The International Space Station is in constant motion ... So where should you direct this hypothetical letter? Node 2, Deck 5, ISS, LEO 51.603. Pettit explains how he arrived at this address ...

What If is a Webby Award-winning science web series that takes you on a journey through hypothetical worlds and possibilities, some in distant corners of the universe, others right here on Earth.

Several other space companies have plans to construct their own space stations as well, including Northrop Grumman, Axiom Space, Nanoracks and Sierra Space. NASA needs at least one of them on orbit ...

To get it in your inbox, sign up for free here. Exploring space has opened our eyes to numerous wonders, but these cosmic feats haven’t come without challenges. Each SpaceX Starship launch from ...