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Great. And now let's build a telescope on the dark side of the moon!

michael_j_ward 6y ago
The dark side is only dark from our perspective on earth. It still receives two weeks of sunlight a month. If you wanted to minimize sunlight, you'd want to put a telescope at L2 [1], which is in fact where the James Webb Space Telescope will be deployed [2]. It's launch was recently pushed back from March to October of 2021 [3] (or [4] for non paywalled version) [1] https://www.space.com/30302-lagrange-points.html https://www.space.com/30302-lagrange-points.html [2] https://en.wikipedia.org/wiki/James_Webb_Space_Telescope https://en.wikipedia.org/wiki/James_Webb_Space_Telescope [3] https://www.nytimes.com/2020/07/16/science/nasa-james-webb-space-telescope-delay.html https://www.nytimes.com/2020/07/16/science/nasa-james-webb-s... [4] https://outline.com/bsWKnf https://outline.com/bsWKnf
- nickff 6y ago
  The dark side of the moon would be much better for a telescope array; given that the moon has no atmosphere and isn't seismically active, you could form a massive, scalable array with incredible resolution.
  - raducu 6y ago
    Is the Earth that much of a hassle if we built on the near side instead of the far side? Perhaps for radio astronomy? Or build it on the far side, near the poles, with a solar array just across the pole -- perhaps that way you could have solar power all year long.
    - nickff 6y ago
      Most large telescope arrays (that I know of) are for radio astronomy, largely for geographical reasons (as far as I know). Earth is a source of noise throughout the electromagnetic spectrum, so I think the benefits of building on the far side (eliminating Earth noise), will likely outweigh the costs (limited/more costly bandwidth). I think a mixed array, consisting of "radio" and "light" telescopes could present very interesting possibilities, especially because you could dynamically allocate sparse sets of the array to different tasks. All of that being said, I am an engineer (with an interest in array signal processing), not an astronomer.
- dylan604 6y ago
  And at L2, we'll never be able to upgrade it or even service if something were to go wrong before end of scheduled mission. Something on the moon would be much more accessible for upgrades or basic servicing missions. Even with 2 week on/2 week off schedule, it would be so useful. During those 2 weeks off, it would be charging its batteries. Never would it suffer from cloudy nights.
  - Rebelgecko 6y ago
    OTOH, a trip to the moon requires about 10x more fuel than going to L2. Although I suppose a moon telescope could synergize nicely with other lunar activities Edit: I think I misread the table I was looking it, it's more like 2x or 3x instead of 10x, and that assumes a start from LEO
  - theandrewbailey 6y ago
    There are and have been probes and observatories at L1 and L2: https://en.wikipedia.org/wiki/List_of_objects_at_Lagrangian_points#Sun%E2%80%93Earth_Lagrangian_points https://en.wikipedia.org/wiki/List_of_objects_at_Lagrangian_...
- peroporque 6y ago
  Sunlight is reflected from earth too.
smoorman1024 6y ago
I believe the dark side of the moon would be more apt for radio astronomy. The obvious reason being that the Moon is blocking interference of artificial radio signals on Earth.
- penagwin 6y ago
  The moon is interfering with radio signals? Doesn't this only happen if the moon is literally blocking line of sight? It seems like being outside of earth's atmosphere and ionosphere would be the biggest benefit for radio.
  - JshWright 6y ago
    There's still a lot of rf noise that can penetrate that far. ~3,400km of solid rock is a much better attenuator.
  - nickff 6y ago
    The moon is basically a giant reflector for (many bands of) radio. The reason the US government funded so many radio telescope arrays was to monitor Soviet ballistic missile tests, by looking at signals reflected off the moon.

The dark side is only dark from our perspective on earth. It still receives two weeks of sunlight a month. If you wanted to minimize sunlight, you'd want to put a telescope at L2 [1], which is in fact where the James Webb Space Telescope will be deployed [2]. It's launch was recently pushed back from March to October of 2021 [3] (or [4] for non paywalled version) [1] https://www.space.com/30302-lagrange-points.html https://www.space.com/30302-lagrange-points.html [2] https://en.wikipedia.org/wiki/James_Webb_Space_Telescope https://en.wikipedia.org/wiki/James_Webb_Space_Telescope [3] https://www.nytimes.com/2020/07/16/science/nasa-james-webb-space-telescope-delay.html https://www.nytimes.com/2020/07/16/science/nasa-james-webb-s... [4] https://outline.com/bsWKnf https://outline.com/bsWKnf

nickff 6y ago
The dark side of the moon would be much better for a telescope array; given that the moon has no atmosphere and isn't seismically active, you could form a massive, scalable array with incredible resolution.
- raducu 6y ago
  Is the Earth that much of a hassle if we built on the near side instead of the far side? Perhaps for radio astronomy? Or build it on the far side, near the poles, with a solar array just across the pole -- perhaps that way you could have solar power all year long.
  - nickff 6y ago
    Most large telescope arrays (that I know of) are for radio astronomy, largely for geographical reasons (as far as I know). Earth is a source of noise throughout the electromagnetic spectrum, so I think the benefits of building on the far side (eliminating Earth noise), will likely outweigh the costs (limited/more costly bandwidth). I think a mixed array, consisting of "radio" and "light" telescopes could present very interesting possibilities, especially because you could dynamically allocate sparse sets of the array to different tasks. All of that being said, I am an engineer (with an interest in array signal processing), not an astronomer.
dylan604 6y ago
And at L2, we'll never be able to upgrade it or even service if something were to go wrong before end of scheduled mission. Something on the moon would be much more accessible for upgrades or basic servicing missions. Even with 2 week on/2 week off schedule, it would be so useful. During those 2 weeks off, it would be charging its batteries. Never would it suffer from cloudy nights.
- Rebelgecko 6y ago
  OTOH, a trip to the moon requires about 10x more fuel than going to L2. Although I suppose a moon telescope could synergize nicely with other lunar activities Edit: I think I misread the table I was looking it, it's more like 2x or 3x instead of 10x, and that assumes a start from LEO
- theandrewbailey 6y ago
  There are and have been probes and observatories at L1 and L2: https://en.wikipedia.org/wiki/List_of_objects_at_Lagrangian_points#Sun%E2%80%93Earth_Lagrangian_points https://en.wikipedia.org/wiki/List_of_objects_at_Lagrangian_...
peroporque 6y ago
Sunlight is reflected from earth too.

smoorman1024 6y ago

I believe the dark side of the moon would be more apt for radio astronomy. The obvious reason being that the Moon is blocking interference of artificial radio signals on Earth.

penagwin 6y ago
The moon is interfering with radio signals? Doesn't this only happen if the moon is literally blocking line of sight? It seems like being outside of earth's atmosphere and ionosphere would be the biggest benefit for radio.
- JshWright 6y ago
  There's still a lot of rf noise that can penetrate that far. ~3,400km of solid rock is a much better attenuator.
- nickff 6y ago
  The moon is basically a giant reflector for (many bands of) radio. The reason the US government funded so many radio telescope arrays was to monitor Soviet ballistic missile tests, by looking at signals reflected off the moon.