The bone in question was a piece of debris created during the breakdown of bone 23106 (Pegasus R/B). This is the upper stage of a Pegasus type launcher, which was launched on May 19, 1994 and broke up on June 3, 1996
The space station pictured from SpaceX Crew Dragon November 2021
The space station was photographed from the SpaceX Crew Dragon Endeavor during the spacecraft's exit from it for its return to Earth on November 8, 2021. Credit: NASA's Johnson Center
Last Friday (December 3, 2021) at 1:58 EST, the engine of the Russian Progress 79 spacecraft, attached to the space station, was fired for 2 minutes and 41 seconds to lower the station's orbit slightly. This maneuver provided a separation margin from a fragment of Pegasus rocket debris (object 39915) that ballistic experts were tracking. The 66th crew of the space station is out of danger, NASA said in a statement.
The Pre-Discovered Debris Avoidance Maneuver, or PDAM, is coordinated between NASA flight controllers, the Russian Space Agency and in particular the Russians responsible for operating the Progress spacecraft and the station's other international partners.
Bone 39915 was a piece of debris created during the breakup of bone 23106 (Pegasus R/B). This is the upper stage of a Pegasus type launcher, which was launched on May 19, 1994 and broke up on June 3, 1996.
This is not the first time in recent weeks that the operators of the International Space Station had to change its course. A few weeks earlier, on November 15, Russia conducted a test of an anti-satellite weapon directly launched from the ground to destroy one of its satellites that has been in orbit since 1982, creating a trail of at least 1,500 pieces of low-orbiting debris that can be tracked and threaten the safety of the astronauts.
The missile launched by Russia for the purpose of the experiment was a Nudol PL-19 model, an interceptor designed to intercept ballistic missiles that also functions as an anti-satellite weapon. The USA, Russia and China are competing with each other in the development of space missiles that can not only destroy ballistic missiles in the phase of movement towards the target in space but also intercept satellites in orbit.
The destruction of the defunct Russian satellite, known as Cosmos 1408, prompted the seven crew members aboard the International Space Station — four Americans, two Russians and a German — to take cover several times as the station's orbit intersected with the debris stream and to seal some of the station's models to prevent oxygen leaking in the event of a collision. that holes should be drilled in the wall of the station. The collision happened about 500 kilometers above the surface of the earth and 80 kilometers above the orbit of the space station.
These fragments joined more than 27,000 pieces of orbital debris, or "space debris," being tracked by the US Department of Defense's Global Space Surveillance Network (SSN) sensors. / A much larger number of debris components too small to track, but large enough to threaten human spaceflight and robotic missions - hovering in the near-Earth space environment. Since both the debris and the spacecraft are traveling at extremely high speeds (about 15,700 km/h in low Earth orbit), even a tiny piece of orbital debris hitting a spacecraft could cause trouble.
The growing population of space debris increases the potential danger to all space vehicles, including the International Space Station and other manned spacecraft such as SpaceX's Crew Dragon.
NASA takes the threat of collisions with space debris seriously and has a long-standing set of guidelines on how to deal with any potential collision threat to the space station. These guidelines, part of a larger body of decision-making aids have been compiled into flight rules that indicate when the expected proximity of a piece of debris increases the probability of a collision sufficiently that evasive action or other precautions are necessary to ensure the safety of the crew.
Space debris includes both natural meteoroid debris and artificial (man-made) debris. Meteoroids are in orbit around the Sun and reach the Earth randomly (most of them burn up in the atmosphere as meteors - falling stars), while most artificial debris is permanently in orbit around the Earth (hence the term "orbital" debris).
Orbital debris is any man-made object in orbit around the Earth that no longer serves a useful function. Such debris includes defunct spacecraft, abandoned launch stages, as well as debris created by collisions between large pieces of debris that created many small pieces.
There are about 23,000 pieces of debris larger than a tennis ball orbiting the Earth. They travel at speeds of up to 17,500 km/h, fast enough for a relatively small piece of orbital debris to hit a satellite or spacecraft. There are half a million pieces of debris the size of a marble or larger (up to 1 centimeter) or larger, and about 100 million pieces of debris XNUMX millimeter or larger in diameter. There are many more micrometer-sized smaller debris fragments.
Even tiny paint spots can damage the spacecraft when traveling at these speeds. Several windows of the space shuttles were replaced due to damage caused by material that was analyzed and proved to be paint stains. In fact, millimeter-sized orbital debris is the highest risk factor for mission termination for most robotic spacecraft operating in low Earth orbit.
In 1996, a French satellite was hit and damaged by debris from a French rocket that had exploded a decade earlier.
On February 10, 2009, a decommissioned Russian spacecraft collided with and destroyed an active American Iridium-series commercial spacecraft. The collision added more than 2,300 large, traceable pieces of smaller debris to the inventory of space debris.
China's 2007 anti-satellite test, which used a missile to destroy an old weather satellite, added more than 3,500 pieces of large, trackable debris and countless other small fragments.
Space debris tracking
The Ministry of Defense maintains a highly accurate satellite catalog of objects in Earth's orbit. Most of the objects cataloged are larger than 10 centimeters.
NASA and the US Department of Defense collaborate and share responsibility for characterizing the satellite environment (including orbital debris). The space surveillance network of the Ministry of Defense tracks separate objects with a diameter (5 centimeters) in low Earth orbit and about one meter in geosynchronous orbit (the orbit at an altitude of 36 thousand km in which the communication satellites circle in synchronization with the ground). As of today, about 27,000 objects are cataloged that are still in orbit and most of them have a diameter of 10 cm or more. Using special sensors from the ground and tests of satellites returned from space, NASA has statistically determined the extent of the population for objects with a diameter of less than 10 cm.
While accident shields provide protection against impacts from particles smaller than one centimeter, larger particles require preparation and possibly even a change of the orbit of the space station, as happened this week.
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