Starlink dark coating reduces reflectivity by half
Astronomers in Japan have now confirmed that the dark coating SpaceX has been putting on its more recent Starlink satellites has successfully reduced their reflectivity by half.
They looked at the satellites across a range of wavelengths.
Observations conducted from April to June 2020 revealed for the first time in the world that artificial satellites, whether coated or not, are more visible at longer wavelengths, and that the black coating can halve the level of surface reflectivity of satellites. Such surface treatment is expected to reduce the negative impacts on astronomical observations.
Knowing this detail will allow commercial satellite companies such as SpaceX to further refine their coatings to better hide their satellites from ground-based telescopes.
While good news, it doesn’t change the fundamental lesson that astronomers need to learn. They must move their telescopes off the Earth and into space. In the long run ground-based astronomy is a dead-end.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Astronomers in Japan have now confirmed that the dark coating SpaceX has been putting on its more recent Starlink satellites has successfully reduced their reflectivity by half.
They looked at the satellites across a range of wavelengths.
Observations conducted from April to June 2020 revealed for the first time in the world that artificial satellites, whether coated or not, are more visible at longer wavelengths, and that the black coating can halve the level of surface reflectivity of satellites. Such surface treatment is expected to reduce the negative impacts on astronomical observations.
Knowing this detail will allow commercial satellite companies such as SpaceX to further refine their coatings to better hide their satellites from ground-based telescopes.
While good news, it doesn’t change the fundamental lesson that astronomers need to learn. They must move their telescopes off the Earth and into space. In the long run ground-based astronomy is a dead-end.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
We were able to see the very first Starlink “train” of satellites within 24 hrs of launch.
Probably, the most astounding, artificial sight in the heavens I’ve ever witnessed.
Since then, on multiple attempts, even under optimum viewing conditions, we’ve never seen another Starlink.
Random satellites everywhere, but zero Starlinks.
Bummer.
Just because they are painted black doesn’t mean they won’t still be in the way of telescopes.
There is also a typo – most should be must.
Bob L. Thank you. Typo fixed.
Captain, I saw a Starlink train (the second time I’ve seen it) bigger than life just a few nights ago. The first time I saw a Starlink train, probably about a year ago, it scared the willies out of me because I had no idea what it was. I can only wonder what the earth’s current stone-age folks think when they see it.
Mr. Z, fascinating that ground-bound astronomy is destined to be obsolete. I wonder if the possibility might exist that it will still have some unforeseen valuable application that can only be achieved earth-bound?
Also Mr. Z or anyone knowledgeable, why do some satellites apparently blink off like someone flicked a switch, or blink on, at random sometimes? Or both within a 20 minute period from what looks earthbound like a fixed position? What is a satellite doing when it blinks on again and a short (relatively!) beam of light emits from it, and within a half second blinks off again? What’s the satellite doing, I wonder? Amazing tech.
Janyuary: The blinking on and off by satellites could be caused by two things. First, the angle of their solar panels might be catching sunlight and sending down to the observer, but only for a short time.
Second, they simply could be moving in and out of sunlight, based on their orbit.
Thank you, Mr. Z. I’ll remember those dynamics may be at play next time I see it happen.
As an observer of satellites, another reason for it “blinking” is it is tumbling or spinning. Sometimes they are not satellites, but spent upper stages.
Jay, thank you, reflecting from angles of tumbling craft makes good sense. From my perspective on the ground, then, does that blinking satellite appear to remain in the same place? Even if it is tumbling? It must …
Thanks again!
Hi Janyuary,
OK, if it is in the same place and blinking it is probably a plane’s lights or it is a star. Some stars like Arcturus and Capella looks like they are blinking. Are you sure it is not a plane or helicopter going towards or away from you? I know some student pilots from the nearby airport who fly at night look like they are hanging in one spot. If it is slow, it is an airplane.
If a satellite is not moving in relation to you, it would be in geostationary orbit, but that orbit is about 23k miles away circling the equator south of you (I assume you are in the U.S.). Plus, you could not see it at that distance with your eyes. You can see those satellites with a telescope though.
Thank you, Jay!
Maybe I’ll ask Santa for a telescope, though sky visibility on the California coast a few dozen miles north of Vandenberg AFB ain’t that great.
The satellites (I assume that’s what they are) don’t really blink. They simply are shining there in the same spot like a bright star … and then are gone, they go out. For minutes at a time or more .. then as I’m standing around wasting time looking at the sky and thinking about nuttin’ in pertikewlar, (I’m a night owl by nature) the star suddenly reappears and stays that way. Then after a minute or two, goes off again. I’ve seen this phenomenon at least a half dozen times over the years. Time is usually between 3:30 and 4:30 am, in the eastern sky.
I am absolutely certain that is is not a helicopter or an airplane. Positive. Not at that altitude, and not over this terrain.
Thank you, Jay!