The long core phase of March 5B is likely to re-enter the Earth’s atmosphere in the next few days.
Helsinki-China launched the first module of its space station into orbit late Wednesday, but the mission launcher has also reached orbit and is slowly and unexpectedly returning to Earth.
The Long March 5B is a variant of China’s largest rocket. Successfully started The 22.5 metric tons of Tianhe components shipped from Wenchang on Thursday, local time. After a 492-second flight, Tianhe separated from the core stage of the launcher and directly entered its planned initial orbit.
Long March 5B is specially designed for launching the space station module into low earth orbit. It uniquely uses the core stage and four side boosters to place its payload directly into low earth orbit.
However, this core phase is now also in orbit, and due to the increasing interaction with the atmosphere, it may once again run out of control and enter the earth in the next few days or a week. If this is the case, it will be one of the largest instances of a spacecraft̵
Most expendable rockets will not reach orbital speed in the first stage, unable to re-enter the atmosphere and land in a predetermined re-entry zone. Some other larger second stages undergo deorbiting combustion to reduce altitude, shorten the time in orbit, and reduce the chance of collision with other spacecraft, or immediately re-enter the atmosphere.
There have been speculations that the Long March 5B nuclear will take the initiative to get itself out of track, but this does not seem to happen. At the Wenchang press conference held on Thursday, Wang Ju, the commander-in-chief of the Long March 5B launch vehicle, said:Chinese people) The second Long March 5B is an improvement over the first launch, but the possible down-orbit maneuvers are not explained.
The ground radar used by the US military to track spacecraft and other objects in space has detected an object and classified it as a Long March 5B rocket. Now named 2021-035B, it is about 30 meters long and 5 meters wide. The core stage of the Long March on May 5 was in a 170 x 372 kilometers high-altitude orbit, and its speed exceeded 7 kilometers per second.
Possible amateur basis Observed The flickering of the core of the rocket shows that the regular flickering indicates that it is rolling and is therefore out of control.
For the launch of Vega, there is still no TLE. Tianhe launched another TLE on Object B, and its slow decay rate confirmed that it was a CZ-5B core level pic.twitter.com/0dVkUkcpjA
— Jonathan McDowell (@planet4589) April 30, 2021
The first launch of Long March 5B also saw the first phase reach orbit and an uncontrolled return six days later. According to the 18th Space Control Squadron of the US Space Force, the reentry occurred over the Atlantic Ocean.
If the event occurs 15 to 30 minutes ago, the debris will not be destroyed by the reentry heat and may fall on American soil.event The then director of NASA drew criticism Jim Bradenstein.
It is impossible to predict when and where the new Long March Phase 5B will land. As the atmospheric drag drops it denser, the attenuation of its orbit will increase. The speed of this process depends on the size and density of the object. Variables include atmospheric changes and fluctuations. These changes and fluctuations themselves are affected by solar activity and other factors.
The high speed of the rocket means that it orbits the earth approximately every 90 minutes, so a change in reentry time of only a few minutes will result in thousands of kilometers of reentry point.
The orbital inclination of the core phase of the Long March 5B is 41.5 degrees, which means that the rockets traveled a little farther to the north than New York, Madrid and Beijing, and farther south than Chile’s southern and New Zealand’s Wellington, and can be within this range. Re-enter the area at any location.
The most likely event will be any debris that survives the surviving reentry heat and falls into the ocean or uninhabited areas, but there is still a risk of damage to people or property.
Space Observer Jonathan McDowell told Space news The previous Long March 5B launch was the largest uncontrolled return in decades and the fourth largest ever. “The core phase of Long March 5B is seven times larger than the second phase of Falcon 9, which attracted widespread media attention when it re-entered Seattle a few weeks ago and dumped some pressure tanks in Washington State.”
McDowell said that he hopes that after China separates from Tianhe, it can strengthen the core stage for a controlled derailment. McDowell said: “I think it is unacceptable to reenter it into an uncontrolled state according to current standards.”
“Since 1990, there has been no deliberate delivery of heavy objects exceeding 10 tons into the orbit to allow it to re-enter uncontrollably.” The Long March 5B core stage has no four side boosters and is considered to have a mass of 21 tons Dry weight”, that is, when there is no propellant.
Holger Krag, head of the European Space Agency’s Space Security Program Office, said that based on their experience, the average mass is about 100 tons. reenter Every year in an uncontrolled manner “This involves approximately 50-60 independent events per year.”
“It is always difficult to assess the quantity of surviving mass and the quantity of debris without knowing the design of the object, but a reasonable “rule of thumb” is about 20-40% of the original dry mass.”
Components made of heat-resistant materials (such as water tanks and propellers made of stainless steel or titanium) can reach the ground. Objects that survived the deceleration will fall vertically and travel at their final speed.
The largest and most famous event was the entry of NASA’s 76-ton Skylab into the atmosphere in 1979. The atmosphere entered the atmosphere uncontrollably, with debris spread throughout the Indian Ocean and Western Australia.
Reenter at night to enjoy spectacular views, such as Recent reentry Fortunately, no fragments caused damage during the second phase of the Falcon 9 battle.
China’s 8-ton “Tiangong-1” space laboratory has attracted much attention Uncontrollable reentry In 2018, the successor Tiangong-2 was Off track Conducted in a controlled manner in 2019.