CAPE CANAVERAL, Fla. — On Thursday, two European satellites were successfully launched into space, marking the beginning of an innovative mission to generate artificial solar eclipses using advanced formation flying skills.
Each artificial eclipse is expected to last for six hours once operations are fully underway next year, affording scientists significantly longer periods for investigating the sun’s corona compared to the transient few minutes associated with natural solar eclipses visible from Earth.
This significant launch took place from India. “We are a very happy science team here,” expressed Joe Zender, the mission scientist from the European Space Agency, in an email statement.
Designed primarily as a technology demonstration, the two satellites are scheduled to part ways in about a month. When they reach their designated orbit, they will maintain a distance of approximately 492 feet (150 meters) between them and align perfectly with the sun to allow one satellite to cast a shadow over the other.
Achieving this alignment will necessitate extreme precision, as the positional accuracy must be within just one millimeter—comparable to the thickness of a fingernail, as noted by the European Space Agency. The satellites will harness GPS, star trackers, lasers, and radio communications to operate autonomously and keep their formations intact.
Each satellite, designed in a cube shape, measures less than 5 feet (1.5 meters) in width. The shadowing satellite will deploy a disk that effectively blocks sunlight from the telescope positioned on the other satellite, simulating how the moon obscures the sun during a natural total solar eclipse, while the other satellite mimics Earth.
According to Dietmar Pilz, the technology and engineering director of the European Space Agency, “This has huge scientific relevance” beyond just the high-precision formation flying trials.
To conduct detailed investigations of the sun’s corona—its outer layer that appears as a crown-like structure—scientists need the bright solar disk completely obscured. Particular interest lies in exploring why the corona is hotter than the sun’s surface, alongside gaining insights into coronal mass ejections, which release vast amounts of plasma and magnetic fields into space.
These eruptions can create geomagnetic storms that interfere with power and communication systems both on Earth and in orbit, while also triggering breathtaking auroras in regions where they are not typically viewed.
The satellites will travel in an unbalanced orbit ranging from 370 miles (600 kilometers) to 37,000 miles (60,000 kilometers) above Earth, completing nearly a 20-hour orbit around the planet. During certain parts of their journey, six hours will be dedicated to creating these artificial eclipses, while the rest will focus on formation flying experiments.
The first results from the artificial eclipses are anticipated in March, following the initial testing phase of both spacecraft. Zender mentioned that eclipses will be produced at least twice weekly, allowing for six-hour observation periods of the corona during each event. The actual occurrence frequency will depend on solar activity and will be a significant advantage for researchers who now travel globally just to experience a fleeting three to five minutes of natural totality during rare eclipses.
This ambitious mission, named Proba-3, has a budget of $210 million and seeks to provide at least 1,000 hours of “on-demand” totality over its planned two-year operational period. Upon completing their mission, both satellites will gradually descend until they incinerate upon re-entry into the atmosphere, expected to occur within five years.
The launch was postponed by a day due to a last-minute issue with the backup propulsion system of one of the satellites, an essential component for precise formation flying. Engineers overcame this challenge with a computer software solution, as detailed by the European Space Agency.
