Starlink orbits vary, but some have an altitude as low as between 211 and 217 miles (340 to 350 km), his paper shows, which is near that of the ISS. An April 2020 peer-reviewed paper from McDowell adds that low Earth orbit has seen "a dramatic increase in the population" of satellites in recent years almost solely as a result of Starlink. Starlink numbers nevertheless are numerous.Īs of March 2023, SpaceX has launched approximately 4,000 satellites in orbit since its first Starlink group in 2019, according to a table maintained by space object tracker Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics. "To accomplish safe space operations in a scalable way, SpaceX has developed and equipped every SpaceX satellite with an onboard, autonomous collision avoidance system that ensures it can maneuver to avoid potential collisions with other objects," company officials wrote in a February 2022 update. SpaceX has said it has procedures in place to move Starlinks out of the way of trouble. The vast majority of new satellites come from SpaceX, which is aiming to have at least 12,000 operational Starlink broadband satellites in low Earth orbit in the near term and has applied for approval for 30,000 more. "The number launched this year is more than the total number of operating satellites in 2016, just six years ago," he said. The number of operational satellites currently in orbit is "astounding", wrote Steven Young, the Washington, D.C. (They base their information off of frequently updated statistics from the United Nations Office of Outer Space Affairs.) The Union of Concerned Scientists tracked 5,465 active satellites as of May 2022, which is a 12% increase from only six months beforehand (December 2021) with 4,852 recorded satellites. (Image credit: NASA/Canadian Space Agency) How bad is the space debris problem? These images from NASA and the Canadian Space Agency show the location of a space debris strike on the International Space Station's Canadarm2 robot arm spotted on and released on May 28. "When predictions indicate that any tracked object will pass close enough for concern and the quality of the tracking data is deemed sufficiently accurate, Mission Control centers in Houston and Moscow work together to develop a prudent course of action," agency officials wrote in May 2021 of ISS avoidance procedures. (Trackable pieces in that orbital plane are roughly 2 inches (5 centimeters) in diameter, but even paint flecks can cause issues given the high velocities involved with objects in orbit.) The box is roughly 2.5 by 30 by 30 miles (4 by 50 by 50 kilometers) with the ISS at the center, according to agency officials. NASA's long-standing guidelines require the ISS to maneuver if any satellite comes within a "pizza box"-shaped area of space surrounding the orbit of the station. That's in part because the number of satellites is increasing, and in part due to space debris. Within the next week, astronauts aboard the space station will say goodbye to the members of Crew-5, scheduled to depart as early as Thursday (March 9), and begin to prepare for the arrival of SpaceX's CRS-27 cargo Dragon, currently scheduled to launch March 14.The ISS orbit, which is about 250 miles (400 kilometers) above Earth, is more crowded with space junk than ever before. Monday's PDAM comes amidst a heavy traffic time for the ISS, and just a few days after the arrival of SpaceX's Crew Dragon Endeavour and the members of Crew-6. However, "about 20 minutes prior to the PDAM, a 'green update' was received on the conjunction," Jones said, adding, "thrusters were already enabled so the burn was still conducted." A pre-determined avoidance maneuver (PDAM) was calculated, and crews aboard the ISS in tandem with NASA and Roscosmos ground teams prepared for the scheduled thruster burn. Monday's course correction came with ample notice, with NASA receiving initial alerts for the potential collision approximately 30 hours ahead of the satellite's projected closest approach, Jones told. Last year, two such corrections were necessary to avoid debris from the Cosmos 1408 satellite, which Russia destroyed in an anti-satellite (ASAT) weapons test in November 2021 - a demonstration that has since been largely condemned by the international space community. A graph showing the numbers of ISS collision avoidance maneuvers between 19 (Image credit: NASA Orbital Debris Program Office (ODPO))
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