This month, NASA was forced to change the orbit of the ISS to avoid a potential collision with a piece of space junk. At the incredible velocities that objects orbit the Earth, even a small piece of space junk has the potential to cause catastrophic damage if it impacts the ISS. The space junk caused NASA to make an “urgent change of orbit” on November 11.
The ISS has been orbiting the Earth for 23 years and is beginning to show its age, but it is still safe and continually occupied by astronauts from around the world. During the more than two decades in orbit, the space station has had 30 close calls with orbital debris that required the orbit to be changed to avoid a collision. NASA reports that three of those 30 close calls happened during 2020.
While none of those close calls posed a real threat to the ISS once the orbit was changed, in its 23 years in space, the station has been hit by space debris. In May, it was discovered that the Canadian-built robotic arm aboard the ISS had been hit by space debris. In that instance, the Canadarm2 robotic arm, which is used to manipulate cargo and objects outside the space station, was discovered to have a hole in its thermal blanket. The impact didn’t harm the performance of the robotic arm but shows that even the smallest pieces of space debris is a significant threat to the station.
The orbital change last week was to avoid a piece of debris that the Chinese government created when it destroyed the Fengyun-1C weather satellite while testing an anti-satellite missile. The missile impact created over 3500 pieces of orbital debris. Thrusters aboard a Russian Progress supply spacecraft were fired for more than six minutes to change the speed of the ISS by 0.7 meters per second and increase its orbital height by about 0.7 miles.
The thrusters aboard the Russian Progress spacecraft were fired intentionally in this instance and performed as expected. However, there have been multiple instances of thrusters aboard Russian spacecraft firing inadvertently in recent months. For example, in mid-October of this year, a Russian spacecraft attached to the ISS conducted a thruster firing test. However, when mission controllers attempted to turn the thrusters off, the thrusters continued to fire, resulting in a loss of attitude control for the space station.
At the time, NASA officials said the ISS was in no danger and that the crew was awake during the event. However, the space station was briefly pushed 57 degrees out of its normal orientation. In that instance, thrusters stopped firing on their own, with NASA stating they believe they reached their propellant limit. At the time, Russian flight controllers were looking into the cause of the accident.
SpaceX recently transported four new crewmembers to the ISS with its Crew-3 mission. That mission was repeatedly delayed due to weather and one of the astronauts having some sort of minor medical issue. Crewmembers aboard the space station are constantly conducting ,experiments with one of the most recent having to do with attempts to grow fresh food. In that experiment, the astronauts were able to harvest chili peppers and had tacos in space. The peppers were harvested on October 29 and were the first crop of chili peppers grown in the Plant Habitat-04 study.