Jan 20, 2021 03:51 AM
(This post was last modified: Jan 20, 2021 03:56 AM by C C.)
https://www.universetoday.com/149700/ast...-starlink/
EXCERPTS: The constellation of hundreds (and eventually thousands) of satellites reflect light back to the Earth, impinging on the darkness of the skies for professional astronomers and stargazers alike. [...] One potential solution to this issue is applying a dark coating to the reflective antennae on the satellites’ ground-facing side.
In January of 2020, SpaceX launched the experimental DarkSat to test the effectiveness of such a coating. Astronomers around the world observed the new satellite. In December of 2020, a team from the National Astronomical Observatory of Japan (NAOJ) released a paper in The Astrophysical Journal showing detailed measurements of the efficacy of DarkSat.
[...] In the visible portion of the electromagnetic spectrum, the DarkSat appears half as bright as uncoated Starlink satellites. ... Dr. Horiuchi continued to explain that the light energy absorbed by the coating is then converted to heat. All objects with a measurable temperature radiate in the infrared. Since the DarkSat is warmed by its coating more than a typical Starlink satellite, it follows that DarkSat radiates more in the infrared. Essentially, when viewed in IR, DarkSat is brighter than a typical Starlink.
Is the higher brightness in the infrared portion of the spectrum something that will impact astronomical observations? Professor Masatoshi Ohishi, Head of the Spectrum Management Office at NAOJ and another author of the paper, commented, “The higher level of infrared flux would have a negative impact on infrared observations.” Ohishi continued to explain that this is not a surprise and was precisely what was expected of the coating... (MORE - details)
EXCERPTS: The constellation of hundreds (and eventually thousands) of satellites reflect light back to the Earth, impinging on the darkness of the skies for professional astronomers and stargazers alike. [...] One potential solution to this issue is applying a dark coating to the reflective antennae on the satellites’ ground-facing side.
In January of 2020, SpaceX launched the experimental DarkSat to test the effectiveness of such a coating. Astronomers around the world observed the new satellite. In December of 2020, a team from the National Astronomical Observatory of Japan (NAOJ) released a paper in The Astrophysical Journal showing detailed measurements of the efficacy of DarkSat.
[...] In the visible portion of the electromagnetic spectrum, the DarkSat appears half as bright as uncoated Starlink satellites. ... Dr. Horiuchi continued to explain that the light energy absorbed by the coating is then converted to heat. All objects with a measurable temperature radiate in the infrared. Since the DarkSat is warmed by its coating more than a typical Starlink satellite, it follows that DarkSat radiates more in the infrared. Essentially, when viewed in IR, DarkSat is brighter than a typical Starlink.
Is the higher brightness in the infrared portion of the spectrum something that will impact astronomical observations? Professor Masatoshi Ohishi, Head of the Spectrum Management Office at NAOJ and another author of the paper, commented, “The higher level of infrared flux would have a negative impact on infrared observations.” Ohishi continued to explain that this is not a surprise and was precisely what was expected of the coating... (MORE - details)