Japan’s Ibuki Satellite Carrying On Without OCO Assist

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  Space News Business

Japan’s Ibuki Satellite Carrying On Without OCO Assist

By PAUL KALLENDAR-UMEZU
Space News Correspondent
posted: 05 March 2009
02:30 pm ET






— A Japanese satellite launched in late January to map carbon dioxide and methane – two common gases that contribute to global warming – will be able to complete its mission as planned despite the unexpected loss of a complementary NASA satellite to a Feb. 24 launch mishap.

Exactly one month prior to the failed launch of NASA’s Orbiting Carbon Observatory, ‘s Greenhouse Gases Observing Satellite, since renamed Ibuki, was lofted into orbit by an H-2A rocket.

The 1,750-kilogram satellite is expected to spend the next five years mapping the global distribution of carbon dioxide and methane, filling the gaps in measurements currently obtained from a worldwide network of ground-based greenhouse gas monitoring stations.

Ibuki (Japanese for “breath”) is a joint mission undertaken by the Japan Aerospace Exploration Agency (JAXA), ‘s Ministry of Environment and National Institute for Environmental Studies at a cost of some 18.3 billion yen ($196.1 million).

Tatsuya Yokota, GOSAT project leader and chief of satellite remote sensing at the Tsukuba, Japan-based National Institute for Environmental Studies (NIES), said NIES was planning to use Orbiting Carbon Observatory (OCO) data to fine tune Ibuki’s instruments but can make do without it.

“It’s a great pity for everyone that OCO was lost, because OCO and Ibuki were complementary,” he said in a Feb. 25 telephone interview. “But fundamentally this does affect the validation of our data. We’d like to continue to collaborate with our friends in the and

‘s Environment Ministry has long regarded the Ibuki satellite as a flagship project and major Japanese contribution to the monitoring and resolving of global warming issues. “We hope our contribution will be highly evaluated by the international community,” Toru Hashimoto, section chief for the Environment Ministry’s Global Environment Bureau, said Feb. 24.

With the loss of NASA’s OCO spacecraft, Ibuki’s role has become even more important and researchers in are anxiously waiting for the satellite to finish its on-orbit checkout and start returning data.

The first maps showing greenhouse gas concentrations will be available as early as mid-April, Yokota said.

“Since achieving ‘first light’ in February, the data was very good and we are very satisfied. We don’t see any major problems so far,” he said.

Greenhouse gases are currently observed at approximately 280 points around the world but there are few, if any, observation points, for example, in South America or over the ocean, said JAXA’sIbuki project manager Takashi Hamazaki.

Ibuki, in contrast, can collect data from the equivalent of tens of thousands of points around the world every three days, he said.

Ibuki is designed to measure the global density distribution of carbon dioxide down to 14 parts per million concentrations, and methane in even smaller concentrations. The satellite will also map the global distribution of greenhouse gas sources and so- called sinks, such as forests, that remove carbon dioxide from the atmosphere.

“This data will be distributed to scientists all over the world… Ibuki will contribute to international efforts to solve the global warming mechanism,” Hamazaki said in a Feb. 24 interview.

Enabling such accuracy are two sensors, an interferometer designed to detect and measure the density of atmospheric methane and carbon dioxide, and an auxiliary cloud and aerosol sensor. NIES’s first priority is to obtain monthly global distributions of carbon dioxide and methane and validate the obtained values.

A team of 30 scientists backed by two major supercomputers will be crunching output from Ibuki, which will be shared with 52 research teams, including 29 outside of , as part of a major international cooperative research effort, Yokota said.

A second research announcement next spring will further boost the number of researchers involved in this project, he said.

With prior satellite failures in mind, Hamazaki said has taken great care to make Ibuki as robust as possible to try to ensure it completes its mission.

Ibuki differs radically from previous Japanese flagship Earth observation missions in that it has a singular scientific focus. Following lessons learned from the early demise of its Advanced Earth Observing Satellites (ADEOS) 1 and 2, both of which suffered catastrophic power failures that brought the missions to premature ends, Ibuki’s fundamental design concept was to use proven flight components rather than new or experimental parts, he said.

All major sensor components are equipped with a redundant system so that the satellite mission should not be interrupted by a single failure. ADEOS 1 failed abruptly in June 1997 – just 10 months after its launch – when its thin solar panel collapsed.

ADEOS 2 suffered a mission- ending electrical failure in October 2003, just 11 months after launch.

Ibuki has two solar arrays and dual power bus systems, so even if one or the other of these fails, and power is halved, Ibuki is designed to continue minimum mission operations on a power saving mode, Hamazaki said.

“Furthermore, the critical mechanical components were subjected to mission duty cycle tests for twice the duration of the mission to ensure the lifetime margin,” he said.

Following the loss of OCO, scientists in both the United States and have lost valuable opportunities to compare the advantages and utility of Ibuki and OCO’s data, which would have fed into follow-on missions, Yokota said.

However, the international scientific community was looking forward, he said to the launch of NASA’s proposed OCO follow-on, the lidar-equipped Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) satellite. ASCENDS was one of 15 Earth science missions the National Research Council is recommending NASA undertake in the decade ahead.

“This is a very difficult technology, but will provide the most reliable measurements from space,” Yokota said.