WASHINGTON — The failure of Japan’s H3 rocket on its inaugural flight in March could delay several science missions, including two scheduled to launch on another rocket.

The first flight of the H3 rocket failed to reach orbit March 7 when the rocket’s upper-stage engine failed to ignite. Launch controllers triggered a self-destruct system on destroying the rocket and its payload, the Advanced Land Observing Satellite-3 (ALOS-3) Earth observation satellite.

Neither the Japanese space agency JAXA nor launch vehicle manufacturer Mitsubishi Heavy Industries (MHI) have released details about the investigation and progress on finding the root cause. Some reports have suggested a problem with the electrical system on the upper stage that prevented the engine from igniting.

The H3 upper stage uses an engine designated LE-5B-3 developed by MHI and similar to the LE-5B engine used on the existing H-2A rocket. That is putting launches of the H-2A on hold while the investigation continues.

That may delay the upcoming launch of two science missions sharing an H-2A. The X-Ray Imaging and Spectroscopy Mission (XRISM), an X-ray astronomy spacecraft, and the Smart Lander for Investigating Moon (SLIM), a lunar lander, were scheduled to launch together as soon as May on an H-2A.

That launch date is in doubt, said Masaki Fujimoto, deputy director of JAXA’s Institute of Space and Astronautical Sciences, during a panel discussion at the National Academies’ Space Science Week event March 28. “The schedule might have to be shifted, the details of which I don’t know,” he said.

XRISM is a replacement for Astro-H, or Hitomi, a Japanese X-ray observatory launched in 2016 that malfunctioned shortly after launch when it spun out of control. The new X-ray observatory features contributions from NASA and the European Space Agency.

SLIM is a lunar lander primarily intended to be a demonstration of precision landing technologies. The spacecraft will carry a multi-band camera scientists hope to use to study compositions of rocks around the landing site.

“Once we establish these technologies, we will deploy a post-SLIM series of landing missions, and that will constitute our contribution to Artemis,” the NASA-led lunar exploration campaign, he said.

He said he had hoped to hear “good news” about the status of the launch of XRISM and SLIM last week, but did not. “I’m sorry, but I cannot be too positive about this.” The spacecraft themselves are ready for launch, he added.

Even if the H-2A is cleared to return to flight in the near future, it remains uncertain how long the H3 rocket will be grounded. That could affect a third mission. Martian Moons eXploration (MMX). That spacecraft will travel to Mars to study its two moons, Phobos and Deimos. It will collect samples from the surface of Phobos for return to Earth.

MMX is currently scheduled for launch in late 2024 on an H3, the next launch window in the series that opens approximately every 26 months for Mars missions. Fujimoto suggested the H3 failure makes that schedule uncertain. “To be honest, I really don’t know what is going to happen to this timeline,” he said.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...