15 Dec 2022

An eye in the sky to detect methane emissions

From Our Changing World, 5:00 am on 15 December 2022

MethaneSAT - the first NZ-government-funded space mission - is launching a satellite that will detect emissions leaking from pipelines, agriculture, landfill and wetlands.

Science and tech journalist Peter Griffin finds out why and how.

Satellite view of the Earth seen from space. The sun rising over the Europe and north Africa. Cities illuminated in the night. Sunrise

MethaneSAT will launch a satellite that will be able to detect global methane emissions. Photo: 123RF

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The recent COP27 climate summit focused on reducing carbon dioxide emissions with the aim of limiting global temperature increase to within 1.5 degrees Celsius.

Reaching that goal will also require a dedicated effort to reduce methane.

“Ultimately there’s no way to have anything like a habitable world without tackling our CO2 emissions,” says NIWA’s Dr Sara Mikaloff-Fletcher, the leader of the MethaneSAT project at the Crown research institute.

“However if you are thinking about… how you can reduce emissions quickly, there’s a strong argument to be made for including methane in that first tranche of work. Over the next 20 years, methane that we emit today is going to warm the atmosphere 85 times as much as the equivalent amount of CO2.”

A portrait headshot photo of Sara. Her hair is down and she is smiling.

Dr. Sara Mikaloff-Fletcher, principal scientist at NIWA Photo: Supplied

Short-lived but powerful

Methane is a powerful but short-lived greenhouse gas that scientists estimate accounts for about half of the net rise in global average temperature since the pre-industrial era. But methane emissions from oil and gas have been underestimated for years, due in part to a lack of independent monitoring.

A voluntary global effort, the Global Methane Pledge, was launched in 2021 to address the methane issue, with over 100 countries, including New Zealand, undertaking to reduce methane emissions by 30% on 2020 levels by 2030.

Some satellites currently track methane emissions but are unable to zoom in and identify their exact source. MethaneSAT aims to fill that gap.

Primarily funded by the US-based nonprofit Environmental Defense Fund, which is spending over $100 million on the project, MethaneSAT is also New Zealand’s first government-funded space mission, to the tune of $26 million.

While the satellite will primarily be used to pinpoint methane emissions from leaky oil and gas pipelines around the world, New Zealand’s involvement will allow a secondary focus on methane emissions from agriculture - sheep and cows here in New Zealand, but also rice paddy fields, wetlands and animal herds in the developing world.

So how will MethaneSAT detect methane emissions hundreds of kilometres away in space? An imaging spectrometer will separate the narrow band within the shortwave infrared spectrum where methane absorbs light, enabling MethaneSAT to detect methane concentrations as low as three parts per billion.

“Light comes to Earth from the sun. It passes through our atmosphere, hits the ground and bounces out again,” explains Dr Mikaloff-Fletcher.

“While it is in the atmosphere, the greenhouse gasses in the atmosphere interact with that light. Each individual greenhouse gas has sort of a fingerprint of which wavelength of light they absorb.”

“What you do is measure the light on the way out and you know the solar radiation variable, and you can use that to find out how much methane was in the atmosphere,” she adds.

Pinpointing emissions

The NIWA team will then use that data to generate data models and cross-reference them with methane measurements taken on the ground and from sensors mounted to aircraft. The aim is to verify the accuracy of both satellite and Earth-based measurements and more accurately pinpoint the source of the emissions. In doing so, MethaneSAT can then be relied on to a greater degree to give scientists a handle on methane emissions in parts of the world where there is little ground-based monitoring of methane.

Rocket Lab will initially have control of the mission during its crucial launch period and for 6 - 12 months following it, and will then hand off to Te Pūnaha Ātea, the University of Auckland’s Space Institute, who will monitor and control the satellite from its missions operation and control centre based at the university.

A wide angle shot of the control centre showing two rows of monitors, 11 in total, with large ones on top and smaller below. They are displaying maps of the earth, satellite orbits, satellites, rocket launches, and some blank blue screens.

The Mission Operations and Control Centre at Te Pūnaha Ātea Space Institute at the University of Auckland. Photo: University of Auckland

Te Pūnaha Ātea’s head of space operations and ground segment, Chris Jackson, said MethaneSAT will regularly communicate with ground stations dotted around the globe, allowing contact to be maintained throughout its orbit.

“We’ll be tapping into all those ground stations to allow us to contact the satellite 20 - 25 times per day, each time for around 10 minutes,” he says.

“During those times we’ll be able to upload commands to take an image or fire the thrusters to move the orbit a little bit. But we’ll also be able to download the mission data as well.”

MethaneSAT was initially scheduled to be launched this year, but the launch window has now been pushed out until at least October 2023.

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