Adiya-1 Spacecraft

Aditya-L1 is India’s first dedicated solar observatory mission, developed and launched by the Indian Space Research Organisation (ISRO) to study the Sun, its outer atmosphere, and its influence on space weather. The mission represents a major milestone in India’s space science programme, being the first Indian spacecraft to be positioned at the Lagrange Point 1 (L1)—a strategic location approximately 1.5 million kilometres from Earth—from where it can continuously observe the Sun without orbital interruptions.

Background and Development

The concept of an Indian solar mission was first proposed in 2008 as a small satellite named Aditya-1, intended to study the solar corona using a single payload, the Visible Emission Line Coronagraph (VELC). However, as scientific interest grew and technology advanced, the mission was reconfigured into a more comprehensive observatory, renamed Aditya-L1, to be stationed at the Sun–Earth L1 Lagrange point.
The final mission configuration was developed jointly by ISRO and various Indian research institutions, including:

• Indian Institute of Astrophysics (IIA), Bengaluru – responsible for VELC.
• Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune.
• Space Physics Laboratory (SPL) and UR Rao Satellite Centre (URSC).

The spacecraft was successfully launched by the PSLV-C57 rocket on 2 September 2023 from the Satish Dhawan Space Centre, Sriharikota.

Objectives of the Mission

The Aditya-L1 mission aims to enhance scientific understanding of solar processes and their effect on the near-Earth environment. Its main objectives are:

• To study the solar corona, its dynamics, and the mechanisms responsible for coronal heating.
• To investigate solar wind, its origin, and the propagation of energetic particles.
• To observe solar flares and Coronal Mass Ejections (CMEs), which have significant impacts on space weather.
• To study the magnetic field topology and plasma properties of the solar atmosphere.
• To understand space weather drivers that affect satellite operations, communication systems, and power grids on Earth.

Orbit and Position: The L1 Lagrange Point

Aditya-L1 is positioned in a halo orbit around the L1 Lagrange point of the Sun–Earth system, located about 1.5 million km from Earth in the direction of the Sun.
The L1 point is a position in space where the gravitational forces of the Earth and the Sun balance the centrifugal force on a small object, allowing it to remain relatively stable with respect to both bodies.
This location offers key advantages:

• Continuous, uninterrupted view of the Sun.
• No eclipses or occultations by the Earth or Moon.
• Ideal vantage point for real-time monitoring of solar activity and space weather.

It took nearly 125 days after launch for the spacecraft to reach its operational orbit at L1, following multiple Earth-bound manoeuvres and a Trans-Lagrange Injection (TLI) trajectory.

Payloads on Board

Aditya-L1 carries seven scientific payloads, designed to study the Sun’s atmosphere, magnetic fields, and energetic particles across multiple wavelengths.
1. Visible Emission Line Coronagraph (VELC)

• Developed by the Indian Institute of Astrophysics (IIA).
• Studies the solar corona and measures its temperature, density, and velocity.
• Observes coronal mass ejections (CMEs) and other dynamic events in the visible spectrum.

2. Solar Ultraviolet Imaging Telescope (SUIT)

• Developed by IUCAA, Pune.
• Observes the photosphere and chromosphere in the near-ultraviolet band (200–400 nm).
• Provides full-disk images of the Sun and helps study solar irradiance variations.

3. Aditya Solar wind Particle Experiment (ASPEX)

• Measures the composition and energy of solar wind particles such as protons and alpha particles.

4. Plasma Analyser Package for Aditya (PAPA)

• Designed to study the energy distribution and mass composition of solar wind ions.

5. Solar Low Energy X-ray Spectrometer (SoLEXS)

• Monitors low-energy X-rays (1–30 keV) emitted during solar flares.
• Helps understand energy release and particle acceleration in the corona.

6. High Energy L1 Orbiting X-ray Spectrometer (HEL1OS)

• Observes high-energy X-rays (10–150 keV) for studying the most energetic solar events.

7. Magnetometer (MAG)

• Measures the magnetic field around L1 and supports the interpretation of solar wind data.

Together, these instruments provide a comprehensive dataset for understanding solar physics and Sun–Earth interactions.

Spacecraft Design and Technical Features

• Launch Vehicle: PSLV-C57 (Polar Satellite Launch Vehicle).
• Mass: Approximately 1,475 kg (total spacecraft mass).
• Power Generation: Solar panels generating about 700 watts of power.
• Communication: High-gain antenna for continuous data transmission to ground stations.
• Mission Duration: Designed for five years, though it may operate longer depending on system health.

The spacecraft is three-axis stabilised and equipped with precise attitude control systems for accurate pointing towards the Sun.

Scientific Importance

Aditya-L1 marks India’s entry into the field of heliophysics, joining other international solar missions such as NASA’s Parker Solar Probe and ESA’s Solar Orbiter. Its continuous observation capability from L1 provides valuable data for:

• Predicting solar storms and space weather impacts on satellites and communication systems.
• Understanding solar magnetic cycles and their influence on Earth’s climate.
• Advancing knowledge about plasma dynamics, solar radiation, and particle acceleration.
• Supporting safe operation of spacecraft and astronaut missions through improved space weather forecasting.

Achievements and Status

Following its successful insertion into the L1 orbit in early January 2024, Aditya-L1 began transmitting high-quality images and measurements of solar phenomena. Early data confirmed the accurate functioning of VELC and SUIT instruments, revealing detailed structures of the solar corona and chromosphere.
The mission has been lauded globally as a major scientific and technological achievement for India, demonstrating ISRO’s growing capabilities in deep-space and astrophysics research.

Significance

The Aditya-L1 mission holds immense significance in both scientific and strategic terms:

• It enhances India’s position in global space research by venturing into solar and space weather studies.
• It contributes to space-weather prediction systems, crucial for satellite safety and communication infrastructure.
• It supports international collaborations in solar physics, providing complementary data to missions operated by NASA, ESA, and JAXA.
• It demonstrates ISRO’s technical maturity in Lagrange point mission design, a critical step towards future interplanetary exploration.