JavaFX : Use a Thread more than once

I'm new with JavaFX and I've a little problem with a thread: I can execute it twice and I can't find why.

Here is a sum-upt of my code:

Task<Void> task = new Task<Void>() {
    @Override public Void call() throws ImageLoadedException, HomographyException, IOException {
        try{
            System.out.println("GO !");
            return null;
        }
        catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }
    @Override
    protected void succeeded() {
        super.succeeded();
        System.out.println("SUCCEEDED");
     }
};

@FXML protected void launch(ActionEvent event){
    new Thread(task).start();
}

When I click a first time the button who start my thread, my task run without any problem (my console display "GO !" and "SUCCEEDED").

But if I click a second time, nothing append. Am I doing something wrong ? Can't we use a thread more than once ?