The Indian Space Research Organization (ISRO) is set to launch the European Space Agency’s (ESA) Proba-3 mission on December 4. The launch will take place from the Sriharikota spaceport in India, and its main objective is to study the Sun’s corona, the outermost and hottest layer of its atmosphere. This groundbreaking mission will also introduce the concept of “precision formation mater” in space, where two satellites will fly together while maintaining their precise configuration. The Proba-3 mission is part of ESA’s efforts to explore the Sun, following the success of previous missions like Proba-1 (2001) and Proba-2 (2009), which were also launched by ISRO.
ISRO’s PSLV-XL to launch Proba-3, a collaborative mission with European space experts
Proba-3 is a collaborative project involving scientists from several European countries, including Spain, Belgium, Poland, Italy, and Switzerland. With a cost of approximately 200 million euros, the mission is expected to last two years. It consists of two main spacecraft: the Occulter Spacecraft, weighing 200 kg, and the Coronagraph Spacecraft, weighing 340 kg. These two satellites will operate in precise coordination, separated after launch but positioned together to form the solar coronagraph. This instrument will block out the sun’s harsh light, allowing researchers to observe the Sun’s outer atmosphere in unprecedented detail.
The Proba-3 spacecraft will be placed in a highly elliptical orbit, with an altitude of 600 to 60,530 km and an orbital period of 19.7 hours. It will be launched on ISRO’s Polar Satellite Launch Vehicle (PSLV), specifically the PSLV-XL variant, which is equipped with an additional booster for enhanced thrust. PSLV has a proven track record, having launched multiple missions since its first successful flight in 1994. This reliability makes it the preferred choice for domestic and international satellite missions.
The scientific objective of Proba-3
The primary goal of the Proba-3 mission is to study the Sun’s corona, a region that is difficult to observe due to its extreme temperatures, which can reach 2 million degrees Fahrenheit. These layers of the Sun play an important role in space weather phenomena such as solar storms and solar winds, which can disrupt satellite communications, navigation systems, and power grids on Earth. Traditional instruments struggle to study the corona due to the extreme brightness of the Sun, but Proba-3 will overcome this challenge with three special instruments:
- ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun): This coronagraph will provide a clear view of the Sun’s inner and outer corona, a perspective usually only available during rare solar eclipses. It uses a 1.4-meter magic disk to block the Sun’s light, allowing it to examine the corona more closely.
- DARA (Digital Absolute Radiometer): This instrument will continue to measure the Sun’s total energy output, known as total solar irradiance, offering valuable data for solar research.
- 3DEES (3D Energetic Electron Spectrometer): It will measure electron flux as the spacecraft passes through Earth’s radiation belt, contributing to space weather studies.
Proba 3: The use of flying precision formation
What makes the Proba-3 unique is its use of precision formation aircraft. The two satellites will maintain a very specific distance from each other—separated by just a few millimeters—while flying in fixed formation. This precise alignment is critical to simulating the effects of a solar eclipse, where one satellite will block sunlight, allowing the other to study the Sun’s corona. Unlike natural solar eclipses, which last only a few minutes and occur infrequently, Proba-3 will provide up to six hours of continuous observation—equivalent to the total duration of 50 natural solar eclipses each year. This longer observation window will allow scientists to collect more comprehensive data on the corona and solar phenomena.
The Coronagraph spacecraft will be a telescope positioned in the shadow of the Occult satellite, in order to capture images of the Sun’s corona and other hard-to-observe features.
Proba-3: An important milestone for ISRO’s growing role in global space exploration
Proba-3 is not only a technological milestone but also a significant achievement for ISRO. By launching this mission, ISRO continues to be a trusted and valued partner in global space exploration. The success of Proba-3 will further strengthen ISRO’s reputation and highlight its growing capabilities in space.
For India, the Proba-3 mission offers several potential benefits. Indian scientists, especially those specializing in solar physics, are expected to gain valuable insights from the mission’s data. Indian researchers have been working with their European partners to shape the scientific objectives of Proba-3, and there are strong indications that they will have exclusive access to the findings. This access could significantly improve India’s understanding of solar phenomena and space weather, which is essential for protecting Earth-based infrastructure such as satellites and power grids from solar-induced disturbances. marking another important step in India’s space exploration journey.
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