KAIROS Three for Three on Launch Failures

At 11:10 AM JST, Space One’s KAIROS’ rocket launched from Space Port Kii for the third time. Following a failure on its first two flights in early and late 2024, there was hope for a success on the rocket’s third launch attempt. However, roughly two minutes post launch, the rocket exploded leaving multiple fragments falling from the sky, with a primary piece apparently left in an end-over-end tumble. During Space One’s official broadcast, the commentators confirmed a loss of vehicle shortly after. This third failure raises questions regarding not only the future of KAIROS, but of the company that built it.

While in the United States, commercial launch vehicles have become incredibly common, with rockets such as SpaceX’s Falcon 9 flying frequently, it is notable that commercial space has not yet materialized at the same level overseas. Whereas Pegasus, the first privately developed launch vehicle, flew for the first time in 1990, the first private launch from China, i-Space’s Hyperbola 1, occurred in 2019. Similarly, Isar Aerospace’s Spectrum flew just last year, becoming the first private launch vehicle to fly from Europe. Space One and their KAIROS lifter represent a similar page in the story of international commercial spaceflight and their first flight, while brief, was the first such private launch from Japan.

KAIROS, (Kii-based Advanced & Instant ROcket System), is a small, four-stage orbital launch vehicle designed and operated by Space One. It is designed to use three solid fuel stages to reach space, and a small final liquid fuel stage for orbital insertion and payload deployment. It launches from Shimizu Corporation’s Space Port Kii, in Kushimoto, Wakayama, Japan, the nation’s first private facility for orbital launches. KAIROS’ first launch carried a government payload in March of 2024 and exploded just five seconds after lift off, raining debris back down on the surrounding area. A second launch in December of that year carried five small commercial satellites, but lost attitude control shortly after the first stage separated, triggering the vehicle’s flight termination system. KAIROS’ third launch not only failed to carry payloads safely for the first time, but failed to fly further than the previous vehicle. According to a tweet by Space One, the vehicle was destroyed by its flight termination system, seemingly due to deviations from its intended trajectory (launch coverage showed the rocket appearing to turn and attempt corrections throughout ascent).

One may wonder why commercial launch options like KAIROS are important, when privately developed launch vehicles can carry so much risk; this is a multi-faceted question. One notable advantage of a commercial launch industry is the increased accessibility it affords for both government and civil payloads. Having more active launch systems launching payloads into space more often provides a competitive landscape for space launch. Different parties offer different capabilities and pricing for rides to space, with marketplace competition and higher supply for a nation’s launch demands helping to lower launch costs. In 2025 the United States saw over 190 orbital rocket launches, and China saw 93, new records for both nations as they increasingly embrace private launch. Japan, meanwhile, saw only three.

Furthermore, having multiple operational launch vehicles provides backups in worst case scenarios. One such example being the movement of Cygnus resupply spacecraft temporarily onto SpaceX’s Falcon 9 after Antares 230 became unavailable due to the invasion of Ukraine. In fact, Japan itself currently finds itself without space access. Aside from KAIROS, Japan has only two domestic launch systems, both operated by JAXA, Japan’s government space agency: the larger H3 rocket, and the smaller Epsilon rocket. Epsilon has not flown since 2022, and development of a new booster for the upcoming Epsilon S configuration has faced delays due to testing failures, meaning the rocket is not currently operational. Meanwhile H3 experienced a loss of payload on its most recent flight, with the rocket now grounded for an anomaly investigation. 

In continuing comparisons to American private spaceflight, one may recall that SpaceX, now an industry giant, started off with a string of launch failures. The first three of the company’s Falcon 1 rockets all failed to reach orbit, and according to CEO Elon Musk put the company at risk of bankruptcy, before the fourth Falcon finally worked. One may be tempted therefore to believe that while the task of developing a private rocket for the first time is daunting, not to mention in an industry with less experience than the United States’, the associated risks of failure are prepared for and not insurmountable. However, even while the circumstances appear similar, Space One does not appear to have the same financial luxuries that carried SpaceX to its first successes. In the wake of KAIROS’ second launch failure, Space One turned to Ready For, a Japanese crowd funding website, to accumulate the funds needed to support KAIROS No. 3.

With this in mind, it is currently unclear when or if KAIROS will be able to make a fourth launch.

However, even if Space One does not make it to a fourth flight, this does not end the story of Japanese private launch. Interstellar Technologies seeks to eventually launch its orbital rocket, ZERO, a two stage methalox rocket from Hokkaido Spaceport, and has seven payloads already booked for its first launch and has secured a strategic partnership with Toyota. Additionally, Honda has recently indicated interest in developing a reusable orbital launch vehicle for deploying both commercial and internal space assets, and the company completed a subscale vertical take off and landing demonstration in June of 2025. While Honda’s rocket may be several years out, ZERO seeks to launch as soon as 2027. 

Commercial launch is ever-evolving, and internationally is still finding its footing. Not every system is going to pan out and yield successful results, not every company is going to have a straight forward path, or any path, into providing such a service. For every SpaceX there will be a Kistler; for every Electron there will be a Rocket 3. Just as this occurred in the United States, so too will it occur abroad. Even if this was KAIROS’ final attempt to reach the stars (and this is not certain), then it simply means that it is someone else’s turn to try.