From the Spaceflight 101 article Experimental Launch of World’s Smallest Orbital Space Rocket ends in Failure:

SS-520-4 lifted off from the Uchinoura Space Center in Japan’s Kagoshima prefecture at 8:33 a.m. local time on Sunday, 23:33 UTC on Saturday on a one-off demonstration mission, aiming to put the TRICOM-1 CubeSat into an elliptical orbit around Earth. The small launcher quickly vanished from view after an on-time blastoff with a thrust eclipsing the rocket’s initial mass by a factor of seven.

The rocket’s climb to orbit was expected to take seven and a half minutes, however, all telemetry from the ascending launch vehicle was lost around 20 seconds into the planned 31-second firing of the rocket’s first stage. Tracking of the rocket showed the first stage separated from the second stage, reaching a peak altitude just shy of 200 Kilometers before both fell into the Pacific Ocean in a closed zone south-east of the launch site.

Are there plans to try again?

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above: SS-520-4 rocket ready for launch. From here, Photo: JAXA

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above: SS-520-4 rocket. From here, Image: JAXA

SS-520-4 is a three-stage solid-fueled rocket standing 9.54 meters tall, measuring 52 centimeters in diameter and weighing in at 2,600 Kilograms – smaller and lighter than any previous ground-based orbital launch vehicle. It is based on the SS-520 sounding rocket design, modified with a small third stage tasked with injecting a payload into Low Earth Orbit.

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above: TRICOM-1 in Launch Configuration. From here, Photo: JAXA

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above: Person with TRICOM-1 for scale - in this case Professor Hiroto Habu of the Japan Aerospace Exploration Agency. Image from here.


1 Answer 1




Thanks to @Sean's answer, I've made an update here as well.

From Wikipedia's S-Series_(rocket_family); SS-520-5

The second attempt at becoming the smallest orbital launching rocket was made on 3 February 2018. Liftoff, from the Uchinoura Space Centre, occurred at the opening of a ten-minute window at 14:03 local time (05:03 UTC), successfully deploying the TRICOM-1R CubeSat.


  • Height – 31 feet (9.54 meters)
  • Weight – 2.9 tons (2.6 metric tons)
  • Diameter – 20 inches (52 centimeters)
  • Payload to Low-Earth Orbit – ~9 lbs (4 kg)

According to the just posted NASA Spaceflight news item Japanese sounding rocket shoots for record-breaking orbital launch:

Japan conducted another attempt to launch a miniature satellite via a modified SS-520 sounding rocket Saturday, a little over a year after its first attempt failed to achieve orbit. Liftoff, from the Uchinoura Space Centre, occurred at the opening of a ten-minute window at 14:03 local time (05:03 UTC).

If Saturday’s experimental launch was successful, the SS-520 will become the smallest rocket ever to place a satellite into orbit. Its payload, TRICOM-1R, is a three-unit CubeSat with a mass of just three kilograms (7 lb). The satellite is a re-flight of the TRICOM-1 mission, which was lost in SS-520’s failure last year.

[...]Two minutes and 37 seconds after liftoff, a check of the vehicle’s status will have been conducted. This serves two purposes: to ensure that the rocket is in good health and able to continue to orbit, and to determine the optimal time for second stage ignition. If the mission was continuing to plan, a command to enable second stage ignition and a revised ignition time will have been transmitted to the vehicle seven seconds later. Should it have been necessary to terminate the launch this command will not have been sent to the rocket, which prevents the second stage from igniting and the rocket would then fall into the drop zone that had been reserved for the first stage.

The exact timing of second stage ignition depends on the vehicle’s trajectory when the status check is undertaken, however the burn would have begun at around the three-minute mark in the flight and lasted for 24.4 seconds. After the burn ended, the second stage will have remained attached for about 30 seconds before it separated, with third stage ignition taking place three seconds after separation. The third stage burn is for 25.6 seconds, injecting itself and TRICOM-1R into orbit.

The SS-520 was expected to reach an orbit of approximately 180 by 1,500 kilometers (112 by 932 miles, 97 by 810 nautical miles), with inclination of 31 degrees. TRICOM-1R was to separate from the SS-520’s third stage seven minutes and thirty seconds after liftoff. Unusually for a CubeSat, TRICOM-1R does not use a deployment pod and separates directly from the rocket’s upper stage.

SS-520 sounding rocket



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