NASA's going to send robots to frozen alien worlds someday but for now, the agency needs to test its tools, taking advantage of the unique features that ice caves near Mt. Erebus have.

The southernmost active volcano in the planet, Mt. Erebus towers at 12,448 feet over Antarctica's Ross Island. The area is a great substitute for frozen alien worlds because temperatures are well below freezing for the most part of the year. However, Mt. Erebus is one of the select few of the world's volcanoes that have an exposed lake of lava.

Back in December 2016, Aaron Curtis and colleagues spent time underneath Mt. Erebus, exploring the ice caves to test robots and other machinery NASA could one day need to shed light on icy worlds located in the outer solar system. The trip was Curtis' seventh to the volcano.

But why Mt. Erebus?

"We think some features of these caves are similar to what you might see on a moon like Europa," said Curtis. Europa is one of Jupiter's moons.

NASA Tools Tested

NASA's Jet Propulsion Laboratory has a team of engineers called the Extreme Environments Robotics Group. Curtis joined the group in 2016, becoming one of the agency's scientists tasked with developing machines capable of roving, scurrying and climbing across different types of terrain.

Curtis was personally at Mt. Erebus to test several projects. First was the Ice Screw End Effector. An ice drill, ISEE is designed to be incorporated within the feet of a wall-climbing robot known as LEMUR, allowing it to climb walls while gathering ice samples with each step. Depending on humidity, densities and other factors, ice can feel like a light metal or a marshmallow.

PUFFER was also tested. Taking inspiration from origami, the robot sits flat and "puffs up" when being used to explore larger areas. PUFFER has made its way through various environments but this was the first time it had experienced snow.

Curtis aided as well in testing a structured light sensor for creating 3D maps of caves. According to him, ice is hard to model in 3D because it is reflective, so the machine looks like it's dealing with a hall of mirrors.

The Frozen Beauty Of Mt. Erebus

In ancient Greece, Erebus was believed to be the entryway to the underworld. For scientists today, the name is fitting for the volcano because it has its own version of an underworld, albeit one stunningly beautiful.

Curtis wrote a dissertation on the formation of the ice caves beneath Erebus while getting a doctorate at the New Mexico Institute of Mining and Technology. According to him, a diverse range of microscopic organisms have been discovered in the volcano's interior in recent years, and this suggests that it's possible for distant planets with features similar to the caves to also support life.

Filled with cathedral-like ceilings and hoarfrost forests, Mt. Erebus ice caves were carved out by the volcano's gasses. Though frozen, the ice caves are at a cozy 32 degrees Fahrenheit because of the heat coming from the volcano. When cold and warm air mix inside the caves, they form "chimneys" that extend toward the ground.