The Japanese space agency JAXA has launched a new version of its Epsilon launch vehicle called Epsilon 2 which uses upgraded second and third stages. The launch took place from Kagoshima (Uchinora Space Centre) at 1100 GMT on 20 December.
On board was a satellite called ERG which was accurately placed into a highly elliptical orbit of 32,259 km x 228 km at an inclination of 31.4 degrees (figures from Stratcom via Jonathan McDowell).
The ERG (Exploration of Energization and Radiation in Geospace) mission is designed to pass through the Earth’s Van Allen radiation belts and use its instruments and 30 m long antennae to measure the interaction of the Earth’s magnetic fields with charged particles and any waves produced. The spacecraft has the alternative Japanese name “Arase” meaning rough water.
The launch was the first of the new Epsilon 2 variant. The first stage of both the Epsilon 1 and Epsilon 2 launch vehicles use a modified SRB-A3 solid rocket booster taken from the H-2A rocket.
While second stage of the Epsilon 1 launcher used a modified version of the solid-propellant third stage of the M-V launcher, called M-34c, the second stage of the Epsilon 2 uses a larger M-35 solid rocket engine with a fixed nozzle.
The third stage of the Epsilon 1 launcher is called KM-V2b. This is a solid-propellant, modified version of the fourth (kick motor) stage used on the M-V launcher. The third stage of the Epsilon 2 uses the KM-V2c solid engine but has a fixed nozzle instead of the KM-V2b’s extendable one. The third stage is designed to tumble after separation to reduce the chance of collision with payload or fourth stage.
While the earlier launch of the Epsilon 1 was in a four stage configuration using the optional Compact Liquid Propulsion Stage (CLPS), this flight only used three stages.
