Engine Troubles Threaten Japan's Lunar Ambitions
ispace, Japan's commercial lunar company, is facing significant delays in developing a new engine for its next-generation moon landers, threatening a series of high-profile missions including work for NASA's Commercial Lunar Payload Services program. During an earnings call this month, company executives acknowledged that the VoidRunner engine—jointly developed with U.S. propulsion firm Agile Space Industries—is not meeting performance targets for thrust and fuel efficiency, forcing the company to seriously consider switching to an alternative engine entirely.
The cascading delays are already reshaping ispace's financial outlook. The company slashed its revenue forecast for the fiscal year ending March 31 by roughly 40%, cutting projected project revenue from 10 billion yen ($64.6 million) to 6 billion yen ($39.5 million). The engine delays account for the largest portion of that reduction, pushing critical revenue-generating missions into future fiscal years.
A Partnership Gone Sideways
VoidRunner represents the latest chapter in ispace's engine saga. Originally, the company planned to use a different Agile Space engine on its Apex 1.0 lander, which is being developed for NASA's CLPS program. When that engine was swapped out in May 2025 for the VoidRunner alternative, it forced significant lander redesigns—a decision that already delayed the mission from 2026 to 2027. Now, less than a year into that revised timeline, the partnership is hitting turbulence.
Founded in 2010, ispace has positioned itself as a serious contender in commercial lunar logistics, but the company has weathered setbacks. Its Mission 2 lander crashed on the moon in June 2025, and ispace U.S. failed to secure a second CLPS task order for what would have been Mission 5. These failures underscore the brutal reality of lunar operations: the moon remains unforgiving, and the margin for engineering error is razor-thin.
The Technical Crux
According to Jumpei Nozaki, ispace's chief financial officer, the VoidRunner engine is underperforming in both thrust and fuel efficiency—fundamental parameters that determine mission success. While ispace handles the engine's valve system, Agile Space leads overall development, leveraging 3D printing technology to rapidly redesign, manufacture, and iterate when problems surface. CEO Takeshi Hakamada acknowledged ispace's confidence in Agile's capabilities but admitted that the development timeline has extended beyond expectations.
The company is now operating on two tracks: continuing aggressive testing and refinement of VoidRunner while simultaneously evaluating alternative engines as a fallback. Hakamada noted that ispace has dispatched its own engineers to Agile's facility to collaborate on diagnostics and solutions, signaling the seriousness of the situation.
Dominos Begin to Fall
The VoidRunner delays directly threaten at least two major missions. Mission 3, a farside lunar landing led by Draper and funded through NASA's CLPS program, is now at risk of slipping beyond 2027. Mission 4, which will fly ispace's new Series 3 lander design under development in Japan and is currently scheduled for 2028, could also be pushed back depending on how—or if—VoidRunner is resolved.
Despite these headwinds, ispace highlighted progress elsewhere. The company is developing Mission 6, another Japanese-built lander targeted for 2029, and received a 20 billion yen ($129 million) grant from Japan's Space Strategic Fund in January to integrate high-precision landing technology from JAXA's successful Smart Lander for Investigating Moon mission. These advances signal that ispace's broader lunar strategy remains intact—but Mission 3 and 4 represent critical near-term tests of the company's ability to deliver on commercial and government commitments.





