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Lava tubes are natural passageways through which lava travels beneath the surface of a lava flow. They are expelled by a volcano during an eruption.
Lava tubes are common on Earth, but have never before been found on the Moon. However, they have been conjectured to exist by astronomers in the past. One, now, has been found on the Moon.
The article highlighting this discovery is titled “Possible lunar lava tube skylight observed by SELENE cameras.”
It was published in the October 2009 issue of the journal Geophysical Research Letters (J. Haruyama, et al. (2009), Possible lunar lava tube skylight observed by SELENE cameras, Geophys. Res. Lett., 36, L21206, doi:10.1029/2009GL040635)
The research was lead by Dr. Junichi Haruyama, the senior researcher for the Terrain Camera Team of the Kaguya (SELENE) mission. Haruyama is also an assistant professor in the Department of Planetary Science at the Institute of Space and Astronautical Science (ISAS), which is part of the Japanese space agency Japan Aerospace Exploration Agency (JAXA).
The SELENE mission to the Moon was launched on September 14, 2007, from the Tanegashima Space Center (TNSC) in Japan.
The Haruyama-led team stated in the abstract to their paper, “We discovered a vertical hole on the Moon, which is a possible lava tube skylight, using data from SELENE's two high-resolution cameras: the Terrain Camera and the Multi-band Imager.”
Page two continues with further descriptions of the lunar lava tube.
The lunar lava tube is further desribed in the researchers' abstract.
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“We observed the hole at various solar illumination conditions and estimated its depth to be 80 to 88 m [or, about 262 to 289 feet]. The depth/diameter ratio is much larger than for typical impact craters.” [Abstract]
“There are neither conspicuous deposits indicating volcanic eruptions from the hole, nor are there pit craters adjacent to the hole that could be related to an underlying fault or dike. The area around the hole is covered by a thin (20 to 25 m) lava sheet, which may help protect the lava tube from collapse due to meteorite bombardment.” [Abstract]
The 12/31/2009 Fox News article “Hole in the Moon Could Shelter Colonists” states: "Recent discoveries of water and water ice on the moon hold promise that astronauts could journey back and stay for longer periods, perhaps even establish lunar colonies.”
An image of the lava tube is found on the Fox News article.
Within the Fox News article, the team stated, "We discovered a vertical hole on the moon."
The article continues, "The gaping, dark pit on the near side of the moon is as big as a city block and deep as a modest skyscraper."
Page three concludes with why an open lava tube on the Moon could be important to future missions to the Moon and permanent lunar settlements.When humans settle the Moon, they will need protection from space radiation while they work and live within the lunar environment.
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The scientists stated, "Because lava tubes are sheltered from the harsh environment on the moon's surface, such tubes could one day be useful for lunar bases.” [Fox News]
The team believes that billions of years ago, when the Moon was volcanic, flowing lava exited a tunnel. The Moon is over four billion years old.
Eventually, the roof of the tunnel collapsed, forming the lava tube.
The scientists stated, "Lava tubes, underground cave-like channels through which lava once flowed, are commonly found on Earth.”
Such caves on the Moon have been debated to exist by astronomers for years, but have yet to be confirmed--until now, that is.
Thus, the lava tube found at Marius Hills on the Moon could provide radiation shielding for astronauts living in an underground lunar colony.
At the moment, however, it is unclear whether the tube is open and accessible to such astronauts on a mission to the Moon.
For additional information on the discovery, along with an image of the lava tube, please read the 10-22-2009 New Scientist article “Found: first 'skylight' on the moon.”
