Rocket debris from China's space station launch is hurtling back to Earth — and scientists aren't sure where it will land

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CBS News 05 May, 2021 - 05:45am 13 views

What did China launch into space?

Shenzhou 3 and Shenzhou 4 were launched in 2002, carrying test dummies. Following these was the successful Shenzhou 5, China's first crewed mission in space on October 15, 2003, which carried Yang Liwei in orbit for 21 hours and made China the third nation to launch a human into orbit. wikipedia.orgChinese space program

The 30-metre high core of the Long March 5B rocket launched the “Heavenly Harmony” unmanned core module into low Earth orbit on 29 April from Wenchang in China’s Hainan province.

The Long March 5B then itself entered a temporary orbit, setting the stage for one of the largest ever uncontrolled re-entries. Some experts fear it could land on an inhabited area.

“Last time they launched a Long March 5B rocket they ended up with big long rods of metal flying through the sky and damaging several buildings in the Ivory Coast,” he said.

“Most of it burned up, but there were these enormous pieces of metal that hit the ground. We are very lucky no one was hurt.”

On Tuesday the core was orbiting Earth around every 90 minutes at about 27,600km/h and an altitude of more than 300km. The US military has named it 2021-035B and its path can be seen on websites including orbit.ing-now.com.

But McDowell says some pieces of the rocket will survive re-entry and that it would be the “equivalent of a small plane crash scattered over 100 miles”.

Since 1990 nothing over 10 tonnes has been deliberately left in orbit to re-enter uncontrolled. The Long March 5B core stage is thought to be about 21 tonnes.

“What’s bad is that it’s really negligent on China’s part. Things more than ten tonnes we don’t let them fall out of the sky uncontrolled deliberately,” McDowell said.

Based on its current orbit the rocket is passing over Earth as far north as New York, Madrid and Beijing and as far south as southern Chile and Wellington, New Zealand, and could make its re-entry at any point within this area.

Given its velocity, a small change in its path could make a big difference to where it ends up. It’s expected to return to Earth on 10 May, plus or minus two days.

McDowell said once it’s clear the day it is returning to Earth, experts could predict its landing time within a six-hour window.

The rocket’s launch was part of 11 planned missions as part of the construction of China’s space station, which is expected to be completed in late 2022. The T-shaped space station is expected to weigh about 60 tonnes, considerably smaller than the International Space Station, which launched its first module in 1998 and weighs about 408 tonnes.

China’s space station will have a docking port and will also be able to connect with a Chinese satellite. Theoretically it could be expanded to as many as six modules.

Read full article at CBS News

Massive Chinese rocket circling the planet is uncontrolled and could fall to Earth somewhere

pennlive.com 04 May, 2021 - 03:20pm

China launched the first module of its new space station on April 28. The rocket that launched the module is now circling the planet, uncontrolled, and could reenter Earth’s atmosphere in the next few days.

A report by SpaceNews said the roughly 21-ton object is the core stage of the Long March 5B rocket, which is “slowly and unpredictably” heading back to Earth.

Unlike most discarded rocket first stages, which typically do not reach orbital velocity, but rather reenter the atmosphere to land in a pre-designated zone, this core stage is now in orbit and subject to interaction with the atmosphere which will pull it to Earth, the report explained.

If this occurs it will be one of the largest instances of uncontrolled reentry of a spacecraft, with the possibility that it could land on a populated area.

The report noted that an object has been detected by ground based radars used by the U.S. military to track spacecraft and other objects in space. The object has been “catalogued” as the Long March 5B rocket body, now designated 2021-035B. The rocket measures roughly 99 feet long, and 16 feet wide, traveling at more than 4 miles per second.

Where and when the new Long March 5B stage will land is impossible to predict. The “decay of its orbit” will be accelerated by the atmospheric drag, and the speed of this process varies depending on the size and density of the object as well as other variables such as atmospheric variations and fluctuations, which in turn are influenced by solar activity and other factors.

The SpaceNews report explained that “the Long March 5B core stage’s orbital inclination of 41.5 degrees means the rocket body passes a little farther north than New York, Madrid and Beijing and as far south as southern Chile and Wellington, New Zealand, and could make its reentry at any point within this area.”

Due to the high speed of the object, which orbits the Earth roughly every 90 minutes, a fluctuation of just a few minutes in reentry time would result in a reentry point “thousands of kilometers away.”

It was further stated that any debris surviving the intense heat of reentry would most likely fall into the oceans or unpopulated areas, “but the risk remains of damage to people or property.”

“Since 1990 nothing over 10 tons has been deliberately left in orbit to reenter uncontrolled,” said Spaceflight observer Jonathan McDowell.

The Long March 5B core stage, empty of propellent, is said to be an estimated 21 metric tons in mass without its four side boosters.

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