A photo sent to the U.N. Committee on Outer Space by the Permanent Mission of China to the United Nations shows that SpaceX's Starlink satellite has maneuvered to the orbital height of the Chinese space station several times this year, causing the Tiangong space station to have to adjust its orbit twice urgently to avoid possible collisions.
A spokesman for the Chinese Foreign Ministry commented on the matter for two consecutive days.
Zhao Lijian confirmed at a regular press conference on December 28 that in July and October this year, the Starlink satellite launched by the US Space Exploration Technology Company approached the Chinese space station twice. During this period, Chinese astronauts are on missions inside the space station. For safety reasons, the Chinese space station has taken emergency collision avoidance measures.
Zhao Lijian said: The 1967 Outer Space Treaty is recognized as the cornerstone of current international law in the field of outer space. The US side should respect the international order in outer space based on international law, take immediate measures to prevent the recurrence of such incidents, and adopt a responsible attitude to safeguard the life safety of astronauts in orbit and the safe and stable operation of space facilities.
On December 29, Zhao Lijian again said at a regular press conference that outer space is not an extralegal place. "Under the 1967 Outer Space Treaty, States are responsible for all outer space activities of their domestic private companies."
Experts say the satellites are precisely set in orbit before launch, so the chances of a real "collision" are slim. Lin Baojun, chief designer of the Beidou-3 system satellite and vice president of the Institute of Microsatellite Innovation of the Chinese Academy of Sciences, told the first financial reporter that although there is no perfect coordination mechanism in the world, various countries have timely tracking and control capabilities for their own satellites, and they can also control the trajectory of satellites in the sky on the ground.
What is the risk of satellite crashes?
Just a few days ago, two Chinese astronauts from the Tiangong space station just completed their second outgoing activity.
It was unclear whether the Starlink satellites mentioned in the U.N. report attempted to leave the Chinese space station on their own. A report submitted by China shows that during a close encounter in October, the Satellite's "maneuvering strategy is unknown and orbital errors are difficult to assess," prompting the station to urgently adjust its orbit and "avoid potential collisions."
According to the Starlink website, automatic collision avoidance technology is embedded in the Starlink satellites, which can automatically avoid if they detect a potential collision with upcoming space junk, space station or any other space flight object. Musk also responded on Twitter that the orbits of some Starlink satellites have been adjusted to reduce the likelihood of collisions.
Jonathan McDowell, an astronomer at the Harvard Smithsonian Center for Astrophysics, recently published his own analysis on Twitter, saying that given that the Chinese space station is in a stable orbit, he believes that SpaceX has the responsibility to actively evade and notify the Chinese side in advance.
He also analyzed the orbits of the two events, with Starlink 1095 and the Chinese Space Station meeting in July when Starlink was in descending orbit, while in the October encounter, Starlink 2305 continued to ascend without any evasive maneuvering.
Jonathan McDowell argues that while the minor tweaks to Starchain's paths to its satellites may indicate that autonomous systems are operating, he still calls for more international coordination. "Without international coordination, the adjustment of these autonomous systems has little effect." he said.
Construction of China's Tiangong space station began in April this year and is expected to be completed by the end of 2022 after four manned missions.
Chinese aerospace experts also said that they have made full preparations for emergencies, and once a situation occurs, corresponding measures will be taken.
Lin Baojun told the first financial reporter: "Now the evasiveness of satellite orbits is particularly strong, and it can predict whether there will be a risk of impact in advance for a long time, and can send a signal to monitor surrounding objects, so in general, it can react in time to avoid collisions." ”
For the height of satellite launch, Lin Baojun told the first financial reporter that the higher the height of the satellite launch, the weaker the signal, the longer the delay to the ground, so the ideal satellite orbital height generally can not be too high, but also can not be less than 300 kilometers, too low may fall on its own.
A busy and crowded new space age
According to statistics, there are currently about 30,000 satellites orbiting the earth.
The Starlink program, proposed by Musk in 2014, seeks to build a satellite internet covering the globe and send the first 60 satellites into space in 2019. SpaceX has reportedly launched nearly 1,900 satellites to date, and the project plans to launch 12,000 satellites into space — satellites that, once deployed, will be able to provide broadband services to the world and reduce network latency.
SpaceX is just one of many space companies. Last month, about a dozen companies and organizations, including Amazon, Boeing, OneWeb and others, applied to the Federal Communications Commission (FCC) for launch approvals for nearly 40,000 satellites to build or expand broadband networks, all of which hope to use the so-called V-band spectrum to provide broadband services from space to the world.
Amazon, for example, is working to build a constellation called Project Kuiper, originally made up of 3236 satellites. On this basis, Amazon has submitted as many as 7774 satellite applications, Astra (Astra) satellite applications have as many as 13620, and OneWeb and Boeing have also applied for 6372 and 5789 satellites, respectively.
The FCC also previously authorized SpaceX to launch about 7,500 V-band Starlink satellites. According to the second generation of Starlink's "Gen2" system plan, nearly 30,000 satellites will need to be deployed.
However, a major issue with the proliferation of satellites in low-Earth orbit is the risk of collisions and the creation of new space debris. Scientists have urged governments to share data to reduce the risk of a catastrophic space collision.
McDowell said that in recent years, the International Space Station (ISS) has had to avoid debris from anti-satellite tests several times. "It's a feature of a busy and crowded new space age."
Armand Musey, president of Summit Ridge, a consulting firm that specializes in valuing companies in the telecommunications and satellite industries, mentions a phenomenon called the Kesslers yndrome. The theory was proposed by American scientist Donald Kessler in 1978, arguing that when space junk is too dense, a satellite will have a chain reaction when it deviates from its orbit or is hit by a meteor, and a large number of satellites are destroyed, posing a threat to the safety of spacecraft such as the International Space Station.
"Space debris is one of the increasingly important issues in the industry." "If there are too many satellites out there and they start colliding with each other, there's a chain reaction, which is called Kessler syndrome," Musi said. ”
In response to the risk of collisions and the creation of new space debris due to the proliferation of satellites in Earth orbit, Summit Ridge proposed that the full use of autonomous maneuvering systems and the burning of end-of-life satellites falling into the atmosphere were ways to combat this risk.
In addition, astronomers have also protested the deployment of satellite constellations in large areas of Earth's orbit.
According to a report released last year by the European Southern Observatory (ESO), researchers said that large bright satellite constellations in low-Earth orbit will fundamentally alter ground-based optical and infrared astronomy and could affect the observations of astronomers around the world.
Professor Dietrich Baade, honorary astronomer of ESO, told First Financial Reporter: "Satellites and space debris have attracted a lot of attention, but I regret that the impact of a large number of satellite launches on astronomical observations has rarely been mentioned. ”
The ESO report found that the deployment of low-orbit satellites could affect astronomers' search for visible counterparts that include asteroids or gravitational wave sources that threaten Earth. According to the ESO report, SpaceX, Amazon, OneWeb and other companies are developing 18 "giant satellite constellations", which makes ESO's large telescopes subject to "moderate" interference from these constellations. The so-called "giant constellations" generally consist of hundreds or thousands of individual moons.