TOKYO/SAPPORO, Japan -- The rocket engine roared to life with a burst of bright orange flame, firing at 70% of full power for five seconds in a test that featured fuel used to power much of the planet but not harnessed to reach outer space: liquefied natural gas.
Interstellar Technologies, a small Japanese rocket startup, conducted this static firing parallel to the ground in mid-March at its site on Japan's northernmost main island of Hokkaido.
Interstellar plans to use the LNG engine for its Zero satellite launch vehicle, slated for takeoff in 2023. The company is developing the technology and aims to become a global pioneer in rockets powered by liquefied natural gas.
The startup employed an ethanol engine for the May 2019 launch of its Momo-3 suborbital rocket, which reached an altitude of 100 km. But the Zero weighs 36 tons, over 30 times more than the Momo-3, and must be able to maintain a speed of 8 km per second at its peak altitude of 500 km for a successful satellite launch. This means the Zero needs a more energy-dense fuel than ethanol.
LNG, which is composed mainly of methane, is relatively inexpensive, at less than $3 per kilogram -- one-tenth the price of the highly refined kerosene used in some rockets. As tests can burn tens of thousands of dollars in fuel, finding ways to reduce these costs is vital.
LNG also is environmentally friendly in comparison. It vaporizes if spilled, preventing soil or water pollution, and generates lower carbon dioxide emissions when burned. The fuel can even be procured locally, as Hokkaido produces biogas from livestock waste.
This is not Japan's first attempt to commercialize an LNG-fueled engine. A private-public partnership including the Japan Aerospace Exploration Agency and heavy machinery maker IHI planned to use the fuel in the second stage of its GX rocket, development of which ran from 2003 to 2009.
Internal friction and slow decision-making led to repeated delays on the project, and the estimated cost ballooned from 45 billion yen ($418 million at current rates) to more than 100 billion yen. The government ultimately scrapped the plan.
Though the GX failed to make it past the planning stage, JAXA continued studious development of the liquefied natural gas engine at Kakuda Space Center in Miyagi Prefecture. The joint research operation with Interstellar began in fiscal 2018 at the space center, providing the company with access to the agency's equipment and past test data.
What Interstellar really wanted was the technology behind the fuel injector and the turbo pump that sent the fuel from the tank to the combustion chamber. These components are difficult to produce from scratch. The company seeks JAXA's know-how to clear this hurdle inhibiting private-sector rocket development.
The entry of Elon Musk's SpaceX in the U.S. has carved out roles for the public and private sector in space development. While businesses are taking the lead on missions in low Earth orbit, such as for the International Space Station, NASA is shifting toward lunar and planetary exploration.
A successful deployment of an LNG rocket by Interstellar would bring a turning point in Japanese space development as well.
The coronavirus pandemic has thrown a wrench into this plan. The Momo-5 rocket was slated to launch between May 2 and May 6. But Interstellar announced a delay on April 28 under pressure from the Hokkaido town of Taiki. Locals feared the launch would draw spectators, who could bring the virus with them.
Interstellar prioritized rapport with the community, whose cooperation is critical to rocket launches, even if it sent months of coordination with administrators, fishing co-ops and other groups back to square one.
The company faces an uphill battle with no new income or government aid expected in the foreseeable future. But the public appears to have high hopes. A crowdfunding campaign launched May 2 to support Interstellar's fixed costs and research operations raised 20 million yen -- more than double the goal of 9 million yen -- from 1,500 people in just a day and a half.