The development aim is to reduce costs compared to the launch cost of an M-V. The Epsilon costs per launch, which is half the cost of its predecessor. Development expenditures by JAXA exceeded. To reduce the cost per launch the Epsilon uses the existing SRB-A3, a solid rocket booster on the H-IIA rocket, as its first stage. Existing M-V upper stages will be used for the second and third stages, with an optional fourth stage available for launches to higher orbits. The J-1 rocket, which was developed during the 1990s, but abandoned after just one launch, used a similar design concept, with an H-II booster and Mu-3S-II upper stages. The Epsilon is expected to have a shorter launch preparation time than its predecessors. Due to a function called "mobile launch control", the rocket needs only eight people at the launch site, compared with 150 people for earlier systems. The rocket has a mass of and is tall and 2.5 metres in diameter.
Enhanced version
After the successful launch of the Epsilon first flight, the improvement plan was decided to handle the planned payloads. Requirements for the improvement:
Epsilon's first stage has been the modified SRB-A3 which is the solid-rocket booster of H-IIA. As the H-IIA is to be decommissioned and to be replaced by H3, Epsilon is to be replaced by new version, named Epsilon S. Major changes of Epsilon S from Epsilon are:
The first stage is based on SRB-3, the strap-on solid-rocket booster of H3.
The third stage is a new design, whereas Epsilon's third stage was based on the M-V's third stage. New third stage is three-axis stabilized using Post-Boost Stage, whereas Epsilon's third stage was spin-stabilized. Also the third stage is outside the fairing, whereas Epsilon's fairing covered the third stage.
The Post-Boost Stage is mandatory, whereas Epsilon's PBS was optional.
Planned performance of Epsilon S is:
Sun-synchronous orbit : ≧ 600 kg
Low-earth orbit : ≧ 1400 kg
The first launch of Epsilon S is planned in 2023.
Launch statistics
Launch outcomes
Launch history
Epsilon rockets are launched from a pad at the Uchinoura Space Center previously used by Mu rockets. The maiden flight, carrying the SPRINT-Ascientific satellite, lifted off at 05:00 UTC on September 14, 2013. The launch was conducted at a cost of $38 million. On August 27, 2013, the first planned launch of the rocket had to be aborted 19 seconds before liftoff because of a botched data transmission. A ground-based computer had tried to receive data from the rocket 0.07 seconds before the information was actually transmitted. The initial version of Epsilon has a payload capacity to low Earth orbit of up to 500 kilograms, with the operational version expected to be able to place into a orbit, or to a circular orbit at with the aid of a hydrazine fueled stage.
In November 2012, JAXA reported that there had been a possible leak of rocket data due to a computer virus. JAXA had previously been a victim of cyber-attacks, possibly for espionage purposes. Solid-fuel rocket data potentially has military value, and Epsilon is considered as potentially adaptable to an intercontinental ballistic missile. The Japan Aerospace Exploration Agency removed the infected computer from its network, and said its M-V rocket and H-IIA and H-IIB rockets may have been compromised.
