Japan's H-2A racked up its fourth success in as many launches with the orbital delivery of a satellite designed to keep an eye on our home planet.

The advanced booster rocketed away from the Yoshinobu launch complex and into the partly cloudy skies above Japan's Tanegashima Island at 0131 GMT Saturday (8:31 p.m. EST Friday). It was late morning at the launch site.

The H-2A rocket lifts off right on schedule. Photo: NASDA

This flight was the first to head south from Tanegashima instead of being vaulted on an eastward trajectory and into geostationary transfer orbit like the first three launches.

The H-2A was targeting to achieve a circular orbit about 499 miles high with an inclination of 98.6 degrees, also called a Sun-synchronous orbit because it allows satellites to pass over the same spot on the planet at the same local time about every four days.

Sixteen-and-a-half minutes into the launch, the mission's primary payload -- the National Space Development Agency's $587 million Advanced Earth Observing Satellite-2 -- was deployed into orbit. Several minutes later, the rocket's upper stage ejected a trio of piggyback payloads.

The rocket maneuvers to the proper heading. Photo: NASDA

Ground controllers established contact with the ADEOS-2 craft and confirmed its power-generating solar wing had been extended.

With its ascent to orbit a success, ADEOS-2 was given the nickname 'Midori-2'. It replaces the original ADEOS Earth-watcher -- named Midori -- whose mission was ended prematurely in 1997 by a solar array malfunction that left the spacecraft with no power supply.

NASDA spokesperson Junichi Moriuma told Spaceflight Now that every possible measure was put into place to prevent a similar accident from happening on ADEOS-2. New mechanisms to control tension and vibrations, as well as strengthened hinges between the actual solar panels themselves were installed to combat any recurrence of the problems experienced over five years ago with the first ADEOS.

ADEOS-2 actually fills only a portion of the void left by the failure of ADEOS. Some high-resolution capability that was also lost will be replaced by the Advanced Land Observation Satellite, due to be launched in 2004 aboard another H-2A.

Passing over areas of the Earth at about 10:30 a.m. local time, ADEOS-2 will monitor changes in the planet's environment that affect all parts of the world over long periods of time, such as global warming and climatic trends.

For at least three years, ADEOS-2 and its complement of instruments will gather data and information on the Earth system. The mission could extend for as much as five years or even longer.

ADEOS-2 carries a suite of five scientific payloads that will each monitor a particular facet of Earth's environment and characteristics.

An illustration of ADEOS-2 in orbit. Credit: NASDA

NASDA's Advanced Microwave Scanning Radiometer will observe the distribution of water vapor in the atmosphere, along with ocean winds, sea surface temperatures, and sea ice. It aims to gather data on the water and energy circulations worldwide. AMSR will also work with a sister-instrument called AMSR-E aboard NASA's Aqua environmental eye in the sky.

"In cooperation with Aqua, two sensors, AMSR and AMSR-E make it possible to catch data on the Earth alternatively, that is, sight in local morning by ADEOS-2 and sight in local afternoon by Aqua," Moriuma said in response to written questions.

The other NASDA instrument on ADEOS-2 is the Global Imager, which will study reflected sunlight to monitor plant life and vegetation primarily in marine areas.

NASA's Jet Propulsion Laboratory also has a stake in ADEOS-2 with the SeaWinds payload that is similar to one flying on the agency's QuikSCAT satellite. The $138 million instrument will observe the speed and direction of winds across Earth's oceans.

"Winds play a major role in every aspect of Earth's weather," said NASA Associate Administrator for Earth Science, Dr. Ghassem Asrar. "They directly affect the turbulent exchanges of heat, moisture and greenhouse gases between Earth's atmosphere and the ocean that drive ocean circulation and climate. The SeaWinds instrument will provide a critical tool for improving weather forecasting, detecting and monitoring severe marine storms, identifying subtle changes in the global climate and better understanding global weather abnormalities, such as El Nino and La Nina. NASA is pleased to partner with Japan on this important endeavor."

The ADEOS-2 mission logo. Credit: NASDA

The National Oceanic and Atmospheric Administration, or NOAA, will use data collected from the SeaWinds scientific payloads on both ADEOS-2 and QuikSCAT to better forecast tropical systems, which can be difficult to predict. Having a mass of 441 pounds, NASA officials say SeaWinds will make up to 400,000 measurements per day.

"With its ability to 'see' ocean level winds through clouds, data from SeaWinds on ADEOS-2 will be an invaluable tool for hurricane tracking and high seas marine forecasting," said Helen Wood, said NOAA's director of the Office of Satellite Data Processing and Distribution. "NOAA will quickly process the data for weather forecasting use by NOAA's National Weather Service, the Japanese Meteorological Agency as well as other national weather agencies around the world."

SeaWinds will be turned on about 27 days after launch, with checkout and calibration due to begin in April. Operational science will commence in October 2003.

Japan's Ministry of Environment built the Improved Limb Atmospheric Spectrometer-2 to keep watch on the status of the ozone layers above the polar regions of Earth.

The final instrument aboard ADEOS-2 is the French Polarization and Directionality of the Earth's Reflectances experiment. It will measure solar radiation reflected by both Earth's surface and the atmosphere and will attempt to distinguish between the radiation bounced back from the atmosphere and that reflected from the surface.

ADEOS-2 weighs about 8,100 pounds and is one of the largest satellites in the history of NASDA.

Sharing the ride to space with ADEOS-2 were three small microsatellites, which were deployed one-by-one from the rocket's upper stage.

The three piggyback payloads: WEOS (left), Micro-LabSat (center) and FedSat (right). Photo: NASDA

FedSat was the first of the trio scheduled to be released to begin a three-month mission. The craft helps celebrate the hundredth anniversary of modern Australia -- which occurred in 2001 -- and is the first scientific satellite from the nation in over 30 years.

The 128-pound FedSat spacecraft gives Australian engineers valuable experience in spaceflight operations to use on possible future projects. While in orbit, the craft itself will perform a variety of communications, science, and engineering tests.

The Whale Ecology Observation Satellite will operate in orbit for one or two years, tracking a large number of whales fitted with special electronic packs that provide location, environmental information, and various other data points. The mission was developed by the Chiba Institute of Technology.

NASDA's Micro-LabSat spacecraft was built by young Japanese engineers to allow them to gain experience when they become aerospace leaders in the future. The satellite carries several experimental components including a new computer, a state-of-the-art power control system, imaging technologies, and a off-the-shelf commercial parts.

The H-2A rocket has completed four flights to date. Photo: NASDA

NASDA eventually hopes to turn over control of the H-2A program to a private company for normal operations. The agency developed the rocket as a replacement to the H-2 launcher, which failed in its last two flights. Four consecutive successful flights has allowed the Japanese rocket program to get back on its feet after the back-to-back failures of the H-2.

A private entity might also be able to better attract commercial customers, though the current market is overwhelmed by too many rockets for not enough satellite payloads. NASDA's backlog now consists of a maximum of nine firm launches booked through about 2007, with possible options for more depending on the progress of the H-2 Transfer Vehicle -- or HTV-- a cargo transport for the international space station that will begin flying in a few years time.

Plans also call for the development of a augmented version of the H-2A that could carry up to 7.5 tons to geostationary transfer orbit. The new version could possibly have a widebody first stage with two LE-7A engines instead of just one. Currently the only payload to warrant such an improvement is the HTV, though any future commercial payloads could require that capability.

The next launch for the H-2A is scheduled for February when the fifth flight will loft a pair of military reconnaissance craft for Japan.