NASA-funded scientists have discovered shadowy places in pits on the moon that always hover around a comfortable 63 F (about 17 C) using data from NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft and computer modeling.
The pits and caves they may lead to would make thermally stable sites for lunar exploration compared to areas on the moon’s surface that heat up to 260 F (about 127 C) during the day and cool to minus 280 F (about minus 173 C) at night. Lunar exploration is part of NASA’s mission to explore and understand the unknown in space, to inspire and benefit humanity.
The pits were first discovered on the moon in 2009, and since then scientists have wondered if they lead to caves that could be explored or used as shelters. Pits or caves will also offer some protection from cosmic rays, solar radiation and micrometeorites.
“About 16 of the more than 200 pits are likely collapsed lava tubes,” said Tyler Horvath, a doctoral student in planetary sciences at UCLA who led the new study, published recently in the journal Geophysical Research Letters.
“Moon craters are a fascinating feature of the lunar surface,” said LRO project scientist Noah Petro of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Knowing that they create a stable thermal environment helps us paint a picture of these unique lunar features and the prospect of one day exploring them.”
Lava tubes, also found on Earth, form when molten lava flows under a field of cooled lava or crust forms over a river of lava, leaving a long, hollow tunnel. If the ceiling of a solidified lava tube collapses, it opens a pit that can lead to the rest of the cave-like tube.
Two of the most prominent pits have visible overhangs that clearly lead to caves or cavities, and there is strong evidence that the overhang of another may also lead to a large cave.
“Humans evolved living in caves, and we may go back to caves when we live on the moon,” said David Page, a co-author of the paper who led the Diviner Lunar Radiometer experiment outside LRO, which took the temperature measurements used in the study.
Horvath processed data from the Diviner – a thermal camera – to find out if the temperature in the pits differed from that on the surface.
Focusing on a 328-foot-deep (100-meter) roughly cylindrical depression the length and width of a football field in an area of the moon known as Mare Tranquillitatis, Horvath and his colleagues used computer modeling to analyze the thermal properties of the rock and lunar dust and to plot pit temperatures over time.
The results reveal that temperatures in the permanently shaded areas of the pit vary only slightly throughout the lunar day, remaining around 63 F or 17 C. If a cave extends from the bottom of the pit, as images taken by LRO’s Lunar Reconnaissance Orbiter camera suggest will also have this relatively comfortable temperature.
The team, which includes UCLA planetary science professor David Page and Paul Hein of the University of Colorado Boulder, believes that shading is responsible for the stable temperature, limiting how hot things get during the day and preventing heat from radiating at night.
A day on the Moon lasts about 15 Earth days, during which the surface is constantly bombarded by sunlight and is often hot enough to boil water. The brutally cold nights also last about 15 Earth days.
The research was funded by NASA’s Lunar Reconnaissance Orbiter Extended Mission 4 project. LRO is operated by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, for the Science Mission Directorate at NASA Headquarters in Washington. Launched on June 18, 2009, LRO has collected a treasure trove of data with its seven powerful instruments, making invaluable contributions to our knowledge of the Moon. Diviner was created and developed by UCLA and NASA’s Jet Propulsion Laboratory in Pasadena, California.
NASA is returning to the Moon with commercial and international partners to expand the human presence in space and bring back new knowledge and capabilities.
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