Astronomie - SpaceX working on fix for Starlink satellites so they don’t disrupt astronomy



President and COO Gwynne Shotwell said the Starlink brightness problem caught the company by surprise

LOS ANGELES — One of the Starlink satellites in the next batch of 60 that SpaceX plans to launch in late December will be treated with a special coating designed to make the spacecraft less reflective and less likely to interfere with space observations, SpaceX president and chief operating officer Gwynne Shotwell said Dec. 6.

“We are going to get it done,” Shotwell said during a meeting with reporters at SpaceX’s headquarters in Hawthorne.

SpaceX already has deployed 120 satellites that beam high-speed internet, and thousands more will be launched over the next few years. Soon after the first launch in May, astronomers noted that the satellites were extremely bright, prompting concerns that the constellation will interfere with scientific research and views of the night sky.

Shotwell said the next batch has one satellite “where we put a coating on the bottom.” She noted that this is just an experiment and could not predict if it will work. “We’re do trial and error to figure out the best way to get this done,” said Shotwell.

Since reports first surfaced of Starlink satellites disrupting astronomers, the company has taken the problem seriously, Shotwell insisted. “We want to make sure we do the right thing to make sure little kids can look through their telescope,” she said. “Astronomy is one of the few things that gets little kids excited about space.”

When people look through their telescopes, “it’s cool for them to see a Starlink. But they should be looking at Saturn, at the moon. .. and not want to be interrupted.”

The coating that is being applied to one of the satellites in the third batch of Starlinks is just the first step toward finding a permanent solution as more satellites get deployed. Shotwell said the company plans to launch batches of 60 satellites every two to three weeks over the next year to build the constellation that by mid 2020 will be ready to provide global coverage.

Shotwell admitted that nobody in the company anticipated the problem when the satellites were first designed.

“No one thought of this,” she said. “We didn’t think of it. The astronomy community didn’t think of it.”

The experimental coating that would make the satellite less reflective could affect its performance, so that is something that will be examined, said Shotwell. “It definitely changes the performance of the satellite, thermally. It’ll be some trial and error but we’ll fix it.”

Quelle: SN


Satellite mega-constellations stir a debate over avoiding catastrophic orbital crashes


An image of the NGC 5353/4 galaxy group, made with a telescope at Arizona’s Lowell Observatory on May 25, shows the trails of reflected light left by SpaceX’s freshly launched Starlink satellites as they pass through the telescope’s field of view. The brightness diminishes once the satellites reach their intended altitude. (Lowell Observatory Photo via IAU / Victoria Girgis)

The retired commander of the U.S. Strategic Command says the tens of thousands of satellites that SpaceX, OneWeb and Amazon are planning to put into orbit over the next few years will require a new automated system for space traffic management — and perhaps new satellite hardware requirements as well.

Retired Gen. Kevin Chilton laid out his ideas for dealing with potentially catastrophic orbital traffic jams at the University of Washington on Friday, during the inaugural symposium presented by UW’s Space Policy and Research Center.

“We need to develop technologies that will improve space domain awareness, that will enable autonomous systems onboard satellites to automatically maneuver so as to avoid collision with another satellite, or with a known piece of man-made debris,” he said.

The issue is expected to become increasingly critical as commercial ventures deploy more satellites into low Earth orbit, or LEO, to widen broadband internet access to the billions of people around the world who are currently underserved. An estimated 2,200 active satellites are in orbit today, but if all the plans come to pass, that figure could go beyond 45,000 in the years ahead.

In addition to the commercial applications, LEO constellations could have national security applications. “The Department of Defense is talking about it for both global missile warning and to have a system that can track what we see coming down the road, which is hypersonic intercontinental re-entry vehicles,” Chilton said.

In fact, one of the funders for SpaceX’s Starlink constellation happens to be the Air Force Research Laboratory, which kicked in $28.7 million last year to run data connectivity demonstrations.

SpaceX has already launched 120 of its Starlink satellites, which are built at the company’s facilities in Redmond, Wash. Hundreds more of the satellites are due to be launched in advance of the start of limited service next year.

Some observers — including Chilton — aren’t fully convinced that commercial mega-constellations will be as profitable as their builders anticipate.

“I’m still questioning the business case,” Chilton said. “I still haven’t figured out how you make money doing what they’re proposing. The best I can tell, the people in the world today that can afford laptop computers and connectivity to the internet are connected. The people who can’t, won’t be able to connect to the satellite constellation. I don’t know, I’m not a businessman.”

Today the Los Angeles Times quoted SpaceX President Gwynne Shotwell as saying that the company will take pre-sales for customer service, adopting a strategy that CEO Elon Musk has used for electric cars at Tesla, his other multibillion-dollar venture. Amazon’s Project Kuiper, meanwhile, is likely to follow a different business model: using its satellite data service to boost online sales well as its AWS cloud service, Alexa AI services and Amazon Prime Video.

However the business model works out, Chilton said the proliferation of mega-constellations will require better coordination. Satellite collisions could add dramatically to the traffic problems posed by orbital debris, and September’s close encounter between a SpaceX Starlink satellite and a European wind-monitoring satellite highlighted the risk.

“At least let’s have them talking to each other while they’re up there, electronically,” Chilton said. “Let’s have them transmitting their positions. Let’s make sure there’s a central location that knows their position, so that when we launch … we know where they are, we know how to safely deconflict.”

Some steps are being taken already: The U.S. Commerce Department is working on the creation of an open-architecture data repository that draws upon data from the Air Force and other sources to keep track of satellites more precisely and identify potential problems further in advance. The European Space Agency, meanwhile, is talking about using machine learning to automate space traffic management.

Another issue has to do with the impact of mega-constellations on the night sky. In May, when SpaceX started launching Starlink satellites in batches of 60, astronomers were horrified to discover how much they interfered with their observations.

Chilton noted that satellite interference could degrade the capabilities of observatories in which tens of millions of dollars have been invested. “It’s a problem they have to address,” he said.

Space News quoted SpaceX’s Shotwell as saying the next batch of 60 Starlink satellites, due for launch as early as this month, will include one spacecraft that’s been treated with a coating to make it less reflective and less likely to interfere.

Shotwell said that no one at SpaceX thought the satellites’ glare would pose a problem in advance of the first 60-satellite launch. Now SpaceX is using “trial-and-error to figure out the best way to get this done,” she said.

The trial-and-error approach is required because making the satellites less reflective could change the satellites’ thermal performance in undesirable ways, Shotwell said. Chilton agreed with that assessment of the challenge: “Mostly they’re silver for a reason,” he told GeekWire.

In a blog post, the American Astronomical Society’s Kelsie Krafton said an AAS working group has been meeting with representatives of SpaceX and other satellite industry players, as well as with policymakers and other scientists.

Krafton said the talks are “moving in a hopeful direction.” The working group is currently conducting a survey of research observatories to get a sense of the brightness level that SpaceX should be targeting for its satellites.

“All of our options for impact mitigation will require iterative processes,” she said. “Until we have collected the survey data, we and SpaceX will proceed as if satisfying the Large Synoptic Survey Telescope’s needs is the high bar to aim for.”

The $473 million Large Synoptic Survey Telescope, currently under construction in Chile, is expected to help revolutionize ground-based astronomy when it goes into operation in the 2020s. A decade ago, Microsoft co-founder Bill Gates and former Microsoft executive Charles Simonyi contributed a total of $30 million to support its creation. Today, UW’s DIRAC Institute is managing the development of analytical tools for the flood of data that the LSST is expected to produce.

Quelle: GeekWire

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