The origin of Phobos and Deimos, the two Martian moons, has been a mystery to astronomers. These two bodies are a fraction of the size and mass of the Moon, measuring just 22.7 km (14 mi) and 12.6 km (7.83 mi) in diameter. Both have a rapid orbital period, taking just 7 hours, 39 minutes, and 12 seconds (Phobos) and 30 hours, 18 minutes, and 43 seconds (Deimos) to complete an orbit around Mars. Both are also irregular in shape, leading many to speculate that they were once asteroids that got kicked out of the Main Belt and were captured by Mars’ gravity.
There’s also the theory that Phobos and Deimos were once a single moon hit by a massive object, causing it to split up (aka. the “splitting hypothesis”). In a recent paper, an international team of scientists led by the Institute of Space and Astronautical Science (ISAS) revisited this hypothesis. They determined that a single moon in a synchronous orbit would not have produced two satellites as we see there today. Instead, they argue, the two moons would have collided before long, producing a debris ring that would have created an entirely new moon system.
Everyone loves looking at the Moon, especially through a telescope. To see those dark and light patches scattered across its surface brings about a sense of awe and wonder to anyone who looks up at the night sky. While our Moon might be geologically dead today, it was much more active billions of years ago when it first formed as hot lava blanketed hundreds of thousands of square kilometers of the Moon’s surface in hot lava. These lava flows are responsible for the dark patches we see when we look at the Moon, which are called mare, translated as “seas”, and are remnants of a far more active past.
In a recent study published in The Planetary Science Journal, research from University of Colorado Boulder (CU Boulder) suggests that volcanoes active billions of years ago may have left another lasting impact on the lunar surface: sheets of ice that dot the Moon’s poles and, in some places, could measure dozens or even hundreds of meters (or feet) thick.
In the coming years, NASA and other space agencies hope to explore the southern polar region of the Moon. Recent surveys of this region have revealed an environment rich in volatiles – elements that vaporize rapidly due to changes in conditions. In particular, missions like NASA’s Lunar Reconnaissance Orbiter (LRO) and the Lunar CRater Observation and Sensing Satellite (LCROSS) have detected abundant water ice in the permanently-shadowed craters around the South Pole-Aitken Basin.
Where this water came from has remained the subject of much debate, with theories ranging from it being deposited by volcanic activity or solar wind to being delivered by comets. After examining LCROSS data on the Cabeus crater near the Moon’s south pole, a multinational team of researchers from the U.S. and France determined that the water ice and volatiles in the crater were likely delivered by the impactor (a comet) that created it.
According to the most widely accepted theories, the Moon formed about 4.5 billion years ago after a Mars-sized object (Theia) collided with Earth. After the resulting debris accreted to create the Earth-Moon system, the Moon spent many eons cooling down. This meant that a few billion years ago, lakes of lava were flowing across the surface of the Moon, which eventually hardened to form the vast dark patches (lunar maria) that are still there today.
Thanks to the samples of lunar rock brought back to Earth by China’s Chang’e 5 mission, scientists are learning more about how the Moon formed and evolved. According to a recent study led by the Chinese Academy of Geological Sciences (CGAS), an international team examined these samples to investigate when volcanism on the Moon ended. Their results are not only filling in the gaps of the Moon’s geological history but also of other bodies in the Solar System.
During the Apollo Era, one of the most important operations conducted by astronauts was sample-returns, where lunar rocks were procured and brought back to Earth. The study of these rocks revealed a great deal about the composition, structure, and geological history of the Moon. This led to profound discoveries, including the presence of water on the Moon and the fact that both Earth and its only satellite formed together.
Over time, scientists have taken advantage of new techniques and technology to conduct more in-depth analyses to learn more about the formation and evolution of the Moon. Recently, a team of researchers from Brown University and the Carnegie Institution for Sciences (CIS) examined some of these samples for sulfur isotopes to shed new light on the early history of the Moon and its evolution.
When astronauts return to the Moon in the next few years (as part of Project Artemis) they will be scouting locations and resources around the South Pole-Aitken Basin that will eventually help them to stay there. In this cratered, permanently-shadowed region, water ice has been found in abundance, which could one-day be harvested for drinking water, irrigation, and the creation of oxygen gas and rocket fuels.
A critical aspect to planning for all or this is to consider how future missions may affect the local environment. Based on new research from a team of planetary scientists and engineers, a major risk comes in the form of contamination by lunar landers. In short, exhaust from these vehicles could spread around the Moon and contaminate the very ices the astronauts hope to study.
In the coming years, multiple space agencies will be sending missions (including astronauts) to the Moon’s southern polar region to conduct vital research. In addition to scouting resources in the area (in preparation for the construction of a lunar base) these missions will also investigate the possibility of conducting various scientific investigations on the far side of the Moon.
However, two prominent scientists (Dr. Karan Jani and Prof. Abraham Loeb) recently published a paper where they argue that another kind of astronomy could be conducted on the far side of the Moon – Gravitational Wave astronomy! As part of NASA’s Project Artemis, they explain how a Gravitational-wave Lunar Observatory for Cosmology (GLOC) would be ideal for exploring GW in the richest and most challenging frequencies.
With the passage of the NASA Authorization Act of 2010, work began on a launch vehicle that would carry cargo and crews back to the Moon and beyond. This vehicle is known as the Space Launch System (SLS), a heavy-launch system that (once fully operational) will be the most powerful rocket in the world since the Saturn V– the venerable vehicle that took the Apollo astronauts to the Moon.
Unfortunately, the development of the SLS has suffered from multiple delays over the past few years, causing no shortage of complications. However, engineering teams at NASA’s Stennis Space Center near St. Louis, Mississippi, recently completed a Green Run of the SLS’s Core Stage, which involved testing the rocket’s critical systems in preparation for its inaugural launch by November of 2021.
In March of 2019, NASA was directed by the White House to land human beings on the Moon within five years. Known as Project Artemis, this expedited timeline has led to a number of changes and shakeups at NASA, not the least of which has to do with the deprioritizing of certain elements. Nowhere is this more clear than with the Lunar Gateway, an orbital habitat that NASA will be deploying to cislunar space in the coming years.
Originally, the Gateway was a crucial part of the agency’s plan to create a program of “sustainable lunar exploration.” In March of this year, NASA announced that the Lunar Gateway is no longer a priority and that Artemis will rely on an integrated lunar lander instead. However, NASA still hopes to build the Gateway, and according to a recent interview with ArsTechnica, this could be done with the help of SpaceX and the Falcon Heavy.