A sophisticated joint European-Japanese satellite has been launched to measure how clouds affect the climate.
Some low-level clouds are known to cool the planet, while others at high altitude will act as a blanket.
The Earthcare mission will use laser and radar to probe the atmosphere to see exactly where the balance lies.
It’s one of the big uncertainties in the computer models used to predict how the climate will respond to rising levels of greenhouse gases.
“Many of our models suggest that cloud cover will decrease in the future, meaning 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.” Dr Robin Hogan of the European Center for Medium-Range Weather Forecasts told BBC News.
The 2.3-ton satellite was launched from California on a SpaceX rocket.
The project is being led by the European Space Agency (ESA), which has described it as the organization’s most complex Earth observation undertaking to date.
The technical challenge of making the tools work as intended was certainly enormous. A full 20 years passed from the approval of the mission to the launch.
Earthcare will orbit the Earth at an altitude of about 400 km (250 miles).
In fact, it has a total of four tools that will work together to get to the information climate scientists are looking for.
The simplest is the imager—a camera that takes pictures of the scene passing beneath the spacecraft to provide context to the measurements made by the other three instruments.
Earthcare’s European Ultraviolet Laser will see thin, high clouds and cloud tops below. It will also detect small particles and droplets (aerosols) in the atmosphere that affect the formation and behavior of clouds.
Japan’s radar looks into the clouds to determine how much water they carry and how it precipitates as rain, hail and snow.
And the radiometer will sense how much energy hitting Earth from the Sun is reflected or radiated back into space.
“The balance between this total amount of outgoing radiation and the amount coming in from the Sun is what fundamentally controls our climate,” said Dr. Helen Brindley of the UK’s National Earth Observation Centre.
“If we change that balance, for example by increasing greenhouse gas concentrations, we reduce the amount of energy going out compared to what’s coming in, and we warm the climate.”
In addition to the long-term climate perspective, Earthcare data will be used in the here and now to improve weather forecasting. For example, how a storm develops will be affected by the initial state of its clouds, as observed by satellite a few days ago.
The original scientific concept of Earth Care was put forward by Professor Anthony Illingworth of Reading University and his colleagues in 1993.
He said it was a dream come true to finally see the satellite fly: “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 key technical issues was the space laser, or lidar.
Developer Airbus-France had a tough time coming up with a design that would work reliably in the vacuum of space. A major reconfiguration of the instrument was required, which not only led to delays but contributed significantly to the final cost of the mission, which today is estimated at around €850 million (£725 million).
“These aren’t missions that you set up to be cheap and quick to fix small problems; that’s complicated. The reason it’s taking so long to take care of the Earth is because we want a gold standard,” said Dr. Beth Greenaway, head of Earth. observations by the British Space Agency.
Earthcare won’t have long to collect its data. Flying at an altitude of 400 km means that at that altitude it will feel the drag of the residual atmosphere. 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 Esa’s Dr. Michael Eisinger.
Industrial development of Earthcare was led by Airbus-Germany with the basic chassis or structure of the spacecraft built in the United Kingdom. Britain also supplied a radiometer from Thales Alenia Space UK and a sensor from Surrey Satellite Technology Ltd. GMV-UK has set up the ground systems to process all the data.
The Japanese Space Agency (Jaxa) will follow its usual practice of giving the spacecraft a nickname – “Hakuryu” or “White Dragon” because of its keen interest in the mission.
In Japanese mythology, dragons are ancient and divine creatures that rule the water and fly in the sky. This year 2024 is also the Japanese Year of the Dragon, known as “tatsu-doshi”.
The connection also has the appearance of the satellite, which is covered in white insulation and has a long, rear solar panel, resembling a tail.
“Caring for the Earth, like a dragon soaring into space, will become the entity that foresees our future,” said Jaxa project manager Eiichi Tomita.