Epsilon-1 Flies: New Japanese Rocket Launches SPRINT-A Ultraviolet Observatory Into Orbit

Japan's Epsilon vehicle represents a marriage of technology from the H-IIA and M-V rockets. Image Credit: JAXA
Japan’s Epsilon vehicle represents a marriage of technology from the H-IIA and M-V rockets. Image Credit: JAXA

Good things come to those who wait, and success has finally visited the Japan Aerospace Exploration Agency (JAXA) with a rousing launch of its first Epsilon rocket from the Uchinoura Space Center in Kagoshima Prefecture. Liftoff of the 78-foot-tall vehicle occurred at 2 p.m. Japan Standard Time (1 a.m. EDT) Saturday, following a slight delay, and at the time this article was being prepared the mission seemed to be proceeding without incident. The Epsilon will deliver JAXA’s 700-pound Spectroscopic Planet Observatory for Recognition of Interaction of Atmosphere (SPRINT-A) into low-Earth orbit to observe Venus, Mars, and Jupiter with ultraviolet spectrometers and guiding cameras.

Originally scheduled to fly on 27 August, the first launch attempt was scrubbed due to “an attitude abnormality” with the Epsilon vehicle. The glitch arose about 19 seconds ahead of liftoff, during the automatic countdown sequence, and JAXA engineers spent more than two weeks addressing the root cause. On 5 and 8 September, they conducted a pair of launch simulations to resolve a “time-synching” glitch between the ground and on-board computers. The successful completion of this work was confirmed Thursday, 12 September when JAXA formally announced the Saturday target launch date.

With spectators at the Uchinoura Space Center reportedly numbering around 20,000, today’s launch was expected to occur at the start of a 45-minute “window,” which opened at 1:45 p.m. JST (12:45 a.m. EDT). According to NASASpaceflight.com, this was finely adjusted by JAXA in the final hour of the countdown, and the precise liftoff time was shifted by 15 minutes to the right. Launch got underway with the ignition of the Nissan-built solid-fueled rocket motor on Epsilon’s first stage, which produced an estimated 505,000 pounds of thrust. The first stage is a modified version of the Solid Rocket Booster (SRB) from Japan’s H-IIA rocket. This burned for about two minutes, after which the vehicle coasted for almost a minute and the payload fairing was jettisoned, ahead of first-stage separation, at T+2 minutes and 40 seconds.

The SPRINT-A satellite undergoes final checkout, ahead of its scheduled launch aboard the first Epsilon rocket. Photo Credit: JAXA/ISAS
The SPRINT-A payload for today’s mission undergoes pre-flight checkout. Photo Credit: JAXA/ISAS

The turn then came of the Epsilon’s second stage, which is powered by a modified variant of the M-34 upper stage from the 2006-retired M-V launch vehicle. This burned perfectly for almost two more minutes, by which time the vehicle had reached an estimated velocity of 11,400 mph and a downrange distance of more than 250 miles east of Uchinoura. The Epsilon coasted for a further six minutes, preparatory to second-stage separation and the ignition of the third stage—whose engine is based upon the KM-V2b upper stage, also from M-V rocket heritage—at T+10.5 minutes. It burned for 89 seconds and upon its shutdown the vehicle coasted for six more minutes.

With the separation of the third stage at 2:16 p.m. JST (1:16 a.m. EDT), about 16 minutes and 50 seconds after liftoff, the final role fell to the Post-Boost Stage (PBS). Unlike the Epsilon’s lower three stages—all of which are solid-fueled—the liquid-fed PBS utilizes hydrazine and was tasked with two “burns” to inject the SPRINT-A satellite into orbit. The first of these burns began about 19 minutes after launch and lasted for almost 11 minutes, shutting down at 2:30 p.m. JST (1:30 a.m. EDT). By now in a “parking orbit,” the combo coasted for almost 30 minutes, before the PBS ignited again at T+54 minutes to begin the insertion of SPRINT-A into its desired orbital slot.

Burning for six minutes, the second PBS burn ended at 3 p.m. JST (2 a.m. EDT), exactly an hour after liftoff, by which time the payload was in an orbit with a “high point” (or “apogee”) of 714 miles and a “low point” (or “perigee”) of about 590 miles, inclined 31 degrees to the equator. Separation of SPRINT-A from the PBS was confirmed at 3:01:40 p.m. JST (2:01:40 a.m. EDT), about 61 minutes and 40 seconds into the flight … and precisely as advertised in JAXA’s pre-mission press kit.

Described by its project manager as a vehicle which will literally “open up the future,” the Epsilon stands 78 feet tall and marries one Solid Rocket Booster (SRB) from Japan’s H-IIA rocket with upper-stage hardware from the 2006-retired M-V launcher. The Epsilon is reportedly capable of lofting up to 2,600 pounds of payload into low-Earth orbit, but its maiden flight was already delayed by five days past 22 August, as JAXA needed additional time to resolve a problem surrounding an incorrect line routing in the signal relay equipment used to check the rocket’s critical functions. The launch attempt on 27 August proceeded relatively smoothly until the last-minute scrub.

Artist's impression of the SPRINT-A extreme ultraviolet observatory in low-Earth orbit. Image Credit: NASA
Artist’s impression of the SPRINT-A extreme ultraviolet observatory in low-Earth orbit. Image Credit: NASA

It is the cost savings—estimated to be about 30 percent better than the M-V—which JAXA is particularly keen to stress about the new Epsilon. Saturday’s flight was estimated to cost 5.3 billion yen ($53 million), significantly lower than the 7 billion yen ($70 million) for an M-V, and such savings have been made primarily through the streamlining of launch procedures. It is anticipated that subsequent Epsilon launches may bring costs still lower, into the 3.0-3.8 billion yen ($30-38 million) bracket.

Japan has been flying solid-fueled “pencil” rockets since the mid-1950s, and Epsilon stands firmly upon the shoulders of previous titans, as well as utilizing new, cutting-edge technology. “We aim to greatly simplify the launch system by using artificial intelligence,” said Project Manager Yasuhiro Morita, quoted in a JAXA interview. Morita is a professor in the Department of Space Systems and Astronautics with the Institute of Space and Astronautical Science (ISAS), a subdivision of JAXA. “Today, a typical scenario is hundreds of people assembling at the launch center and working for several months in preparation for a launch. On the day of the launch, dozens of people are in the control room, monitoring every aspect. The Epsilon launch vehicle will drastically change this picture.” By running autonomous health and other checks, supported by artificial intelligence, it is hoped that control personnel with ultimately be able to run the whole show from a pair of laptop computers.

“Rockets use technology from many generations ago,” explained Morita, “so they are like a showcase of deficiencies. There has long been a notion that new technology should be tested over an extended period of time before being used in actual launch vehicles. Consequently, the latest artificial intelligence applications have not yet been employed in rockets. The Epsilon launch vehicle will be the first rocket with artificial intelligence that will perform checks and monitor its own operation autonomously.”

Moving forward from desktop and laptop computers, it is Morita’s hope that by 2017 the Epsilon will be in a position to “monitor and judge its own flight safety autonomously, so that we can remove the radar and antenna used to track and send commands to the rocket.” By assigning further artificial intelligence assets to the vehicle—including the capability to act as its own Range Safety Officer and destroy itself in the event of off-nominal events—the Epsilon will eliminate the need for expensive, ground-based hardware and further simplify launch and tracking facilities.

As the maiden flight of the Epsilon, Saturday’s mission has attracted a great deal of publicity, both in Japan and around the world. In April-May 2013, it was the subject of a New Launch Vehicle Message Posting Campaign. Some 5,812 messages—the vast majority in Japanese and a few hundred in other languages—were received as part of an effort to share individuals’ “expectations, hopes, dreams, or feelings toward our new launch vehicle.” JAXA then processed these messages into strings of small letters on the Epsilon itself, in order to “make people feel more familiar with space, gaining more understanding of and support for space programs.” According to JAXA, this was a key goal of the Epsilon project.

Testing and processing of the new rocket has gone relatively smoothly, with its upper stage motor static-fired in September 2011 to evaluate the performance of insulation material, followed by last October’s extension test of the second stage motor nozzle. More recently, in April 2013, it was reported that a full-scale model of Epsilon had been transferred from the maintenance tower to the launch pad to demonstrate rollout and other pre-launch protocols.

The satellite is expected to operate for about a year in an orbit of 590-715 miles, inclined 31 degrees to the equator, from which it will observe the magnetospheric environments of Venus, Mars, and Jupiter. “Capturing the extreme ultraviolet rays emitted from a planet and its periphery, which cannot be observed from the ground, allows us to collect information on the atmosphere that flows into space and the magnetosphere covering the planet,” noted JAXA in its SPRINT-A mission brochure. “This enables us to analyze the composition of the atmosphere and the behavior of the magnetosphere. Our primary theme is each planet’s magnetosphere, the region where the magnetic field of a planet has influence.” Jupiter’s magnetic field is 10,000 times stronger than that of Earth and rotates on its axis at a high rate of around 10 hours per cycle, whereas those of Venus and Mars are far weaker. SPRINT-A will focus on the interactions between planetary magnetospheres and the solar wind.

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