A sophisticated joint European-Japanese satellite has been launched to measure the impact of clouds on the climate.
It is known that some low clouds cool the planet, others at high altitudes will act as a blanket.
The Earthcare mission will use laser and radar to probe the atmosphere to see exactly where the balance is.
That’s one of the big uncertainties in the computer models used to predict how the climate will respond to rising greenhouse gas levels.
“Many of our models suggest that cloudiness will decrease in the future, which means that clouds will reflect less sunlight back into space, more will be absorbed at the surface, and that will act as an amplifier of the warming we would get from carbon dioxide,” he said. Dr Robin Hogan of the European Center for Medium-Range Weather Forecasts for BBC News.
The 2.3-ton satellite was launched from California on a SpaceX rocket.
The project is led by the European Space Agency (Esa), which has described it as the organization’s most complex Earth observation undertaking to date.
It is certain that the technical challenge of making the instruments work properly was enormous. It took a full 20 years from mission approval to launch.
Earthcare will orbit the Earth at an altitude of about 400 km (250 miles).
It actually has a total of four instruments that will work in concert to get the information that climatologists are looking for.
The simplest is the imager – a camera that will record the scene passing under the spacecraft to give context to the measurements made by the other three instruments.
Earthcare’s European ultraviolet laser will see thin, high clouds and cloud tops lower. It will also detect small particles and droplets (aerosols) in the atmosphere that affect the formation and behavior of clouds.
The Japanese radar will look at the clouds to determine how much water they carry and how it falls as rain, hail and snow.
And the radiometer will sense how much energy falling on the Earth from the Sun is reflected or radiated back into space.
“The balance between this outgoing total amount of radiation and the amount coming in from the Sun is what fundamentally drives our climate,” said Dr Helen Brindley of the UK’s National Earth Observation Centre.
“If we change that balance, for example by increasing the concentration of greenhouse gases, we reduce the amount of energy going out compared to what comes in and we warm the climate.”
As with the long-term climate outlook, Earthcare data will be used here and now to improve weather forecasting. For example, the development of a storm will be influenced by the initial state of the clouds as observed by the satellite days earlier.
The original scientific concept for Earthcare was presented by Prof. Anthony Illingworth from the University of Reading and his colleagues in 1993.
He said it was a dream come true to see the satellite finally fly: “It has been a long and challenging journey with an incredible team of dedicated scientists and engineers from the UK and abroad. Together we have created something truly remarkable that will change the way we understand our planet. “
One of the key technical battles was the space laser or lidar.
Developer Airbus-France struggled to come up with a design that would work reliably in the vacuum of space. A fundamental reconfiguration of the instrument was required, which not only resulted in delays, but also significantly increased the final cost of the mission, which is now estimated at around €850m (£725m).
“These are not missions that you set up to be cheap and quick, to solve small problems; this is complex. The reason Earthcare has taken so long is because we want a gold standard,” said Dr. Beth Greenaway, head of Earth. observation at the Great Britain Space Agency.
Earthcare will not need to collect its data for long. A flight at 400 km means that he will feel the resistance of the residual atmosphere at that height. This will pull the satellite down.
“It has fuel for three years with another year to spare. Basically the lifetime is limited by low orbit and drag,” said Dr. Michael Eisinger of Esa.
Industrial development of Earthcare was led by Airbus-Germany, with the basic chassis or spacecraft structure built in the United Kingdom. Britain also supplied a radiometer, from Thales Alenia Space UK, and an imager, from Surrey Satellite Technology Ltd. GMV-UK has prepared the ground systems that will process all the data.
The Japanese Space Agency (Jaxa), due to the high interest in the mission, will follow its usual practice of giving the spacecraft a nickname – “Hakuryu” or “White Dragon”.
In Japanese mythology, dragons are ancient and divine beings that rule the water and fly in the sky. This year, 2024, is also the Japanese Year of the Dragon, known as “tatsu-doshi”.
There is also a connection in the appearance of the satellite, which is covered in white insulation and has a long tail-like solar panel.
“Earthcare, like a kite soaring into space, will become the entity that predicts our future,” said Jaxa project manager Eiichi Tomita.