Some astronomers and observatories are complaining that satellites sent into low earth orbit by private companies to provide global internet and other services will impact night sky observation and ruin astrophotography.
A new, advanced telescope observatory, the Vera C. Rubin Observatory has recently sent out a document outlining the potential risks these satellite links will have on their work.
What is the Vera C. Rubin Observatory?
Formerly known as the Large Synoptic Survey Telescope (LSST), the Vera C. Rubin Observatory is named after Vera Rubin, an American astronomer who headed up work on galaxy rotation rates and advanced dark matter understanding.
What Does It Do?
The observatory is designed to track dark energy and dark matter, detect brief optical events such as supernovae, map the Milky Way galaxy, and map small objects in the solar system. Tracking of such near-earth asteroids and objects in the Kuiper belt may give us enough warning to prepare a defense against impending earth collisions coming from space. It does all this while recording the entire night sky for the majority of its time in use, with around 10% of its time dedicated to deep field work.
So, What’s the Problem?
Several private companies are aiming to launch a link of satellites into low earth orbit (LEO) in order to provide a host of services globally. SpaceX, founded by Elon Musk, and designed to reduce space transportation cost, is one of the first private companies to launch into this new idea.
Towards the end of May 2019 they sent up 60 satellites to start testing this program. There have been more sent up since and SpaceX’s aim is to release 42,000 satellites to provide the world with possible internet connection, with launches likely to leave earth every fortnight. Amazon, OneWeb, Samsung and other companies are also entering the race in order to compete with SpaceX.
Why Is This an Issue?
Well, just listen to what the observatory have to say on low earth orbit satellite links:
Every night for 10 years, Rubin Observatory will take 1,000 exposures of the deep sky with its 3,200 megapixel camera with each exposure covering a 10 square degree field of view. Because of Rubin Observatory’s large collecting area, each 30-second exposure can reveal distant objects that are 20 million times fainter than visible with the unaided eye. By comparison, a typical LEO satellite can be seen for several hours in twilight without the aid of a telescope and is over 20 million times brighter than a typical distant galaxy seen with Rubin Observatory.
It’s not just that the satellites will obscure the night sky, rendering some work invalid or requiring work to be repeated when portions of the night sky are clear, but it also creates noise on the CCD sensors the telescope uses. The same is true of our less sensitive, much less expensive camera gear — they’ll be leaving light trails in our long, night-time exposures. Already photographers are plagued with condensation trails, the clouds that planes leave behind, interrupting natural landscape photographs, but now the night sky looks set to be overcome with man-made obstacles, too.
40% impact on twilight observing time – less in winter. Rubin Observatory would have to point to a place in the sky where briefly there were no LEO satellites. We estimate one LEO satellite trail per three exposures of the LSST camera for the full Starlink constellation. Extrapolating to a more crowded sky in the mid-2020s, we must multiply by about three for the other LEOsat corporate plans (from FCC filings). Nearly every exposure within two hours of sunset or sunrise, on average, would Impact on Optical Astronomy of LEO Satellite Constellation | Document-33805 | Latest Revision Date 2020-03-03 3 have a LEOsat streak, and a few of those will be sufficiently bright to far exceed saturation of the CCD sensor, taking out all CCD segments traversed – typically a row of 13-16 CCDs. Rarely, they would be so bright that ghosts (i.e. scattered light in the camera optics) would destroy the scientific usefulness of the entire exposure.
On Monday 9th March 2020, Elon Musk, CEO of SpaceX spoke at Satellite Conference 2020 on the new Starlink launches and predicted zero impact on night sky studies.
“I am confident that we will not cause any impact whatsoever, in astronomical studies. Zero. That’s my prediction. And we’ll take corrective action if it’s above zero.”
Just how 42,000 satellites in low earth orbit won’t impact imaging and observing the night sky in any way, we’ve yet to learn. Will astronomical observatories have to take to the skies themselves, similar to the Hubble Space Telescope, to avoid night sky obscurities? What do you think the real life impact of satellite links in low earth orbit will be for photographers and astronomers alike? Share your thoughts in the comments below.