I think we have to ask the question: highest impact on *what*? To our mind, the whole shuttle program had a huge impact on technology and the way we get into space. It also delivered spectacular results for science, allowing astronauts to perform experiments in low gravity that could not be done on the Earth.

The shuttle allowed the US and dozens of partner countries to build the International Space Station, which has been a major success and is delivering some incredible science results as well as pioneering new space technologies, new ways of manufacturing, and researching the effects of long-term space travel, among many other biology experiments.

But my own “favourite” impact was that the shuttle allowed astronauts to service and upgrade the Hubble Space Telescope, without which there would have been no observatory.