A Chinese private space launch provider took a giant leap after conducting the first successful orbital launch of a methane-powered rocket.
Historic Maiden Launch
On July 12, private aerospace enterprise Landscape Technology Corp successfully launched the Zhuque-2 (ZQ-2), a medium-sized commercial launch vehicle powered by a mix of methane and liquid oxygen or methalox.
In December 2022, an attempt was made to launch the vehicle, but it failed to reach orbit due to an anomaly in the second stage. Despite the disaster, this attempt was still a first for the company because it got the edge of space before aborting the launch, indicating that the ZQ-2 was the first methane-fueled rocket to reach space.
Elon Musk's SpaceX has also worked on a spacecraft powered by methalox like the small ZQ-4 and its Magpie TQ-12 engine. Musk has attempted to use the explosive mixture in his larger Starship vehicle but failed to travel the space or even reach orbit. In its most recent launch in April, Starship failed in a fireball thirty minutes after lifting off from a launchpad located in South Texas. Since then, the U.S. Federal Aviation Administration has suspended the world's largest attempt at a rocket launch.
Other rival companies such as Rocket Lab, Blue Origin, Relativity Space, and United Launch Alliance have all been working on rockets powered by methalox. So far, none has followed the success displayed by ZQ-2.
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How Effective is Methalox as Rocket Fuel?
Humanity has been sending missions into space for decades, but methane-fueled rockets have not flown before due to complex issues in chemistry and engineering. However, recent designs in spacecraft prioritize features such as reusability and in-site resource utilization (ISRU). Because of this, the mixture of methane and oxygen has become the standard for next-generation launch vehicles.
In a hydrogen engine, the combustion process occurs in a state where hydrogen gas molecules surround oxygen during ignition. For methane fuel, the boiling points are the same, so there is no obvious state where both molecules will exist during vaporization and combustion. This leads to combustion instability, making methane harder to work with when fueling space rockets.
Fortunately, advancements in rocket propulsion technology have made methane rockets more feasible. While hydrogen is a cleaner fuel option, it encounters problems in reusability. Meanwhile, methalox offers more benefits regarding clean burning, density, and propellant efficiency. Methane has a density that is almost similar to kerosene while providing a specific impulse comparable with hydrogen rocket engines. In addition, the temperature of liquid oxygen and liquid methane are nearly the same, making it easier to apply a common bulkhead between their tanks within a stage.
Recently, private companies trying to dominate the space race have preferred using methalox for such reasons. Currently, there are fewer environmental studies focusing on the impact of methalox emissions, so it is still unclear if using this fuel will improve the space launch industry.
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