Japan’s Epsilon launches with SPRINT-A

by William Graham

Japan’s Epsilon rocket has made its maiden launch carrying JAXA’s SPRINT-A ultraviolet astronomy satellite early on Saturday morning. Liftoff from the Uchinoura Space Centre was delayed from last month after the first launch attempt was scrubbed due to issues during the latter part of the countdown.


Japanese Launch Overview:

Epsilon, which will replace the M-V rocket which was retired in 2006, is a three or four stage rocket which combines upper stages used on the M-V with a first stage derived from the H-IIA’s strap-on boosters. It is the latest in a line of solid-fuelled orbital launch systems operated by Japan, following the Lambda and the Mu.

Historically, Japan had two space agencies, each with its own fleet of rockets. The Institute of Space and Astronautical Science, or ISAS, developed small solid-fuelled rockets, while the National Space Development Agency, or NASDA, opted for larger, liquid-fuelled vehicles.

NASDA and ISAS, along with Japan’s National Aerospace Laboratory, merged in 2003 to form the Japan Aerospace Exploration Agency, or JAXA. ISAS operated the Lambda and Mu rockets from the Uchinoura Space Centre, while NASDA flew the N and H from Tanegashima.

ISAS’ Labmda-4S rocket, which was built in cooperation with Nissan, was used for Japan’s early attempts to orbit a satellite. Derived from the Lambda series of sounding rockets, which first flew in 1963, the first attempt to orbit a satellite occurred on 26 September 1966; failing to achieve orbit due to a fourth stage attitude control problem.

Further launches in December 1966, April 1967 and September 1969 also failed, before at the fifth attempt a Lambda-4S orbited Osumi on 11 February 1970, making Japan the fourth country to place a satellite into orbit – following the Soviet Union, United States and France.

The Lambda-4S was retired following the launch of Osumi, however launches of the Lambda as a sounding rocket continued until 1977. In its place, ISAS began operating the Mu family of rockets for orbital launches.

Following two test flights in the late 1960s, the first operational version of the Mu, the Mu-4S, made the type’s first orbital launch attempt on 25 September 1970. That launch failed to achieve orbit after the fourth stage failed to ignite, however another Mu-4S successfully deployed the Tansei 1 satellite in February 1971.

In total the four-stage Mu-4S, which consisted of eight SB-310 boosters, and M-10, M-20, M-30 and M-40 stages, made four flights with just the one failure, before it was replaced by the three-stage Mu-3C.

The Mu FamilyThe Mu-3C replaced the M-20 second stage of the Mu-4S with an M-22; which incorporated a vectorable nozzle. The third stage was replaced with an M-3A, while the fourth stage was no longer required. Following its first flight in February 1974 with Tansei-2, the Mu-3C also launched the Taiyo satellite successfully, before its third flight in February 1976 failed to place CORSA-A into orbit.

A new variant, the Mu-3H, with a lengthened M-13 first stage, flew in February 1977, successfully making three launches. In February 1979 a fourth and final Mu-3C orbited a replacement for CORSA-A; CORSA-B or Hakucho.

ISAS’ next rocket, the Mu-3S, was similar to the Mu-3H but incorporated thrust vector control on the first stage. Four were launched between 1980 and 1984, all successfully, before the Mu-3S-II replaced it.

The Mu-3S-II retained the first stage of the Mu-3S, however the eight SB-310 boosters were replaced with a pair of larger SB-735s, and the second and third stages were replaced by an M-23 and an M-3B respectively. In its eight flights, the Mu-3S-II deployed, in addition to Earth-orbit scientific payloads, Japan’s first missions to the Moon and beyond.

The maiden flight of the Mu-3S-II in January 1985 carried Sakigake, the first of two Japanese probes in the “Halley Armada” which visited the comet 1P/Halley when it passed through the inner solar system in 1986. The second probe, Suisei, was the payload for the next launch seven months later. The fifth Mu-3S-II launch carried the Hiten and Hagoromo spacecraft, which visited the Moon.

The final flight of the Mu-3S-II occurred on 15 January 1995, with the EXPRESS microgravity research satellite. An attitude control system failure on the second stage resulted in the spacecraft being deployed into a far lower orbit than had been planned. With a perigee of only 110 kilometers (68 mi, 59 nmi), EXPRESS decayed from orbit before completing a single revolution; reentering over Ghana.

The Mu-3S was replaced by the Mu-5, more commonly known as the M-V. A three-stage rocket, it consisted of M-14, M-24 and M-34 stages, with the M-24 being replaced with an M-25 from the fourth flight onwards. For some launches a fourth stage; either a KM-V1 or KM-V2; was used however this was considered part of the payload.

The M-V made its maiden flight on 12 February 1997, carrying the Haruka (MUSES-B) radio astronomy satellite which used a KM-V1 upper stage to reach its highly elliptical orbit.

The second M-V launch carried Nozomi, Japan’s first attempt to send a probe to Mars. Like Haruka, Nozomi was equipped with a KM-V1 upper stage. Despite its successful launch, Nozomi failed to complete its mission after problems with its fuel supply.

M-V LaunchThe M-V’s third flight, in February 2000, was its only launch failure. The rocket went out of control 41 seconds after launch and flew off course. After first stage separation, the second and third stages fired normally, however the ASTRO-E satellite could not be injected into orbit.

M-V launches resumed in 2003 with the launch of the Hayabusa mission to asteroid (25143) Itokawa. Conducted on 9 May, the Hayabusa launch was the last conducted by ISAS before it became part of JAXA on 1 October. JAXA’s first M-V launch came on 10 July 2005 with Suzaku, or ASTRO-E2, a replacement for the failed ASTRO-E.

In February 2006, the Akari or ASTRO-F spacecraft was deployed along with two secondary payloads; CUTE-1.7+APD and SSSat-1, however this marked the penultimate flight of the M-V, which retired that September with the launch of Hinode, or SOLAR-B, along with HITSAT-1 and SSSat-2.

The M-V had a high cost per launch for its payload capacity, making it uneconomical for JAXA to continue operating it. Since its retirement, Japan has launched its small research satellites as secondary payloads on H-IIA launches, or on foreign rockets.

In the 1990s NASDA and ISAS attempted to develop an alternative, the J-I, using the second and third stages of the Mu-3S-II, with a first stage derived from the solid rocket motors used on the H-II rocket. Only one was launched, using a two stage configuration with a suborbital hypersonic research payload.

In concept, the Epsilon is similar to the J-I, combining the upper stages of the Mu with a first stage derived from the boosters used by the liquid-fuelled rocket of the era; in this case the H-IIA rather than the H-II. The H-IIA was developed to reduce costs and improve reliability over the H-II, which was retired in 1999 after seven launches.

The H-IIA incorporated refined first and second stages, re-engined with LE-7A and LE-5B engines respectively. The H-II’s two large boosters were replaced with two or four of the smaller SRB-A, with some configurations – all of which have now been retired – using additional Castor-4AXL boosters to further augment first stage thrust.

A modified version of the SRB-A, the SRB-A2 was in development in 2005, however following a launch failure on the sixth H-IIA flight caused by an SRB-A failing to separate, the design was modified and these modifications superseded the SRB-A2. From the fourteenth launch, which orbited the Ibuki, or GOSAT, climate research satellite in 2009, the SRB-A3 has replaced the modified SRB-A.

Four SRB-A3s are also used on the H-IIB rocket, which has made four flights – the most recent earlier this month with the Kounotori 4 spacecraft bound for the ISS. In total, 32 SRB-A3s have been launched, in eight H-IIA and four H-IIB missions.

EpsilonWhile used as a booster rocket on the H-IIA and H-IIB, the SRB-A3 forms the first stage of the Epsilon. The second stage is an M-34c, adapted from the M-34 flown as the third stage of the M-V. A KM-V2b is used as the third stage – derived from the KM-V2 upper stage used during the Hayabusa launch – although in use on the M-V the KM-V upper stages were considered part of the payload rather than part of the rocket.

This three-stage all-solid rocket is the standard configuration for Epsilon, and is capable of placing 1,200 kilograms (2,600 lb) of payload into a 250 by 500 kilometer (155 by 310 statute mile; 135 by 270 nautical mile) orbit.

JAXA has also developed a four-stage configuration, with a liquid-fuelled Compact Liquid Propulsion System as the fourth stage – designated a “Post Boost Stage” by JAXA.

The four-stage configuration was used for the launch. It can place a 700 kilogram (1,500 lb) payload into a minimum-inclination circular orbit at 500 kilometres altitude, or a 450 kilogram (1,000 lb) payload into the same orbit at a sun-synchronous inclination.

Launch ProfileOnce the countdown reached zero, the SRB-A ignited, beginning the Epsilon’s debut launch. The rocket flew an azimuth of 112 degrees, with the first stage burn lasting 112 seconds.

Following burnout, the vehicle coasted for 53 seconds before second stage ignition. During that time, two important events occurred; the payload fairing, which encapsulates the second, third and fourth stages as well as the satellite, separated 15 seconds before ignition with the first stage jettisoned eleven seconds later; four seconds before stage two ignition.

Ignition of the second stage occurred 148 kilometers downrange at an altitude of 162 kilometers (92.0 and 101 statute miles, 79.9 and 87.5 nautical miles, respectively), with the vehicle travelling at a velocity of 2,400 meters per second (5,370 mph).

StagingThe second stage burn lasted for 102 seconds and its burnout four minutes and 27 seconds after liftoff followed by a second, longer, coast phase. Nine minutes and 57 seconds later, the second stage separated, in preparation for third stage ignition four seconds later.

The third stage burn lasted 89 seconds, increasing the vehicle’s velocity to 7.5 kilometers per second (16,800 mph). Separation of the third stage came four minutes and 51 seconds after the stage was all-burnt, with the fourth stage igniting to begin the first of two planned burns 140 seconds after staging.

This burn lasted ten minutes and 58 seconds, concluding two seconds short of the half-hour mark in the flight.

The fourth stage and payload then coasted for twenty three minutes and 52 seconds, before the start of the stage’s second burn. Six minutes and forty seconds after ignition, the fourth stage engine cut off once more, concluding powered flight. Spacecraft separation occurred 70 seconds later, 61 minutes and 40 seconds after liftoff.

The target orbit for the deployment of SPRINT-A is 950 by 1,150 kilometers (590 by 715 statute miles; 510 by 620 nautical miles), with an inclination of 31 degrees and a period of 106 minutes.

SPRINT-AA 340 kilogram satellite, SPRINT-A has dimensions of four meters by one meter by one meter (13 by 3 by 3 feet), and will be powered by two solar arrays generating 900 watts of power. With its solar arrays extended, SPRINT-A will have a span of seven meters (23 feet). The satellite is three-axis stabilized, and expected to operate for at least a year.

SPRINT-A, Spectroscopic Planet Observatory for Recognition of Integration of Atmosphere, is an ultraviolet astronomy satellite dedicated to studying the magnetospheres and atmospheres of other planets in the Solar system. It will focus on Mercury, Jupiter and Saturn for magnetospheric research, and Venus and Mars for atmospheric research. The satellite’s primary instrument is an extreme UV spectrometer

SPRINT-A is the first satellite in JAXA’s Small Scientific Satellite project, which aims to reduce the cost and development time for small satellite missions by introducing a standard, modular bus. JAXA aims to launch three such satellites every five years, using the Epsilon rocket to deploy them in order to provide greater flexibility compared to launching as a secondary payload on an H-IIA flight. SPRINT-A is based on the NEXTAR NX-300L bus developed by NEC.

Kagoshima Space CentreThe launch took place from the Uchinoura Space Centre. Known until 2003 as the Kagoshima Space Centre, Uchinoura was the site of Japan’s first satellite launch in February 1970 with a Lambda-4S carrying Osumi, following four failed attempts in as many years. No orbital launches have been conducted from the centre in almost seven years, since the retirement of the M-V in September 2006.

Epsilon’s launch pad at Uchinoura was originally built in the 1960s for the Mu family of rockets. It was first used for the single flight of the Mu-1 rocket, an atmospheric test vehicle which reached an apogee of 34 kilometres (21 miles) in October 1966.

A suborbital launch was conducted from the pad in August 1967 with a Mu-3D, before the first orbital attempt from the pad, and the first attempted orbital launch of a Mu rocket, was made using a Mu-4S in September 1970; the first successful launch came five months later.

The Launch ComplexThe launch complex consists of a tower, in which the rocket is integrated vertically, and a launcher. Prior to launch, doors on the corner of the tower open, and the launcher rotates to bring the rocket out onto the pad. During its operational life the pad has been modified, with an additional level being added to the tower for the M-V.

For Epsilon, the launcher has been modified extensively to support a vertical launch configuration instead of the rail-launched Mu. The Mu’s launch rail has been adapted to serve as an umbilical tower.

In addition to the lone Mu-1 and Mu-3D launches, the Mu pad at Uchinoura was used by four Mu-4S, four Mu-3C, three Mu-3H, four Mu-3S, eight Mu-3S-II and seven M-V rockets. The Epsilon is the thirty-third rocket to fly from the pad, making the thirty-first orbital attempt from it.

It was the thirty-sixth orbital launch attempt from Uchinoura; five Lambda-4S carrier rockets were launched from a nearby pad shared by the Lambda and Kappa sounding rockets.

The launch was the third of four planned Japanese launches in 2013, following January’s launch of a pair of reconnaissance satellites on an H-IIA, and the launch of Kounotori-4 to the ISS by an H-IIB earlier this month. Japan’s next scheduled launch is planned for December, with an H-IIA orbiting the ALOS-2 radar imaging satellite along with several secondary payloads.

The next Epsilon launch is expected to occur in 2015, with the SPRINT-B. Another launch, with the ASNARO-2 satellite, is currently under evaluation.

(Images via JAXA and Historical).

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