PARIS (AFP) – A European mission was launched from India yesterday, aiming to catch a rare glimpse of the Sun’s mysterious atmosphere by imitating a solar eclipse using two satellites flying with millimetre-level precision.
The European Space Agency’s Proba-3 mission blasted off on an Indian rocket from a launchpad on the island of Sriharikota at around 4.04pm, an online broadcast showed.
Around 20 minutes later, the spacecraft separated from the rocket, which marked a successful launch and was met with applause by mission control in India, according to the ESA broadcast.
The mission’s aim is to find out more about the Sun’s corona, the outermost part of its atmosphere, which is not visible on Earth except during a total solar eclipse when the Moon blocks out the light.
The half-tonne spacecraft, which has been deployed into Earth’s orbit, holds two satellites that will separate from each other early next year.
They will then line up around 150 metres apart, so that one casts its shadow on the other.
In tandem, and without guidance from the ground, the solar-powered satellites will embark on an extremely elliptical 19-hour orbit, swinging out towards the Sun around 60,000 kilometres from Earth.
One satellite has a 1.4-metre shield that will play the role of the Moon in blocking the Sun’s light. The other satellite will then be able to observe and measure the Sun’s corona from the shadow.
While total eclipses on Earth last just minutes and only occur around 60 times a century, it is hoped that Proba-3 will manage to secure 10 to 12 hours of observations a week over two years, the ESA has said.
To achieve this feat, the two satellites will need to fly in formation at a level of precision never before seen in such a mission, according to the ESA.
“The two satellites need to achieve positioning accuracy down to the thickness of the average fingernail while positioned one and a half football pitches apart,” ESA’s Proba-3 project manager Damien Galano said in a statement.
The Sun’s corona, which is several million kilometres thick, still remains little understood. Invisible to the naked eye and telescopes, it is normally hidden by the bright light coming from the Sun. The biggest mystery is why the corona is so much hotter than the Sun’s surface. It can clock in at up to two million degrees Celsius, while the Sun’s surface is normally around 6,000 degrees Celcius.
