Just so you know, this is a question about space law, which above all else is a subset of international law. That means that anything discussed about space law has to be viewed in the context of the enforceability and credibility of international law. Also, it's not really history question.

The 1967 Outer space Treaty is the relevant document.

Article VIII says that you retain ownership even when it leaves the planet.

A State Party to the Treaty on whose registry an object launched into outer space is carried shall retain jurisdiction and control over such object, and over any personnel thereof, while in outer space or on a celestial body. Ownership of objects launched into outer space, including objects landed or constructed on a celestial body, and of their component parts, is not affected by their presence in outer space or on a celestial body or by their return to the Earth. Such objects or component parts found beyond the limits of the State Party of the Treaty on whose registry they are carried shall be returned to that State Party, which shall, upon request, furnish identifying data prior to their return.