than the launches, and at the time it certainly seemed natural that the first Voyager mission to reach Jupiter would be Voyager 1.



In Exploring Space by William E. Burrows, there is the following footnote:




Three weeks before the scheduled launch, the spacecraft that was
originally to be Voyager 2 developed mechanical problems. As a result,
a "spare" that actually carried the designation Voyager 3 became
Voyager 2. Once repaired, the original Voyager 2 was made Voyager 1.
The original voyager 1 was shipped back to JPL.




This at least shows that the naming had nothing to do when when each piece of hardware became available, since they renamed the hardware when they had to swap it out.



A reference to a NASA memo or even contemporaneous media coverage specifically supporting this reason would be a better answer, but this is what I have.






share|improve this answer



















  • 2




    It's not from a contemporaneous source, but here's something from NASA's Voyager mission page stating this is the reason: nasa.gov/mission_pages/voyager/multimedia/pia01480.html
    – Elezar
    yesterday










  • This is correct. This is also covered in The Interstellar Age: Inside the Forty-Year Voyager Mission by Jim Bell.
    – Brian Rogers
    yesterday












  • The original Voyager 1 remains on display today in the von Karman auditorium at JPL.
    – Mark Adler
    yesterday











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1 Answer
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active

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up vote
65
down vote



accepted










Voyager 1 was the first to reach Jupiter and the first to reach Saturn, as it was launched on a "shorter and faster trajectory" (Wikipedia, NASA). So the numbering was chosen to reflect the order of the main part of the mission, not the launches.



I have not found any sources explicitly stating that as the reason, but the arrivals at Jupiter and Saturn received much more publicity than the launches, and at the time it certainly seemed natural that the first Voyager mission to reach Jupiter would be Voyager 1.



In Exploring Space by William E. Burrows, there is the following footnote:




Three weeks before the scheduled launch, the spacecraft that was
originally to be Voyager 2 developed mechanical problems. As a result,
a "spare" that actually carried the designation Voyager 3 became
Voyager 2. Once repaired, the original Voyager 2 was made Voyager 1.
The original voyager 1 was shipped back to JPL.




This at least shows that the naming had nothing to do when when each piece of hardware became available, since they renamed the hardware when they had to swap it out.



A reference to a NASA memo or even contemporaneous media coverage specifically supporting this reason would be a better answer, but this is what I have.






share|improve this answer



















  • 2




    It's not from a contemporaneous source, but here's something from NASA's Voyager mission page stating this is the reason: nasa.gov/mission_pages/voyager/multimedia/pia01480.html
    – Elezar
    yesterday










  • This is correct. This is also covered in The Interstellar Age: Inside the Forty-Year Voyager Mission by Jim Bell.
    – Brian Rogers
    yesterday












  • The original Voyager 1 remains on display today in the von Karman auditorium at JPL.
    – Mark Adler
    yesterday















up vote
65
down vote



accepted










Voyager 1 was the first to reach Jupiter and the first to reach Saturn, as it was launched on a "shorter and faster trajectory" (Wikipedia, NASA). So the numbering was chosen to reflect the order of the main part of the mission, not the launches.



I have not found any sources explicitly stating that as the reason, but the arrivals at Jupiter and Saturn received much more publicity than the launches, and at the time it certainly seemed natural that the first Voyager mission to reach Jupiter would be Voyager 1.



In Exploring Space by William E. Burrows, there is the following footnote:




Three weeks before the scheduled launch, the spacecraft that was
originally to be Voyager 2 developed mechanical problems. As a result,
a "spare" that actually carried the designation Voyager 3 became
Voyager 2. Once repaired, the original Voyager 2 was made Voyager 1.
The original voyager 1 was shipped back to JPL.




This at least shows that the naming had nothing to do when when each piece of hardware became available, since they renamed the hardware when they had to swap it out.



A reference to a NASA memo or even contemporaneous media coverage specifically supporting this reason would be a better answer, but this is what I have.






share|improve this answer



















  • 2




    It's not from a contemporaneous source, but here's something from NASA's Voyager mission page stating this is the reason: nasa.gov/mission_pages/voyager/multimedia/pia01480.html
    – Elezar
    yesterday










  • This is correct. This is also covered in The Interstellar Age: Inside the Forty-Year Voyager Mission by Jim Bell.
    – Brian Rogers
    yesterday












  • The original Voyager 1 remains on display today in the von Karman auditorium at JPL.
    – Mark Adler
    yesterday













up vote
65
down vote



accepted







up vote
65
down vote



accepted






Voyager 1 was the first to reach Jupiter and the first to reach Saturn, as it was launched on a "shorter and faster trajectory" (Wikipedia, NASA). So the numbering was chosen to reflect the order of the main part of the mission, not the launches.



I have not found any sources explicitly stating that as the reason, but the arrivals at Jupiter and Saturn received much more publicity than the launches, and at the time it certainly seemed natural that the first Voyager mission to reach Jupiter would be Voyager 1.



In Exploring Space by William E. Burrows, there is the following footnote:




Three weeks before the scheduled launch, the spacecraft that was
originally to be Voyager 2 developed mechanical problems. As a result,
a "spare" that actually carried the designation Voyager 3 became
Voyager 2. Once repaired, the original Voyager 2 was made Voyager 1.
The original voyager 1 was shipped back to JPL.




This at least shows that the naming had nothing to do when when each piece of hardware became available, since they renamed the hardware when they had to swap it out.



A reference to a NASA memo or even contemporaneous media coverage specifically supporting this reason would be a better answer, but this is what I have.






share|improve this answer














Voyager 1 was the first to reach Jupiter and the first to reach Saturn, as it was launched on a "shorter and faster trajectory" (Wikipedia, NASA). So the numbering was chosen to reflect the order of the main part of the mission, not the launches.



I have not found any sources explicitly stating that as the reason, but the arrivals at Jupiter and Saturn received much more publicity than the launches, and at the time it certainly seemed natural that the first Voyager mission to reach Jupiter would be Voyager 1.



In Exploring Space by William E. Burrows, there is the following footnote:




Three weeks before the scheduled launch, the spacecraft that was
originally to be Voyager 2 developed mechanical problems. As a result,
a "spare" that actually carried the designation Voyager 3 became
Voyager 2. Once repaired, the original Voyager 2 was made Voyager 1.
The original voyager 1 was shipped back to JPL.




This at least shows that the naming had nothing to do when when each piece of hardware became available, since they renamed the hardware when they had to swap it out.



A reference to a NASA memo or even contemporaneous media coverage specifically supporting this reason would be a better answer, but this is what I have.







share|improve this answer














share|improve this answer



share|improve this answer








edited yesterday

























answered yesterday









Mark Foskey

1,303613




1,303613








  • 2




    It's not from a contemporaneous source, but here's something from NASA's Voyager mission page stating this is the reason: nasa.gov/mission_pages/voyager/multimedia/pia01480.html
    – Elezar
    yesterday










  • This is correct. This is also covered in The Interstellar Age: Inside the Forty-Year Voyager Mission by Jim Bell.
    – Brian Rogers
    yesterday












  • The original Voyager 1 remains on display today in the von Karman auditorium at JPL.
    – Mark Adler
    yesterday














  • 2




    It's not from a contemporaneous source, but here's something from NASA's Voyager mission page stating this is the reason: nasa.gov/mission_pages/voyager/multimedia/pia01480.html
    – Elezar
    yesterday










  • This is correct. This is also covered in The Interstellar Age: Inside the Forty-Year Voyager Mission by Jim Bell.
    – Brian Rogers
    yesterday












  • The original Voyager 1 remains on display today in the von Karman auditorium at JPL.
    – Mark Adler
    yesterday








2




2




It's not from a contemporaneous source, but here's something from NASA's Voyager mission page stating this is the reason: nasa.gov/mission_pages/voyager/multimedia/pia01480.html
– Elezar
yesterday




It's not from a contemporaneous source, but here's something from NASA's Voyager mission page stating this is the reason: nasa.gov/mission_pages/voyager/multimedia/pia01480.html
– Elezar
yesterday












This is correct. This is also covered in The Interstellar Age: Inside the Forty-Year Voyager Mission by Jim Bell.
– Brian Rogers
yesterday






This is correct. This is also covered in The Interstellar Age: Inside the Forty-Year Voyager Mission by Jim Bell.
– Brian Rogers
yesterday














The original Voyager 1 remains on display today in the von Karman auditorium at JPL.
– Mark Adler
yesterday




The original Voyager 1 remains on display today in the von Karman auditorium at JPL.
– Mark Adler
yesterday


















 

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