2 weeks Ago
How long did totality last for you during Apr. 8’s total solar eclipse in North America ? A minute? Maybe two? Although it is possible for a total solar eclipse to bring darkness in the day — and a chance to see the sun's majestic corona with the naked eye — for up to 7 minutes 31 seconds, according to eclipse calculator Jean Meeus , most last just a couple of minutes. That's a shame because what happens in the corona is critical to understanding solar activity and its impacts on space weather.
Time in totality will not be a problem for Proba-3, a tech demo mission by the European Space Agency (with Belgium and Spain as the main contributors) that will see satellites together try to create totality for up to six hours about 50 times yearly. Fuel limitations will mean 1,000 hours of totality during the two-year mission. Formation Flying Launching on a Polar Satellite Launch Vehicle-XL rocket this week from the Satish Dhawan Space Centre near Chennai, India, the Proba-3 is, in essence, the world’s first precision formation flying mission.
Two satellites fly in formation to form an external coronagraph in space, with one satellite eclipsing the sun to allow the second to study the solar corona, the scorching and dynamic region of the sun's atmosphere that is typically obscured by the bright light of the sun's disk. During a total solar eclipse, the moon and the sun align perfectly, with the former blocking out the latter. They can only occur at new moon when the moon is between Earth and the sun.
Artificial Eclipses Artificial total solar eclipses in space will allow scientists to conduct in-depth studies of the corona in unprecedented detail, something that's hard to do outside of a total solar eclipse. Although NASA’s Solar Dynamic Observatory and NOAA's newest GOES satellite have coronagraphs, they’re only positioned a few meters in front of the telescope. That creates a lot of stray light, so the coronagraphs are enlarged to ensure bright sunlight cannot enter their telescopes.
In doing so, they block out the low corona where, arguably, the action happens. SDO can only observe to 2.2 solar radii.
Casting Shadows The further your occulter is from your telescope, the less stray light and the closer you can see down to the lower corona. Proba-3 will see down to just 1.1 solar radii from the sun’s surface — into the low corona — minimizing stray light during observations and providing data more like that collected during naturally occurring total solar eclipses.
The Proba-3 mission consists of two satellites flying 500 feet (150 meters) apart — the Occulter Spacecraft will block the sun’s light, casting its shadow precisely onto the Coronagraph Spacecraft, which will observe the corona and capture short HD videos. That will be possible for six hours in every 19-hour orbit, some 3,700 miles (60,000 kilometers) above Earth. Next Eclipse The pair of satellites will fly together in a fixed configuration as if they were a single sizeable rigid structure in space, proving out formation flying and rendezvous tech.
Both spacecraft will have to maintain accurate positioning to just a few millimeters, using GPS, star trackers and radio links to get roughly aligned. A visual-based sensor that uses cameras and LED lights will be used to get precisely aligned. Total solar eclipses on Earth are relatively rare, occurring roughly once every 18 months.
They’re also visible only from within a narrow path across Earth. The next is on Aug. 12, 2026, with the path of totality passing across eastern Greenland, western Iceland and northern Spain.
Wishing you clear skies and wide eyes..
