TOKYO — The Japan Aerospace Exploration Agency (JAXA) and Mitsubishi Heavy Industries (MHI) are set to begin work on upgrades to the H-2A and H-2B rockets that will boost their performance and enhance their appeal to a commercial launch market that to date has proved elusive, according to officials with both organizations.
The planned upgrades will come in two stages, with Phase 1 funded at about $100 million and set to begin in April, Teiu Kobayashi, manager at JAXA’s Space Transportation Mission Directorate, said March 1. Phase 1 will make changes to the upper stage used on both vehicles to improve their ability to deliver satellites to geostationary transfer orbit, he said.
Phase 2, which is not yet fully funded, would replace the LE-7A main-stage engine for the H-2A and H-2B with an improved variant dubbed LE-X featuring improved performance and reliability, Kobayashi said. The funding and schedule of the Phase 2 upgrades will not be decided before this summer, he said.
JAXA and MHI, the lead contractor on the H-2A and H-2B, have long had commercial ambitions for those vehicles but have yet to find any takers for a variety of reasons, including cost and restrictions, which recently were lifted, that limited launches from Japan’s Tanegashima Space Center to two relatively brief periods each year. The Phase 1 improvements are intended to broaden the vehicles’ commercial market appeal by enabling them to leave communications satellites in better position to reach their final geostationary-orbit destinations.
The program calls for modifying the restartable LE-5B upper-stage engine to allow its thrust to be throttled back to 60 percent of capability during missions. With this throttling capability, the stage will be able leave satellites closer to their final geostationary orbit, meaning they will have to consume less on-board fuel to get there.
The fuel savings will extend the operational lifetime of geostationary satellites launched on upgraded versions of the H-2A and H-2B for three to five years over those launched aboard current versions of the vehicles, Kobayashi said. Satellites must consume fuel to maintain their positions in geostationary orbit 36,000 kilometers above the equator.
The first launch of the so-called H-2A Upgrade is planned for early in 2013.
Shoichiro Asada, general manager of the Space Systems Department at MHI, said while the improvement will not actually lower launch costs, it will make the H-2A more appealing to the commercial market.
“Our customers require us to meet international standards for satellite lifetimes, and this has recently climbed to more than 15 years. With this improvement, the H-2A will become able to launch heavier satellites while keeping the 15-year lifetime requirement,” Asada told Space News, March 2.
The upgrade is part of the Basic Plan for Space Policy drawn up in June 2009 that gives direction to Japan’s space development over five- and 10-year time frames and requires the Japanese government to provide financial support to improve the commercial competitiveness along with the performance and safety of the H-2A, Kobayashi said.
Planned Phase 1 improvements also include:
- Measures to limit upper-stage fuel evaporation during extended operation, including a new exterior coating and inducing a slow, uniform roll of the vehicle.
- Improved thermal protection of the avionics and other on-board systems, and enhanced radio links and navigation sensors.
- A new payload release mechanism to give satellites a gentler ride.
Meanwhile, JAXA and MHI are busy testing prototype components for the LE-X engine, which passed its preliminary design review in August, Kobayashi said.
