- 05/05/2021 at 2:27 AM #36819Anonymous UserParticipant
Rocket part weighing 21 tons on earth course
Out of control: A piece of space junk 30 meters long and weighing a good 20 tons is currently hurtling towards its crash – in extreme cases, its debris could hit inhabited areas. It is still unclear where the core stage of the Chinese Long March 5B rocket will hit. The crash is said to occur in the days around May 10th. The CZ-5B is currently orbiting the earth at an altitude of around 300 kilometers, but is rapidly losing altitude.
Not only the earth orbit is filled with space debris, parts of it also keep raining down on earth. While small pieces of debris burn up completely in the atmosphere, larger components often leave debris, which then hit the surface of the earth. Therefore, such scrap pieces should be brought to a crash in a controlled manner over unpopulated areas or the ocean – actually.
Consciously accepted a crash?
But time and again it happens that orbital junk unintentionally gets out of control – or that its creators consciously accept an uncontrolled crash. China in particular stands out ingloriously: the Tiangong-1 space station crashed at Easter 2018, followed by the 20-ton main combustion stage of a Langer Marsch 5B (CZ-5B) rocket in May 2020. China has apparently taken no measures in its missile program to prevent larger parts from falling.
“Before the CZ-5B began to fly, there have been no uncontrolled re-entries of objects larger than ten tons since 1990,” said Jonathan McDowell from the Center for Astrophysics at Harvard on Twitter. The crash of the rocket combustion stage in May 2020 was therefore the worst uncontrolled crash in 30 years. Most of the debris fell into the Atlantic, but some metal parts fell on the Ivory Coast and damaged buildings. “We’re very lucky no one was injured,” said McDowell.
Burning level in uncontrolled descent
Now another crash is imminent – and again it is the burning stage of a Langer Marsch 5B missile. The launcher was launched from the Chinese spaceport in Hainan on April 29, 2021 to bring the core module (Tianhe) of a new space station into low earth orbit. After this was done, the 30-meter-long and roughly 21-tonne main combustion stage itself entered orbit. Since then, the non-powered scrap part has been racing around the earth, gradually sinking deeper and deeper.
The rocket part CZ-5B flies at almost 28,000 kilometers per hour and orbits the earth once every 90 minutes. The flight path is at an angle of 41 degrees to the equator, so that the rocket stage is constantly oscillating back and forth between the mid-latitudes of the northern and southern hemispheres. The high pace and this pendulous trajectory make it particularly difficult to predict when and where exactly the debris will enter the atmosphere and crash.
Crash date around May 10th, location still unknown
According to the current status, the rocket stage could crash on May 10 – but also up to two days earlier or later. The crash site is even more uncertain: Just a few minutes difference can decide whether the scrap falls over densely populated areas such as the east coast of the USA, Europe or Southeast Asia or over the ocean. You will probably only know more about this a few hours in advance.
According to McDowell, the likelihood of a crash over the sea is very likely – after all, oceans take up most of the planet’s surface. Should the rocket fall over land, however, the amount of debris that had not burned up could correspond to that of a small aircraft. However, these metal parts would then be distributed over more than 100 kilometers.
Start of the construction of a modular space station
The latest launch of the Lange Marsch 5B is just one of a total of eleven flights planned to bring further components of the Chinese space station into orbit. Some of the flights will be manned, but at least two more will use CZ-5B missiles. It remains to be seen whether China will then let their main burning stages crash again in an uncontrolled manner.
When the Chinese space station Tiangong is finished at the end of 2022, it should weigh around 80 tons. It will therefore be significantly smaller than the 400-tonne International Space Station ISS and more similar to the Russian Mir space station.
Source: SpaceNews, Twitter, orbit.ing-now, NASA
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