Intuitive Machines, a private space company, has made history with its lunar lander, Odysseus. After spending seven days on the moon, the lander officially lost power, marking the first time an American hardware has reached the lunar surface since 1972 and the first privately built spacecraft to land on the moon. However, it is the lander’s revolutionary cryogenic propulsion system that has captured attention and could potentially transform space exploration.
Unlike most spacecraft that use toxic “space storable” or hypergolic propellants, Odysseus utilizes a combination of cryogenic liquid oxygen and liquid methane. These propellants, commonly used in high-performance rocket engines like SpaceX’s Raptor and Blue Origin’s BE-4, offer higher energy efficiency and are considerably less dangerous. However, they require active cooling to extremely low temperatures, presenting unique challenges.
To overcome the issue of storing fuels at such low temperatures, Intuitive Machines and SpaceX adopted a novel approach. They fueled the lander’s VR900 engine just three hours before lift-off, while the rocket was on the launch pad and the spacecraft was already inside the payload fairing. This required SpaceX to develop new capabilities, including modifying the launch pad and the second stage of the Falcon 9 rocket.
The collaboration between Intuitive Machines and SpaceX faced some hurdles during the mission. Two wet dress rehearsals were conducted before the launch, and issues with propellant loading resulted in a one-day delay. Additionally, there was a brief delay in chilling the liquid oxygen feed line. However, once these challenges were overcome, the engine was successfully fired in space for the first time.
The use of cryogenic propellants allowed Odysseus to take a more direct trajectory to the moon, reducing its exposure to damaging high-energy particles in the Van Allen belt. This efficiency opens up possibilities for future missions and de-risks space exploration for other commercial providers.
Intuitive Machines plans to utilize two VR900 engines on its larger spacecraft, the “Nova-D,” which will have a payload capacity of 500-750 kilograms. The company’s use of cryogenic propellants is not limited to lunar landers. Impulse Space’s kick stage, Helios, also plans to employ cryogens to deliver payloads directly to geostationary orbit.
The significance of Intuitive Machines’ cryogenic propulsion system extends beyond its own mission. One of the payloads carried by Odysseus, the Radio Frequency Mass Gauge statement from NASA’s Glenn Research Center, leverages the cryogenic propulsion system to measure propellant levels in the engine’s tanks. This technology is crucial for measuring fuel levels during long-duration space missions, where microgravity and “slosh” pose challenges.
NASA’s Artemis missions, aimed at returning humans to the lunar surface, will rely on spacecraft that use cryogenic propellants. SpaceX’s Starship Human Landing System and Blue Origin’s Blue Moon are among the spacecraft that will require transferring large amounts of cryogenic fluids from on-orbit depots. The success of Intuitive Machines’ mission paves the way for the use of cryogenic propellants in future space exploration endeavors.
Intuitive Machines’ Odysseus lunar lander has not only made history but has also revolutionized space exploration with its cryogenic propulsion system. The use of cryogens offers higher energy efficiency and reduced risks compared to traditional hypergolic propellants. With the successful demonstration of this technology, the door has been opened for future missions that utilize cryogenic propellants, including NASA’s Artemis missions. As we venture further into space, Intuitive Machines’ achievement marks a significant milestone in our quest for exploration and discovery.
