Context
Aditya-L1, India’s first solar observatory, was successfully placed in the final orbit, its desired destination from where it will make observations of the Sun for the next five years.
About
- Aditya-L1 was successfully inserted into the Larange Point 1, one of the five locations in the Earth-Sun system.
- A satellite in a Halo orbit around the L1 point has the major advantage of continuously viewing the Sun without any occultations or eclipses.
- Halo-Orbit Insertion (HOI) of its solar observatory spacecraft, Aditya-L1 was accomplished at around 4 pm on January 6, 2024.
Halo Orbit
- This Halo orbit is a periodic, three-dimensional orbit at L1 involving Sun, Earth and a spacecraft.
- 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 sun.
Aditya-L1
- Aditya-L1 was launched by the Indian Space Research Organisation (ISRO) on September 2, 2023 with the mission of observing, and helping us better understand the Sun.
- The mission aims to observe the Sun’s corona and understand its extreme heat from a halo orbit around the first Sun-Earth Lagrangian point (L1), which is located roughly 1.5 million km from the Earth.
Aditya-L1 has seven instruments for the observation of all the radiation and charged particles such as:
- Visible Emission Line Coronagraph (VELC)
- Solar Ultra-Violet Imaging Telescope (SUIT) payload
- ASPEX and Plasma Analyser Package for Aditya (PAPA) payloads
- Solar Low Energy X-ray Spectrometer (SoLEXS) and High Energy L1 Orbiting X-ray Spectrometer (HEL1OS)
- Magnetometer payload
Why study the Sun?
The Sun produces energy through nuclear fusion in its interior, and emits it from its outer layers.
- The photosphere, a 6,000-degree Celsius layer, emits all visible and infrared light, crucial for life.
- Above is the chromosphere, and higher still is the million-degree Celsius hot corona.
- The corona is much hotter than the inner layers of the Sun — there must be some energy source which provides this heat.
- It also emits ultraviolet and X-ray radiation which would be lethal to life on Earth, without the presence of the atmosphere which absorbs most harmful radiation.
The Sun also continuously streams electrically charged particles — a stream known as the Solar wind.
- These charged particles produce the spectacular aurorae, known as the Northern and Southern Lights, seen close to the north and south poles of the Earth.
- There are also sudden bursts and ejections of charged particles from the Sun into interplanetary space, known as Solar flares and coronal mass ejections.
- These directly affect space weather, space-reliant technologies like satellite communication networks, and can produce electric power blackouts in Earth’s higher latitudes.
Why L1 Point is Important?
L1 is the sweet spot between Earth and the Sun, where the gravitational force exerted on a spacecraft by the two celestial bodies, and the centrifugal force cancel each other.
- Lagrange 1 point, is one of the five locations in the Earth-Sun system.
- • It is a relatively stable point for a spacecraft to be parked, and observe the Sun.
L1 is on the line joining the Sun and the Earth. As Earth rotates around the Sun, L1 goes around the Sun too, while always remaining on the same line.
- Thus, rather than being at the same point in space, Aditya will remain at the same position, relative to the Sun and Earth.
- The L1 point is about 1.5 million kilometres from the Earth.
- This is just 1 percent of the total distance between the Earth and Sun.
• Location: Aditya-L1 is located outside the Earth’s atmosphere, its instruments can observe the ultraviolet radiation from the corona, and in the process, better understand its workings.
- It monitors the Solar atmosphere and the corona continuously to monitor eruptions on the Sun, and study the properties of charged particles in the Solar wind.
- This will then help provide early warning of Solar eruptions, and allow us to initiate actions to minimise the disruption they may cause.
Other Solar Space Missions
A few solar missions are already parked around the L1 point, including:
- The LISA Pathfinder, and Solar and Heliospheric Observatory (SOHO), both collaborative missions of NASA and European Space Agency.
- STEREO (Solar Terrestrial Relations Observatory) is a NASA mission.
- Hinode (Solar-B) is a Japanese mission.
- YOHKOH (Solar-A) mission of Japan.