The ISS and its international crew have been silently orbiting the Earth for many years now. Typically, the ISS maintains a consistent orbit, but at times, that orbit has to be tweaked to avoid any debris that might be in the path of the space station. The smallest chunk of space trash traveling at the very high velocities that are achieved in orbit can destroy the space station and risks the astronauts' lives.
Early Sunday morning specialists at the Russian mission control center that handles the ISS decided to raise the orbit of the space station. The orbit was changed to avoid chunk of debris left over from a Chinese anti-satellite missile test conducted in 2007. The mission controllers felt the chunk of space debris was going to pass too close to the space station for comfort.
The orbit of the ISS was raised by 1.7 km, putting the station at an orbit 391.6 km above the surface of the earth. The orbit change was made using the Zvezda service module's engines. It took the ISS 64 seconds to change the orbit. The chunk of debris was from the Chinese Fengyun-1C weather satellite the Chinese military targeted with an anti-satellite weapon leaving a massive amount of space debris that spacefaring nations will have to deal with for many, many years to come.