Towards the end of 2024, a SpaceX Falcon 9 rocket will take a payload into orbit that I’ll be following closely. The payload in question will be one of Intuitive Machines‘ Nova C landers, whose objective will be to touch down on the Connecting Ridge near the Moon’s South Pole. On board the lander will be a drill and a mass spectrometer known as PRIME-1 (Polar Resources Ice Mining Experiment-1) that, as the name suggests, will be used to drill for water in the form of ice. It’s a fascinating mission with significant implications!
Landing Location – Connecting Ridge
To help get our bearings, here’s a short video clip that zooms in on the relevant landing location.
The image below shows a close up of the Connecting Ridge. The sharply defined Shackleton Crater is found to the east of the Connecting Ridge with the larger de Gerlache Crater located to the west.
The benefit of this location, as P Glaser et. al. pointed out in their 2014 paper is that “a lander or rover landing at Connecting Ridge 1 will benefit from excellent illumination conditions and will only need to survive periods in darkness of less than 5 days.”
Towards the end of the video above, the movement of the shadows gives you a sense of the illumination conditions.
Intuitive Machines’ 18 July 2024 news release confirmed this advantage and highlighted other reasons for the landing site. They commented, “Working with NASA, Intuitive Machines selected a 200-meter diameter elliptical region on the Shackleton Connecting Ridge with favorable terrain, Earth communications position, and solar angles for power generation“
Conditions On The Moon
Consider this:
“The Moon has no atmosphere, any substance on the lunar surface is exposed directly to vacuum. For water ice, this means it will rapidly sublime directly into water vapor and escape into space, as the Moon’s low gravity cannot hold gas for any appreciable time. Over the course of a lunar day (~29 Earth days), all regions of the Moon are exposed to sunlight, and the temperature on the Moon in direct sunlight reaches about 395 K (395 Kelvin, which is equal to about 250 degrees above zero F). So any ice exposed to sunlight for even a short time would be lost. The only possible way for ice to exist on the Moon would be in a permanently shadowed area.” Source: NASA
The Source Of The Water Ice
“The Moon’s surface is continuously bombarded by meteorites and micrometeorites. Many, if not most, of these impactors contain water ice, and the lunar craters show that many of these were very large objects. Any ice which survived impact would be scattered over the lunar surface. Most would be quickly vaporized by sunlight and lost to space, but some would end up inside the permanently shadowed craters, either by directly entering the crater or migrating over the surface as randomly moving individual molecules which would reach the craters and freeze there. Once inside the crater, the ice would be relatively stable, so over time the ice would collect in these “cold traps“, and be buried to some extent by meteoritic gardening. Such a possibility was suggested as early as 1961 (The behavior of volatiles on the lunar surface, Watson et al., Journal of Geophysical Research, v. 66, p. 3033, 1961).” Source: NASA.
Evidence Of Water Ice
Evidence of water ice on the moon has been growing steadily over recent decades.
“On 5 March 1998 it was announced that data returned by the Lunar Prospector spacecraft indicated that water ice might be present at both the north and south lunar poles, in agreement with interpretations of Clementine results for the south pole reported in November 1996. The ice originally appeared to be mixed in with the lunar regolith (surface rocks, soil, and dust) at low concentrations conservatively estimated at 0.3 to 1 percent. Subsequent data from Lunar Prospector taken over a longer period has indicated the possible presence of discrete, confined, near-pure water ice deposits buried beneath as much as 18 inches (40 centimeters) of dry regolith, with the water signature being stronger at the Moon’s north pole than at the south.” Source: NASA
NASA’s Lunar Prospector was launched into lunar orbit in January 1998 carrying an instrument called a Neutron Spectrometer, designed to detect low levels of water ice.
NASA described the Neutron Spectrometer as follows;
“The instrument concentrated on areas near the lunar poles where it was thought these water ice deposits might be found. The Neutron Spectrometer looks for so-called “slow” (or thermal) and “intermediate” (or epithermal) neutrons which result from collisions of normal “fast” neutrons with hydrogen atoms. A significant amount of hydrogen would indicate the existence of water. The data show a distinctive 4.6 percent signature over the north polar region and a 3.0 percent signature over the south, a strong indication that water is present in both these areas. The instrument can detect water to a depth of about half a meter.”
Chandrayaan-1
A few years later, India’s Chandrayaan-1 Moon Mission in 2008 carried a range of instruments, including NASA’s imaging spectrometer called Moon Minerology Mapper (M3). The mission also carried a Moon Impact Probe (MIP) that was deliberately crashed into the Moon, releasing debris that was analysed by the orbiting spacecraft’s science instruments. The probe was crashed near the Shackleton Crater at the lunar south pole.
In September 2009, scientists published results of data collected by NASA’s M3 instrument which had detected absorption features on the polar regions of the surface of the Moon usually linked to hydroxyl- and/or water-bearing molecules.
To recap, the Connecting Ridge has been selected because of favourable terrain, Earth communications position, solar angles for power generation and the potential for buried, preserved meteor ice in the shadows of the craters.
Intuitive Machines’ Nova-C Lunar Lander
The Nova-C lander, built by Nasdaq-listed Intuitive Machines (NASDAQ: LUNR), has a hexagonal body with six landing legs. It can carry payloads of between 100kg to 130kg to the Moon’s surface, which are sited on the outside of the hexagonal frame and is designed to use solar panels to generate 200W of power while on the surface. This use of solar panels is why a landing location with good illuminations, yet close to the suspected ‘cold traps’, is so important.
Liquid methane is the fuel of choice with liquid oxygen as the oxidiser.
The PRIME-1 experiment is made up of the TRIDENT (The Regolith and Ice Drill for Exploring New Terrain) drill and MSolo (Mass Spectrometer for Observing Lunar Operations) spectrometer which can be seen in the image below, attached to the outside of the lander. Combined the PRIME-1 payload weighs about 40kg.
The following brief video gives a good overview of the mission.
The following presentation provides further detail on MSolo.
The Implications
Should significant indications of water be found in ‘cold traps’ near the south pole, the possibility exists to use this water ice to produce liquid hydrogen and liquid oxygen by electrolysis or other means.
The second stage of the Saturn V rocket used a liquid hydrogen fuel and a liquid oxygen oxidiser as propellants.
The Moon might soon become a service station for rockets low on propellants bound for Mars! According to NASA, the current schedule for the PRIME-1 mission is quarter 4, 2024.
If you’re interested in understanding more about the exploration of the moon, I highly recommend this informative and enjoyable video by NASA:
