Japanese orbiter finds lunar cave that could someday house astronauts

As safest location for astronauts, lava tubes could be ideal sites for constructing Moon bases.
By Laurel Kornfeld | Oct 19, 2017
The Japanese space agency's Kaguya spacecraft, which orbited the Moon for nearly two years between 2007 and 2009, imaged a large openlava tube on the lunar surface that could potentially serve as a future habitat for astronauts.

Lava tubes are conduits formed by lava that flowed beneath a hardened surface that has hardened over time. That surface forms a "roof" that covers the area beneath it, which becomes hollow once the liquid lava stops flowing and drains out of the tunnels it initially created.

Analysis of radar data returned by the spacecraft, also known as Selene, by scientists at the Japan Aerospace Exploration Agency (JAXA) revealed several possible entrances to a lava tube near the Marius Hills region on the Moon.

Space suits are insufficient for protecting astronauts on the Moon from radiation, extreme temperatures, and meteorite impacts, which is why no Apollo astronauts stayed there for more than three days.

The Moon's lack of both an atmosphere and a magnetic field makes it vulnerable to impacting meteorites.

If astronauts could take shelter in a lava tube or cave, they would be safe from the environmental hazards on the Moon's surface. This makes these features ideal locations for construction of a lunar base.

"It's important to know where and how big lunar lava tubes are if we're ever going to construct a lunar base," emphasized JAXA senior researcher Junichi Haruyama.

"But knowing these things is also important for basic science. We might get new types of rock samples, heat flow data, and lunar quake observation data."

Because Kaguya's radar system was designed to study the Moon's geology and origin rather than to find lava tubes, the spacecraft did not fly close enough to the Moon's surface to obtain accurate data about what is present beneath that surface.

To assist them in finding lava tubes from Kaguya's data, JAXA scientists consulted with their colleagues from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission, which studied the Moon's gravitational field from orbit.

Studying GRAIL data, the researchers specifically looked for areas with lower subsurface masses as a means of pinpointing possible lava tubes.

By combining radar data with GRAIL's gravity data, they were able to determine the depths and widths of the lava tubes and the fact that they comprise a single, larger system, noted GRAIL co-investigator Jay Melosh, who is also a Distinguished Professor of Earth, Atmospheric, and Planetary Sciences at Purdue University.

A lava tube must be several kilometers long and have a height and width of one kilometer at minimum to be detectable by gravity data.

Based on GRAIL findings, the Marius Hills lava tube has enough space to hold one of the US's larger cities.

Findings of the study have been published in the journal Geophysical Research Letters.







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