ROK-U.S. joint solar telescope CODEX launches to space station

A pre-launch photo of the “Solar Coronagraph (CODEX)” jointly developed by the Korea Astronomy and Space Science Institute and NASA. (Korea AeroSpace Administration)

A longstanding puzzle in astrophysics - the extreme temperature of the sun’s outer layer, the corona - could be moving closer to an answer. Although it is located about 2 million to 7 million kilometers above the sun’s surface, the corona is vastly hotter than the sun’s 6,000-degree surface, reaching temperatures of 1 million to 5 million degrees. To investigate this anomaly, a team of scientists from South Korea and the United States launched a specialized instrument into space to gather data that could eventually improve space weather forecasting.

On Wednesday, the Korea AeroSpace Administration (KASA) confirmed that “CODEX,” a solar coronagraph developed jointly by the Korea Astronomy and Space Science Institute (KASI) and NASA, reached the International Space Station (ISS). Launched on November 5th, 2024, aboard SpaceX’s Falcon 9 rocket from Kennedy Space Center in Florida, the CODEX payload was transported by SpaceX’s Dragon cargo ship, which successfully docked with the ISS at 11:52 p.m. KST.

NASA will use the ISS’s robotic arm to mount CODEX on an external platform (ELC3-3) between November 9th and 11th. Following installation, CODEX will conduct up to 55 minutes of observation during each 90-minute orbit, with initial test operations scheduled for one month before its potential two-year mission.

Traditionally, coronal observations were limited to brief total solar eclipses, but coronagraphs like CODEX simulate these conditions by blocking the sun’s disk to reveal the corona. Unlike previous models, CODEX will simultaneously capture the corona’s temperature and speed in 2D images, providing unprecedented data on solar dynamics. This is the world’s first coronagraph to produce 2D images, offering a new level of information, according to the KASI.

Solar phenomena such as the solar wind, which accelerates from tens to hundreds of kilometers per second as it moves beyond the corona, are major drivers of space weather. By analyzing data from the corona, scientists hope to enhance predictions of solar wind outbursts and other space weather events. CODEX will be operated and monitored from NASA’s Goddard Space Flight Center, with the KASI receiving data remotely.