Isro to launch Europe's Proba-3 to create artificial eclipse, study the Sun

At the heart of Proba-3 are two satellites: the Coronagraph spacecraft and the Occulter spacecraft.

In Short

• The Occulter will position itself between the Coronagraph and the Sun
• Data gathered by Proba-3 could prove crucial
• It could help in understanding the Sun's role in Earth's climate system

The Indian Space Research Organisation (Isro) is set to launch Europe's Proba-3 mission, a pioneering project that employs two spacecraft working in tandem to study the Sun's corona and measure its energy output with unprecedented precision.

This ambitious mission, scheduled for launch in December 2024 from India's Sriharikota spaceport, marks a significant leap in solar observation technology.

At the heart of Proba-3 are two satellites: the Coronagraph spacecraft and the Occulter spacecraft.

The Occulter will position itself between the Coronagraph and the Sun, creating an artificial eclipse that allows the Coronagraph to observe the Sun's faint corona, typically obscured by the solar disk's intense brightness.

The Occulter's continuous Sun-facing position makes it an ideal platform for additional scientific instruments. One such instrument is the Davos Absolute Radiometer (DARA), a shoebox-sized device developed by the Physical Meteorological Observatory Davos (PMOD) in Switzerland.

DARA will provide continuous measurements of the Sun's total energy output, known as total solar irradiance (TSI).

Dr. Wolfgang Finsterle, DARA Principal Investigator at PMOD, emphasizes the importance of tracking TSI: "It's essential to keep track of the total solar irradiance, because it is the dominant energy input to the surface of the Earth... even the tiniest variations are hugely significant".

DARA represents an improvement over previous radiometer designs, featuring an optimised cavity design to minimise unwanted straylight and a multi-channel measuring system for self-calibration.

Its fully digital control loop allows for higher frequency observations, potentially providing more detailed data on solar energy fluctuations.

The Proba-3 mission's unique highly elliptical orbit, reaching up to 60,000 km from Earth, will offer new perspectives on solar observation. This innovative approach to studying the Sun is expected to yield valuable insights into solar phenomena and their impact on Earth's climate.

As the world grapples with climate change, the data gathered by Proba-3 could prove crucial in understanding the Sun's role in Earth's climate system.

By maintaining a continuous record of TSI, scientists will be better equipped to analyse long-term solar energy trends and their potential effects on our planet's climate.