South Korea suffered its second space launch failure in as many tries June 10 due to an as-yet-unexplained mishap that occurred shortly after liftoff, according to Russia’s Khrunichev State Research and Production Space Center, builder of the vehicle’s first stage.

The payload was an experimental satellite built by the Korea Aerospace Research Institute.

“The liftoff was nominal,” Khrunichev said in an English-language statement posted on its website June 10. “However, 136 seconds into the flight all telemetry data downlink was terminated. It can be concluded at this point that an off-nominal event had occurred.”

South Korean press reports quoted a senior government official as saying the vehicle is believed to have exploded.

A board of Korean and Russian experts will be convened to investigate the causes of the incident, the Khrunichev statement said.

The Korea Space Launch Vehicle (KSLV)-1 features a Korean-developed second stage and payload fairing. A problem with the payload fairing was blamed in the KSLV-1 failure on its maiden flight Aug. 25.

The latest launch attempt had been postponed for one day due to a fire suppression system malfunction at the Naro Space Center launch site that left the pad covered in fire-extinguishing chemicals, Khrunichev said.