Isro's Proba-3: How two satellites will create 50 solar eclipses a year from orbit

A groundbreaking European space mission took flight on Thursday, using precision formation flying to simulate solar eclipses in Earth’s orbit. The European Space Agency’s (ESA) Proba-3 mission launched atop an Indian Polar Satellite Launch Vehicle (PSLV) from the Satish Dhawan Space Center at 5:35 a.m. EST (1035 GMT).

Originally set for launch a day earlier, the mission faced a brief delay due to a propulsion anomaly in the Coronagraph spacecraft, ESA Director-General Josef Aschbacher explained. "The propulsion system, crucial for maintaining orientation and pointing, required adjustments during pre-launch checks," he said.

“Mission Success! The PSLV-C59/PROBA-3 Mission has successfully achieved its launch objectives, deploying ESA’s satellites into their designated orbit with precision. A testament to the trusted performance of PSLV, the collaboration of NSIL (NewSpace India Ltd) and ISRO, and ESA’s (European Space Agency) innovative goals," ISRO said in a post on X.

How it works
The mission features two satellites: the Occulter spacecraft (200 kg) and the Coronagraph spacecraft (340 kg). These will separate post-launch and maintain a precise orbital formation, positioning themselves 150 meters apart to block the Sun's glare and expose its corona—a region usually visible only during natural eclipses.

This innovation allows researchers to study the Sun’s corona for up to six hours at a time, equivalent to observing 50 solar eclipses annually. Such extended data collection promises groundbreaking insights into solar storms, solar winds, and space weather phenomena that affect Earth's communications and navigation systems.

Why it matters
The Proba-3 mission is the fourth in ESA's Proba series, which focuses on low-cost, technology-demonstrating orbital projects. With a $210 million budget, this mission also marks a new level of collaboration between ESA and India’s ISRO, leveraging PSLV's reliable track record.

Instruments aboard Proba-3 include the ASPIICS coronagraph for solar imaging and 3DEES spectrometer for space weather data, among others. The mission’s two-year timeline aims to deliver valuable insights into the Sun's energy output and its interactions with Earth’s atmosphere.

With its precision flying and unique approach, Proba-3 could redefine how space research tackles the mysteries of our nearest star.