Isro launches Europe's Proba-3 mission: What is the significance of this mission?

This evening (December 5), a pair of European satellites, Proba-3, blast into space from Indian Space Research Organisation (Isro)’s Sriharikota launchpad.

The launch was initially planned for Wednesday. However, minutes before the lift-off, following the request from the European Space Agency, Isro rescheduled the launch of PSLV-C59/PROBA-3 to December 5, 4.04 pm.

Europe’s Proba-3 (Project for Onboard Anatomy) consists of two satellites — Coronagraph (310 kgs) and Occulter (240 kgs) — in which two spacecraft would fly together as one, maintaining precise formation down to a single millimetre to study the corona, the sun’s outer atmosphere.

So, what makes this mission unique? How will India benefit from this mission? Here’s a closer look.

What is Proba-3 mission?

The term Proba derives from the Latin phrase “Let’s try,” representing a series of experimental missions by the European Space Agency (ESA).

The journey began with Proba-1, followed by the Sun-observing Proba-2 in 2009, and then the Earth-observing Proba-V for Vegetation in 2013.

The Proba-3 mission, developed at an estimated cost of 200 million euros, involved teams from 14 European countries and 29 industrial partners. These teams worked for over a decade to create the satellites for the mission, in collaboration with Isro’s commercial arm, NewSpace India Limited (NSIL), which helped develop the launch vehicle.

Designed for a mission life of two years, Proba-3 aims to study the Sun’s corona at an entirely new scale by creating an artificial eclipse.

The PSLV-C59 launch vehicle will carry two ESA satellites, each weighing approximately 550 kg, into a highly elliptical orbit of around 600 x 60,530 km and have an orbital period of 19.7 hours.

The Proba-3 satellites were launched from the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh, at 4:12 pm from the spaceport’s first launch pad.

Why the Proba-3 mission is one of a kind

The Proba-3 mission will be unique as it marks the first time two satellites — the Occulter Spacecraft (weighing 200 kg) and the Coronagraph Spacecraft (weighing 340 kg) — will work together to mimic a natural solar eclipse.

Launched together in a stacked configuration, the two small satellites will demonstrate “precise formation flying,” as stated by Isro. After launch, they will separate and fly in a coordinated manner, creating an artificial solar eclipse in Earth’s orbit.

Observing the Sun’s ring-like corona has always been a challenge due to its high temperature, which makes it difficult for instruments to study closely. Scientists had previously only been able to study the corona during solar eclipses, when the moon blocks enough sunlight to make the corona visible from Earth.

This limited observation time often required scientists to chase eclipses around the world, with sometimes only minutes of observation or no time at all if clouds obscured the view.

Studying the corona is crucial for scientists, as it is the source of all space weather and its associated turbulences such as solar storms, solar winds, etc

According to ESA, the Proba-3 mission’s artificial eclipse will offer a remarkable 100-fold increase in study time. The mission is expected to generate around 50 ’eclipses’ per year, each lasting six hours, giving researchers an unparalleled opportunity to study the Sun’s complex atmospheric interactions.

How will India benefit from Proba-3?

Proba-3 is being hailed as ESA’s technology demonstration mission and Isro’s role in launching the mission highlights India’s reliable space launch facilities and its growing space capabilities. Further, it will be an addition to India’s rising reputation for cost-effective space missions.

According to Indian Express, there is also a strong possibility that the Indian solar physicist community will have exclusive access to the Proba-3 data as Indian scientists helped conceptualise the scientific goals of this mission. This data can offer an opportunity for collaborative research between the two space agencies and contribute to India’s own solar missions.

With input from agencies