Vera Rubin, due to its wide field of view and exceptional sensitivity, was to feel their presence especially keenly.
The Vera Rubin telescope, which is set to open its eyes to the sky later this month, has a 26-foot-wide (8.4 meters) mirror, one of the largest in the world.
SpaceX was initially talking about a constellation of 12,000 satellites but now plans a fleet of 42,000 spacecraft.
Currently, about 10,000 satellites orbit Earth, but the number could increase to 100,000 in the next decade if all those plans come to fruition.
They are so bright, in fact, that the Vera Rubin Telescope must plan for their passes in advance in order to avoid them, according to Rawls.
The sky above Chile’s Cerro Pachón, where the star-observing device was to be situated, looked different in the 1990s when astronomers first envisioned the Vera Rubin Observatory.
A single satellite would occasionally cross it, which was .ted with millions of stars, galaxies, and nebulas. A few years prior to the anticipated opening of the observatory, the megaconstellation era began to take off, and astronomers were rushing to figure out how to shield the telescope’s images from satellite interference. There was not much time for them.
Everything was still on track when the $680 million observatory’s construction got underway in 2015. When the first Starlink internet satellites were launched by SpaceX four years later, Starlink trains were established, and astronomers discovered that the satellites, which were only 340 miles (550 kilometers) above Earth, were too bright to obstruct their observations. Vera Rubin was to sense their presence particularly strongly because of its broad field of vision and extraordinary sensitivity.
Vera Rubin Observatory’s research scientist Meredith Rawls said, “Vera Rubin Observatory is going to see a whole bunch of these satellites because of all the features that make it so great for surveying the whole southern sky.”. An astronomer from the University of Washington and the Rubin Observatory Legacy Survey of Space and Time (LSST) told Space . com.
The 26-foot (8.4-meter) wide mirror of the Vera Rubin telescope, which is scheduled to open its eyes to the sky later this month, is among the biggest in the world. Additionally, it has the largest camera ever constructed for an astronomical telescope, a 3,200-megapixel lens with 189 CCD detectors that is 5 feet 4 inches (1 foot 65 meters) wide.
To perform a complete sky survey every three days, the telescope will have the ability to tilt its mirror to alter its view of the sky each night. Along with the thousands of satellites that are millions of times brighter than those priceless astronomical targets, the telescope will record the myriads of stars and far-off galaxies that are invisible to the naked eye with every sweep of the celestial dome. Furthermore, this issue will only worsen over time.
Originally discussing a constellation of 12,000 satellites, SpaceX is now planning a fleet of 42,000 spacecraft. Other broadband services, such as the Chinese projects Guowang, Qianfan, and Geespace, as well as Amazon’s Kuiper network, plan to launch tens of thousands of satellites of their own. About 10,000 satellites orbit the Earth at the moment, but if all of those plans are realized, that number could rise to 100,000 within the next ten years.
“It’s regrettable that the decade in which Vera Rubin has been operating coincides with this massive increase [in the number of satellites],” Rawls said. Our perceptions of the universe are being disrupted by the numerous objects we are launching into space, which is existentially annoying. “.
Since 2016, Rawls has been involved in the Vera Rubin Observatory project. Initially, he developed image processing algorithms to detect unexpected celestial phenomena like supernova explosions and filter out camera sensor faults. She had to refocus when Starlink and its counterparts arrived. These days, she creates methods for identifying satellites in photos and differentiating them from astronomically significant objects, such as passing moons.
But according to Rawls, Vera Rubin’s scientific mission is not in danger of failing because of the satellite streak issue. According to her, the satellite streaks occasionally obscure the view without totally destroying it, much like “bugs on a windshield” on a summer night.
“A satellite streak will be present in a significant portion of exposures, but the field of view is large, so the number of actual pixels affected is very small,” Rawls stated. “The satellite streaks are only a few hundred pixels wide at most. However, the camera has 189 CCD detectors that track the sky, and each detector has 4,000 pixels. “.
Professor Noelia Noël of the University of Surrey in the United Kingdom teaches astrophysics. K. told Space . com that streaks are expected to appear in up to 40% of the photos taken by the Vera Rubin telescope during its ten-year mission.
“Over 4 million of the 10 million images you take could be degraded,” Noël, who is also involved with Vera Rubin’s LSST project, stated. “This is a massive waste of tax dollars. Vera Rubin’s observations run about £60,000 [roughly $81,000] per night. You will therefore be wasting your money if you destroy the pictures. “.”.
The satellites could also be mistaken for actual celestial phenomena, in addition to outshining legitimate objects of interest. For instance, when a team of scientists noticed a sudden brightening in images captured by the Keck Telescope in Hawaii in 2021, they believed that a star had exploded in the oldest known galaxy. The astronomers’ instrument was pointing toward the galaxy when a piece of debris passed in front of their field of view, reflecting sunlight, as they discovered later.
According to Rawls, “we don’t want to give people a catalog of data where each pixel is supposed to be an actual star, and then to their surprise, a third of them are just bright detections where it happened to be in the satellite trail.”.
The algorithms created by Rawls and her colleagues will compare several photos of the same area of the sky using a stacking technique in order to identify and flag outliers. A passing satellite is more likely to be the cause of a bright object that appears in one image and vanishes in the next than a stellar explosion or dimming, according to Rawls.
Megaconstellations such as Starlink are just one aspect of the issue. A constellation of AST SpaceMobile’s BlueBird satellites, which are essentially enormous antenna arrays with a combined surface area of 693 square feet (64 square meters), was first launched in 2022. Although the satellites are incredibly bright, their purpose is to deliver 5G directly to smartphone users on Earth. According to Rawls, the Vera Rubin Telescope has to schedule its passes ahead of time to avoid them because they are so intelligent.
Rawls stated, “Looking at that area of the sky with that extremely bright object passing through would be a waste of thirty seconds.”. Fortunately, the number of these enormous, extremely bright satellites is still quite small. However, I’m concerned that could change in the years to come. “,”.
It remains to be seen how much science will be lost as a result of passing satellites obscuring Vera Rubin’s priceless sky views. Rawls is hopeful that efforts to darken satellites—which SpaceX has already tested with poor results—will eventually be successful and minimize light pollution.
Satellite manufacturers have previously been urged by the International Astronomical Union (IAU) to aim for satellites that are invisible to the unaided eye, or magnitude 7, on the scale used to gauge the brightness of celestial objects. Each subsequent grade is 2–5 times dimmer than the one before it because the magnitude scale is logarithmic and inverse to the actual brightness. Starlink satellites have so far received magnitude ratings ranging from 3 to 5.
“The impact on ground-based astronomy would be minimal if satellite operators could keep their hardware within roughly the IAU brightness limit,” Rawls stated. That doesn’t actually happen in practice because it’s very difficult to make things that dark. “.
