Raumfahrt - Chinese rocket’s chaotic fall to Earth highlights problem of space junk



China has played down fears that its Long March 5B rocket could hit a populated area or a plane in flight but there is no shortage of problem debris in orbit


Sometime this weekend the upper stage of a Chinese Long March 5B rocket will plunge back to Earth and most of it will burn up on re-entry – but perhaps not all.

Military experts in the US expect the booster stage to come down on Saturday or Sunday, but have warned it is difficult to predict where it will land and when and how much material might hit the ground – or if it could knock a plane out of the sky. 

The Chinese government, perhaps predictably, is playing it calmly. “The probability of causing harm to aviation activities or [on people and activities] on the ground is extremely low,” the foreign ministry spokesman, Wang Wenbin, said on Friday.

But the fiery fate of the booster, wherever it comes down, speaks to the larger issue of space debris and space sustainability, especially as space becomes a target not just for national space programs but also increasingly the private sector. Under international treaty, private space actors, who are expected to put 45,000 satellites in low Earth orbit over the next several years, are under the legal responsibility of their host nations.

Add to that, an estimated 9,300 tons of space junk that’s already orbiting the planet and the issue of space collisions and debris pollution is an issue of concern.

Last month, mission controllers at SpaceX headquarters in California warned orbiting astronauts to put on their spacesuits and get back in their seats because a piece of space debris could strike the capsule. Previously, a piece of paint the size of a fingernail struck the windscreen of a space shuttle, piercing two of three layers of glass.

“Space debris has been known for a while, but now you have more competition in space. You don’t just have two space-faring nations – the Chinese are very significant, as is the European Space Agency, among others. When you have more actors and more stuff, it gets more complicated,” said Joanne Gabrynowicz a professor at the National Center for Remote Sensing, Air, and Space Law at the Mississippi Law Center.

Experts have repeatedly voiced their worry about the risk of collisions since 2009, when two satellites – Iridium 33 and the derelict Russian military Kosmos-2251 –accidentally collided at 26,000mph over Siberia, shattering both in thousands of pieces. The European Space Agency hosted a major conference on the subject last month.

“There’s a lot of stuff being put into low Earth orbit, and some of it could possibly hit one another,” said Gabrynowicz.

According to Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, China had every reason to know Long March 5B was unpredictable and would become uncontrollable. “It’s my judgment that the Chinese are negligent. China says it will probably fall in the ocean. But probably is doing a lot of work here. The last one would probably fall in the ocean, except it didn’t. It fell on the Ivory Coast,” he said.

An Ivorian gendarme takes notes next to debris that fell from space in the village of N’Guessankro near Bouake in central region in Ivory Coast on 12 May 2020.
An Ivorian gendarme takes notes next to debris that fell from space in the village of N’Guessankro near Bouake in central region in Ivory Coast on 12 May 2020.Photograph: AFP via Getty Images

The fate of Long March 5B could refocus governments and international bodies on the issue of space sustainability, and that could provide more opportunity to firms like UK-based Astroscale that are preparing to tackle the debris problem with commercial junk-collecting services.

According to the European Space Agency, about 6,900 of 11,370 satellites placed into Earth orbit are still circulating, with about 4,000 functioning. But the number of debris objects regularly tracked by Space Surveillance Networks stands at 28,160. The discrepancy is accounted for by more than 560 “break-ups, explosions, collisions, or anomalous events resulting in fragmentation”.

Astroscale is currently demonstrating a vehicle called “ELSA-d” in lower Earth orbit to show that space debris clean-up is indeed possible. It’s a fiendishly difficult task, especially if the target satellite is spinning and tumbling. The test is using a satellite to capture a test drone using a magnet; in time, larger objects will require a robotic arm.

The company’s managing director, John Auburn, said the real problem might not be the big pieces of debris that create the headlines and cause people back on ground to cast a nervous eye in the skies.

“The big problem in space is not big debris, but when big debris breaks up and becomes small debris,” Auburn said. “A one-centimetre fragment can destroy your spacecraft and it’s traveling so fast you don’t know it’s there from the ground. We don’t want a disaster, so it’s very important that governments build into licences requirements that old and broken stuff is brought back down.”

Quelle: The Guardian


Second stage of Chinese space rocket may enter atmosphere over Pacific May 9

The object is now steadily losing altitude, the apogee of its orbit being 267 kilometers, and perigee, 156 kilometers, Russia’s space corporation Roscosmos told TASS
The second stage of China’s space rocket CZ-5B, which carried into space the core module of a future space station, may enter the dense layer of the atmosphere over the Pacific on May 9, Russia’s space corporation Roscosmos told TASS on Friday.

"According to calculations made as of May 7, the second stage may enter the atmosphere over the Pacific during the night hours of May 9 Moscow time," Roscosmos said, adding that the object was now steadily losing altitude, the apogee of its orbit being 267 kilometers, and perigee, 156 kilometers.

The space rocket CZ-5B blasted off from the Wenchang launch site on April 29 to orbit the core module Tianhe (Milky Way) of China’s future space station. The second stage of the launch vehicle is unable to maneuver and is currently in the process of uncontrolled reentry. Its dry mass is about 18 tonnes.

Russia’s chief information and analysis center of the Warning Automated System of Hazardous Situations in near-Earth Space is gathering and processing information about the rocket stage’s trajectory. Earlier, Rocsosmos told TASS the rocket stage’s debris do not pose any risk to Russia.

Quelle: TASS


China acknowledges Long March 5B situation as rocket heads for weekend reentry

Latest reentry predictions project Long March 5B reentry to occur between late morning Saturday and early Sunday.

HELSINKI — China’s foreign ministry on Friday acknowledged the imminent uncontrolled reentry of the Long March 5B  as the orbit of the first stage continued to lose altitude.

At a Foreign Ministry regular news conference May 7, spokesperson Wang Wenbin responded to a question from Bloomberg stating that it is “common practice across the world for upper stages of rockets to burn up while reentering the atmosphere.” 

The second Long March 5B rocket successfully launched the Tianhe core module for China’s space station late April 28 Eastern. It soon became apparent, as reported by SpaceNews, that the first stage had also reached orbit and was slowly returning to Earth.

Latest orbital data from has the U.S. Space Force’s 18th Space Control Squadron reveals the roughly 30-meter-long, 21-metric-ton Long March 5B in a 154 by 241-kilometer altitude orbit. 

The current US 18 SPCS prediction points to a reentry during a window between 10:13 a.m. Eastern Saturday, May 8, and 4:13 a.m. Sunday, May 9. EU Space Surveillance and Tracking (EU SST) estimates reentry between 2:00 p.m. May 8 and 6:00 a.m. May 9.

The latest prediction from the Aerospace Corporation shows blue and yellow ground tracks over which the rocket body will pass during the predicted window. 


The large windows are due to uncertainties stemming from modeling challenges, including the non-spherical shape of the Earth, fluctuations in atmospheric density.

“China is following closely the upper stage’s reentry into the atmosphere. To my knowledge, the upper stage of this rocket has been deactivated, which means that most of its parts will burn up upon reentry, making the likelihood of damage to aviation or ground facilities and activities extremely low. The competent authority will release relevant information in a timely manner,” Wang said.

The “upper stage” referred to by Wang is also the first—typically the largest—stage of the Long March 5B. While most upper stages enter orbit and eventually reenter due to atmospheric drag, first stages of most expendable rockets do not reach orbital velocity and reenter the atmosphere and land in a pre-defined reentry zone.

Between 60 and 80 percent of the rocket stage is generally predicted to burn up during its high velocity reentry in the atmosphere, meaning some components consisting of heat resistant material are expected to reach the surface.

At a news conference a day earlier, Wang responded to a question on the situation only by reiterating that “China is always committed to the peaceful use of outer space.”

Wang acknowledged there was risk associated with the reentry but that this was “extremely low,” an assessment shared by space debris modelling experts. 

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. 

Governed by voluntary guidelines

Christopher Newman, professor of space law and policy at Northumbria University, told SpaceNews that there are no international laws that dictate how reentry of space objects is supposed to be accomplished. 

“There are broad principles of safety that have been captured in the Long Term Sustainability (LTSG) of Outer Space Guidelines, but these are not legally binding. It is national regulators to authorise and supervise national space activities. According to [University of South Hampton] Prof. Hugh Lewis, there are numerous spent rocket bodies in orbit that will make an uncontrolled re-entry.” 

Holger Krag, head of the Space Safety Programme Office for the European Space Agency, toldSpaceNews last week that an average mass of about 100 tons is reentering in an uncontrolled way through 50-60 individual events per year.

In the case of damage, Newman says Article VII of the Outer Space Treaty makes nation at ates liable for the damage caused by a space object. “The Liability Convention of 1972 provides a little more clarity on this, with Article II of the 1972 convention making a State absolutely liable should a space object or part of a space object be shown to cause damage on Earth or to an aircraft in flight.” 

The  Liability Convention “operates on an international level between nation states, so individuals will not have recourse to this. They will have to seek a domestic remedy and look to the government to recover any costs from the other state. This works on a diplomatic level.” 

Significantly, in practical terms, engaging the Liability Convention is as much a foreign policy decision as a legal one, says Newman. “The ‘victim’ state may be heavily dependent on the ‘liable’ state for infrastructure or investment and might not wish to rock the boat. So it is by no means certain that the 1972 Convention will be invoked.”

Brian Weeden of the Secure World Foundation told SpaceNews via email that while there is an emerging international norm towards controlled de-orbiting of rocket stages, it’s definitely not universal. 

“It’s not hard law that’s binding on countries, only a voluntary guideline, and that’s because countries like the United States did not want to create a binding law as they sometimes need to deviate from it themselves,” says Weeden. 

Weeden also notes that what we are seeing now are the results of decisions, such as having a non-restartable Long March 5B first tage, taken a long time ago. 

“I don’t know when that design decision was made, but it might have been quite a while ago. That’s a problem we have with orbital debris mitigation in general; lots of design decisions made decades ago that are still in play today because technological advancement is just not that fast. Once built, big rockets and satellites tend to get used for decades.”

China is planning two further Long March 5B launches in 2022 to send two experiment modules to join Tianhe in orbit. How China will respond to this situation, which has detracted from the successful Tianhe launch, remains to be seen. 

Ultimately, Weeden says, mission requirements, in absence of hard law, may win out. “Who’s going to tell the Pentagon or CNSA they can’t put up a critical new military satellite or a politically important space station because the rocket might have a small chance of landing on someone?”

Quelle: SN


Update: 10.05.2021


China says most rocket debris burned up during reentry

China’s space agency says a core segment of its biggest rocket has reentered Earth’s atmosphere in the Indian Ocean above the Maldives

BEIJING -- China's space agency said a core segment of its biggest rocket reentered Earth’s atmosphere above the Maldives in the Indian Ocean and that most of it burned up early Sunday.

Usually, discarded rocket stages reenter the atmosphere soon after liftoff, normally over water, and don’t go into orbit.

China’s official Xinhua News Agency later clarified that reentry occurred Sunday at 10:24 a.m. Beijing time. “The vast majority of items were burned beyond recognition during the reentry process," the report said.

Despite that, NASA Administrator Sen. Bill Nelson issued a statement saying: “It is clear that China is failing to meet responsible standards regarding their space debris.”

The roughly 30-meter (100-foot) long rocket stage is among the biggest space debris to fall to Earth. China's space program, with its close military links, hasn’t said why it put the main component of the rocket into space rather than allowing it to fall back to earth soon after discharging its payload, as is usual in such operations.

The Long March 5B rocket carried the main module of China’s first permanent space station — Tianhe, or Heavenly Harmony — into orbit on April 29. China plans 10 more launches to carry additional parts of the space station into orbit.

An 18-ton rocket that fell last May was the heaviest debris to fall uncontrolled since the former Soviet space station Salyut 7 in 1991.

China’s first-ever space station, Tiangong-1, crashed into the Pacific Ocean in 2016 after Beijing confirmed it had lost control. In 2019, the space agency controlled the demolition of its second station, Tiangong-2, in the atmosphere. Both had been briefly occupied by Chinese astronauts as precursors to China's permanent station, now under construction.

In March, debris from a Falcon 9 rocket launched by U.S. aeronautics company SpaceX fell to Earth in Washington and on the Oregon coast.

China was heavily criticized after sending a missile to destroy a defunct weather satellite in January 2007, creating a large field of hazardous debris imperiling satellites and other spacecraft.

Quelle: abcNews


NASA criticizes China's handling of rocket re-entry as debris lands near Maldives


New York (CNN Business)NASA has lambasted China for its failure to "meet responsible standards" after debris from its out-of-control rocket likely plunged into the Indian Ocean Saturday night.

"Spacefaring nations must minimize the risks to people and property on Earth of re-entries of space objects and maximize transparency regarding those operations," said NASA Administrator Sen. Bill Nelson in a statement released on the space agency's website Sunday.
"China is failing to meet responsible standards regarding their space debris," he added.
Most of the huge Long March 5B rocket, however, burned up on reentering the atmosphere, the China Manned Space Engineering Office said in a post on WeChat, before landing just west of the Maldives.
It was unclear if any debris had landed on the atoll nation.
The US Space Command said the Long March 5B had reentered Earth over the Arabian Peninsula.
The rocket, which is about 108 feet tall and weighs nearly 40,000 pounds, had launched a piece of a new Chinese space station into orbit on April 29. After its fuel was spent, the rocket had been left to hurtle through space uncontrolled until Earth's gravity dragged it back to the ground.
Generally, the international space community tries to avoid such scenarios. Most rockets used to lift satellites and other objects into space conduct more controlled reentries that aim for the ocean, or they're left in so-called "graveyard" orbits that keep them in space for decades or centuries. But the Long March rocket is designed in a way that "leaves these big stages in low orbit," said Jonathan McDowell, an astrophysicist at the Astrophysics Center at Harvard University.
In this case, it was impossible to be certain exactly when or where the booster would land.
The European Space Agency had predicted a "risk zone" that encompassed "any portion of Earth's surface between about 41.5N and 41.5S latitude" — which included virtually all of the Americas south of New York, all of Africa and Australia, parts of Asia south of Japan and Europe's Spain, Portugal, Italy and Greece.
The threat to populated areas of land was not negligible, but fortunately the vast majority of Earth's surface area is consumed by oceans, so the odds of avoiding a catastrophic run-in were slim.
The rocket is one of the largest objects in recent memory to strike the Earth after falling out of orbit, following a 2018 incident in which a piece of a Chinese space lab broke up over the Pacific Ocean and the 2020 reentry of an 18-metric-ton Long March 5B rocket.
Despite recent efforts to better regulate and mitigate space debris, Earth's orbit is littered with hundreds of thousands of pieces of uncontrolled junk, most of which are smaller than 10 centimeters.
Objects are constantly falling out of orbit, though most pieces burn up in the Earth's atmosphere before having a chance to make an impact on the surface. But parts of larger objects, like the Long March rocket in this instance, can survive reentry and threaten structures and people on the ground.
"Norms have been established," McDowell said.
"There's no international law or rule — nothing specific — but the practice of countries around the world has been: 'Yeah, for the bigger rockets, let's not leave our trash in orbit in this way.'"
Quelle: CNN
No damage caused by China's rocket remnants, Foreign Ministry reiterates

There have been no reports of injuries or damage caused by the remnants of Chinese Long March-5B carrier rocket, said Hua Chunying, spokesperson of China's Ministry of Foreign Affairs on Monday, responding to Western media claims that the rocket could cause damage when re-entering the Earth's atmosphere. 

The remnants of the rocket re-entered the Earth's atmosphere at 10:24 a.m. (0224 GMT) on Sunday, with most of the debris burning up and the rest landing in the Indian Ocean at a location near 72.47 degrees east longitude, 2.65 degrees north latitude, according to the China Manned Space Engineering Office.

The Chinese government has paid close attention to the re-entry of the rocket since it successfully sent the Tianhe core module into preset orbit last month, said Hua. During the re-entry process, China closely tracked the trajectory of the rocket and issued an announcement of the re-entry situation in advance.

"As far as I know, the last stage of the rocket has been passivated to prevent it from exploding in orbit and creating space debris," the spokesperson said, adding that most of its components were burned up upon re-entry, and the probability of causing harm to aviation activities and the ground is "extremely small."

China also shared the results of the re-entry forecast through international cooperation mechanisms, Hua added.

She pointed out that it is an international practice for carrier rockets, following their gradually decaying orbits, to finally burn up while re-entering the atmosphere.

'Double standard'

Hua stressed that China always carries out activities in the peaceful use of outer space in accordance with international law and practices, and is willing to expand international exchanges and cooperation on the issue of space debris, to ensure the long-term sustainability of outer space activities.

However, she said some U.S. media clearly have double standards on this issue, referring to the re-entry of a SpaceX rocket's remnantsin March that was rendered as "a light show" which "lights up the sky."

She urged all sides to be objective and rational, saying: "We are willing to work with countries, including the U.S., to strengthen cooperation in the use of outer space, but we also oppose double standards on this issue."

Quelle: CGTN



Raumfahrt+Astronomie-Blog von CENAP [-cartcount]