1.12.2021

Postponement comes a day after Nasa official warned of elevated debris risk due to Russian missile test

Astronauts (from left) Matthias Maurer, Raja Chari, Thomas Marshburn and Kayla Barron during training. Photograph: SpaceX

Nasa has postponed a planned spacewalk outside the International Space Station due to flying “debris”, two weeks after Russia blew up one of its own satellites in a missile test that created clouds of zooming shrapnel in orbit.

Washington’s space agency did not mention the Russian test in its announcement, but a Nasa official had warned a day earlier of a slightly elevated risk to astronauts due to the 14 November incident.

The strike generated thousands of pieces of “space junk” that are now hurling around the Earth at about 17,000 mph (27,400km/h) – much faster than the speed of a bullet. At that velocity, even tiny flecks of paint can damage spacecraft, with spacesuits even more vulnerable.

On Tuesday, about five hours before the astronauts Thomas Marshburn and Kayla Barron were due to venture outside the space station, Nasa said on Twitter that the spacewalk to fix a failed antenna had been cancelled.

“Nasa received a debris notification for the space station. Due to the lack of opportunity to properly assess the risk it could pose to the astronauts, teams have decided to delay the 30 November spacewalk until more information is available,” it tweeted.

Moscow has said its test to destroy its own spacecraft, Tselina-D, which had been in orbit since 1982, was successful and the debris posed no “threat to space activity”.

But following the test, the astronauts onboard the ISS – four Americans, a German and two Russians – were ordered to immediately seek shelter in docked capsules. The crew had to then take further precautions, such as closing and reopening hatches to the station’s individual labs every 90 minutes or so as they passed near or through the space debris.

The Nasa administrator, Bill Nelson, said at the time that he was outraged. “It’s unbelievable that the Russian government would do this test and threaten not only international astronauts, but their own cosmonauts that are onboard.”

Antony Blinken, the US secretary of state, said Russia had shown it was “willing to imperil the exploration and use of outer space by all nations through its reckless and irresponsible behaviour”.

On Monday, ahead of the planned spacewalk, Dana Weigel, Nasa’s deputy manager for the ISS, said the debris had since “dispersed out quite a bit more”. But she added that the agency had calculated a 7% higher risk of spacewalkers’ suits being punctured, compared with before Russia’s missile test.

Nasa TV had planned to provide live coverage of the six-and-a-half-hour spacewalk, which was scheduled to begin at 7.10am ET (12.10pm GMT). The objective had been to remove a faulty S-band radio communications antenna assembly, which is more than two decades old, and replace it with a new antenna already stowed outside the space station.

The malfunctioning antenna recently lost its ability to send signals to Earth, although the station has other antennae.

Millions of pieces of space debris, including from disused rocket parts as well as natural dangers such as meteoroids, pose a threat to the space station. They can remain in orbit for years or decades before they descend into the atmosphere.

In 2007, a Chinese missile test created dangerous space junk that continues to be tracked today. Two years later, a defunct Russian spacecraft collided with and destroyed a US commercial spacecraft more than 400 miles (650km) above Earth.

As governments have become increasingly reliant on satellites for communications and observation, anti-satellite weapons have been seen as a way to disrupt an enemy. While they have still not been used in warfare, the development of such missiles by the US, Russia, India and China has raised fears of a new arms race.

Analysts warn that their deployment will be catastrophic, and in the worst-case scenario, make low Earth orbit so cluttered with debris that satellites are unable to operate.

Quelle: The Guardian