TOKYO — Japan’s workhorse H-2A rocket, having undergone a top-to-bottom review and significant modifications following a November 2003 failure, is set to return to flight Feb. 24 carrying a government weather and air traffic control satellite.
A successful launch will validate the corrective actions and, perhaps more importantly, enable Japan to get on with the future of its space program, according to government and industry space officials here. Another failure, either in this launch or the five planned thereafter, could ignite a debate over the future of the program, one expert observer said.
The last H-2A launch ended in failure after one of the vehicle’s Solid Rocket Booster-A (SRB-A) strap-on motors suffered a burn-through in the throat of its nozzle. The burn-through damaged the H-2A’s SRB-A separation system, and the vehicle, unable to jettison the weight of the spent booster, was ordered destroyed after range safety engineers determined it would not reach orbit. The failure destroyed a pair of high-priority imaging satellites — one optical and one radar — that were to be part of a four-satellite constellation intended to keep tabs on North Korean military activities.
Since April 2004, a 15-member committee headed by Japan Space Activities Commission member Hiroki Matsuo has worked with the Japan Aerospace Exploration Agency (JAXA) and H-2A lead contractor Mitsubishi Heavy Industries Ltd. to get the vehicle flying again. The government-industry team has made four major changes to the SRB-A, said Kimikazu Iwase, director of the Space Development and Utilization Division at the Ministry of Education, Culture, Sports, Science and Technology, which oversees the space program.
The modifications included switching from a conical to a bell-shaped nozzle to better handle the exhaust plume stresses; increasing nozzle thickness; extending the nozzle’s carbon-carbon composite heat shielding into the booster’s throat; and reducing the booster’s burn pressure.
The modified SRB-A will fire for 120 seconds, 20 seconds longer than before, to compensate for the 23 percent reduction in burn pressure, Takanobu Suito, deputy director of the science ministry’s Space Policy Division, said in a Feb. 16 interview.
Following extensive ground tests, the ministry and JAXA are convinced of the modified SRB-A’s reliability, Iwase said in a Feb. 16 interview. “We have made a full study and evaluation of the tests, reported them to the expert committee and have concluded that the booster is fully certified. We really feel we have done all that we can do and that everything that had to be done, has been done,” he said.
Other SRB-A improvements included moving power-distribution and control wiring to a safer location away from the booster nozzle , and improved production and inspection processes, Koichi Matsuyama, manager of the Space Systems Department at Tokyo-based Mitsubishi Heavy Industries, said in an e-mail response to questions. Numerous other H-2A systems and subsystems were reviewed leading to 23 additional changes, most of which were relatively minor, Suito said. These included telemetry and avionics upgrades as well as control-box circuitry changes on the H-2A’s LE-5B second-stage engine, government and industry officials said.
“After a long wait and a lot of hard work, I am convinced that we will be successful,” said Yoshiharu Kurihara, deputy general manager of Mitsubishi’s Space Systems Department.
Kazuto Suzuki, an assistant professor at the University of Tsukuba near Tokyo and an expert on Japanese space activities, said JAXA has more at stake in the upcoming launch than the payload, the MTSAT-1R weather and air traffic control satellite built by Space Systems/Loral of Palo Alto, Calif.
“They’ve done a lot of changes to the design of the SRB-A and they’ve had extensive testing and, from my observation, JAXA is quite confident they are going to be successful,” Suzuki said in a Feb. 14 interview. “But there are half a million pieces in that rocket, and they keep on saying that they are confident and they fail. Their credibility is at stake.”
So too might be Japan’s future in the launch business, Suzuki said. “You cannot say another failure will be a disaster,” he said. But it “would cause unrecoverable damage … a failure could cause Japan to make a strategic choice between independent launch capability or not,” he said.
Also riding on the upcoming launch — and subsequent missions — are Japan’s future space plans, which have been held up by the failure and investigation. Among them is the privatization of the H-2A program under Mitsubishi, which had been scheduled to occur by April 1 but has been pushed out at least until 2007. After the failure, Mitsubishi and the government negotiated a phased approach under which the company will assume full responsibility for H-2A production, infrastructure and operations only after the modified vehicle successfully completes six flights . Other upcoming H-2A missions will launch payloads including JAXA’s Advanced Land Observing Satellite and another high-resolution reconnaissance satellite.
“Our basic stance has unchanged, and we still accept the H-2A, but we have introduced a transitional phase before it is completely privatized,” Kurihara said in a Feb. 15 interview.
Japan also hopes to start developing a new five-year national space plan that must be finalized before April 2006, said Iwase.
“We have two major issues: naturally one is a successful return to flight, but the second is to decide the priorities for the next space plan,” Iwase said. “We have to finish one and put energy and resources into the other. It’s time to think about the future.”