The objects humans send to space teach us a lot about the universe, but they are also cluttering it up. While some objects are close enough to be retrieved, others become dangerous, fast-moving bullets that can cause serious damage.

In addition to cleaning up what's already there, MIT Assistant Professor Danielle Wood says that we need to think more sustainably about the technology used in future missions. "We have to ask the question, will we respect the rights of people and the environment as we go forward in space," Wood says.

One possible solution is a wax-based fuel source (made of beeswax and candle wax) for satellites that would be less toxic and more affordable than currently used inorganic compounds, and that would help bring the objects closer to Earth for deorbiting and destruction.

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