Two European satellites launch a mission to erase the sun – for science

Two spacecraft developed by the European Space Agency launched atop an Indian rocket on Thursday, kicking off a mission to test new formation flight technologies and observe a rarely seen patch of the Sun's etheric corona.

ESA's Proba-3 mission is purely experimental. The satellites are equipped with advanced sensors and instruments that enable the two spacecraft to orbit the Earth. Proba-3 will attempt to achieve millimeter-scale precision, several orders of magnitude better than the requirements for a spacecraft closing in on docking with the International Space Station.

“In a nutshell, it is an experiment in space to demonstrate a new concept, a new technology that is technically challenging,” says Damien Galano, project manager of Proba-3.

The two Proba-3 satellites launched from India at 5:34 a.m. EST (10:34 UTC) on Thursday, riding on a Polar Satellite Launch Vehicle (PSLV). The PSLV placed Proba-3 into an extended orbit with a low of about 356 miles (573 kilometers), a high of 37,632 miles (60,563 kilometers), and an inclination of 59 degrees to the equator.

After initial checkouts, the two Proba-3 satellites, each smaller than a compact car, will separate to begin their technical demo experiments early next year. The larger of the two satellites, known as the Coronagraph spacecraft, carries a suite of scientific instruments to image the Sun's corona, or outer atmosphere. The smaller spacecraft, called Occulter, features navigation sensors and low-impulse thrusters to help it maneuver into a position within 500 feet of its Coronagraph companion.

From the Coronagraph spacecraft's point of view, this is just the right distance for a 1.4-meter disk mounted on Proba-3's Occulter spacecraft to obscure the Sun's surface. The occultation will block the sun's blinding glare and cast a shadow of just 8 centimeters on the Coronagraph satellite, revealing the wispy, superheated gases that make up the solar corona.