Four months after the Moon landing, the Indian Space Research Organization (ISRO) inserted its Aditya-L1 spacecraft– India’s first mission to study the Sun – into its destination orbit on Saturday afternoon, yet again demonstrating its capabilities to execute complex and advanced space missions.
Aditya-L1 moved into the ‘halo’ orbit around the L1 point in the Earth-Sun system, from where it will make observations of the Sun for the next five years.
L1, or Lagrange 1 point, is one of the five locations in the Earth-Sun system where the gravitational effects of the Earth and the Sun, as also the centripetal force on any satellite placed there, roughly cancel each other out. It is a relatively stable point for a spacecraft to be parked, and observe the Sun. The L1 point is about 1.5 million kilometer’s from the Earth. This is just 1 per cent of the total distance between the Earth and Sun.
ISRO Chairman S Somanath said Saturday’s event was about only placing the Aditya-L1 in the precise ‘halo’ orbit. “It was moving towards the ‘halo’ orbit but we had to do a little bit of corrections to put it at the right place. So something like a 31 metres per second velocity had to be given cumulatively to the satellite to keep it at the right orientation,”
What the ISRO scientists have achieved is exact placement based “on our measurement and very correct prediction of the velocity requirement.” The space agency further said the orbit of Aditya-L1 spacecraft is a periodic one, on the continuously moving Sun-Earth line, with an orbital period of about 177.86 Earth days.
“This specific ‘halo’ orbit is selected to ensure a mission lifetime of 5 years, minimising station-keeping manoeuvres and thus, fuel consumption, and ensuring a continuous, unobstructed view of the Sun… The success of this insertion not only signifies ISRO’s capabilities in such complex orbital manoeuvres, but it gives confidence to handle future interplanetary missions,” ISRO said.
Placing the Aditya spacecraft in the ‘halo’ orbit around L1 point was not as simple as putting a satellite in an orbit around Earth, or any other planetary body like the Moon or Mars, which ISRO and other space agencies routinely do.
“Usually, satellites are put into orbits around physical bodies like Earth, Moon, Mars etc. In this case, at L1, there’s no physical object. It is an empty space, just a location. Besides, closed orbits around celestial bodies are either circular or elliptical. The orbit around L1 is more complex. It is almost perpendicular to the line joining the Earth and the Sun. As such, the insertion into this orbit required a very challenging manoeuvre. Even after the insertion, ISRO would need to carry out correction manoeuvres periodically to remain in the orbit,” A N Ramaprakash, a senior professor at Pune-based Inter-University Centre for Astronomy and Astrophysics (IUCAA) who has worked on one of the main payloads on-board the Aditya mission, said.
Background: The Sun has always been a subject of fascination and curiosity for scientists, providing the energy that sustains life on Earth. However, its complex behavior, solar flares, and magnetic storms remain relatively poorly understood. Recognizing the need to enhance our knowledge of solar phenomena, ISRO has embarked on a mission that aims to bring us closer to the Sun than ever before.
Mission Objectives:
The primary objectives of ISRO’s Sun mission encompass a comprehensive study of solar activity, understanding the Sun’s influence on space weather, and advancing our knowledge of the solar atmosphere. The mission is designed to:
- Proximity and Observation: Utilize cutting-edge technology to position a spacecraft in close proximity to the Sun, enabling unprecedented observations of solar phenomena.
- Solar Dynamics: Investigate the dynamic behavior of the Sun, including solar flares, prominences, and coronal mass ejections, to enhance our understanding of these phenomena.
- Space Weather Impact: Study the impact of solar activities on space weather, including their effects on Earth’s magnetosphere, ionosphere, and communication systems.
- Solar Atmosphere: Examine the Sun’s outer layers and the intricate details of its atmosphere, shedding light on the mechanisms driving solar processes.
- Technology Demonstrations: Showcase technological advancements in spacecraft design, thermal protection, and instrumentation required for close proximity to the Sun.
Proposed Instruments:
ISRO’s Sun mission is expected to carry a suite of state-of-the-art instruments, including:
- Solar Imaging Spectrometer: Capturing high-resolution images and spectra of the Sun’s surface and atmosphere.
- Solar Wind Analyzers: Monitoring the solar wind and its variations to understand its impact on space weather.
- Magnetic Field Detectors: Investigating the Sun’s magnetic field and its role in solar activities.
- Corona Graphs: Observing the solar corona to unravel its mysteries and dynamics.
Conclusion:
ISRO’s Sun mission represents a significant stride in India’s space exploration journey, aiming to unravel the secrets of our nearest star. As the spacecraft ventures closer to the Sun than ever before, the data it gathers promises to enhance our understanding of solar physics, space weather, and the fundamental processes driving the dynamic behavior of our Sun.