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How do you propose to power a fleet of spacecraft at 550AU? Would you be able to acquire enough RTGs? What about DSN time for the downlink?

by s1dev 6y ago

PopeDotNinja 6y ago
And how would you get them out to, and stop at, 550 AU? Voyager 1 and 2 are nuclear powered with RTGs and they are respectively about 150 AU and 125 AU from the sun, and they are going really fast. The Voyager RTGs are also fairly depleted at this point. I’m guessing these spacecraft would need a faster, more efficient mode of propulsion, like a nuclear thruster or ion drive (or Epstein drive?!). One could also get a lot more fuel for the journey if the the probes didn’t have to launch fully fueled from the Earth’s surface.
- rini17 6y ago
  No need to stop at 550AU, the gravitational lens keeps working beyond that(theoretically all the way to infinity). As for how to get there, yes, innovative propulsion is required. My idea is that the probe would dive close to Sun and use solar energy (sail? electric propulsion?) to accelerate itself out to hundreds of km/s.
- 205guy 6y ago
  I was wondering how fast myself and found this: https://voyager.jpl.nasa.gov/mission/status/ https://voyager.jpl.nasa.gov/mission/status/ Voyager-1 is the fastest at 38,000 mph (61000 km/h) with respect to the Sun, but currently about 90,000 mph (144000 km/h) relative to earth (I guess this fluctuates annually).
- pas 6y ago
  Sun slingshot, solar sail https://www.youtube.com/watch?v=NQFqDKRAROI https://www.youtube.com/watch?v=NQFqDKRAROI
pvarangot 6y ago
That webpage says a tech demo is due 2024, with launch in 2034 and the constellation would reach 550AU by 2064, so probably a lot of how this will work is still WIP.
- skissane 6y ago
  The problem with dates like that is they are pure best wishes. They might have funding for a demo in 2024 – although it isn't even clear they've got that yet, it sounds like they may just have funding to develop their proposal further. Even assuming the tech demo is successful, it sounds like they don't even yet have a detailed costed proposal for a 2034 launch, and no idea how likely that it will actually get funded. Politicians and bureaucrats want immediate results, so a "launch now and see results in 30 years" mission – by which time many of the senior decision-makers will likely be dead – is going to be less attractive than competing missions offering results much sooner. If you go back through the history of space exploration, it is full of proposals that "by year X we will be doing Y!" which never came to pass, because the money never turned up.
  - withinboredom 6y ago
    > Politicians and bureaucrats want immediate results This makes me sad. The entire point of Government is to be an enterprise spanning multiple generations.
    - skissane 6y ago
      The downside of electoral democracy, is if you are only going to be be in power for 5-10 years max, why care about the state of the country in 30 years time, except out of the goodness of your heart? And electoral politics often does a rather poor job of selecting leaders with goodness in their hearts. Of course, non-democratic systems have their own, equally serious downsides. Consider China: a system which is arguably much better at making long-term investments in public infrastructure than most democratic countries are (witness China's high-speed rail system), but also a system which ruthlessly suppresses dissent and locks up over a million of its citizens in "re-education camps"
pas 6y ago
the recommendation is RTG + rad-hardened battery, naturally the question of will there be enough RTGs is a perfectly valid one. https://arxiv.org/ftp/arxiv/papers/2002/2002.11871.pdf https://arxiv.org/ftp/arxiv/papers/2002/2002.11871.pdf for downlink can't they launch a few extra sats that just sit around the Sun and form a big virtual dish (via baseline interferometry or what's that occult DSP magic called these days)?

How do you propose to power a fleet of spacecraft at 550AU? Would you be able to acquire enough RTGs? What about DSN time for the downlink?

by s1dev 6y ago

How do you propose to power a fleet of spacecraft at 550AU? Would you be able to acquire enough RTGs? What about DSN time for the downlink?

PopeDotNinja 6y ago

And how would you get them out to, and stop at, 550 AU? Voyager 1 and 2 are nuclear powered with RTGs and they are respectively about 150 AU and 125 AU from the sun, and they are going really fast. The Voyager RTGs are also fairly depleted at this point. I’m guessing these spacecraft would need a faster, more efficient mode of propulsion, like a nuclear thruster or ion drive (or Epstein drive?!). One could also get a lot more fuel for the journey if the the probes didn’t have to launch fully fueled from the Earth’s surface.

rini17 6y ago
No need to stop at 550AU, the gravitational lens keeps working beyond that(theoretically all the way to infinity). As for how to get there, yes, innovative propulsion is required. My idea is that the probe would dive close to Sun and use solar energy (sail? electric propulsion?) to accelerate itself out to hundreds of km/s.
205guy 6y ago
I was wondering how fast myself and found this: https://voyager.jpl.nasa.gov/mission/status/ https://voyager.jpl.nasa.gov/mission/status/ Voyager-1 is the fastest at 38,000 mph (61000 km/h) with respect to the Sun, but currently about 90,000 mph (144000 km/h) relative to earth (I guess this fluctuates annually).
pas 6y ago
Sun slingshot, solar sail https://www.youtube.com/watch?v=NQFqDKRAROI https://www.youtube.com/watch?v=NQFqDKRAROI

pvarangot 6y ago

That webpage says a tech demo is due 2024, with launch in 2034 and the constellation would reach 550AU by 2064, so probably a lot of how this will work is still WIP.

skissane 6y ago
The problem with dates like that is they are pure best wishes. They might have funding for a demo in 2024 – although it isn't even clear they've got that yet, it sounds like they may just have funding to develop their proposal further. Even assuming the tech demo is successful, it sounds like they don't even yet have a detailed costed proposal for a 2034 launch, and no idea how likely that it will actually get funded. Politicians and bureaucrats want immediate results, so a "launch now and see results in 30 years" mission – by which time many of the senior decision-makers will likely be dead – is going to be less attractive than competing missions offering results much sooner. If you go back through the history of space exploration, it is full of proposals that "by year X we will be doing Y!" which never came to pass, because the money never turned up.
- withinboredom 6y ago
  > Politicians and bureaucrats want immediate results This makes me sad. The entire point of Government is to be an enterprise spanning multiple generations.
  - skissane 6y ago
    The downside of electoral democracy, is if you are only going to be be in power for 5-10 years max, why care about the state of the country in 30 years time, except out of the goodness of your heart? And electoral politics often does a rather poor job of selecting leaders with goodness in their hearts. Of course, non-democratic systems have their own, equally serious downsides. Consider China: a system which is arguably much better at making long-term investments in public infrastructure than most democratic countries are (witness China's high-speed rail system), but also a system which ruthlessly suppresses dissent and locks up over a million of its citizens in "re-education camps"

pas 6y ago

the recommendation is RTG + rad-hardened battery, naturally the question of will there be enough RTGs is a perfectly valid one. https://arxiv.org/ftp/arxiv/papers/2002/2002.11871.pdf https://arxiv.org/ftp/arxiv/papers/2002/2002.11871.pdf for downlink can't they launch a few extra sats that just sit around the Sun and form a big virtual dish (via baseline interferometry or what's that occult DSP magic called these days)?