By BlueShift and AFP | 2024-12-06

India on December 5 launched into space a pair of European satellites that will create artificial solar eclipses to help scientists catch a rare glimpse of the Sun's mysterious atmosphere.

The ESA's Proba-3 mission blasted off on an Indian rocket from a launchpad on the island of Sriharikota at about 4:04 pm, an online broadcast showed.

About 20 minutes later, scientists broke into rapturous applause at the launch site as Indian Space Research Organisation (ISRO) chief Sreedhara Panicker Somanath announced the spacecraft had been ejected as planned.

"The spacecraft has been placed in the right orbit," he said.

The mission's aim is to find out more about the Sun's corona, which is not visible on Earth except during a total solar eclipse when the Moon blocks out the light.

The half-ton 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 about 150 meters 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 about 60,000km from Earth.

No need for moon shadow

One satellite has a 1.4-meter-diameter 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 occur only about 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 Proba-3 project manager Damien Galano said in a statement.

The Sun's corona, which is several million kilometers thick, still remains little understood.

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 about 6,000°C.

Improving solar weather forecasts

The corona is also where solar weather comes from, so another question Proba-3 will examine is why solar winds reach such tremendous speeds.

There are also coronal mass ejections, which are giant explosions of plasma and magnetic fields that can damage satellites and can cause other problems when they reach Earth.

Proba-3 project scientist Joe Zender told a news conference that better understanding the physics behind the corona "can improve our models -- and subsequently improve our forecasts for satellites and the impact on Earth" these solar storms will have.

The ESA hopes that future space missions or even commercial satellites will benefit from the high level of precision and delicate maneuvers carried out by the €200 million ($210 million) Proba-3 mission.

The ISRO hailed the "proud moment" for India's space efforts in a post on X.

The ESA determined that the PSLV-C59 rocket was the "most economical solution" to launch Proba-3 into its specific orbit, said Dietmar Pilz, the space agency's director of technology, engineering and quality.

The ESA has struggled to launch its missions into space since Russia pulled out its rockets in 2022 over the war in Ukraine.

The Proba-3 launch had been planned for December 4 but was postponed by one day for a technical issue, according to the ESA.