“Proba-3: An Exciting Encounter with the Sun’s Eclipse”
ESA’s Proba-3 mission aims to achieve what was previously considered impossible in space exploration. The mission involves two dual satellites that will perform precise formation flying in order to cast a shadow from one platform to the other. This shadow will block out the intense light of the Sun, allowing scientists to observe the faint atmosphere surrounding it for an extended period of time.
Before the launch of the Proba-3 satellites, a team of scientists had the opportunity to see the spacecraft in person. They visited the satellites at Redwire near Antwerp in Belgium, where the final integration was taking place. The team consisted of 45 solar physicists from Europe and around the world, who will make use of Proba-3 observations for their research.
The scientists who visited the satellites are experienced in studying terrestrial solar eclipses, but they are eager to explore the new perspective that Proba-3 will provide on the faint solar corona. The solar corona is a mysterious region that plays an important role in the creation of coronal mass ejections and the generation of solar storms. It also impacts the velocity of the solar wind, which is important for space weather forecasting. The close-up view of the satellite hardware amazed the scientists, particularly the camera head on the Coronagraph spacecraft, which is positioned less than a meter away from the solar array. The camera must remain in complete darkness to capture precise images, without any stray light. This highlights the importance of maintaining a small and precisely held shadow cast by the Occulter spacecraft.
Russell Howard, a renowned astrophysicist from John Hopkins University Applied Physics Lab, who has been involved in NASA’s Parker Solar Probe and ESA-NASA SOHO mission, also visited the Proba-3 satellites. He expressed excitement about the unique mission concept of Proba-3, which involves placing an occulter 150 meters away from the telescope to allow close imaging of the solar limb. This has never been attempted before, and Howard expects it to provide spectacular images of the Sun’s corona for hours on end.
The team then progressed to the Royal Observatory of Belgium in Brussels to discuss preparations for the mission, including data processing and distribution, co-observations with other space missions, and assessing Proba-3’s performance compared to existing coronagraph instruments. Traditional coronagraph telescopes use internal occulting discs to block out the solar disc, but they still experience diffraction or light spilling around their edges, which can obscure faint signals of interest. Proba-3 aims to solve this problem by flying the Coronagraph and Occulter on separate platforms, positioned 150 meters apart for up to six hours per orbit. This increased distance between the two components reduces diffraction, improving the quality of observations.
The meeting also highlighted how Proba-3’s filter wheels, developed for ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), will be used to observe a solar eclipse over Northern America on April 8, 2024. This will provide valuable insights into the results expected from Proba-3. Additionally, the meeting discussed Proba-3’s second instrument, the Digital Absolute Radiometer (DARA), which measures the total solar irradiance. Precise measurements of the Sun’s energy output are crucial for understanding its influence on Earth’s climate.
Proba-3 is scheduled for launch in September this year, using the PSLV launcher from India. The mission holds great promise for unveiling new insights into the Sun’s corona and its effects on Earth, thanks to the innovative approach of using formation flying to achieve unprecedented observations of our closest star.
