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December 26, 2021

We have exciting news!  The International Astronomical Union Working Group for Planetary System Nomenclature has recently approved a lunar crater to be named for Dr. Paul D. Spudis. His expertise in lunar and terrestrial planetary geology were felt by many in planetary science, and his contributions are highlighted as NASA leads the US in returning astronauts back to the Moon in a few years.

A lunar crater named for Dr. Paul D. Spudis
Dr. Paul D Spudis 

Dr. Spudis was a geologist at the U.S. Geological Survey, Branch of Astrogeology, in Flagstaff, Arizona from 1980-1990. He was Principal Investigator on a NASA Grant called “The Geology of Lunar Multi-ring Basins,” work done in support of his dissertation efforts. He earned his PhD in Geology from Arizona State University and soon became a Faculty Research Associate there as well. While working for the USGS, he served as the Principal Investigator for NASA’s Planetary Geology Program.

Additional information about Spudis can be found here, including his education, careers, bibliography and more.

Spudis passed away in 2018 and is greatly missed by many people in the science community. Anyone who knew of his work is not the least bit surprised that a lunar crater was named after him: he was known as a “Giant” in the field of Moon exploration and a relentless advocate for astronauts returning to the Moon. He often voiced the many benefits the Moon holds for future human space travel and advocated a presence in cislunar space.

Features on planetary bodies have specific rules and regulations for naming conventions, and lunar craters can be named after “Scientists, engineers, and explorers, as well as others connected with astronomy, planetary, or space research who have made outstanding or fundamental contributions to their field.”

Dr. Mark Robinson, at Arizona State University, proposed to the International Astronomical Union (IAU) that a lunar crater be named after Spudis.

Our planetary nomenclature database manager, Tenielle Gaither said, “Dr. Robinson’s proposal to the IAU for this crater name was motivated by his team’s lunar south pole geologic mapping efforts in preparation for the Intuitive Machines 2 (IM-2) CLPS mission. This provided a strong scientific justification for the name proposal, and Paul Spudis’ contributions to lunar science more than qualified his name to fit the IAU’s nomenclature theme for lunar craters.”

Therefore Spudis’ mark of fame on the lunar surface is a great success, deserved, and can remind us of his great contributions to science, especially when we look at the Moon. Spudis crater is now listed in the Gazetteer of Planetary Nomenclature, which is maintained by the Astrogeology Science Center. You can head on over to the IAU website to learn the inner workings of how names are proposed and reviewed, and find the latest names that have been approved on our website in the Nomenclature News.

Spudis Crater on the Moon
Spudis crater is 13 km in diameter and located at -89.3 °, -89.73 ° latitude and -65.09 °, -107.79 ° longitude. 

If Spudis were here now, he would see that NASA’s Artemis mission program mirrors much of what he advocated for, and it is likely that he would have still been involved in some capacity, having built much of the framework for these discussions himself.

Spudis was a spokesperson who exuded strength, expertise, and passion about the Moon in many venues and communication outlets, including the Senate Hearing on "Lunar Exploration" in 2003.

Here are, among many, a few viewpoints Spudis made during the hearing, including a plea that humankind should return to the Moon now:

  • The Moon is close and has resources that we can use to create a true, economical space-faring infrastructure.
  • The Moon is a scientifically rich object for study, and offers abundant material and energy resources as the feedstock of an industrial space infrastructure.
  • The Moon, once established as a space infrastructure, can provide routine access between the Earth and the Moon, and beyond.
  • The Moon’s resources are likely found at the poles.
The image shows the distribution of surface ice at the Moon’s south pole
The blue color shows the locations of water ice at the Moon's South Pole detected by a NASA instrument aboard India's Chandrayaan-1 spacecraft in 2018.


Humans are going back to the Moon

The Artemis mission program indicates it will land astronauts on the Moon at the South Pole in a few years, in 2025. The South Pole is the chosen designation to investigate and learn more about water processes on the Moon.  It is also hoped that humans can establish a Moon base and prepare for cislunar travel (travel between the Earth and the Moon) in the next decade, with ambitions to send humans to Mars and beyond.

Humans will need water resources

Humans rely on water and its components (oxygen and hydrogen) for many things on Earth, so then it makes sense that human space travelers must have access to water anywhere they go in space. Scientists have targeted water-ice as an invaluable resource to enable a sustained human presence on the Moon. Rather than transport resources like water, oxygen, and fuel from the Earth to the Moon, which gets expensive, scientists will look for and aim to extract resources that are already there: Spudis believed this makes economic sense!

Robots have revealed water at the South Pole

Scientists observed ice on the Moon in 1996 using data acquired from the Clementine spacecraft. Some robotic missions, such as Lunar Reconnaissance Orbiter (still active) provided snapshots that have been interpreted as being water ice. India’s Chandrayaan-1 orbiter confirmed the presence of ice at Shackleton crater. As expected, Spudis was involved in all those missions! He was a team member of the Mini-RF instrument on Lunar Reconnaissance Orbiter, led the Mini-SAR radar instrument that flew on India’s Chandrayaan-1 orbiter, and in 1994 served as deputy leader of the Clementine Mission team.

Although water ice is reportedly found all over the Moon, one problem is subsurface ice in sunlit regions do not last long enough to be an adequate resource for drinking water, oxygen, and fuel. It quickly turns to water vapor and escapes into space, due to the Moon’s lack of atmosphere. Even certain areas of the South Pole like some of the walls of Shackleton crater receives sunlight, which melts the ice.

So, where do scientists look for water that is concentrated enough, is accessible, and unaffected by sunlight at the South Pole?

Spudis and other scientists believe that ice reserves can be found in cold, permanently-shadowed craters that have not seen sunlight for billions of years. Water gathered from comets, asteroids, water vapor, and other volatiles are thought to collect in these craters with no way out due to some crater’s frigid temperatures and lack of sunlight. Whatever stuff gets in these craters are cold-trapped by lunar temperatures of -272 degrees Celsius (-458 Fahrenheit), three times colder than the coldest place on Earth: the Eastern Antarctic Plateau, Antarctica.

Scientists will persevere with a plan

In 2023, NASA's Volatiles Investigating Polar Exploration Rover (VIPER) will roam the South Pole and determine where the water is and how much is available for use as a resource.  

If sufficient water-ice is found, scientists think going forward they can use machinery to split the water into hydrogen and oxygen for drinking water, breathable air, and rocket fuel.  Rockets and robots then will have a "filling station" to refuel before cislunar travel or to other distant bodies in our Solar System.

Now, all those are simple conceptually, but we’ve never done them in practice,” said Spudis, “so we don’t know how difficult it is. But by sending the small robotic missions to the Moon and practicing this via remote control from Earth, we can evaluate how difficult it is — where the chokepoints are — and what are the most efficient ways to get to these deposits and to extract a usable product from them.

Meanwhile, scientists also intend to find out how water vapor and other volatiles migrate to the poles where they are adsorbed in the polar cold traps. This, too, is part of the objectives in the Artemis program. For the first time since Apollo 17, over 50 years ago, NASA grows closer to returning astronauts to the Moon, and if Spudis was here he would be ecstatic!


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