“It’s important to know where and how big lunar lava tubes are if we’re ever going to construct a lunar base,” said Junichi Haruyama, a senior researcher at JAXA, Japan’s space agency. SELENE’s radar system wasn’t designed to detect lava tubes, it was built to study the origins of the moon and its geologic evolution. For these reasons, it didn’t fly close enough to the moon’s surface to get extremely accurate information on what is (or isn’t) underneath. But now, ir helped a lot.
The existence of lava tubes on the moon has been speculated in the past, but this combination of radar and gravity data provides the clearest picture of what they look like and how big they are yet. This information might be more useful than previously expected. For a lava tube to be detectable by gravity data, it would need to extend several kilometers in length and at least one kilometer in height and width , which means the lava tube near the Marius Hills is spacious enough to house one of the United States’ largest cities. So it’s something of interest here. The safest place to seek shelter is the inside of an intact lava tube, when humans will return on moon.