There were a total of 32 TV episodes made, plus two feature films ("Thunderbirds are Go!" and "Thunderbird 6"). The first TV series comprised 26 episodes, which were so well received that Gerry Anderson's company began to make a second series. However this was mysteriously cancelled (possibly due to cancellations by US networks taking the show) and only 6 episodes of the second series were ever completed.
There are rumours that it could be brought back with heavy use of computer graphics to make it - this would get my vote!