Introduction

The European Space Agency (ESA) has launched Proba-3, a mission that will create an artificial solar eclipse to study the Sun's atmosphere, known as the corona. This mission aims to demonstrate new technology and address unresolved questions about the Sun's outer layers.

What is an Artificial Solar Eclipse?

• Definition: An artificial solar eclipse mimics the natural phenomenon where the moon blocks sunlight, allowing detailed observation of the Sun’s corona.
• Created By: The eclipse is created by two satellites, which align to block the Sun's light and generate a controlled shadow for scientific study.
• Purpose: The goal is to study the Sun’s corona, particularly to understand why it is significantly hotter than the Sun’s surface.

How Does the Proba-3 Create an Eclipse?

Launch and Spacecraft

Proba-3 was launched on December 5 from the Satish Dhawan Space Centre in India. The mission uses two satellites:

• Coronagraph Spacecraft (CSC): This spacecraft guides the other satellite.
• Occulter Spacecraft (OSC): This satellite has a disk that creates a controlled shadow onto the CSC.

Formation Flying

Using Precise Formation Flying (PFF) technology, the two spacecraft maintain a precise distance of 150 meters (492 feet) apart, aligning perfectly with the Sun. This alignment mimics the effect of a solar eclipse.

Precision Requirements

The eclipse will need to maintain millimetre-level accuracy for up to six hours per orbit to provide scientists with stable observational conditions.

Mission Goals

• Demonstrating PFF Technology: One of the primary objectives of the Proba-3 mission is to demonstrate PFF technology. This involves using GPS and inter-satellite radio links for positioning, as well as maintaining a precise distance between the two spacecraft.
• Studying the Sun’s Corona: Another goal is to understand why the corona is hotter than the Sun's surface. The onboard instruments, including a coronagraph, will help with this research. The coronagraph will block out the Sun’s bright light, enabling clearer observations of the corona.
• ASPICCS Coronagraph: The Proba-3 coronagraph, named the Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun (ASPICCS), is designed to observe the corona in high detail, mimicking the observational conditions of a total solar eclipse.

Why Is This Such a Big Deal?

• Revealing the Sun’s Corona: The Sun’s corona is typically invisible because it is much less bright than the Sun’s surface. It can only be seen during a solar eclipse when the Moon blocks the Sun's light.
• Predicting Space Weather: Studying the corona helps scientists predict space weather and geomagnetic storms, which can disrupt satellites and other systems on Earth.
• Extended Observations: Unlike natural solar eclipses, which last only a few minutes, Proba-3 can provide six hours of observation time in each orbit (approximately 19 hours and 36 minutes), allowing for continuous study of the corona.

What is Precise Formation Flying (PFF) Technology?

• Definition: PFF technology allows satellites to maintain exact positions and orientations relative to each other in orbit.
• Mechanism: The technology uses GPS, inter-satellite radio links, and automated control systems to ensure alignment.
• Implementation in Proba-3: In the Proba-3 mission, the Coronagraph and Occulter spacecraft stay 150 meters apart, using PFF to maintain millimetre-level precision, which is crucial for simulating a solar eclipse.
• Benefits: PFF enhances mission accuracy and provides a platform for advanced observational techniques that will enable more detailed studies of the Sun's corona.

Conclusion

Proba-3 is a groundbreaking mission that will offer unprecedented insights into the Sun’s corona by simulating solar eclipses using advanced satellite technology. By studying the Sun’s outer layers, scientists aim to improve our understanding of space weather and the mysterious temperature anomaly of the corona.