Inside a large sphere, engineers meticulously examined their equipment. In front of them lay a shiny metallic device wrapped in colorful wires – a box intended to one day produce oxygen on the moon.
After the team left the sphere, the experiment commenced. The box-shaped machine started processing small amounts of dusty regolith – a blend of dust and sharp grit matching the composition of lunar soil.
Before long, the regolith transformed into a viscous substance. A portion of it was heated to temperatures exceeding 1,650°C, and by introducing certain reactants, oxygen-containing molecules began to emerge.
"We've completed all our tests on Earth," shared Brant White, a program manager at Sierra Space, a private company. "The next stage is the moon."
Sierra Space's endeavor unfolded at NASA's Johnson Space Center this summer, among a plethora of similar technologies being developed to supply future lunar base inhabitants with essential resources.
Apart from breathing, astronauts on the lunar base will need oxygen for fueling rockets that may launch from the moon to distant locations like Mars.
Moreover, these base residents could potentially extract metals from the abundant dusty debris covering the lunar surface, provided reactors can efficiently extract resources.
"It could significantly reduce mission costs," explained Mr. White, highlighting the challenges and expenses of transporting ample oxygen and spare metals from Earth to the moon.
While the process of extracting oxygen from metal oxides is well-known on Earth, implementing it on the moon presents unique challenges due to the lunar environment.
Sierra Space's testing chamber, used in July and August of this year, simulated lunar conditions such as vacuum, temperature, and pressure. Continuous improvements were made to the machine to withstand the abrasive nature of lunar regolith. "It wears out mechanisms and gets everywhere," shared Mr. White.
Moreover, the influence of lunar gravity, significantly lower than Earth's, poses yet another challenge unattainable to replicate on Earth or in orbit.
Addressing the criticality of lunar gravity for oxygen extraction technologies, Paul Burke from Johns Hopkins University highlighted potential impediments due to the slower oxygen bubble detachment in the moon's dense regolith.
Countermeasures like vibration or smoother electrodes are being explored to facilitate the detachment of oxygen bubbles.
Sierra Space's carbothermal process differs by allowing oxygen-containing bubbles to form freely within the regolith, minimizing the risk of obstructions, according to Mr. White.
Emphasizing the importance of oxygen for lunar expeditions, Dr. Burke estimated the daily oxygen requirement for an astronaut to be roughly two to three kilograms of regolith, subject to the individual's fitness and activity levels.
While a lunar base's life support systems will likely recycle exhaled oxygen, reducing the necessity to process large amounts of regolith solely for sustaining lunar residents.
Beyond life support, the primary role of oxygen-extracting technologies lies in providing oxidizers for rocket fuels, crucial for ambitious space exploration.
Sierra Space's system involves the introduction of carbon, with a substantial portion recyclable after each oxygen production cycle to minimize the need for resupply missions.
In combating the detachment issue in low gravity, Ms. Patel and her team integrated a "sonicator" into their system, utilizing sound waves to dislodge oxygen bubbles adhered to electrodes.
Ms. Patel envisions future lunar machines extracting resources like iron, titanium, or lithium from regolith. These materials could support lunar inhabitants in manufacturing spare parts using 3D printing technology for their base or spacecraft repairs.
Highlighting the versatility of lunar regolith, Ms. Patel shared experiments where simulated regolith was transformed into a durable, dark, glass-like material.