Part of the wreckage from the uncontrolled crash of a Communist Party-launched Long March 5B Yaoji rocket may have landed in an unknown location on Earth. But experts say the chances of the wreckage falling on a densely populated area are slim.
The following is an analysis related to the fall of the wreckage of the Long March Long March 5B remote 2 rocket.
Why did the Long March rocket fall?
On April 29, the Long March 5B Yaoji rocket was launched from the Wenchang Spaceport in Hainan Province with the core capsule of the Chinese space station Tianhe, which broke away from the main structure of the Long March rocket after 492 seconds of flight and went directly into its original orbit.
The Long March rocket was sent directly into low Earth orbit by the main structure and four thrusters, but the main structure was also in orbit, and the interaction with the atmosphere became stronger and stronger, causing the rocket to fall toward the Earth.
If so, this would be one of the most serious incidents of an uncontrolled re-entry of a space vehicle into the atmosphere, with the possibility of landing in an inhabited location.
What is the most likely scenario?
The most likely scenario is that any wreckage not destroyed by atmospheric heat would land in the ocean or an uninhabited area, but would still have the potential to cause damage to people or property.
The altitude of the rocket is between 150 and 250 kilometers above the surface, and re-entry into the atmosphere is very unpredictable.
The European Space Agency (European Space Agency, ESA) is responsible for engineering and research and development innovation director Bobrinskoy (Nicolas Bobrinskoy) said that because the lower atmosphere is more prone to conditions of density change, “we can not conclude exactly when it will happen “.
As of the evening of the 7th European time, there were predictions that the rocket would re-enter the atmosphere between 21:00 GMT on the 8th (5:00 a.m. Taipei time on the 9th) and 7:00 a.m. on the 9th (3:00 p.m. Taipei time on the 9th).
But Bobrinskoy noted that even an hour before re-entry, the uncertainty remains high.
What is certain is that the main structure of the Long March rocket is circling the equator at an elevation angle of about 41 degrees, meaning that any debris will land between 41 degrees north and 41 degrees south latitude.
Greece, Spain and North Africa are included, as well as the United States and much of China, but not France or Germany.
The most likely area of contact is water, as nearly 3/4 of the Earth’s surface is covered by oceans.
Florent Delefie, an astronomer at the Paris-PSL Observatory, said, “The chances of the wreckage landing in an inhabited area are very small, maybe one in a million.”
Even if the rocket wreckage does land on a building, the speed of impact would be relatively slow, about 200 kilometers per hour, compared to the 36,000 kilometers per hour at which a meteorite could hit the Earth.
What is the most serious threat in the past?
The re-entry of the 76-ton NASA Skylab space station in 1979 was the most serious and well-publicized accident, a runaway accident that scattered debris across the Indian Ocean and Western Australia.
In 2020, the wreckage of another Long March rocket landed in a village in the African nation of Côte d’Ivoire, destroying buildings but causing no casualties.
Since mankind entered the space age more than 60 years ago, about 6,000 runaway objects have re-entered the Earth’s atmosphere, and only once has a wreckage hit a human.
How can this problem be avoided?
Astronomer Jonathan McDowell (Jonathan McDowell) said he expects China to strengthen the main body of the rocket to perform controlled de-orbiting operations after the Tianhe core module is detached from the rocket, “I don’t think uncontrolled re-entry is tolerable by current standards.
He said that “since 1990, no wreckage in excess of 10 tons has been deliberately left in orbit without a controlled re-entry” and that the net weight of the main body of the Long March 5B Yao-2 rocket is about 21 metric tons without four thrusters or no fuel in the thrusters.
How can other countries avoid this problem?
In most expendable rockets, the first section of the structure cannot reach orbital velocity and cannot re-enter the atmosphere and land in the original intended re-entry zone. Other larger structures have a second section that performs an off-orbit ignition to reduce altitude, time in orbit, and the chance of collision with other spacecraft or immediate re-entry.
It was previously speculated that the main body of the Long March 5B Yaoji rocket would perform an automatic de-orbit, but this situation does not appear to have occurred. Wang, the chief commander of the Long March 5 launch vehicle, said at a press conference at the Wenchang Spaceport on April 29 that the (Chinese) 2nd launch was a marked improvement over the first, but did not mention deorbiting operations.
Ground-based radars used by the U.S. military to track space vehicles and other space objects have detected an object classified as the main body of the Long March rocket, which is about 30 meters long and 5 meters wide and labeled 2021-035B, moving at a speed of more than 7 kilometers per second.
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