How do they know where they are?

[jero]

I was just reading an article about the Mars Reconnaissance Orbiter and they were talking about how the scrubbed one of the trajectory correction maneuvers. I am assuming that there is a fair amount of precision involved, so how do they know where they are in space with such a degree of accuracy? Do they watch the position of known objects in space, or is it all math. If so what kind of math? Calculus?

 

[spacechump]

http://www.braeunig.us/space/basics.htm<br /><br />Excellent site for the beginner.

 

[rybanis]

Yeah, the thing has to do a half-hour long burn. Kind of reminds me of Cassini.<br /><br />I'd love to see some info on what types of thrusters these probes carry. Are the thrusters/engines used on these things custom built for each probe? <div class="Discussion_UserSignature"> </div>

 

[jero]

That is an excellient site! Thanks.