ISRO to launch ESA's Proba-3 mission, set to create artificial solar eclipse

The two spacecrafts will be launched together by the PSLV-XL launcher and placed in the highly elliptical orbit which will ascend to 60,000 km away from Earth before coming as low as just 600 km.

India's Satish Dhawan Space Centre in Sriharikota is set to witness another watershed moment in the history of astronomy as the spaceport will be used to launch the European Space Agency's Proba-3 mission on Wednesday.

The Proba-3 mission which aims to create an artificial solar eclipse with the help of satellites flying in close formation will help the scientists study the outermost layer of Sun's atmosphere, the corona.

How will Proba-3 work?

According to the European Space Agency's website, Proba-3 is actually a pair of two satellites — the Occular satellite and Coronagraph satellite. The two spacecrafts will be launched together by the PSLV-XL launcher and placed in a highly elliptical orbit — one which will ascend to 60,000 km away from Earth before coming as low as just 600 km.

The high orbit is required because the pair of spacecraft will perform their active formation flying for a planned six hours at a time around their maximum altitude, where Earth's gravitational pull will be diminished, as will the amount of propellant needed to fine-tune their positions.

Proba-3's two satellites will enable sustained views of the Sun's faint surrounding atmosphere, or corona, that has previously only been visible for a few brief moments during solar eclipses viewed from the Earth.

To achieve this, the shadow being cast between the spacecraft must remain in a precise position, which means they must fly autonomously in formation to an accuracy of a single millimetre — about the thickness of an average fingernail.

This is the first time since 2001's Proba-1 Earth observation mission that an ESA mission is using an ISRO launcher.

By blocking out the fiery disc of the Sun, Proba-3’s ‘Occulter’ spacecraft will mimic a terrestrial total solar eclipse, to open up views of the Sun’s corona, which is a million times fainter than its parent star.

Proba-3’s second ‘Coronagraph’ spacecraft hosts the optical instrument that will observe the solar corona.

As total solar eclipses are a rare occurrence in nature, Proba-3 will help the scientists study why the corona is several times hotter than the Sun through this artificial 'eclipse'.

Proba-3 launch time

“This mission will place ESA’s PROBA-3 satellites (550kg) into a unique highly elliptical orbit, reinforcing PSLV’s reliability for complex orbital deliveries,” ISRO said in a post on ‘X’.

The spacecraft will be launched from India’s Satish Dhawan Space Centre in Sriharikota, on the Bay of Bengal coast, at 4.08 pm local time (10.38am UK time) on Wednesday.

(With inputs from PTI)