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Why it’s a good thing NASA didn’t buy Canadian

by Emily Chung, CBCNews.ca

Sadly, a NASA satellite designed to track global carbon dioxide emissions ended up in the ocean instead of in orbit last week.

The $280 million US Orbiting Carbon Observatory landed in the waters near Antarctica after failing to separate properly from the moulded structure surrounding it. On board were instruments designed to identify gases emitted into the atmosphere and measure how much was being released.

In fact, Canadian engineers have designed a key component of such an instrument for an orbiting satellite. But fortunately, their instrument is safely in orbit around the Earth, on board the Japanese Aerospace Exploration Agency (JAXA) Ibuki satellite, also known as GOSAT (Greenhouse Gases Observing Satellite). That satellite launched successfully on Jan. 23.

GOSAT’s main carbon dioxide detector is its Fourier Transform Spectrometer (TANSO-FTS), which was successfully activated earlier in February.

One of its main components is a device called a spatial interferometer, developed by Quebec City-based ABB Canada.

“It’s the heart of the sensor,” said Marc-André Soucy, the company’s manager of remote sensing industry, on Friday.

The job of the device is to separate out different wavelengths or “colours” of infrared light. Molecules such as carbon dioxide are constantly vibrating, and when they do so, they absorb and emit infrared light.

“Because each molecule has its own way of vibrating, it does that at unique wavelengths or frequencies,” Soucy said.

By separating out the different colours, researchers can “see” carbon dioxide and figure out how much is being emitted.

A spatial interferometer separates out the different colours by splitting a light beam into two, having the two beams travel different paths, and then recombining them to create interference patterns. A mathematical process called fourier transform can then be used to separate out different wavelengths from the patterns.

2 satellites, 2 technologies

Soucy said NASA’s OCO uses a different technology called a grating spectrometer, which is similar to a prism, to separate out the different wavelengths of light.

For the purposes of measuring carbon dioxide, he added, “the two technologies are both good ways of achieving the same result.”

ABB Bomem spent three years developing the interferometer after winning a $10 million contract by NEC Toshiba Space Systems, which was the main supplier of instruments to the IBUKI program.

The device is based on an earlier instrument for the Canadian Space Agency’s SCISAT-1 satellite, which was launched in 2003 to monitor ozone depletion in the atmosphere.

Soucy said the IBUKI team has been collaborating with NASA and had been hoping the data from the two satellites could be used to validate each other. Checking and confirming IBUKI'’s data will still be possible using other methods, but will be more difficult since the OCO’s demise.

“It’s always very sad to see,” he said. “It always reminds us that space is…not an easy avenue.”

IBUKI is to monitor carbon dioxide at 56,000 sites around the planet. It is currently in the middle of an initial three-month functional check.

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