It is not an app, but a free mobile service. It gives you free text or email notifications whenever the International Space Station is visible. Bright enough to be seen even from a city, you’ll always know when to look up. https://spotthestation.nasa.gov
SpaceX’s Mars Travel Posters: A Sneak Peek into the Future
Have you ever thought about traveling to Mars? Well, if you haven't, then there's no better way to start than by checking out SpaceX's Mars travel posters. These posters depict…