SEOUL, South Korea – Japan has delayed the launch of a H-2A rocket planned for May to no earlier than August in the wake of the failed inaugural flight of H3 rocket.

The Japanese space agency JAXA announced the delay March 31, saying it is “difficult to start the preparation for the [H-2A] launch this month, because an investigation of the H3 launch failure is underway.” The H3 and H-2A rockets share many components, particularly in their upper stage engines. The H3 upper stage uses an engine designated LE-5B-3, developed by Mitsubishi Heavy Industries (MHI), which is similar to the LE-5B engine used on the existing H-2A rocket. An interim investigation report suggests a problem with the electrical system on H3’s upper stage that prevented the engine from igniting. And this has put launches of the H-2A on hold while the investigation continues.

JAXA’s decision will leave two Japanese space missions grounded for several more months. The affected H-2A rocket was supposed to lift off from the Tanegashima Space Center, carrying the X-Ray Imaging and Spectroscopy Mission (XRISM), an X-ray astronomy spacecraft, and the Smart Lander for Investigating Moon (SLIM), a lunar lander.

XRISM is a replacement for Astro-H, or Hitomi, a Japanese X-ray observatory that failed within weeks of its 2016 launch. 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.

The space agency said for the H-2A rocket to meet its May launch date, the fueling process for the SLIM lander must begin in March, but it is “difficult” to do so due to the investigation of H3 failure. JAXA said August is seen as the next launch window for the mission, considering the moon’s orbit. But it could be delayed further, should the H3 investigation drag on, according to the agency.

Park Si-soo covers space industries in South Korea, Japan and other Asian countries. Park worked at The Korea Times — South Korea's leading English language newspaper — from 2007 to 2020. He earned a master’s degree in science journalism from Korea...