How does a spacecraft change course?
First, AutoNav has to figure out exactly where DS1 is in space. It does this by using triangulation. MICAS takes pictures of three asteroids in space. Depending on where DS1 is compared to the asteroids, different stars will be in the background.
DS1 has been programmed to know where the stars should be compared to the asteroids if DS1 is on the right course. If the stars are shifted away from that, AutoNav can tell that DS1 is off course.
In order to fix the course, it compares the location to where DS1 should be if the course was perfect. Once it knows where it is compared to where it should be, AutoNav can fix the course. Once AutoNav makes a new course direction and speed (vector), it fires the attitude thrusters to point DS1 in the right direction, and then the main thruster gives it a push forward.
Why does DS1 get off course?
What is a course correction?
What is AutoNav?
What is triangulation?
Do small errors in space navigation matter?
How does DS1 take pictures?
What is an asteroid?
How do AutoNav and the remote agent work together?
When does DS1 do a course correction?
What is MICAS?
What is attitude control?
What are vectors?
How do we know what's in space?