The April 8 total solar eclipse will provide a rare and brief window for scientists to study the Sun’s perplexing corona.
It is the outermost part of the Sun’s atmosphere, which extends some millions of kilometers above the visible surface of the Sun.
During an eclipse, the corona appears as a faint white halo in the darkened ambiance of the Sun. On most days, the view of the super-heated corona is obstructed by the Sun’s surface’s extreme brightness.
However, a new, unique mission will allow scientists to perform long-term studies of the Sun’s corona.
This will be achieved by creating an artificial eclipse in space, thanks to the upcoming mission Proba-3 of the European Space Agency (ESA).
This bold mission comprises a pair of satellites that will perfectly align to perform an orbital solar eclipse on demand.
The occulter and coronagraph satellites are undergoing pre-flight testing at the Redwire Space facility in Kruibeke, Belgium.
“The two spacecraft will act as if they are one enormous 150-m long instrument,” said Dietmar Pilz, ESA Director of Technology, Engineering and Quality.
“Achieving this will be extremely technical challenging however, because the tiniest bit of misalignment and it won’t work,” added Pilz.
Hundreds of millions of people will witness next week’s total #SolarEclipse across North America. Meanwhile @ESA is preparing to make our own in orbit, with the dual spacecraft of the new #Proba3 mission, presented to media today https://t.co/5QswphVz7X pic.twitter.com/1CbNs7aMXb
— ESA Technology (@ESA_Tech) April 3, 2024
The duo will form an artificial eclipse for over six hours
In this alignment, the occulter satellite positions itself between the Sun and the coronagraph. This setup will effectively block direct sunlight from reaching the coronagraph’s view.
The occulter satellite will fly around 150 meters distant from its orbital partner, the coronagraph.
Per the press release, each orbit of the Proba-3 mission lasts roughly 19 hours and 36 minutes. During each orbit, there will be opportunities to create artificial eclipses for up to six hours.
This extended duration of observation allows for a more in-depth study of the solar corona as well as gaining new insights into the Sun’s fiery atmosphere.
Proba-3’s main instrument, ASPIICS, will produce data as if “aboard a single rigid spacecraft.” ASPIICS stands for Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun.
Proba-3 achieves millimeter precision by integrating precise positioning technologies such as satellite navigation, inter-satellite communications, visible-light cameras, and laser beams.
This formation flight will occur automatically at a high orbital height of about 60,000 kilometers. At this height, gravitational, atmospheric, and magnetic disturbances have little impact on orbiting satellites.
Apart from the time of formation, the duo will passively drift safely.
Understanding the Sun’s corona
Astronomers have been puzzled by the Sun’s corona since the 19th century.
The Sun’s corona temperature is known to spike up to two million degrees Kelvin, while the underlying surface (some 1,000 miles below) simmers at very low temperatures.
Scientists have been trying to figure out what makes corona so hot.
Corona does not produce or reflect much light despite its incredibly high temperature. Because of this, the corona is only visible during the total solar eclipse.
Furthermore, the corona influences space weather by generating solar wind. These solar winds sometimes accompany coronal mass ejections, which might harm orbiting satellites and terrestrial power and communication networks.
This unique in-space calibration will allow scientists to obtain close glimpses of our host star’s ghostly surrounding atmosphere. If Proba-3 is successful, it will be “the first-ever precision formation space flight,” noted the press release.
