Earthcare cloud mission launches to solve climate unknowns

Image caption, Artwork: It took over twenty years to get Earthcare into space

An advanced joint European-Japanese satellite has been launched to measure how clouds affect the climate.

Some low-altitude clouds are known to cool the planet, while others at high altitudes act like a blanket.

The Earthcare mission will use a laser and radar to probe the atmosphere to see exactly where equilibrium lies.

It is one of the major uncertainties in the computer models used to predict how the climate will respond to increasing amounts of greenhouse gases.

“Many of our models suggest that cloud cover will decrease in the future and that means that clouds will reflect less sunlight back into space, absorb more at the surface and that will act as an amplifier of the warming we would 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 sent up from California on a SpaceX rocket.

The project is led by the European Space Agency (Esa), which describes it as the organization’s most complex Earth observation undertaking to date.

Certainly, the technical challenge of making the instruments work as intended was enormous. It took more than twenty years to go from mission approval to launch.

Image caption, Clouds play an integral role in the energy balance at the Earth’s surface

Earthcare will orbit the Earth at an altitude of approximately 400 km (250 miles).

It has a total of four instruments that work together to obtain the information sought by climate scientists.

The simplest is an imager: a camera that takes pictures of the scene passing beneath the spacecraft to give context to the measurements from the other three instruments.

Earthcare’s European ultraviolet laser will see the thin, high clouds and the lower cloud tops. It will also detect the small particles and droplets (aerosols) in the atmosphere that influence the formation and behavior of clouds.

The Japanese radar will look into the clouds to determine how much water they carry and how that precipitates in the form of rain, hail and snow.

And a radiometer will observe how much of the energy falling to Earth from the sun is reflected or radiated back into space.

Image caption, Earthcare is approximately 2.5 meters wide and 3.5 meters deep. The solar panel (not shown) is 11 meters long

“The balance between this outgoing total amount of radiation and the amount coming in from the sun is what fundamentally drives our climate,” says Dr Helen Brindley of Britain’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 compared to what comes 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 forecasts. For example, the way a storm develops is influenced by the initial state of the clouds, as observed by the satellite days earlier.

Image caption, Earthcare’s observations of clouds will also help with current weather forecasts

The original scientific concept for Earthcare was put forward in 1993 by Prof. Anthony Illingworth of Reading University and colleagues.

He said it was a dream come true to see the satellite finally fly: “It has been a long and challenging journey with an amazing team of dedicated scientists and engineers from Britain and abroad. Together we have created something truly remarkable created that will change the way we understand our planet.”

One of the main technical problems was the space laser or lidar.

Developer Airbus-France had a torrid time coming up with a design that would work reliably in the vacuum of space. A fundamental reconfiguration of the instrument was required, which not only led to delays but also contributed significantly to the final cost of the mission, which today is estimated at around 850 million euros.

Image caption, Sahara dust: The laser will investigate how small particles influence the formation of clouds

“These are not missions you set up to be cheap and fast, to solve small problems; this is complex. The reason Earthcare has lasted so long is because we want the gold standard,” said Dr. Beth Greenaway, head from Earth Care. observation at the UK Space Agency.

It won’t take Earthcare long to collect the data. Flying at 400 km means it will feel the resistance of the remaining atmosphere at that altitude. This will work to pull the satellite down.

“It has fuel for three years with the reserve of another year. Its lifespan is basically limited by its low orbit and the air resistance there,” says Dr. Michael Eisinger of Esa.

Earthcare’s industrial development was led by Airbus-Germany, with the basic chassis or structure of the spacecraft built in Britain. Britain also supplied the radiometer, from Thales Alenia Space UK, and the image sensor, from Surrey Satellite Technology Ltd. GMV-UK has prepared the ground systems that will process all the data.

Image caption, The Japanese Space Agency has nicknamed the mission “Hakuryu” or “White Dragon”.

The Japanese Space Agency (Jaxa), due to its strong interest in the mission, will follow the usual practice of giving the spacecraft a nickname: “Hakuryu” or “White Dragon”.

In Japanese mythology, dragons are ancient and divine creatures that control the water and fly in the air. This year, 2024, also happens to be Japan’s Year of the Dragon, known as “tatsu-doshi”.

There is also a connection between the appearance of the satellite, which is covered in white insulation and has a long, trailing solar panel that resembles a tail.

“Earthcare, like a dragon rising into space, will become an entity that represents the future for us,” said Jaxa project manager Eiichi Tomita.

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