An anonymous reader writes: In an unassuming building at Johnson Space Center, NASA maintains clean rooms and employs curators to support its collection of rocks and other matter from elsewhere in the solar system. Ars got to tour the facility and take pictures of the samples inside. "The collection houses about 20,000 rocks, but the most famous of those rocks is ALH84001. Sometime around 16 million years ago, a large meteorite or asteroid 0.5 to 1 km across or larger struck the Martian surface and blasted some rocks into space at a speed greater than the red planet's escape velocity. One of them flew through space until about 13,000 years ago when it crashed into Antarctica." NASA keeps bits of a comet trapped in aerogel, as well as the remains of the Genesis probe that captured particles of solar wind. Of course, this is dwarfed by the vast collection of lunar rock samples brought back by the Apollo missions. Some of them have yet to be opened. "They were collected in the vacuum of the lunar surface, placed inside vacuum sealed tubes, and remain that way to this day. NASA is preserving them for some theoretical future where science has progressed to enable some new, powerful method of analysis."