The Tianhe module, which stands for “Harmony of the heavens,” was launched on April 29 on a 5B Y2 long march, China’s largest rocket. While most rockets launch in two stages, the first stage usually returns to a known location, or some stay in orbit and end up burning on reentry (only SpaceX Falcon first stage rockets return to Earth during a controlled landing). However, due to the size of the Long March 5B, some space experts predict that some of its components could reach Earth.
“There’s a good chance this thing will fall apart over the ocean,” said Jonathan McDowell, an astronomer at Harvard University’s Center for Astrophysics. “But there is a chance that it will hit a populated area. And then we could be looking for some material damage, hope there will be no casualties. “
This is not exactly unprecedented for China.
“This is the second launch of this type of rocket, the Long March 5B,” McDowell said. “The first one was a year ago, and it also came back and caused damage in villages in Côte d’Ivoire. He littered pieces of metal over about 100 miles of land. ”
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While not unprecedented, it is considered bad practice for countries and business enterprises to allow things to fall into Earth orbit uncontrollably.
“It’s just considered bad practice to throw large chunks of metal out of the sky,” McDowell said.
At the start of the space age, in the 1970s, even NASA allowed things to fall out of orbit because it was highly likely to reach an inhabited place on Earth. After all, the planet is over 70% water.
However, that all changed after the US 77-ton Skylab space station desorbited in 1979. Parts large and small eventually hit the ground – most famously part of an oxygen tank that fell to the ground. in the Australian outback.
“It’s the only thing over 10 tonnes that has been purposefully designed to fit in unchecked since the late 1980s,” McDowell said. “China is really going against what I think are set standards, at least for a space activity. And it’s not clear why they made this design decision. “
Tianhe weighs 22 tons. The rocket is 32 meters long and five meters in diameter. And while it’s mostly an empty tank, it has big rocket motors on one end. In there are long, thin metal rods that were part of the fuel system. It is these rods – due to their shape – that could withstand re-entry combustion. This is what happened to the ground in Côte d’Ivoire with the other Long March 5B in 2020.
When and where
At the time of writing this article, Aerospace Corporation, an independent nonprofit research organization in California, predicted re-entry time for the worn rocket – which was designated CZ-5B / 2021-035B – is May 9 at 12:37 p.m. ET, with a margin error on either side of about 28 hours.
the European Union space surveillance and monitoring also said they were tracking the debris and would update its orbit in the coming days.
Because it is not controlled, the exact time and place of re-entry remain largely unknown.
There is good news for Canadians, however: the rocket’s orbit is less than 41 degrees north latitude, which means we won’t be in danger if something does manage to land. (Most of Canada is above 49 degrees north latitude, with the country’s southernmost point at 42 degrees.)
Typically, most debris that enters Earth’s atmosphere burns. But if it is large enough, it is likely that some will reach the ground or the ocean.
Some people may remember that a rocket stage from a SpaceX launch burned down when it returned to Earth’s atmosphere last month. It has been seen all over the state of Vancouver and Washington. Some debris did manage to land, and it was only a three-ton rocket stage.
“It’s a much larger step, so the likelihood of debris reaching the Earth’s surface is much higher,” McDowell said.
Still, the chances of anyone being injured by space debris are extremely low. In the history of space launches, there has never been a death as a result of such an incident.
“I would say, you know, don’t worry about it: it’s not something you have to worry about for an individual, because the chances of you being hit by something falling from the sky somewhere on Earth [are] pretty thin, ”McDowell said.
“But it should be of concern to space agencies and space lawyers, and so on, how we’re going. Avoiding losses from space debris or property damage from space debris, how we deal with that, how we recommend that larger objects really not be allowed to fit in this way. ”