Space is vast and endless so a collision may seem farfetched. But the fact is it is more probable than you think. Most of the space programs around the world are exploring the same part of the space. So a collision might happen anytime, and it almost happened to NASA.
NASA’s MAVEN spacecraft and Phobos would have met at an intersection in their projected orbits withing 7 seven seconds of each other. Mars has two moons and Phobos is the larger one. MAVEN would have crashed into Phobos if it was not monitored and left on its own orbit. NASA scientists kept a close eye on the spacecraft to make sure it didn’t run into any celestial bodies and it paid off because they were able to predict the collision in advance. NASA scientist performed collision avoidance maneuvers successfully and was able to avert the disaster.
On Tuesday MAVEN carried out a rocket motor burn that boosted its velocity by just around <1 mile hour. This maneuver was enough to avoid the collision with Phobos by two and a half minutes. MAVEN was launched in late 2013 and reached Mars in late 2014 and since then it is effortlessly orbiting Mars and collecting data to determine the reason behind the vanishing of atmosphere and water over time.