Satellite constellation operators are constantly forced to move satellites due to encounters with other spacecraft and space debris.And thanks SpaceX Estimates based on available data will continue to increase the number of such dangerous approaches on Starlink satellites.
SpaceX Starlink According to Huw Lewis, head of the Astronomy Research Group at the University of Southampton, UK, satellites alone are involved in about 1,600 close encounters between two spacecraft each week. These encounters include situations where two spacecraft pass within a distance of 0.6 miles (1 km) from each other.
Lewis, Europe’s leading expert on space debris, regularly estimates orbital conditions based on data from the Socrates (Satellite Orbit Coupling Report assessing encounters with space threats) database. .. Managed by Celestrack, this tool provides information about satellite orbits and models future orbits to assess the risk of collisions.
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Lewis publishes regular updates on Twitter and has seen worrisome trends in data that reflect the rapid deployment of Starlink constellations.
“We’ve looked at data dating back to May 2019, when Starlink was first launched to understand the burden of these mega constellations,” Lewis told Space.com. “Since then, the number of encounters acquired by the Socrates database has more than doubled, and Starlink now accounts for half of all encounters.”
The current 1,600 closed paths include the path between the two Starlink satellites. Except for these encounters, the Starlink satellite approaches other operators’ spacecraft 500 times a week.
The July update of conjunctions, including #Starlink and #OneWeb, predicted by #SOCRATES (https://t.co/CjUGwoALuU) is a continuous (exponential) number of closed paths on August 2, 2021. You can see the increase.
By comparison, Starlink’s competitors OneWebAccording to Lewis data, it currently flies over 250 satellites and is involved weekly in 80 proximity passes with satellites from other operators.
And the situation must get worse. Only 1,700 satellites So far, tens of thousands of expected constellations have been put into orbit. Lewis’s calculations suggest that as SpaceX launches all 12,000 satellites of the first-generation constellation, Starlink satellites will be involved in 90% of all approach approaches.
And another of @ cosmos4u: number of conjunctions August 3, 2021
Risk of collision
Siemak Heser, CEO and co-founder of Kayhan Space, based in Boulder, Colorado, confirms this trend. His company, which develops commercial autonomous space traffic management systems, estimates that on average, operators managing about 50 satellites receive up to 300 official connection alerts per week. These alerts include encounters with other satellites and debris.Of these 300 alerts, you will need an operator to run up to 10 alerts Avoidance operationHeather told Space.com.
Kayhan Space US Space Surveillance Network.. Managed by the U.S. Space Force, this radar and telescope network closely monitors and orbits approximately 30,000 living and non-functional satellites, as well as debris up to 4 inches (10 centimeters) in size. Provides the most accurate position data for objects that orbit around.
Heather added that the size of this catalog will increase tenfold in the near future, partly due to the growth of mega constellations such as Starlink and improved sensors that can detect even smaller objects. The more objects in the catalog, the more dangerously close the encounter.
“This problem is really out of control,” Hezar said. “The current process is very manual, not scalable, and there is not enough information sharing between the parties that could be affected in the event of a conflict.”
Heather compared this problem to driving on the freeway and not knowing that there was an accident a few miles away. When two spacecraft collide in orbit, a cloud of debris generated by the collision threatens other satellites passing through the same area.
“You want to have that situational awareness for other actors flying in the neighborhood,” Heather said.
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Despite concerns, only three orbital collisions have been identified so far. Earlier this week, Jonathan McDowell, an astrophysicist and satellite tracker based at the Harvard-Smithsonian Astrophysicist Center in Cambridge, Massachusetts, found evidence from Chinese meteorological satellites in space tracking data. Sea of clouds 1-02The one that collapsed in March of this year was actually hit by debris debris.
Worst known space collision ever It occurred in February 2009 when the US communications satellite Iridium 33 and Russia’s abolished military satellite Cosmos 2251 crashed at an altitude of 490 miles (789 kilometers). The incident produced more than 1,000 debris larger than 4 inches (10 cm). Many of these fragments were subsequently involved in further orbital accidents.
Lewis is concerned that increasing the number of closed passes also increases the risk of operators making wrong decisions at some point. Avoidance operations require fuel, time, and effort. Therefore, operators always carefully assess such risks. However, the decision not to take evasive action after a warning like Iridium made in 2009 can disrupt the orbital environment for years and decades.
“If you’re receiving alerts every day, you can’t do everything,” says Lewis. “Maneuvering uses propellant and satellites cannot provide service. Therefore, some threshold is required. But that means you are accepting some risk. The problem is at some point. So you can make the wrong decision. “
Heather said the uncertainty in the location of satellites and debris remains considerable. For satellites in operation, the error can be as large as 330 feet (100 meters). For debris, the uncertainty about its exact location can be on the order of a mile or more.
“This object can be anywhere in the bubbles over the last few kilometers,” Heather said. “At this point, and in the foreseeable future, avoidance is our best bet. Those who say,’I’m going to take the risk,’ in my humble opinion, it’s irresponsible. “
Lewis is concerned about the increasing influence of a single actor (Starlink) on the safety of orbital maneuvers. In particular, he says, spaceflight companies have only recently entered the world of satellite operations.
“We rely on a single company to do the right thing,” Lewis said. “Most of the operations we see are related to Starlink. They used to be launch providers, but now they are the world’s largest satellite operators, but only two years have passed since they did it. There is a certain amount because there is no. Inexperienced. “
SpaceX uses an autonomous collision avoidance system to keep the fleet away from other spacecraft. However, this can cause additional problems. According to Lewis, automatic trajectory adjustment changes the predicted trajectory, making collision prediction more complicated.
“Starlink doesn’t publish all the operations they’re doing, but it’s believed they’re always making a lot of small corrections and tweaks,” Lewis said. “But that causes problems for everyone else, because no one knows where the satellite will go and what it will do in the next few days.”
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According to scientists, the SpaceX Starlink satellite is responsible for more than half of close encounters in orbit.
Source link According to scientists, the SpaceX Starlink satellite is responsible for more than half of close encounters in orbit.