Editor-DN
The Indian space agency ISRO today successfully launched the European Space Agency’s PROBA-3 satellite. The launch was on ISRO’s workhorse rocket – the Polar Satellite Launch Vehicle or PSLV, in its 61st commercial mission ‘C-59’.
Here’s what you need to know about the European satellite PROBA-3: PROBA, short for Project On Board Anatomy, is a space program under the European Space Agency, or ESA. Under Proba, a series of satellite launches is underway. Today’s was the third in the series, hence the name PROBA-3.PROBA-3 is a solar mission. Its aim is to study the Sun’s corona at a level never before done. PROBA-3 consists of two independent, three-axis stabilized spacecraft – the Coronagraph Spacecraft or CSC, which weighs 310 kg and the Occulter Spacecraft or OSC, which weighs 240 kg. Both spacecraft will have a highly elliptical orbit around the Earth with a maximum distance of 60,500 km from the surface of the planet at the equator. According to the European Space Agency, the mission will perform a ‘formation flight’. – Scientific experiment at scale. The two orbiting spacecraft will create the Solar Coronagraph, about 150 meters long, to study the Sun’s faint corona closer to the solar rim than has ever been achieved before. By flying so close – 150 meters – the occulter spacecraft will cast an exact shadow on the coronagraph telescope, thereby blocking direct sunlight. Coronagraph will then be able to map and image the Sun’s corona across the full electromagnetic spectrum – including visible light, ultraviolet radiation (UV rays) and infrared radiation (IR). It will also be able to image the solar corona in polarized light – which is made up of waves that vibrate in the same plane and includes linearly, circularly and elliptically polarized light. CSC will be able to do this for several hours at a time. The scientific objective of the PROBA-3 mission is to observe the Sun’s corona at 1.1 solar radius in the visible wavelength range (visible light). The solar radius is a unit of distance used to describe the size of stars compared to the size of the Sun. 1 solar radius is equal to 6.95700 x 10 (to the power of 8) meters or 695,700 km. It is about 109 times the radius of the Earth. This will make PROBA-3 the most accurate satellite for mapping and imaging the Sun’s corona. PROBA-3 marks the next phase of formation flying. As a world first, its two satellites — the Coronagraph spacecraft and the Occulter spacecraft — will maintain alignment to a few millimeters and be about 150 meters apart for six hours per 19-hour, 36-minute orbit. In effect, the pair would form a virtual giant satellite. And this will be achieved autonomously without relying on terrestrial guidance. Now that the two satellites have been successfully placed into orbit, there will be a short preparation time for both satellites with some safety tests being conducted by the European Space Agency. Since these two satellites will be independent but flying in close proximity, collision maneuvers will be tested. After these tests are completed, the two satellites will be placed in a safe relative tandem orbit. Then they can be released safely without risk of collision or running into each other. PROBA-3 satellites will perform repeated acquisition, rendezvous, proximity operations, formation flying, coronagraph observations, separation and convoy flights in each orbit. According to the European Space Agency, PROBA-3 will be a “laboratory in space”. Tactics, guidance, navigation and control, and other algorithms, such as related GPS navigation, were first tested in ground simulators. ESA said the mission included a rendezvous experiment. It will test sensors and algorithms for rendezvous (cooperative and uncooperative) satellites in elliptical orbits. This advanced technology could be used for future Mars sample return missions and to deorbit satellites from low Earth orbit – which would also help eliminate space around Earth.
