Voyager is my all-time favorite mission. <img src="/images/icons/wink.gif" /> It consisted of two spacecraft: Voyager 1 and Voyager 2. They are twins of one another, but were launched at different times and followed somewhat different trajectories. Voyager 1 visited Jupiter and Saturn before being propelled out of the plane of the ecliptic so it could observe Saturn's pole. This precluded any more planet flybys. Voyager 2, however, visited all four gas giants. A delay in the mission unfortunately ruled out a trip to Pluto.<br /><br />I will attempt to answer your questions. <img src="/images/icons/wink.gif" /><br /><br /><b>Hey i don't know much about voyager missions but how come it didn't detect the 10th planet?</b><br /><br />The Voyager spacecraft carry instrumentation designed to help them study planets as they pass near them. They are not very useful for planet-hunting, and the neccesary maneuvers to scan for planets would be very expensive in terms of propellant. Since any propellant once burned is gone forever, mission planners are reluctant to use the Voyagers for something like this. Besides, there are Earth-based instruments better suited to the job.<br /><br />Still, it was hoped that one of the Voyagers might be lucky enough to stumble upon a tenth planet. The most likely way for this to happen would be if mission controllers on Earth noticed that the spacecraft's radio signal was changing, indicating that something had gravitationally deflected its trajectory. But this would be pure luck. As it happens, neither Voyager has passed close enough to a previously undiscovered object to be gravitationally deflected by it.<br /><br />There's a lot of luck involved in detecting a planet, if it's not one of the obvious ones like Jupiter. You have to be looking in just the right place at just the right time -- and you have to be that lucky twice, so that you can see that the object has moved and therefore is not a star.<br /><br /><b>Is it dead?</b><br /><br />No. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em> -- The Tenth Doctor, "Blink"</font></p> </div>