Tuesday, December 26, 2017

Japan Launches H-IIA Rocket with Two Earth-Observing Satellites

An HII-A rocket carrying GCOM-C1 and SLATS satellites launches from Tanegashima Space Center on December 23. Photo Credit: Mitsubishi Heavy Industries, Ltd./JAXA

An H-IIA rocket took to the skies on Saturday, December 23, carrying GCOM-C1 (nicknamed SHIKISAI) and SLATS (dubbed TSUBAME) Earth-observing satellites. The liftoff occurred at 10:26 a.m. local time (8:26 p.m. EST on December 22) from the Yoshinobu Launch Complex at the Tanegashima Space Center in Japan.

Countdown campaign for the launch commenced about 14 hours before the planned liftoff when the H-IIA booster was rolled out to the launch pad. Both satellites were encapsulated in a protective payload fairing and attached to the launch vehicle one day earlier.

Few hours ahead of the launch, last testing operation began and the rocket was filled with propellants. All the pre-launch preparations led to the ignition of the LE-7A engine some five seconds before liftoff.

The rocket thundered off from the pad when its twin SRB-A boosters were ignited and the launch vehicle commenced a short vertical ascent. Afterward, the H-IIA rocket turned south-east and started heading over the Pacific Ocean.

The two boosters powered the mission for the first one and a half minutes and were separated 17 seconds after their burnout. Then, some four minutes and five seconds into the flight, the payload fairing was detached what unveiled the mission’s duo of passengers. About two minutes and 39 seconds later, the rocket’s first stage was also separated and the second stage took control over the mission for the rest of the flight.

The second stage ignited its LE-5B engine nearly seven minutes after liftoff and was shut down some eight minutes later. The first shutdown of the second stage cleared the way for the separation of the GCOM-C1 satellite at T+16:21 minutes.

Next, the longest phase of the mission started during which the LE-5B engine conducted two more bursts. The second stage was shut down for the final time at nearly one hour and 47 minutes into flight. Slightly more than one minute later, the SLATS spacecraft was released into orbit.

GCOM-C1 was placed into an approximately circular sun-synchronous orbit (SSO) at an altitude of 496 miles (798 kilometers), inclined by 98.6 degrees. SLATS was delivered to a low-Earth orbit (LEO) at an altitude of 112 by 167 miles (180 by 268 kilometers).

“JAXA received telemetry data from SHIKISAI and TSUBAME, confirming that their satellite attitude control system had transitioned to the steady state. Current status of both satellites is stable,” Japan Aerospace Exploration Agency (JAXA) said in a press release.

Weighing around two metric tons, GCOM-C1 (Global Change Observation Mission - Climate "SHIKISAI") has dimensions of 15 by 53.4 by 9.2 feet (4.6 by 16.3 by 2.8 meters). It is equipped in the SGLI (Second generation GLobal Imager) optical instrument, collecting data related to the carbon cycle and radiation budget, such as measurements of clouds, aerosols, ocean color, vegetation, and snow and ice. The satellite generates power of 4 kW and its design lifetime is five years.

GCOM-C1 is part of the Global Change Observation Mission project, which main goal is the global, long-term observation of Earth's environment. JAXA expects that GCOM will play an important role in monitoring both global water circulation and climate change, and examining the health of Earth from space. First satellite of the GCOM project, GCOM-W1 (Global Change Observation Mission - Water "SHIZUKU") was launched into space in May 2012.

SLATS (Super Low Altitude Test Satellite "TSUBAME") is the first Earth observation satellite to use a super low orbit - with an altitude lower than 186 miles (300 kilometers). The spacecraft weighs around 880 lbs. (400 kilograms) and its dimensions are: 8.2 by 17 by 2.9 feet (2.5 by 5.2 by 0.9 meters). The satellites is designed to be operational for at least two years.

SLATS is a technology demonstrator designed to test the feasibility of operating satellites in a super low orbit for exploitation in Earth observation and atmospheric science. It will use the ion engine technology developed by JAXA in order to verify its technology for orbit control at super low altitudes. Besides photographing the Earth, the spacecraft will also collect technical data related to the atmosphere, which will be used in the design of future satellites.

The 174-feet (53-meters) tall HII-A is a two-stage booster operated by Mitsubishi Heavy Industries for JAXA. With a mass of about 445 metric tons, its heaviest variant is capable of launching up to 15 metric tons to LEO and six metric tons to geostationary transfer orbit (GTO). The rocket’s maiden flight was took place in August 2001.

Saturday’s launch was the seventh orbital flight for Japan and the sixth liftoff from Tanegashima in 2017.

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