Elon Musk minimizes the risk of orbital disorder posed by his satellites

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[EN VIDÉO] How many satellites revolve around the Earth?
2,787 satellites were operational as of December 31, 2020 according to the UCS (Union of Concerned Scientists) association, more than half of which were launched by the United States. Three quarters of the satellites in operation rotate in low orbit (between 500 and 2,000 km altitude), and are used for telecommunications systems, terrestrial imaging or meteorology.

The information site SpaceDaily posted a very interesting article that reports the point of view ofElon Musk concerning the orbital disorder that could cause, therefore in the conditional, the satellites of the starlink constellation from SpaceX. In an interview at FinancialTimes, Elon Musk, never in half measures, responded to the numerous allegations that satellites star link of his company occupy too much space on theorbit land, claiming that ” tens of billions of spacecraft could fit in near-Earth orbits!

Musk explained that because space is ” simply extremely large and that the satellites that he sends there are very small », the situation is not as disastrous as it seems. ” This is not a situation where we actually block others in any way. We haven’t stopped anyone from doing anything, and we don’t intend to. “, he added. According to him, each orbital “shell” encircling the Earth is larger than the surface of the Planet, with another shell every 10 meters or so further out in space, which he says would allow these ” tens of billions of satellites to revolve around the Earth in complete serenity. According to Elon Musk, there is enough room for tens of billions of satellites and “ a few thousand satellites is nothing “.

Elon Musk says there’s room for tens of billions of satellites and ‘a few thousand satellites is nothing’

This assertion by Musk has obviously been disputed by many specialists in the management of the space traffic. According to Jonathan McDowell, astronomer at the Harvard-Smithsonian Center for Astrophysics (Massachusetts, USA), the satellites moving at almost 28,000 km/h need much more space to have time to change their orbits if a collision seems possible “. The expert calculated that at this speeda three-second interval would only place about 1,000 satellites in each orbit.

As it is complex to determine the trajectory of such a large number of distinct satellites in relation to each other, and as variations in the weather report solar modify their trajectories, the risks of potential collisions are difficult to predict. And when this risk arises, which does not mean that a collision is certain but that two satellites threaten to pass each other only less than a kilometer away, there will come a day when it will be too late to carry out a maneuver of avoidance.

The density of space traffic could prevent astronauts from living and working in safety

But these problems are not the only ones that worry space agencies and space users. The mega-constellations that will eventually unfold with hundreds of thousands of small satellites by 2030 could seriously complicate human activity in low orbit.

At this horizon, in fact, it is estimated that there could be more or less 4,000 satellites going up and coming down (end of life, breakdown, de-orbitation). A chain of satellites that must be constantly monitored and avoided! Under these conditions, the probability of losing a active astronaut in the next ten years is a one in sixty chance!

In conclusion, and there everyone agrees, it is quite simply a problem of traffic management and there is an urgent need to provide space with a binding “highway code”, capable of alone to regulate space traffic. This is what the European Commission is proposing with the Spaceways project that Telespazio drives.

Chinese space station forced to maneuver to avoid Starlink satellites

Article of Remy Decourt published on December 29, 2021

The chinese space station would have been forced to correct its trajectory twice in order to avoid the risk of collision with a satellite of the constellation SpaceX’s Starlink. A situation that shows the urgency of providing space with a “highway code” to manage space traffic, as the European Commission wishes with the Spaceways project.

In a document recently released by the UN Office for Outer Space Affairs in Vienna, China informed the UN Secretary-General that, twice, satellites of the starlink constellation of SpaceX have “ consisting of the dangers to the life or health of astronauts aboard the Chinese space station “. Chinese Foreign Ministry spokesperson Zhao Lijian added a layer of this on Tuesday by pointing out that the “ United States ignores its obligations under international treaties, which poses a serious threat to the lives and safety of astronauts “.

In other words, China accuses SpaceX of irresponsible and dangerous conduct in space and the United States of laxity in the management of its space activities. Accusations that can make you smile when you know that the Chinese military is responsible for thousands of debris following a test of missile anti-satellite carried out in January 2007. Located at an altitude of some 800 kilometers, an out of order Chinese weather satellite had been destroyed by a missile generating a profusion of debris which, for once, is much more dangerous than the Starlink satellites because less predictable and maneuverable.

That said, there’s no denying that the hundreds of Starlink satellites already in orbit have increased the number of collision risks since the constellation’s deployment began. The Chinese space station, currently occupied by a crew of three taikonauts, which is in a near-circular orbit at an altitude of about 390 kilometers with an orbit inclination of about 41.5 degrees, is no more exposed than other space users. In September 2019, theEuropean Space Agency had been forced to maneuver the Aeolus satellite to avoid a Starlink satellite. But as China knows how to be heard and respected, the controversy quickly swelled on the social networks Chinese.

It is therefore not surprising that, as China points out, two of them found themselves in July and October on a trajectory which could lead them, in theory, to collide with the Chinese space station. In theory, because we identify a risk of collision when a satellite can get closer to less than a few kilometers from an object that it could hit. Strictly speaking, neither of the two Starlink satellites incriminated by China was heading straight for the Chinese space station. However, this situation highlights the need to quickly establish a space traffic management system to regulate human activities in space. This is what the European Commission is proposing with the Spaceways project that Telespazio drives.

Two collision risk avoidance maneuvers

Discover, below, the information relating to the two collision avoidance maneuvers carried out by the Chinese space station as presented by China to the United Nations Office for Outer Space Affairs.

Since April 19, 2020, the Starlink-1095 satellite has been moving stably in orbit at an average altitude of about 555 kilometers. Between May 16 and June 24, 2021, the Starlink-1095 satellite maneuvered continuously to an orbit of approximately 382 kilometers and then remained in that orbit. A rapprochement took place between the Starlink-1095 satellite and the Chinese space station on 1er July 2021. For safety reasons, the Chinese space station took the initiative to perform an evasive maneuver on the evening of that day to prevent a potential collision between the two spacecraft.

The second collision avoidance was potentially more dangerous. On October 21, 2021, the Starlink-2305 satellite approached the Chinese space station. Since the satellite was in continuous maneuvering, the maneuvering strategy was unknown and the orbital errors were difficult to assess, there was therefore a risk of collision between the Starlink-2305 satellite and the Chinese space station. To ensure the safety and lives of astronauts in orbit, China’s space station performed a new evasive maneuver on the same day to prevent a potential collision between the two spacecraft.

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