Carbon Mapper satellite network to find super-emitters

A constellation of satellites will be flown this decade to try to pinpoint significant releases of climate-changing gases, in particular carbon dioxide and methane.

The initiative is being led by an American non-profit organisation called Carbon Mapper.

It will use technology developed by the US space agency over the past decade.

The satellites - 20 or so - will be built and flown by San Francisco's Planet company.

Planet operates today the largest fleet of Earth-observing spacecraft.

• Satellites picture methane across the globe

• Eye in the sky leaves polluters nowhere to hide

• European satellites to map global CO2 emissions

CO2 is tracked today - but not everywhere, in fine detail and at high frequency

There are already quite a few satellites in the sky that monitor greenhouse gases, but the capability is far from perfect.

Most of these spacecraft can sense the likes of methane over very large areas but have poor resolution at the local level, at the scale, say, of a leaking pipeline. And those systems that can capture this detail will lack the wide-area coverage and the timely return to a particular location.

The Carbon Mapper project wants to fix this either-or-situation by flying multiple high-resolution (30m) sensors that can deliver a daily view, or better.

They will look for super-emitters - the actors responsible for large releases of greenhouse gases. These would include oil and gas infrastructure, or perhaps poorly managed landfills and large dairy factory facilities.

If the information is available it can be acted upon

Often these emitters want to know they have a problem but just don't have the data to take action.

"What we've learned is that decision support systems that focus just at the level of nation states, or countries, are necessary but not sufficient. We really need to get down to the scale of individual facilities, and even individual pieces of equipment, if we're going to have an impact across civil society," explained Riley Duren, Carbon Mapper's CEO and a research scientist at the University of Arizona.

"Super-emitters are often intermittent but they are also disproportionately responsible for the total emissions. That suggests low-hanging fruit, because if you can identify and fix them you can get a big bang for your buck," he told BBC News.

The aim is to put the satellite data in the hands of everyone, and with the necessary tools also to be able to understand and use that information.

The satellites' sensor technology has been honed on airborne platforms

The project is being supported in large part by philanthropy - from the likes of the High Tide Foundation and Bloomberg.

It also has buy-in from the US State of California. State law commits California to reduce its greenhouse gas emissions by 40% below 1990 levels by 2030, and to eventually get to carbon neutrality.

"We can't meet those targets without a focus on methane (CH4), carbon dioxide (CO2) and hydrofluorocarbons (HFCs)," said Richard Corey, executive officer at California's Air Resources Board.

"Whether you're talking about oil and gas operations, landfills, wastewater treatment facilities - we know that if we can identify leaks efficiently, they can be repaired. It's about getting that information in front of folks in a timely way. That will make it actionable."

Central to the constellation's success will be the imaging spectrometer technology developed by Nasa.

This hyperspectral instrument was developed and refined for airborne use. Now it will go into orbit.

Methane plumes seen in false colour over the Permian Basin of the southwest US

The Permian Basin, which straddles Texas and New Mexico, is a major oil and gas production area. These plumes are likely coming from individual well heads and compressor stations. Watch a video of the flyover.

The near-500 channels on the sensor can detect and classify all manner of targets and phenomena on the ground, but these bands are also very good at detecting carbon dioxide and methane in the atmosphere.

The Planet company will launch two satellite prototypes in 2023. Each spacecraft is expected to be about 150-200kg in size.

"Our role is to design and manufacture these two satellites, and to process all of the data," explained Robbie Schingler, Planet's co-founder and chief strategy officer.

"This project is really taking Planet back to its founding principles, which is to use space to help life on Earth. And there's nothing more important right now than getting people on a common operating picture, to understand the crisis that we're in."

The rest of the constellation will roll out from 2025. Planet intends to exploit commercially the broader capabilities of the Nasa sensor technology but then revenue-share back to Carbon Mapper to help sustain its mission.

California has targets to reduce its emissions of warming gases

Paul Palmer is an expert on the observation of carbon emissions from space. The Edinburgh University, UK, scientist said the "impressive" project would rapidly change the way we monitored changes in atmospheric CO2 and CH4.

"I’m glad to hear about Carbon Mapper's plans to make these data publicly available, which are essential for ensuring transparency when quantifying emission estimates and for understanding how they complement data collected by publicly funded satellites.

"But we can’t afford to be complacent. I hope this is the start of a competition between companies, institutions, and space agencies about providing the most accurate atmospheric CO2 and CH4 satellite data to help meet the challenges associated with reducing greenhouse gas emissions," Prof Palmer told BBC News.