A sophisticated European-Japanese joint satellite has been launched to measure how clouds affect climate.
Some low-level clouds are known to cool the planet, while others act as a blanket at higher altitudes.
The Earthcare mission will use laser and radar to probe the atmosphere to see exactly where the balance is.
This is one of the biggest uncertainties in computer models used to predict how the climate will respond to increasing levels of greenhouse gases.
“Many of our models suggest that cloud cover will decrease in the future, meaning that clouds will reflect less sunlight back into space and absorb it at the surface, and this will act as an amplifier for the warming we get from carbon dioxide,” Dr Robin Hogan, from the European Center for Medium-Range Weather Forecasts, told BBC News. .
The 2.3-ton satellite was launched by a SpaceX rocket from California.
The project is led by the European Space Agency (Esa), which it describes as the organization’s most complex Earth observation effort to date.
Of course, the technical challenge is huge in making the tools work as intended. It takes a full 20 years from mission clearance to launch.
Earthcare will orbit the Earth at an altitude of about 400 km (250 mi).
It actually has a total of four instruments that work in unison to obtain the information sought by climate scientists.
The simplest is an imager — a camera that takes pictures of the scene as it passes below the spacecraft to provide context for the measurements made by the other three instruments.
Earthcare’s European UV laser will look below thin, high clouds and cloud tops. Small particles and water droplets (aerosols) in the atmosphere affect the formation and behavior of clouds.
The Japanese radar looks at the clouds and determines how much water they carry and how it falls as rain, hail and snow.
And a radiometer can sense how much energy falling from the sun to Earth is reflected or re-radiated back into space.
“The balance between this outgoing total radiation and the amount coming in from the Sun is what fundamentally drives our climate,” said Dr Helen Brindley of the UK’s National Center for Earth Observation.
“If we change that balance, for example by increasing greenhouse gas concentrations, we reduce the amount of energy going out relative to coming in and warming the climate.”
Earthcare’s data will be used in the here and now to improve weather forecasts, along with a long-term climate outlook. For example, how a storm develops can be influenced by the initial state of its clouds, which were observed by satellite a few days earlier.
The original scientific concept for Earthcare was put forward in 1993 by Professor Anthony Illingworth and colleagues from the University of Reading.
Seeing the satellite finally fly is a dream come true, he said: “It’s been a long and challenging journey with an amazing team of dedicated scientists and engineers from the UK and abroad. Together, we’ve created something truly remarkable that will change the way we understand our planet.”
One of the major technological struggles is the space laser, or lidar.
Developer Airbus-France had a difficult time coming up with a design that would work reliably in the vacuum of space. A fundamental re-configuration of the tool was required, which not only resulted in delays but also added significantly to the final cost of the work, which today is worth some €850m (£725m).
“These aren’t things you do that are cheap and quick to fix small problems; it’s complex. The reason Earthcare has taken so long is because we want the gold standard,” said Dr Beth Greenway, President of Earth. Monitoring at the UK Space Agency.
Earthcare doesn’t take long to collect its data. Flying at 400 km would feel the drag of the remaining atmosphere at that altitude. This will work to pull down the satellite.
“It’s got fuel for three years with a reserve for another year. It’s basically lifetime limited by its low orbit and drag,” said Esa’s Dr. Michael Eisinger.
Industrial development of Earthcare was led by Airbus-Germany, with the spacecraft’s basic chassis or structure built in England. Britain provided the radiometer from Thales Alenia Space UK and the imager from Surrey Satellite Technology Ltd. GMV-UK has prepared the ground systems that process all the data.
The Japanese Space Agency (JAXA), taking a keen interest in the mission, will follow the usual practice of giving the spacecraft the nickname “Hakuryu” or “White Dragon”.
In Japanese mythology, dragons are ancient and divine creatures that rule the waters and fly in the sky. This year, 2024, is also the Japanese Year of the Dragon, known as “Tatsu-toshi”.
There’s also a connection to the satellite’s appearance, which features white insulation and a long, trailing solar panel that resembles a tail.
“Earthcare, like a dragon soaring through space, will become a company that imagines the future for us,” said Jaxa Project Manager Eiichi Tomita.
