The Moon is 384,000 kilometres away from Earth, but one of the best places to study its surface is much closer to home. Western planetary scientist Catherine Neish and PhD candidate Sashank Vanga travelled to Hawai'i Volcanoes National Park in June to investigate lava flows that could reveal new clues about the Moon's volcanic past.
This summer's field study helped the team interpret remote observations from NASA's Lunar Reconnaissance Orbiter (LRO), a spacecraft that has transformed our understanding of Earth's nearest neighbour since its launch in 2009.
LRO provides scientists with detailed images, elevation measurements and other data that allow them to study the Moon's geology, identify potential exploration sites and better understand its history. But spacecraft data can only tell part of the story.
Neish and Vanga, members of LRO's Miniature Radio-Frequency (Mini-RF) science team, used the landscape of Volcanoes National Park as an analogue for lunar lava flows, studying how volcanic features form and how they appear through remote sensing instruments.
"By studying lava flows on Earth, where we know the geology, we can better understand what the LRO, and the Mini-RF in particular, are telling us about similar volcanic features on the Moon," said Neish, a professor of Earth sciences.
The Mini-RF instrument was originally designed to search for evidence of water ice deposits in the permanently shadowed regions of the Moon. Its data has since become a powerful tool for understanding much more about the Moon, from ancient volcanism to impact cratering and the geological processes that shaped its surface.
"When you're looking at something from orbit, you have to interpret what you're seeing," said Neish, an expert in orbital radar observations and the geology of planetary surfaces. "Going into the field allows us to understand what those features actually look like up close."
It is a challenge captured in a famous observation attributed to British statistician George Box: "All models are wrong, but some are useful."
The useful model, like Hawai'i offers, is essential for NASA's future Artemis missions, helping planetary scientists connect observations made on Earth with the landscapes they hope to explore on other worlds.
The Hawai'i fieldwork helped bridge the gap by connecting two perspectives: LRO's view from above and the physical view from Earth's surface.
'Improve the tools we use to explore other worlds'
Hawaiʻi's volcanic landscape offers more than dramatic scenery. Its rough lava flows create radar signatures similar to those observed on the Moon, giving researchers like Neish and Vanga a rare opportunity to compare spacecraft observations with landscapes they can explore firsthand.
"We focus on really fine-scale topography because that's where LiDAR and radar excels," said Neish. "It can detect roughness variations at the centimetre scale, revealing incredibly fine details hidden from optical images."
Using a backpack-mounted LiDAR system, the team mapped the surface in extraordinary detail before comparing those measurements with radar observations collected by LRO., said Neish, professor in the department of Earth sciences.
Earth Sciences PhD candidate Sashank Vanga wearing a backpack LiDAR in Hawai'i Volcanoes National Park as part of a NASA analogue mission. (Catherine Neish)
As a member of Neish's lab for the past four years, Vanga studies LiDAR and radar remote sensing methods for planetary science and exploration, developing techniques that help scientists better understand planetary surfaces from afar. LiDAR, or Light Detection and Ranging, is a remote sensing technology that uses pulsed lasers to measure distances and generate high-resolution, 3D models of environments.
The field experience in Hawai'i allowed Vanga to connect the data collected by spacecraft with the types of landscapes those instruments are trying to measure.
"Remote sensing gives us incredible information about planetary surfaces, but understanding what that data means requires connecting it back to what we know from the ground," said Vanga, a PhD candidate in geology with a specialization in planetary science. "Field studies like this help us better interpret what spacecraft are seeing and improve the tools we use to explore other worlds."
For graduate students like Vanga, opportunities like this are an important part of learning how to become planetary scientists. Space missions may capture images and measurements, but scientists still need to understand how those observations translate into the realities of rocks, landscapes and geological processes.
"Being able to study these environments firsthand changes the way you think about the data. It helps us ask better questions and develop better methods for exploring places we may one day visit." - Sashank Vanga, Western PhD candidate in Earth sciences
The work also highlights the importance of Earth-based analogues in preparing for future exploration. The Artemis program is bringing renewed attention to the Moon, with plans to return astronauts to the lunar surface and eventually establish a sustained human presence.
Those missions will depend on scientists having a deeper understanding of lunar landscapes before astronauts arrive. The better scientists understand the Moon today, the better prepared they will be to explore it tomorrow.
For Neish, that preparation begins with understanding the worlds we can reach.
"The Moon is not just a distant object in the sky," said Neish, a professor in Western's department of Earth sciences. "It's a world with a history, and we're trying to understand that history."
Earth sciences professor near the summit of Mauna Kea, a dormant volcano on the Island of Hawai'i. (Catherine Neish)
Lost and found
When NASA launched the Mini-RF aboard LRO in 2009, it was expected to deliver answers to some of the Moon's biggest questions. Then, shortly after arriving in lunar orbit, something went wrong.
"In December of 2010, Mini-RF's transmitter broke," said Neish, a member of Western's Institute for Earth and Space Exploration. "Suddenly we didn't have a transmitter, and we had to come up with this very unique idea of transmitting from Earth and then receiving on LRO. We've been doing that ever since."
What could have become a major setback became an unexpected engineering solution - and a reminder that exploration rarely follows a perfect plan.
The original scientific goal of the LRO mission was ambitious: identify safe, scientifically interesting landing sites for future human explorations, which included whether there was evidence of water ice at the lunar poles.
The discovery of accessible water ice would have enormous implications for future exploration because water is not just scientifically interesting, it is a critical resource for astronauts, providing potential sources of drinking water, oxygen and rocket fuel.
"We didn't really find much evidence, honestly, for water ice with the Mini-RF instrument," said Neish. "But what we did find was a lot of great information about volcanism and impact cratering and all the geologic processes that shape the Moon - all critical for future space missions and humanity's eventual lunar outposts."
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