Lunar Reconnaissance Orbiter images of pits indicate that the Moon has caves. Could they become astronaut habitats? Scientists have discovered that parts of the pits are always about 63°F (17°C), differing from extreme temperatures at the Moon's surface
Jul 26, 2022NASA’s LRO Finds Lunar Pits Harbor Comfortable TemperaturesNASA-funded scientists have discovered shaded locations within 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 to which they may lead, would make thermally stable sites for lunar exploration compared to areas at the Moon’s surface, which 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 goal to explore and understand the unknown in space, to inspire and benefit humanity.Pits were first discovered on the Moon in 2009, and since then, scientists have wondered if they led to caves that could be explored or used as shelters. The pits or caves would also offer some protection from cosmic rays, solar radiation and micrometeorites.“About 16 of the more than 200 pits are probably collapsed lava tubes,” said Tyler Horvath, a doctoral student in planetary science at the University of California, Los Angeles, who led the new research, recently published in the journal Geophysical Research Letters.“Lunar pits are a fascinating feature on 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 beneath a field of cooled lava or a 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 into the rest of the cave-like tube.Two of the most prominent pits have visible overhangs that clearly lead to caves or voids, and there is strong evidence that another’s overhang may also lead to a large cave.“Humans evolved living in caves, and to caves we might return when we live on the Moon,” said David Paige, a co-author of the paper who leads the Diviner Lunar Radiometer Experiment aboard LRO that made the temperature measurements used in the study.Horvath processed data from Diviner – a thermal camera – to find out if the temperature within the pits diverged from those on the surface.Focusing on a roughly cylindrical 328-foot (100-meter)–deep depression about the length and width of a football field in an area of the Moon known as the Mare Tranquillitatis, Horvath and his colleagues used computer modeling to analyze the thermal properties of the rock and lunar dust and to chart the pit’s temperatures over time.The results revealed that temperatures within the permanently shadowed reaches of the pit fluctuate only slightly throughout the lunar day, remaining at 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, it too would have this relatively comfortable temperature.The team, which included UCLA professor of planetary science David Paige and Paul Hayne of the University of Colorado Boulder, believes the shadowing overhang is responsible for the steady temperature, limiting how hot things gets during the day and preventing heat from radiating away at night.A day on the Moon lasts about 15 Earth days, during which the surface is constantly bombarded by sunlight and is frequently hot enough to boil water. Brutally cold nights also last about 15 Earth days.The research was funded by NASA’s Lunar Reconnaissance Orbiter project, Extended Mission 4. LRO is managed 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 an invaluable contribution to our knowledge about the Moon. Diviner was built and developed by the University of California, Los Angeles, and NASA's Jet Propulsion Laboratory in Pasadena, California.NASA is returning to the Moon with commercial and international partners to expand human presence in space and bring back new knowledge and opportunities.Bill SteigerwaldNASA Goddard Space Flight Center, Greenbelt, Maryland[email protected]Last Updated: Jul 26, 2022Editor: Bill Steigerwald
NASA’s Lunar Reconnaissance Orbiter Camera has now imaged the Marius Hills pit three times, each time with very different lighting. The center panel, with the Sun high above, gives scientists a great view of the Marius Hills pit floor. The Marius pit is about 34 meters (about 111 feet) deep and 65 by 90 meters (approximately 213 by 295 feet) wide.Credits: NASA/GSFC/Arizona State University
This is a spectacular high-Sun view of the Mare Tranquillitatis pit crater revealing boulders on an otherwise smooth floor. This image from LRO's Narrow Angle Camera is 400 meters (1,312 feet) wide, north is up.Credits: NASA/Goddard/Arizona State University
Setting up a thread for discussing lunar caves, namely the lava tubes and skylights. If any missions, such as the proposed Moon Diver, get underway for visiting them post here too.The first 2 questions I wish to poise are:1) How many skylights and lava tube locations are currently known on the Moon?
2) Are any sites known to exist within the South Pole–Aitken basin?
Imagine the numbers of Bigelow inflatables that could be chained like sausages into such a cave. Plenty enough for a space colony, easier than in deep space or lunar surface, much closer than Mars... of course the interior of the cave would need serious "cleaning" in the first place.
The coordinates are quite intriguing: a large part of those tentative huge lava tubes are in a small corner of the Moon. See the attached map. Most of them are (broadly) in the red rectangle. Which mean that Oceanus Procellarum / Ocean of storms underground is kind of giant Swiss cheese.
There would be no advantage to having a pit in SPA, it's a scientifically interesting area but far from being the ideal place for a human habitat, if that was the goal.
Quote from: Phil Stooke on 08/23/2019 06:08 pmThere would be no advantage to having a pit in SPA, it's a scientifically interesting area but far from being the ideal place for a human habitat, if that was the goal.You want a lava tube at a high enough latitude that the internal temperature stays below the freezing point of water. That should cause water vapour released from comet/wet-asteroid impacts to have collected over the last billion-or-so years. "Free" water, "free" cooling for the base, plus the ice (and trapped volatiles) might give you a very clean record of the impact history for the moon. Possibly much cleaner layering than the permanently-shadowed polar deposits, due to micrometeor impacts churning the surface and mixing layers.The average low-latitude temp is around 15°C, which is reflected in pit-temps. Too high for water-ice to accumulate.But I don't know how high latitude you have to go before the average surface temp (and hence constant sub-surface temp) gets below 0°C.Libra/Lampyridae? Is the temp-vs-latitude info in your collections?
Thanks for that. Am curious how far from a pit you'd need to go before a lava tube could reach ambient sub-surface temps, if at all. The Tranquility-paper modelled a few hundred metres from the pit, but there was virtually no fall-off, which is a concern.I disagree with the Tranquility-paper about the suitability of ~20°C for long term habitation. Human activity produces waste heat, with the insulating effects of the surrounding rock, you want a cold sink. That's a bonus from any non-polar water-ice containing environment.[In theory, a warmer (~20°C) tube might provide a good, thermally stable site for short-duration stay, small base infrastructure. But IMO you probably aren't going to be building such a base in a novel environment like a lava-tube. You need to have plenty of exploration of lava-tubes before you'd be comfortable designing a base (and pit access) suitable for them. That exploration requires a non-lava-tube base; so to explore lava-tubes, you've already solved the problem of short-stay surface bases anyway.]
