Smile lifts off on quest to reveal Earth’s invisible shield against the solar wind

Following launch and separation from the rocket, the first signal from Smile was received by ESA's New Norcia ground station in Australia at 06:48 CEST. The spacecraft's solar panels then deployed at 06:49 CEST, meaning that Smile can now collect sunlight to power its systems and science instruments. The completion of this operation marked the launch a success.

Smile is a collaboration between the European Space Agency (ESA) and the Chinese Academy of Sciences (CAS). It will reveal how Earth responds to the streams of particles and bursts of radiation from the Sun, using an X-ray camera to make the world's first X-ray observations of Earth's magnetic shield, and an ultraviolet camera to watch the resulting northern lights non-stop for 45 hours at a time.

"We are about to witness something we've never seen before - Earth's invisible armour in action," says ESA Director General Josef Aschbacher. "With Smile, we are pushing the boundaries of science in an effort to answer big questions that have remained a mystery since we discovered, over seventy years ago, that Earth sits safely within a giant magnetic bubble."

He adds: "ESA and China have a long-standing record of cooperation spanning 25 years, from early data-sharing arrangements in the 1990s to the co-developed Smile mission. This mission stands as a testament to ESA's commitment to international collaboration, advancing scientific knowledge and promoting the peaceful use of space."

"Smile will shed light on the mysteries of Earth's magnetic shield," says ESA Smile Project Manager David Agnolon. "The mission is made possible thanks to a smooth collaboration between ESA and CAS, with contributions from partners across Europe. It marks the first time that ESA and China have jointly selected, designed, implemented, launched and operated a mission together, and we are all really excited for the major scientific discoveries that we expect to come from Smile over the next three years."

The time has come

For almost four billion years, Earth has been holding up a giant shield against the relentless attack of charged particles from the Sun. This solar wind can damage anything in its path, especially when it builds up into solar storms.

The solar wind would turn our thriving green and blue Earth into a rocky brown wasteland - if the magnetic field produced deep within our planet didn't exist. This magnetic field forms a giant protective bubble around us, called the magnetosphere.

For the first time in history, we have reached the point where our scientific tools and technologies have advanced enough that we can get to the bottom of how exactly this defence against the solar wind works.

Professor Carole Mundell, ESA's Director of Science says: "Smile is the newest member of ESA's space science mission fleet. It builds on ground-breaking scientific and technological heritage from previous missions, including Cluster and XMM-Newton, taking tried-and-tested technologies and applying them in a new way to reveal Earth's magnetic environment like never before."

She continues: "The trusted collaboration between our engineering and science teams in Europe and China has endured through global challenges such as pandemic travel restrictions and geographically distributed teams. It's exciting to see this all come together today and I'm looking forward to the new scientific discoveries Smile will deliver."

Smile is equipped with a unique toolbox designed to give us our first complete look at how Earth's magnetic field responds to the Sun's relentless attack.

It will be the first mission to look at Earth's magnetic shield with X-ray vision, to reveal where and how it is hit by the solar wind. This interaction triggers disturbances, from minor substorms to major geomagnetic storms, to ripple through our magnetosphere towards the North and South Poles.

There, the magnetic storms set off a light show of auroras (the northern and southern lights). Smile will use ultraviolet vision to record the northern lights for 45 hours at a time, becoming the first mission to observe them for so long, and the first since 2008 to observe the full circle of auroras around the North Pole in ultraviolet light.

By comparing the X-ray and ultraviolet images, we will be reading the real-time story of how Earth is responding to the solar wind onslaught.

"The evidence that Smile collects will help us better understand planet Earth and our Solar System as a whole," says ESA Smile Project Scientist Philippe Escoubet. "And the science it uncovers will improve our models of Earth's magnetic environment, which could ultimately help keep our astronauts and space technologies safe for decades to come."

Preparing for science

The Vega-C rocket that took Smile into space was chosen as it perfectly matched the needs of the mission.

Géraldine Naja, ESA's Director of Space Transportation says: "From initial idea, to liftoff and then results, thousands of people are working together in teams all over the world to make Smile a success. The precision engineering required for a launch makes each and every one an achievement. Congratulations to all of the partners involved that made Vega-C shine today - in particular Avio, who acted as the launch service operator for the first time - allowing for a smooth start to Smile's science voyage."

The launch is just the beginning. During the next month, Smile will be slowly increasing its altitude through 11 engine burns, ultimately ending up in an extremely elliptical orbit that takes it 121 000 km above the North Pole to collect data, before descending to 5000 km above the South Pole to efficiently deliver it to eagerly awaiting scientists on Earth.

The data collection will begin in earnest in July, after the team has unfolded booms, opened camera covers, and confirmed that everything works as expected.

European collaboration

Smile is a truly international endeavour, with major European contributions.

On behalf of ESA, Airbus Defence and Space in Spain built Smile's payload module. This crucial part of the spacecraft carries three of the mission's four science instruments - including the X-ray and ultraviolet cameras, as well as the unit that controls the instruments, and the communication channel that sends all the valuable science data back down to Earth.

Europe was also responsible for the X-ray camera, Smile's largest instrument. On behalf of ESA, this camera was developed and built in the UK by the University of Leicester, in collaboration with Mullard Space Science Laboratory and the Open University, working with several other institutions across Europe.

Together, the payload module and X-ray camera involved contributions from institutes and companies in 14 European countries, with the United Kingdom and Spain providing the largest contributions.

The financial contribution to the mission from ESA is €130 million, involving over 25 procurement contracts with more than 40 companies and institutes. All ESA Member States contribute indirectly through the agency's Science Programme, with the average contribution to Smile being about 28 cents per European resident.

The Smile project has employed hundreds of people for seven years in Europe and China, and hundreds of scientists will carry out research for years to come using the data that Smile collects.

About Smile

Smile (the Solar wind Magnetosphere Ionosphere Link Explorer) is a joint mission between the European Space Agency (ESA) and the Chinese Academy of Sciences (CAS).

Smile will use four science instruments to study how Earth responds to the solar wind from the Sun. In doing so, Smile will improve our understanding of solar storms, geomagnetic storms and the science of space weather.

ESA is responsible for providing Smile's payload module (which carries three of the four science instruments), one of the spacecraft's four science instruments (the soft X-ray imager, SXI), the launcher, and the Assembly Integration and Testing facilities and services. ESA contributes to a second science instrument (the ultraviolet imager, UVI) and the mission operations once Smile is in orbit.

CAS provides the other three science instruments and the spacecraft platform, and is responsible for operating the spacecraft in orbit.

Smile is part of ESA's Cosmic Vision programme, principally contributing to answering the question 'How does the Solar System work?'

For more information, visit: https://www.esa.int/Science_Exploration/Smile

About Vega-C

Europe's Vega-C rocket can launch 2300 kg into space, such as small scientific and Earth observation spacecraft. At 35 m tall, Vega-C weighs 210 tonnes on the launch pad and reaches orbit with three solid-propellant-powered stages before the fourth liquid-propellant stage takes over for precise placement of satellites into their desired orbit around Earth.

Complementing the Ariane family to launch all types of payloads into their desired orbits, Vega-C ensures that Europe has versatile and independent access to space. ESA leads the Vega-C programme, working with Avio as prime contractor and design authority. For this launch Avio is also launch service operator.

For more information, visit: https://www.esa.int/Enabling_Support/Space_Transportation/Vega/Vega-C

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About the European Space Agency

The European Space Agency (ESA) provides Europe's gateway to space.

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