What drives us to send probes throughout the Solar System and rovers and landers to Mars? It's not cheap, and it's not easy.
Another planetary alignment is coming up next month, and while it won't be a large one, it'll still be enough to dazzle ...
Data from NASA's Magellan spacecraft and Pioneer Venus Orbiter is used in an undated composite image of the planet Venus. It will consist of four planets, including Venus, Saturn, Mercury ...