4 ms·

What? we have a telescope in L2 point(the second Lagrangian point)! it is soo much better there compared to the moon

autokad 4y ago
if we could manufacture the telescopes on the moon, we could build massive ones (and size matters). And, why not have both?
- post-it 4y ago
  Couldn't we manufacture more massive ones in orbit around the moon, since they won't collapse under their own weight? We'd need extra fuel to get resources or parts off the surface of the moon, but that's nothing in comparison to the fuel needed to get off the Earth. Edit: I forgot the moon has a much lower gravity than Earth. It might still be worthwhile to build in orbit, but we can build a lot bigger on the moon than on Earth.
  - sandworm101 4y ago
    Moon orbits are very unstable. Maintaining anything so large there for an extended period would be difficult.
    - shagie 4y ago
      (on the unstable lunar orbits...) https://en.wikipedia.org/wiki/Lunar_orbit https://en.wikipedia.org/wiki/Lunar_orbit > Gravitational anomalies slightly distorting the orbits of some Lunar Orbiters led to the discovery of mass concentrations (dubbed mascons) beneath the lunar surface caused by large impacting bodies at some remote time in the past. These anomalies are of sufficient magnitude to cause a lunar orbit to change significantly over the course of several days. They can cause a plumb bob to hang about a third of a degree off vertical, pointing toward the mascon, and increase the force of gravity by one-half percent. > ... > Study of the mascons' effect on lunar spacecraft led to the discovery in 2001 of "frozen orbits" occurring at four orbital inclinations: 27°, 50°, 76°, and 86°, in which a spacecraft can stay in a low orbit indefinitely. Consider that - there are only four inclinations where you an orbit the moon without needing to do constant adjustments. Whereas with the Earth basically all the inclinations are available. https://en.wikipedia.org/wiki/Frozen_orbit https://en.wikipedia.org/wiki/Frozen_orbit and https://science.nasa.gov/science-news/science-at-nasa/2006/06nov_loworbit/ https://science.nasa.gov/science-news/science-at-nasa/2006/0... for more on this.
  - bryanlarsen 4y ago
    It would mass a lot more in orbit, since the moon itself is providing most of the structure for the proposed telescope.
shagie 4y ago
A radio telescope on the scale of Arecibo - where you are after extremely large surface area for detection of faint signals - is limited by the size of the dish. Arecibo was 73,000 square meters while JWST is "only" 25 square meters. For this, building it in a crater on the moon and allowing the moon itself to help support it is advantageous. ... and has some interesting scaling up possible. https://www.researchgate.net/publication/258694444_Implementing_planetary_meteor_impact_craters_as_high_gain_radio_frequency_dish_reflector_antennas https://www.researchgate.net/publication/258694444_Implement...

if we could manufacture the telescopes on the moon, we could build massive ones (and size matters). And, why not have both?

post-it 4y ago
Couldn't we manufacture more massive ones in orbit around the moon, since they won't collapse under their own weight? We'd need extra fuel to get resources or parts off the surface of the moon, but that's nothing in comparison to the fuel needed to get off the Earth. Edit: I forgot the moon has a much lower gravity than Earth. It might still be worthwhile to build in orbit, but we can build a lot bigger on the moon than on Earth.
- sandworm101 4y ago
  Moon orbits are very unstable. Maintaining anything so large there for an extended period would be difficult.
  - shagie 4y ago
    (on the unstable lunar orbits...) https://en.wikipedia.org/wiki/Lunar_orbit https://en.wikipedia.org/wiki/Lunar_orbit > Gravitational anomalies slightly distorting the orbits of some Lunar Orbiters led to the discovery of mass concentrations (dubbed mascons) beneath the lunar surface caused by large impacting bodies at some remote time in the past. These anomalies are of sufficient magnitude to cause a lunar orbit to change significantly over the course of several days. They can cause a plumb bob to hang about a third of a degree off vertical, pointing toward the mascon, and increase the force of gravity by one-half percent. > ... > Study of the mascons' effect on lunar spacecraft led to the discovery in 2001 of "frozen orbits" occurring at four orbital inclinations: 27°, 50°, 76°, and 86°, in which a spacecraft can stay in a low orbit indefinitely. Consider that - there are only four inclinations where you an orbit the moon without needing to do constant adjustments. Whereas with the Earth basically all the inclinations are available. https://en.wikipedia.org/wiki/Frozen_orbit https://en.wikipedia.org/wiki/Frozen_orbit and https://science.nasa.gov/science-news/science-at-nasa/2006/06nov_loworbit/ https://science.nasa.gov/science-news/science-at-nasa/2006/0... for more on this.
- bryanlarsen 4y ago
  It would mass a lot more in orbit, since the moon itself is providing most of the structure for the proposed telescope.

shagie 4y ago

A radio telescope on the scale of Arecibo - where you are after extremely large surface area for detection of faint signals - is limited by the size of the dish. Arecibo was 73,000 square meters while JWST is "only" 25 square meters. For this, building it in a crater on the moon and allowing the moon itself to help support it is advantageous. ... and has some interesting scaling up possible. https://www.researchgate.net/publication/258694444_Implementing_planetary_meteor_impact_craters_as_high_gain_radio_frequency_dish_reflector_antennas https://www.researchgate.net/publication/258694444_Implement...