The Indian Space Research Organisation (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 primary 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 flying” in space, where two satellites will fly in tandem while maintaining an exact configuration. The Proba-3 mission is part of ESA’s ongoing efforts to explore the Sun, following the successes 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 an estimated cost of 200 million euros, the mission is expected to last for two years. It involves two key 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 a solar coronagraph. This instrument will block out the Sun’s intense light, allowing researchers to observe the Sun’s outer atmosphere in unprecedented detail.
The Proba-3 spacecraft will be placed into a highly elliptical orbit, with an altitude range of 600 to 60,530 km and a 19.7-hour orbital period. It will be launched aboard ISRO’s Polar Satellite Launch Vehicle (PSLV), specifically the PSLV-XL variant, which is equipped with additional boosters for enhanced thrust. The PSLV has a proven track record, having launched numerous missions since its first successful flight in 1994. Its reliability makes it the preferred choice for both domestic and international satellite missions.
Scientific goals 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 up to 2 million degrees Fahrenheit. This layer of the Sun plays a crucial 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 because of the Sun’s overpowering brightness, but Proba-3 will address this challenge with three specialized 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 occulting disk to block the Sun’s light, enabling closer inspection of the corona.
- DARA (Digital Absolute Radiometer): This instrument will continuously measure the Sun’s total energy output, known as total solar irradiance, offering valuable data for solar research.
- 3DEES (3D Energetic Electron Spectrometer): This will measure electron fluxes as the spacecraft passes through Earth’s radiation belts, contributing to space weather studies.
Proba 3: Use of precision formation flying
What makes Proba-3 unique is its use of precision formation flying. The two satellites will maintain a highly specific distance from each other—separated by only a few millimeters—while flying in a fixed formation. This precise alignment is crucial for simulating the effects of a solar eclipse, where one satellite will block the Sun’s light, allowing the other to study the Sun’s corona. Unlike natural solar eclipses, which last for only a few minutes and occur infrequently, Proba-3 will provide up to six continuous hours of observation—equivalent to the total duration of 50 natural solar eclipses each year. This extended observation window will enable scientists to gather more comprehensive data about the corona and solar phenomena.
The Coronagraph spacecraft will act as a telescope positioned in the shadow of the Occulter satellite, allowing it to capture images of the Sun’s corona and other features that are otherwise difficult to observe.
Proba-3: A 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 establish itself as a reliable and cost-effective partner in global space exploration. The success of Proba-3 will further bolster ISRO’s reputation and highlight its growing capabilities in space.
For India, the Proba-3 mission offers several potential benefits. Indian scientists, particularly those specializing in solar physics, are expected to gain valuable insights from the mission’s data. Indian researchers have already collaborated with their European counterparts in shaping the scientific objectives of Proba-3, and there are strong indications that they will have exclusive access to its findings. This access could significantly enhance India’s understanding of solar phenomena and space weather, which are important for protecting Earth-based infrastructure such as satellites and power grids from solar-induced disruptions.The mission also underscores the expanding partnership between ISRO and the European Space Agency, marking another important step in India’s space exploration journey.
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