An international team of Chinese, American, and Russian scientists may have conducted the most extensive study of lunar Permanently Shadowed Region (PSR) ice yet performed. By comparing the reflections from flat surfaces in major PSRs to those of adjacent non-PSRs, they determined that the vast majority contain ice. However, the ice appears to be restricted to the uppermost surface.
NASA was recently directed to return to the Moon by 2024, an announcement first made in remarks given by Vice President Mike Pence at the 5th meeting of the National Space Council on March 26th. However this huge announcement and acceleration in schedule also came with another set of exciting details. He stated, the “lunar South Pole holds great scientific, economic, and strategic value” and that “when the first American astronauts return to the lunar surface, that they will take their first steps on the Moon’s South Pole.” But why the focus on the Moon’s south pole? He explored that as well, saying that we will “mine oxygen from lunar rocks” and “use nuclear power to extract water from the permanently shadowed craters of the South Pole”. These statements are exciting because they specifically include the use of in-situ resource utilization on the Moon, and select human landing locations near the South Pole due to proximity to those resources.
Lava tubes on the Moon represent an enticing location for establishing lunar habitats. In addition to providing protection from radiation and meteorites, lunar lava tubes have a stable temperature range compared to surface conditions. These characteristics will allow the building of safe, yet economical habitats in lava tubes. However, we must first explore and categorize lava tubes before establishing the first settlements in them. One likely platform for enabling this exploration is via the Moon Diver mission and the tethered Axel rover.
Although multiple landers and rovers have touched down on the Moon, no vehicle has visited the Permanently Shadowed Regions (PSRs) at the lunar poles. Water ice has been observed within some PSRs, and therefore represents an ideal target for future lunar missions. An important unknown to study before the first PSR mission is understanding the surface environment, including how much mass the PSR regolith can support. It is critical that rover wheels and landing pads don’t sink into the regolith. To study this, a recent analysis used boulder tracks to evaluate the bearing capacity of regolith in these areas.
The permanently shadowed regions (PSRs) at the lunar poles represent prime locations for finding high concentrations of water bearing material on the Moon. Even though PSRs have been remotely observed for the past few decades, much is still unknown about these areas. Key questions include the origin of the ice, how extensive it is, and how it changes over time. A recent model addresses some of these questions by predicting how long near-surface ice should exists before being sublimated away.
With the China National Space Administration (CNSA) successfully landing their Chang’e 4 lander and Yutu-2 rover in January 2019, China has now had two successful landings on the Moon. Their first successful landing with Chang’e 3 was also the first soft landing on the lunar surface since the Soviet Luna 24 in 1976. China’s most recent landing with Chang’e 4 is an even greater accomplishment as it is the first time any spacecraft has landed on the Moon’s far side. These missions are just the start of China’s ultimate goals for lunar exploration.
As indicated by the title of Robert Heinlein's 1966 novel The Moon is a Harsh Mistress, the Moon is a harsh environment to operate in. There is a scant atmosphere, abrasive dust, and extreme temperature ranges to deal with. Observed temperatures range from a blistering 127 C (260 F) in equatorial sunlight down to a frosty -238 C (-397 F) in the permanently shadowed regions of the poles. Designing missions to survive these conditions pushes current technology to its limits.
There are many exciting opportunities to be found as gradual progress is made to return humans to the Moon to stay in the coming years. With these opportunities there are also various challenges to overcome related to an increasing frequency of landed missions. When spacecraft land they emit large quantities of gases and displace significant amounts of regolith. Because of the Moon’s low gravity and thin atmosphere relative to the Earth, both of these actions have magnified effects.
The Moon is becoming the proving ground for many space organizations. The European Space Agency (ESA) has awarded a contract to study and prepare for an all-European mission to the Moon. If developed, this would be ESA's second mission to the Moon. The most exciting aspect of this proposal is its intent on demonstrating the extraction of water and other volatiles from lunar regolith. Importantly, this recent award further demonstrates Europe's commitment to space resources.