Purple bridge in Star Control II

Solution 1:

The Melnorme bridge turning purple is one of mysteries left by Star Control II.

The creators of Star Control (Fred Ford and Paul Reiche III) promoisied an answer too this question in their next SC project when they were asked about it in a 1998 chat.

Unfortunately the next Star Control project was never completed. Star Control III was made by different developers in 1996 and never seen as the true sequel to Star Control II.

The serious effort of getting a new Star Control and a real answer to the question why the Melnorme's bridge turns purple was in 2008 when Stardock tried to pitch the idea of a new Star Control to Atari. Those negotiations eventually fell apart.

So unless someone starts a new initiative to get us a true sequel to Star Control II this question will probably never have a real answer.

Solution 2:

Because it's a very good and interesting question.

All kidding aside, the answer appears to be that is signifies that they want to trade. Also it may be an allusion to the idea of a "pot of gold" at the end of the Rainbow as they trade handsomely for data on Rainbow Worlds and Purple is the highest frequency color in the visible spectrum.