NASA's hunting for a secret underground cave on the moon

Are there secret underground caves on the moon? NASA has a new program that aims to find out. Though we see it in the sky most nights, the moon still holds an incredible amount of mystery. One such mystery is a large underground cave, or a cavernous tube carved out by ancient lava, that scientists think extends past a particular pit on the moon's surface. And to get to the bottom of it, NASA has selected a project known as GIMLI (the Geophysical Instruments for Marius Lunar pit Investigation, no