Aditya L1 of ISRO: India’s First Mission to the Sun

 

Aditya L1 is a spacecraft that will research the Sun and its numerous phenomena, such as the solar corona, solar wind, flares, and magnetic field. It is the first Indian expedition to the Sun and the first space-based solar observatory in the world to be installed at the Sun-Earth Lagrange point L1, which is a vantage point for watching the Sun without any interruption. Aditya L1 was conceived and built by the Indian Space Scientific Organisation (ISRO) and numerous other Indian scientific institutes. It was launched on September 2, 2023, by a Polar Satellite Launch Vehicle (PSLV-C57) from the Satish Dhawan Space Centre in Sriharikota. It is projected to reach its final orbit around L1 by January 2024 and operate for at least five years.

Why Study the Sun?

The Sun is the most important star in our solar system. It gives us with light, heat, and energy. It also affects our climate, weather, and surroundings. However, the Sun is not a consistent and stable source of energy. It undergoes different variations and cycles affecting brightness, warmth, and activity. The Sun also generates streams of charged particles called solar wind, which interact with the Earth's magnetic field and atmosphere, causing phenomena such as auroras, geomagnetic storms, and radio blackouts. These events are collectively known as space weather, which can have deleterious impacts on satellites, communication systems, power grids, navigation systems, and human health.

Therefore, researching the Sun is crucial for understanding its impact on our planet and society. It can also assist us in predicting and alleviating the consequences of space weather and understanding the secrets of star physics and evolution. Studying the Sun can also reveal information regarding the creation and history of our solar system and other planetary systems in the galaxy.

What is Aditya L1?

Aditya L1 is a spacecraft that will observe the Sun from a unique perspective: the Sun-Earth Lagrange point L1. This is a point in space where the gravitational pulls of the Sun and the Earth balance each other, enabling a stable orbit for a spacecraft. A spacecraft at L1 can continually view the Sun without occultation or eclipses by the Earth or the Moon. This will enable Aditya L1 to monitor solar activity and its real-time variations.

Aditya L1 has a mass of around 1.5 tonnes and carries seven scientific payloads that will perform diverse studies of the Sun in different wavelengths and modes. These payloads are:

• Visible Emission Line Coronagraph (VELC): This is the primary payload of Aditya L1. It will observe the solar corona, the outermost layer of the Sun's atmosphere that spans millions of kilometers into space. The corona is substantially hotter than the surface of the Sun and emits most of the solar wind. However, it is dim and difficult to detect due to the glaring glare of the Sun. A coronagraph is a device that filters off the straight light from the Sun's disk, generating an artificial eclipse that shows the corona. VELC will employ a coronagraph to picture and measure the properties of the corona in visible light. It will also do spectroscopy and polarimetry of the corona to analyze its temperature, density, magnetic field, and motion.
• Solar Ultraviolet Imaging Telescope (SUIT): This payload will observe the photosphere and chromosphere of the Sun, which are the inner layers of the solar atmosphere. The photosphere is the Sun's visible surface, where the light is emitted. The chromosphere is the layer above the photosphere, which is visible during a total solar eclipse as a crimson ring around the Sun. SUIT will photograph these layers under UV light, which can reveal their structure, activity, and variability. SUIT will also measure the spectrum irradiance of the Sun, which is the amount of energy emitted by the Sun at different wavelengths. This knowledge is vital for understanding how solar radiation impacts the Earth's atmosphere, climate, and biosphere.
• Solar Low Energy X-ray Spectrometer (SoLEXS): This payload will monitor the soft X-ray radiation from the Sun produced by heated plasma in the corona. Soft X-rays are high-energy electromagnetic radiation with wavelengths between 10 and 100 nanometers. SoLEXS will monitor the soft X-ray flux from the Sun, which can indicate its activity level, flare occurrence, and heating mechanisms.
• High Energy L1 Orbiting X-ray Spectrometer (HEL1OS): This payload will monitor the hard X-ray radiation from the Sun, which is produced by energetic electrons and ions in the corona and flares. Hard X-rays are high-energy electromagnetic radiation with wavelengths between 0.01 and 10 nanometers. HEL1OS will monitor the complex X-ray flux from the Sun, which can provide information regarding the acceleration and movement of particles in the solar atmosphere.
• Aditya Solar Wind Particle Experiment (ASPEX): This payload will measure the solar wind particles that reach the spacecraft at L1. The solar wind is a stream of charged particles that flows outwards from the Sun at tremendous speeds. It transports the Sun's magnetic field and affects the interplanetary space and the Earth's magnetosphere. ASPEX will measure the energy, mass, charge, and direction of the protons and heavier ions in the solar wind. It will also research the variations and volatility of the solar wind characteristics and their link with solar activity.
• Plasma Analyser Package for Aditya (PAPA): This payload will measure the properties of the ambient plasma around the spaceship at L1. Plasma is a state of matter that consists of ionized gas with unbound electrons and ions. It is the most common state of value in the universe and creates most of the Sun and stars. PAPA will measure the plasma's density, temperature, velocity, and composition around L1. It will also analyze the plasma waves and turbulence generated by the interaction of the solar wind and the Earth's magnetic field.
• Advanced Tri-axial High-Resolution Digital Magnetometers (ATHRDM): This payload will monitor the magnetic field around the spaceship at L1. The magnetic field is a vector quantity that describes the direction and strength of the magnetic force at a location in space. It is generated by electric currents and magnetic materials and influences the mobility and behavior of charged particles. ATHRDM will measure the three components of the magnetic field (Bx, By, and Bz) with great precision and resolution. It will also research the variations and fluctuations of the magnetic field and their association with solar activity.

What are the Objectives and Benefits of Aditya L1?

 Aditya L1 has numerous scientific objectives and benefits that can expand our knowledge and understanding of the Sun and its consequences on our world. Some of these are:

1. To explore the coronal heating problem, which is one of the unsolved riddles of solar physics. The coronal heating problem relates to how the corona is heated to millions of degrees Celsius, whereas the surface of the Sun is only about 6000 degrees Celsius. Various ideas have been presented to explain this occurrence, such as magnetic reconnection, wave dissipation, nanoflares, etc. Aditya L1 will offer high-resolution photos and spectra of the corona that can test these hypotheses and show the mechanics of coronal heating.
2. To research the solar wind acceleration, another unresolved solar physics issue. The solar wind acceleration relates to how the solar wind is accelerated from subsonic to supersonic speeds as it leaves the Sun. Various elements have been postulated to contribute to this process, such as thermal pressure gradients, magnetic forces, wave-particle interactions, etc. Aditya L1 will measure the properties of the solar wind particles that can throw light on these factors and reveal the mechanics of solar wind acceleration.
3. To research the coronal mass ejections (CMEs), which are massive eruptions of plasma and magnetic fields from the Sun that can travel beyond the solar system. CMEs are one of the principal drivers of space weather, which can affect the magnetosphere, ionosphere, and atmosphere and create geomagnetic storms, auroras, radio blackouts, and satellite damage. Aditya L1 will observe CMEs from their origin to their dissemination in interplanetary space and offer early warning of their arrival on Earth.
4. To study the dynamics of the solar atmosphere, which is continually changing due to numerous physical processes, such as convection, magnetic fields, waves, shocks, reconnection, etc. Aditya L1 will monitor these processes in different layers of the solar atmosphere and provide insights into their coupling and interplay.
5. To research solar temperature anisotropy, which measures how much the temperature changes along different directions. The temperature anisotropy can alter the stability and transport properties of the plasma and cause numerous instabilities and waves. Aditya L1 will monitor the temperature anisotropy in different parts of the solar environment and offer information about its genesis and evolution.
6. Providing continuous and high-resolution data on solar activity and its changes can increase our understanding of the solar cycle and its consequences on the EEarth'sclimate and environment. The solar cycle is a cyclical change in the SSun's magnetic field and activity that lasts for around 11 years. It impacts the solar radiation, solar wind, and sunspots that influence the energy temperature, precipitation, and atmospheric circulation. Aditya L1 will monitor the solar cycle and its phases, such as the solar maximum and minimum, and give data for forecasting and modeling.
7. To give valuable contributions to the development of solar physics and space science in India, which can strengthen the country's scientific and technological capabilities and people resources. Aditya L1 is a complex and ambitious mission that comprises numerous parts of engineering, design, manufacture, testing, launch, operation, and data processing. It will create chances for collaboration and cooperation among various Indian research institutes, universities, corporations, and agencies. It will also encourage and motivate young students and researchers to seek careers in science and technology.
8. To contribute to the worldwide scientific community and international cooperation in solar physics and space science, which can develop mutual understanding and exchange of knowledge and expertise. Aditya L1 is a unique project that will complement and supplement other existing and prospective missions to the Sun, such as NNASA'sParker Solar Probe, EESA'sSolar Orbiter, JJAXA'sSolar-C, etc. It will give fresh and valuable data to share and compare with other missions and ground-based observatories. It will also enable cooperative experiments and collaborations with other countries and organizations interested in researching the Sun.

The preceding information is a blog article introducing Aditya L1, the first Indian expedition to the Sun, and the first space-based solar observatory in the world to be deployed at the Sun-Earth Lagrange point L1. The blog post outlines why studying the Sun is essential and the scientific objectives and benefits of Aditya L1. It also details the spacecraft and its seven payloads that will perform diverse observations of the Sun in different wavelengths and modes. Here is a summary of the crucial points:

• Aditya L1 is a spacecraft that will research the Sun and its numerous phenomena, such as the solar corona, solar wind, flares, and magnetic field.

• Aditya L1 is the first Indian expedition to the Sun and the first space-based solar observatory in the world to be deployed at the Sun-Earth Lagrange point L1, which is a vantage point for watching the Sun without any interruption.

• Aditya L1 was conceived and built by the Indian Space Scientific Organisation (ISRO) and numerous other Indian scientific institutes. It was launched on September 2, 2023, by a Polar Satellite Launch Vehicle (PSLV-C57) from the Satish Dhawan Space Centre in Sriharikota. It is projected to reach its final orbit around L1 by January 2024 and operate for at least five years.

• Studying the Sun is vital for understanding its impact on our planet and civilization. It can also assist us in predicting and alleviating the consequences of space weather and understanding the secrets of star physics and evolution.

• Aditya L1 has numerous scientific objectives and benefits that can expand our knowledge and understanding of the Sun and its consequences on our world. Some of these are:

1. To explore the coronal heating problem, one of the unsolved riddles of solar physics.
2. To research the solar wind acceleration, another unresolved solar physics issue.
3. To research the coronal mass ejections (CMEs), which are massive eruptions of plasma and magnetic fields from the Sun that can travel across the solar system and affect the Earth's Earth's magnetosphere, ionosphere, and atmosphere.
4. To study the dynamics of the solar atmosphere, which is continually changing due to numerous physical processes, such as convection, magnetic fields, waves, shocks, reconnection, etc.
5. To research solar temperature anisotropy, which measures how much the temperature changes along different directions.
6. Providing continuous and high-resolution data on solar activity and its changes can increase our understanding of the solar cycle and its consequences on the EEarth'sclimate and environment.
7. To give valuable contributions to the development of solar physics and space science in India, which can strengthen the country's scientific and technological capabilities and people resources.
8. To contribute to the worldwide scientific community and international cooperation in solar physics and space science, which can develop mutual understanding and exchange of knowledge and expertise.

• Aditya L1 carries seven scientific payloads that will perform various observations of the Sun in different wavelengths and modes. These payloads are:

1. Visible Emission Line Coronagraph (VELC): Using a coronagraph, this payload will observe the solar corona in visible light. It will also do spectroscopy and polarimetry of the corona to analyze its temperature, density, magnetic field, and motion.
2. Solar Ultraviolet Imaging Telescope (SUIT): This payload will observe the photosphere and chromosphere of the Sun in ultraviolet radiation. It will also monitor the spectrum irradiance of the Sun, which is vital for understanding how solar radiation impacts the Earth's atmosphere, temperature, and biosphere.
3. Solar Low Energy X-ray Spectrometer (SoLEXS): This payload will monitor the soft X-ray radiation from the Sun produced by heated plasma in the corona. It will monitor the soft X-ray flux from the Sun, which can indicate its activity level, flare occurrence, and heating mechanisms. High Energy L1 Orbiting X-ray Spectrometer (HEL1OS): This payload will measure the hard X-ray emission from the Sun, which is produced by energetic electrons and ions in the corona and flares. It will monitor the complex X-ray flux from the Sun, which can provide information regarding the acceleration and movement of particles in the solar atmosphere.
4. Aditya Solar Wind Particle Experiment (ASPEX): This payload will measure the solar wind particles that reach the spacecraft at L1. It will also research the variations and volatility of the solar wind characteristics and their link with solar activity.
5. Plasma Analyser Package for Aditya (PAPA): This payload will measure the properties of the ambient plasma around the spacecraft at L1. It will also analyze the plasma waves and turbulence generated by the solar wind and the electromagnetic field interaction.
6. Advanced Tri-axial High-Resolution Digital Magnetometers (ATHRDM): This payload will detect the magnetic field around the spacecraft at L1. It will also research the variations and fluctuations of the magnetic field and their association with solar activity.