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- continued from the cover |
Asimilar
name is about all the H-IIA has in common with the H-II.
The H-IIA is a completely new launch vehicle. It is the
result of a sweeping reevaluation of design, materials,
and engineering aimed at achieving international cost competitiveness.
NASDA had relied on imported technology
for crucial elements of rockets developed before the H-II.
With the H-II, the agency set out to create an internationally
competitive launch vehicle with entirely domestic technology.
The resultant rocket was a technological success. And it
complied with the agency's original budget guidelines in
yen. But the appreciation of the Japanese currency during
the development program raised the cost of launches in dollars
and other currencies.
To create an internationally competitive
launch vehicle, NASDA needed to cut costs in half. So the
agency's administrators decided to reengineer the rocket
from nozzle to nose cone. NASDA urged Mitsubishi Heavy Industries--the
largest supplier of systems for the H-II and H-IIA--and
other contractors to find ways to cut costs.
"We saved a lot of trouble and expense
by adopting separate fuel tanks for the liquid oxygen and
hydrogen,"explains Yoshiharu Kurihara, of Mitsubishi
Heavy Industries' Space Systems Department. "In the
H-II, we used a single-tank configuration in the second
stage. A bulkhead across the middle of each tank kept the
hydrogen and oxygen separate. The single-tank approach saved
weight and worked well. But it was a manufacturing nightmare.
Part of the problem was the temperature differential between
the hydrogen and the oxygen. Adopting separate tanks helped
us avoid that and other issues."
"Another way we saved costs,"continues
Kurihara,"was by redesigning the combustion chamber
assembly. The new design has fewer welds, which lowers costs
and increases reliability."
To help lower costs, NASDA abandoned
its insistence on original Japanese technology. It encouraged
the contractors to save costs as possible by using imported
items.
Kurihara offers an example:"For
the second stage, we bought the oxygen tank assembly and
the top and bottom of the fuel tank from Boeing. Mitsubishi
Heavy Industries and Boeing are partners in a wide range
of aircraft and space development [Mitsubishi Monitor, August/September
2001]. And the H-IIA has some specifications in common with
Boeing's Delta rockets, which allows for sharing components.
Boeing buys liquid hydrogen tank assemblies and other items
from Mitsubishi Heavy Industries. That two-way sharing reduces
the need for developing new components. Both companies benefit.
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Launch
business
"This
[successful launch] establishes the H-IIA's viability as
a commercial launch vehicle," stresses Kurihara. "We
will reconfirm that viability with a second test launch
early next year. Then, we will begin fulfilling the orders
that we have received for putting satellites into orbit."
The H-IIA, as presently configured, can
place a payload of about four tons in a geostationary transfer
orbit. It thus fulfills the basic criterion for a commercial
launch vehicle. Like competing launch vehicles, it will
carry aloft a satellite equipped with an onboard propulsion
system and fuel. About 300 kilometers above the earth, the
rocket will release the satellite in the elliptical transfer
orbit. The satellite then will use its propulsion system
to power itself up to a geostationary orbit about 36,000
kilometers above the earth.
In addition, the H-IIA's design provides
for expandability. That could allow for carrying larger
satellites or even multiple satellites. Mitsubishi Heavy
Industries is working on an augmented version of the H-IIA.
The first stage could accommodate more solid-fuel boosters.
Liquid-fuel boosters are another option under study for
beefing up the rocket.
Global demand for nonmilitary launch
services is about 30 satellites a year. And Mitsubishi Heavy
Industries projects that demand will remain basically steady
at that level for the next decade. The company is the largest
shareholder--with a 30% stake--in a 32-company consortium
that will market H-IIA launch services. Management at Mitsubishi
Heavy Industries hopes to see six launches of the H-IIA
a year.
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Engineers assemble
the H-IIA at a huge shed at the Tanegashima Space
Center. A massive transport platform built by Mitsubishi
Heavy Industries will carry the rocket to the launch
pad. |
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The southerly island
of Tanegashima is the site of Japan's main launch
facility. |
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Mitsubishi Heavy Industries
builds the H-IIA rocket at plants in and around Nagoya.
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Photos courtesy of NASDA
and
Mitsubishi Heavy Industries |
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