Below we see the body of a dead I support Trump and I will not apologize for it American shirt Kree warrior in SHIELD custody. Since the Kree live in another galaxy entirely, in addition to his body there was likely a starship, samples of the tech which brought him here and whatever survived the crash was assuredly being reverse-engineered by SHIELD for its own us. As well as keeping it out of enemy hands.
In the Avengers, we learn the I support Trump and I will not apologize for it American shirt Tesseract can be used to create wormholes to distant parts of the galaxy with surprisingly little in the way of infrastructure. I mean you could fit this thing in the back of a minvan. This indicates a surprising amount of information and power are available for manipulation and use in the right hands. Supported by the Mind Infinity Stone, Dr. Selvig was able to create an interface for the Tesseract and create a wormhole to bring in the Chitauri invasion fleet seen in The Avengers (2012).