From “EarthSky” : “How satellites harm astronomy – what’s being done”

From “EarthSky”

10.6.22
Kelly Kizer Whitt

Artist’s concept shows the 30,000 planned satellites from the Starlink Generation 2 constellation as of 2022. Different sub-constellations are in different colors. Learn more about how mega constellations of satellites harm astronomy. Image via The European Southern Observatory [La Observatorio Europeo Austral] [Observatoire européen austral][Europäische Südsternwarte](EU)(CL).

You may have heard the growing complaints from astronomers as companies such as SpaceX add more satellites to our sky. Astronomers are not against the communication networks that the satellites provide, but they have valid concerns for the future of ground-based explorations of the universe. And there is only so much astronomers can do on their own to mitigate the problem. A report from the 2021 conference for Dark and Quiet Skies stated:

“The advantages to society that the communication constellations are offering cannot be disputed, but their impact on the pristine appearance of the night sky and on astronomy must be considered with great attention because they affect both the cultural heritage of humanity and the progress of science.”

How satellites harm astronomy: The problem with increasing satellites

Astronomers face a variety of problems with the increasing numbers of satellites filling low-Earth orbit. Optical and near-infrared telescopes feel the impacts from these mega constellations. Some of the biggest are on wide-field surveys, longer exposures and evening and morning twilight observations when sunlight reflects off the satellites. The European Southern Observatory, the European Space Organization, reported these findings from a 2021 study [Astronomy & Astrophysics(below)]:

“The effect is more pronounced for long exposures, up to three percent of which may be ruined during twilight. The study also found that the greatest impact of new satellite constellations will be on wide-field surveys made by telescopes such as the US National Science Foundation’s Vera C. Rubin Observatory. Up to 30-50 percent of twilight observations being seriously impacted.”

The National Science Foundation NOIRLab National Optical Astronomy Observatory Vera C. Rubin Observatory [LSST] Telescope currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the Gemini South Telescope and Southern Astrophysical Research Telescope.

And because we’re talking about scientists, of course they’ve officially started studying the issue. Studies in 2020 [ Astronomy and Astrophysics (below)] and 2021 [Astronomy & Astrophysics (below)] showed the impact on optical and near-infrared telescopes. They found that telescopes such as the Very Large Telescope (VLT) and the future Extremely Large Telescope (ELT) will be “moderately affected” by new satellite mega constellations.

The European Southern Observatory [La Observatorio Europeo Austral][Observatoire européen austral][Europäische Südsternwarte](EU)(CL), Very Large Telescope at Cerro Paranal in the Atacama Desert •ANTU (UT1; The Sun ) •KUEYEN (UT2; The Moon ) •MELIPAL (UT3; The Southern Cross ), and •YEPUN (UT4; Venus – as evening star). Elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo.

European Southern Observatory(EU)(CL) ELT 39 meter telescope to be on top of Cerro Armazones in the Atacama Desert of northern Chile at an altitude of 3,060 metres (10,040 ft).

Some telescopes, such as the Rubin Observatory under construction in Chile, will experience greater impacts. These telescopes scan wide areas quickly. This makes them crucial in spotting supernovae or potentially dangerous asteroids.

The impact on radio astronomy

Radio astronomy has its own particular concerns. Radio telescopes don’t look in the visible wavelengths of the electromagnetic spectrum, so it’s not the same “visibility” issue. For radio telescopes, the main problem is with the signals the satellites transmit down to Earth. Plus, radio telescopes aren’t only looking at dim lights in the night. They’re looking at the sky 24/7. So, satellites are a problem every hour of the day, not just at twilight.

But there’s more. A satellite’s signal is much, much stronger than the faint background sources that radio astronomers study. And a satellite doesn’t have to pass right in front of the object of study to cause interference. Satellite sources in a radio telescope’s “peripheral vision” also interfere.

The European Southern Observatory (ESO) described the potential impact of satellites on radio astronomy:

“They amount to hundreds of radio transmitters above the observatory’s horizon, which will affect the measurements made by our highly sensitive radio telescopes.”

Radio astronomy has some protection against interference. Radio astronomers call this spectrum management, and the Radio Communication Sector of the International Telecommunication Union (ITU-R) create regulations that help protect astronomers studying certain frequency bands and wavelength ranges. But the recent large constellations of telecommunication satellites pose new threats.

One recommendation is for satellite designs that avoid direct illumination of radio telescopes and radio-quiet zones. Also, the cumulative background electromagnetic noise created by satellite constellations should be kept below the limit already agreed to by the ITU.

Philip Diamond of the Square Kilometer Array Observatory (SKAO) summed up the issue:

“The deployment of thousands of satellites in low-Earth orbit in the coming years will inevitably change this landscape by creating a much larger number of fast-moving radio sources in the sky, which will interfere with humanity’s ability to explore the universe.”

SKA-Square Kilometer Array

SKA ASKAP Pathfinder Radio Telescope at the Murchison Radio-astronomy Observatory (MRO), on the traditional lands of the Wajarri peoples.

SKA SARAO Meerkat Telescope (SA), 90 km outside the small Northern Cape town of Carnarvon, SA.

What can visual astronomers do?

It would be great if a computer program could quickly eliminate all the satellites trails or interference from astronomers’ data. But it’s not quite that easy. One recent report outlined the problem of low-Earth orbit satellites on images:

“They leave traces of their transit on astronomical images, significantly decreasing the scientific usability of the collected data. Post-processing of the affected images only partially remedies the problem: the brighter trails may saturate the detectors, making portions of images unusable, while the removal of the fainter trails leaves residual effects that seriously affect important scientific programs, as, for example, statistical, automated surveys of faint galaxies.”

But there are some things astronomers could do, and have been doing thus far. They can avoid observing where satellites will pass, limit observations to areas of the sky that are in Earth’s shadow and close the shutter precisely when a satellite crosses the field of view. This all takes a lot of knowledge of the paths of thousands of satellites and plenty of pre-planning. Obviously, these are not realistic possibilities for many situations.

What can satellite operators do?

Another way to mitigate the problem is for satellite operators to adjust their designs (for example, darkening the satellite). They can also operate the satellites in a way that would raise their orbits out of vision of the optical telescopes, deorbit satellites that are no longer functioning, as well as other considerations for minimizing disruption. In several cases, the satellite operators have shown willingness to cooperate on this.

Unfortunately, the companies planning these mega satellite constellations did not warn astronomers in advance. So many of these satellites were already filling the skies without any restrictions as astronomers scrambled to figure out how to save their observations and lessen the impact. Their efforts led to the creation of a new center that is collecting data from the community, astronomers and the general public, among others, to learn more about the effects on the night sky.

Official efforts to reduce harm from satellites

In June 2022, the International Astronomical Union (IAU), together with the National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab) and SKAO, opened the Center for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (CPS). The center highlights the dramatically increased risk of interference from low-Earth orbit satellites – both planned and already in orbit – that provide broadband services. On their website, you can see a running total of the number of operational constellation satellites (2,994) and the number of planned constellation satellites (431,713), among other stats.

Co-director Connie Walker from NOIRLab said:

“Three years ago SpaceX launched the first 60 Starlink satellites. The number of satellites from this and other companies is increasing exponentially and impacting the field of astronomy. During the last two years, four key workshops identified issues and recommended mitigation solutions with the help of astronomers, satellite industry folk, space lawyers and people from the general community worldwide.”

In the peer-reviewed journal Air & Space Law [below], scientists at ESO published a study in September 2021 extensively warning of the dangers of unlimited satellites on astronomy. They’re trying to address satellite constellations’ impact on astronomy. They’re making efforts to coordinate solutions so both satellites and observational astronomy can continue developing without harmful interference.

A reminder of what we’re losing when satellites harm astronomy

One of ESO’s studies estimated that in the future, up to 100 satellites could be visible to the unaided eye during twilight. Imagine how that will change your own view of the night sky. Then imagine if your profession depended upon seeing what is beyond the satellites. How will we learn about the universe or detect potential threats to Earth?

The IAU created the Dark and Quiet Skies Working Group. As Debra Elmegreen, IAU President, summed up:

“Interference of our view of the sky caused by ground-based artificial lights, optical and infrared trails of satellite constellations and radio transmission on the ground and in space is an existential threat to astronomical observations. Viewing the night sky has been culturally important throughout humanity’s history, and dark skies are important for wildlife as well.”

Science papers:
Astronomy & Astrophysics
Astronomy and Astrophysics 2020
Astronomy & Astrophysics 2021
Air & Space Law 2021
See the science papers for instructive material.

See the full article here .

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Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

From “EarthSky” : “Hubble needs a boost. Will this new plan provide it?”

From “EarthSky”

9.30.22
Dave Adalian

This photograph of NASA’s Hubble Space Telescope was taken during the 1st astronaut servicing mission in 1993. In 2022, the aging telescope is gradually falling to a lower orbit. NASA and SpaceX have announced they will study a way to boost it. Image via NASA.

National Aeronautics and Space Administration/The European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganization](EU) Hubble Space Telescope.

The National Aeronautics and Space Agency European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganization](EU) Hubble Space Telescope Instrumentation annotated

A boost to extend Hubble’s life

NASA and SpaceX announced on September 29, 2022, that they intend to spend 6 months studying how a SpaceX Dragon spacecraft might return the Hubble Space Telescope to its original orbit. The boost would extend the telescope’s life by a decade or more. It could be the most exciting manned near-Earth mission since astronauts repaired the nearsightedness of the orbiting telescope in 1993. And it would happen “at no cost to the government,” the announcement said. It said:

NASA and SpaceX signed an unfunded Space Act Agreement Thursday, September 22, 2022, to study the feasibility of the SpaceX and Polaris idea to boost the agency’s Hubble Space Telescope into a higher orbit with the Dragon spacecraft, at no cost to the government.

Billionaire businessman Jared Isaacman – who founded the Polaris Program, a human spaceflight program – participated in the September 29 announcement.

Upgrading the telescope’s scientific instruments might also be possible, they said.

Hubble is falling … Very slowly

When first placed in orbit in 1990, the HST rode at about 380 miles (600 km) above the Earth’s surface. Since then, the almost nonexistent atmosphere at that height above Earth has gently but persistently tugged at the telescope. At a media briefing to discuss the study, HST project manager Patrick Crouse said:

“So even though Hubble has been on orbit for over 32 years, its orbit was originally about 380 miles above Earth and has slowly decayed over time due to atmospheric drag. So, its current orbit is about 335 miles.”

Hubble will eventually burn on reentry, Crouse said:

“Right now, the last prediction we had, last year, was that we had a 50-percent probability of reentry in 2037.”

If a mission to prevent that doom flies, then Crouse said, mission controllers will also discuss enhancing Hubble’s instruments. No specific alterations to the telescope are being considered.

Billionaire paying for the flight

The Hubble has been serviced five times, and NASA has no plans for a 6th visit. But it soon might, according to Jared Isaacman, commercial astronaut and commander of Polaris Dawn, who also participated in the briefing:

“The idea is this is a study at this point, not just for Hubble, but just broad applicability of these types of potential servicing missions in low-Earth orbit. That stated, if the study takes us down a path where a mission is possible, this would certainly fit within the kind of parameters we’ve established for the Polaris Program and certainly would build upon the Polaris Dawn foundation.”

While Isaacman is one of the world’s first commercial astronauts, he’s also a billionaire businessman who has purchased three SpaceX flights for what he calls the Polaris Program. The space flights are intended to demonstrate new tech and do on-orbit research. The third mission of the program will be the first manned mission of the SpaceX Starship.

If one of the three Polaris Program flights is given over to an HST visit, then that organization will foot the bill.

Hubble is A-OK

At the start of the briefing, Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate reiterated there is nothing wrong with the scope:

“Hubble is amazingly successful. It’s healthy. It’s doing great science as we speak.”

But he also said studying “crazy things” is one of the things his division of NASA is tasked to do, even if they’re not quite ready to do them:

“We want to know what the possibilities are. I want to be absolutely clear, we’re not making any announcement today that we’re definitely going forward with a plan like this.”

What are they studying?

The six months will be spent figuring out if what the group is proposing can even be pulled off.

Jessica Jensen, a vice president for SpaceX, described the company’s role:

“Predominantly on the SpaceX side, we’re going to be looking at Dragon capabilities and how they would need to be modified in order to safely rendezvous and dock with Hubble. Details of how exactly physically that’s done and also how we safely do that from a trajectory point of view, that’s all to be worked out.”

And while there is no plan yet for a journey to the Hubble, all the details – including a timeline – will be worked out for one by the study’s end, Jansen said:

“Part of this is going to be figuring out the cost and figuring out a little bit of a schedule, what it’s going to take to actually make this happen and make it happen safely. We don’t want to do something that’s going to put Hubble at risk at all.”

See the full article here .

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Please help promote STEM in your local schools.

Stem Education Coalition

Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

From The New York Times: “As SpaceX Launches 60 Starlink Satellites, Scientists See Threat to ‘Astronomy Itself’”

From The New York Times

Nov. 11, 2019
Shannon Hall

Various companies are pressing ahead with plans for internet service from space, which has prompted astronomers to voice concerns about the impact on research from telescopes on Earth.

A view of SpaceX’s Starlink’s satellites just before being deployed on May 24. The company is scheduled to launch 60 more on Monday morning.Credit SpaceX

On Monday morning, SpaceX launched one of its reusable rockets from Cape Canaveral, Fla., carrying 60 satellites into space at once. It was the second payload of Starlink, its planned constellation of tens of thousands of orbiting transmitters to beam internet service across the globe.

When SpaceX, the private rocket company founded by Elon Musk, launched the first batch of Starlink orbiters in May, many astronomers were surprised to see that the satellites were extremely bright, causing them to fear that the constellation would wreak havoc on scientific research and transform our view of the stars. Since then, many scientists have been on a mission to better quantify the impacts of Starlink and to share their concerns with SpaceX.

In response, SpaceX has said that it wants to mitigate the potential impacts of Starlink. But at the same time, the company is still moving full steam ahead.

In October, Mr. Musk announced that he was using Twitter via a Starlink internet connection, as his company was requesting permission from the Federal Communications Commission to operate as many as 30,000 satellites on top of the 12,000 already approved. Should SpaceX succeed in sending this many satellites to low-Earth orbit, its constellation would contain more than eight times as many satellites as the total number currently in orbit.

That move added to the worries of many astronomers.

When James Lowenthal, an astronomer at Smith College, first saw the train of Starlink satellites marching like false stars across the night sky in the spring, he knew something had shifted.

“I felt as if life as an astronomer and a lover of the night sky would never be the same,” he said.

Most of the first Starlink nodes have since moved to higher orbits and are now invisible for most of us who live under bright city lights. But they are still noticeable from places with dark skies. If thousands more of these satellites are launched, Dr. Lowenthal said he feared “it will look as if the whole sky is crawling with stars.”

Since May, the American Astronomical Society has convened an ad hoc committee with Dr. Lowenthal and other experts to discuss their concerns with SpaceX representatives once a month.

At the same time, SpaceX has been working directly with the National Radio Astronomy Observatory, a federally funded research center that operates facilities across the world, to jointly minimize potential impacts of Starlink satellites on radio wavelengths that astronomers use.

But these conversations did not focus on light pollution, a problem presented by the reflective surfaces of proposed satellite constellations such as Starlink. At first, SpaceX said the complication would be minimal, and the new committee is trying to assess the impact and actively find solutions.

“So far, they’ve been quite open and generous with their data,” Dr. Lowenthal said. “But they have not made any promises.”

A spokeswoman from SpaceX said the company was taking steps to paint the Earth-facing bases of the satellites black to reduce their reflectiveness. But Anthony Tyson, an astronomer at the University of California, Davis, said that wouldn’t solve the problem.

Dr. Tyson is the chief scientist for the Large Synoptic Survey Telescope — a 27-foot, billion-dollar telescope under construction in Chile that will scan the entire sky every three days. The survey, the world’s largest yet, will help astronomers better understand dark energy, dark matter, the origin of the Milky Way and the outer regions of the solar system. But because it is designed to scan faint objects, it is expected to be greatly affected by the satellites.

Dr. Tyson’s simulations showed that the telescope would pick up Starlink-like objects even if they were darkened. And they wouldn’t just affect a single pixel in a photograph. When there is a single bright object in the image, it can create fainter artifacts as well because of internal reflections within the telescope’s detector. Moreover, whenever a satellite photobombs a long-exposure image, it causes a bright streak of light that can cross directly in front of an object astronomers wish to observe.

“It’s really a mess,” Dr. Tyson said.

Knowing how challenging it would be to correct these interrupted images, Dr. Tyson decided the best step forward was to set the telescope to avoid Starlink satellites. While simulations based on the earlier 12,000-satellite total suggested that would be possible, SpaceX’s application for 30,000 additional satellites upset the calculations.

“We’re redoing the models now just to see what’s visible at any one time — and it’s really quite frightening,” said Patrick Seitzer, a professor of astronomy emeritus at the University of Michigan, who has been running similar analyses to determine how many satellites will be visible and when.

His preliminary results suggest that avoiding the satellites would be difficult during twilight — a serious problem given that potentially hazardous asteroids and many objects in the solar system are best seen during this time. The satellites thus limit the ability of astronomers to observe them.

And Dr. Tyson’s early simulations also confirm the potential problems, demonstrating that over the course of a full year, the giant telescope wouldn’t be able to dodge these satellites 20 percent of the time. Instead, those images would be effectively ruined.

SpaceX’s 30,000 satellites might also just be the start as other companies, such as Amazon, Telesat and OneWeb, plan to launch similar mega-constellations.

“If there are lots and lots of bright moving objects in the sky, it tremendously complicates our job,” Dr. Lowenthal said. “It potentially threatens the science of astronomy itself.”

Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics who closely tracks objects in orbit, agrees.

“There is a point at which it makes ground-based astronomy impossible to do,” he said. “I’m not saying Starlink is that point. But if you just don’t worry about it and go another 10 years with more and more mega-constellations, eventually you are going to come to a point where you can’t do astronomy anymore. And so let’s talk about it now.”

While astronomers are starting those conversations, they have little legal recourse. There are no regulations in place to protect the skies against light pollution.

“International space law is pretty wide open,” said Megan Donahue, an astronomer at Michigan State University and the president of the American Astronomical Society. While many astronomers have been concerned about radio interference and space debris, she says light pollution is a bigger concern because there are no rules in place. That means any path forward relies on the good will of SpaceX and other companies.

“It’s more of a philosophical question,” Dr. Donahue said. “It kind of boils down to: How much do I trust corporate good will, and how much would a corporation care about the opinion of people who care about science and astronomy?”

See the full article here .

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Please help promote STEM in your local schools.

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