Aditya-L1
Aditya-L1 (/ɑːd̪it̪jə/)(from Sanskrit: Aditya, "sun" and L1, "Lagrange 1 Point") a coronagraphy spacecraft to study the solar atmosphere, designed and developed by the Indian Space Research Organisation (ISRO) and various other Indian research institutes. It will be orbiting at about 1.5 million km from Earth in a halo orbit around the L1 Lagrange point between the Earth and the Sun where it will study the solar atmosphere, solar magnetic storms, and their impact on the environment around the Earth. It is the first Indian mission dedicated to observing the Sun. Nigar Shaji is the project's director. Aditya-L1 was launched aboard the PSLV C57 at 11:50 IST on 2 September 2023, ten days after the successful landing of ISRO's Moon mission, Chandrayaan-3. It successfully achieved its intended orbit nearly an hour later, and separated from its fourth stage at 12:57 IST. It is projected to reach its designated orbit at the L1 point approximately 127 days after its launch. Science objectives 

The main objectives of Aditya L1 are:
 To observe the dynamics of the Sun's chromosphere and corona:
 To study chromospheric and coronal heating, the physics of partially ionised plasma, of coronal mass ejections (CMEs) and their origins, of the coronal magnetic field and heat transfer mechanisms, and flare exchanges
 To observe of the physical particle environment around its position
 To determine the sequence of processes in multiple layers below the corona that lead to solar eruptions
 To study space weather, and the origin, composition and dynamics of solar wind

History 
Aditya was conceptualised in January 2008 by the Advisory Committee for Space Sciences (ADCOS). It was initially envisaged as a small  satellite in a Low Earth Orbit (800 km) with a coronagraph to study the solar corona. An experimental budget of  was allocated for the financial year 2016–2017. The scope of the mission has since been expanded and it became a comprehensive solar and space environment observatory to be placed at Lagrange point L1, hence the mission was renamed "Aditya-L1". , the mission has an allocated cost of  excluding launch costs. Overview 

The Aditya-L1 mission will take around 109 Earth days after launch to reach the halo orbit around the L1 point, which is about  from Earth. The spacecraft is planned to remain in the halo orbit for its mission duration while being maintained at a stationkeeping Δv of 0.2–4 m/s per year. The  satellite carries seven science payloads with various objectives, including instruments to measure coronal heating, solar wind acceleration, coronal magnetometry, origin and monitoring of near-UV solar radiation (which drives Earth's upper atmospheric dynamics and global climate), coupling of the solar photosphere to the chromosphere and corona, and in-situ characterisations of the space environment around Earth by measuring energetic particle fluxes and magnetic fields of the solar wind, and solar magnetic storms. Aditya-L1 will provide observations of the sun's photosphere, chromosphere and corona. Its scientific payloads must be placed outside the interference from the Earth's magnetic field and hence could not have been useful in the low Earth orbit as proposed in the original Aditya mission concept. One of the major unsolved problems in the field of solar physics is coronal heating. The upper atmosphere of the Sun has a temperature of  whereas the lower atmosphere is just . In addition, it is not understood exactly how the Sun's radiation affects the dynamics of the Earth's atmosphere on a shorter as well as a longer time scale. The mission will obtain near-simultaneous images of the different layers of the Sun's atmosphere, which will reveal the ways in which energy is channeled and transferred from one layer to another. Thus, the Aditya-L1 mission will enable a comprehensive understanding of the dynamical processes of the Sun and address some of the outstanding problems in solar physics and heliophysics. Payloads 

The instruments of Aditya-L1 are tuned to observe the solar atmosphere, mainly the chromosphere and corona. In-situ instruments will observe the local environment at L1. There are seven payloads on-board, with four for remote sensing of the Sun and three for in-situ observation. The payloads have been developed by different laboratories in the country with close collaborations of various ISRO centres. Visible Emission Line coronagraph (VELC) 
The Visible Emission Line Coronagraph (VELC) is a key instrument on India's Aditya-L1 space solar mission. The VELC is an internally occulted reflective coronagraph designed to fulfil specific observation needs. The instrument allows for high spatial resolution imaging (1.25-2.5 arc seconds) of the Sun's corona, simultaneous observations in three modes (Imaging, Spectroscopy and Spectro-polarimetry), and even utilities artificial intelligence to aid in the detection of coronal mass ejections (CME's). Solar Ultraviolet Imaging Telescope (SUIT) 
The SUIT is an ultraviolet imaging telescope designed to study the solar spectral radiation in the ultraviolet range, using narrowband and broadband spectral filters in the range of 200-400 nm with the hope of developing a better understanding between solar activity and the atmospheric dynamics of Earth. The SUIT provides near-simultaneous coverage of the solar atmosphere, from lower photosphere to the upper chromosphere. The instrument was developed by Inter University Centre for Astronomy and Astrophysics (lUCAA), in collaboration with ISRO. Solar Low Energy X-ray Spectrometer (SoLEXS) 
The SoLEXS is an X-ray spectrometer designed to continuously measure the solar soft X-ray flux (1 keV-22 keV) from the Sun-Earth Lagrangian point L1. These measurements can be used to better understand the properties of the Sun's corona, in particular, why the temperature of the corona is so high. The SoLEXS will observe solar flares, and in conjunction with data provided by the VELC, will help study the complex thermal properties of the Sun's outer layers. High Energy L-1 Orbiting X-ray Spectrometer (HEL1OS) 
Developed by the Space Astronomy Group, URSC, the HEL1OS (pronounced helios) is an x-ray spectrometer designed to study solar flares in the x-ray spectrum, in particular, energy bands of 10-150 Kev (kilo-electron volts). Utilising a twin-pair of Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (CZT) detectors, the instrument aims to study the acceleration and movement of electrons in the Sun's corona, as well as to study the cut-off energy between thermal & non-thermal solar emissions. Aditya Solar Wind Particle Experiment (ASPEX) 
The ASPEX is an instrument composed of low and high energy particle spectrometers, designed to conduct measurements of the Sun's solar wind particles. SWISS, the low energy spectrometer, contains two analysers, each designed to study particles entering the device in different planes. STEPS, the high energy spectrometer, also consists of two parts, STEPS 1 and STEPS 2, both designed to separate protons and alpha particles and measure the integrated flux. Plasma Analyser Package for Aditya (PAPA) 
The PAPA is an instrument onboard the Aditya-L1 designed to study the temperature, distribution and velocity of the solar winds. The instrument was developed by the Space Physics Laboratory of the Vikram Sarabhai Space Centre. The instrument contains two sensors; the Solar Wind Electron Energy Probe (SWEEP) and the Solar Wind lon Composition Analyser (SWICAR). The detectors are used in conjunction to analyse the energy levels of electrons and ions within the solar wind. Mission profile

Launch 

On 2 September 2023, at 11:50 IST, the Polar Satellite Launch Vehicle (PSLV-C57) accomplished a successful launch of the Aditya-L1 from the Second Launch Pad of the Satish Dhawan Space Centre (SDSC) located in Sriharikota. Aditya-L1, following a flight duration of 63 minutes and 20 seconds, achieved a successful injection into an elliptical orbit around the Earth at 12:54 IST. Aditya-L1 is scheduled to undergo a series of four Earth-bound orbital maneuvres prior to its injection to a transfer orbit towards the L1 Lagrange point. It is projected to reach its designated orbit at the L1 point approximately 127 days after its launch. Orbit raising burns

First orbit raising burn 
On 3 September 2023, the Aditya-L1 performed its first Earth-bound maneuvre, raising its orbit to a  into  orbit. Second orbit raising burn 
On 5 September 2023, Aditya-L1 performed its second Earth-bound maneuvre, raising its orbit to a  into  orbit. Third orbit raising burn 
On 10 September 2023, Aditya-L1 performed its third Earth-bound maneuvre, raising its orbit to a  into  orbit. Fourth orbit raising burn 
On 15 September 2023, Aditya-L1 performed its fourth Earth-bound maneuvre, raising its original orbit to a  into  orbit. This is  the last of such maneuvres, being directly followed by the Trans-Lagrangian 1 Injection, bound to take place on 19 September. Trans-Lagrangian 1 Injection
On 19 September 2023, Aditya-L1 performed its last maneuvre around Earth to escape its orbit and headed towards the Lagrange 1 point. It will take at least 4 months to further reach its destination, 1.5 million kilometers away. On 30 September 2023, Aditya-L1 had escaped the Earth’s sphere of influence and was on the way to the Lagrange 1 point. Trajectory correction maneuvre 
On 6 October 2023, Aditya-L1 performed a Trajectory Correction maneuvre (TCM1). It was needed to correct the trajectory evaluated after tracking the Trans-Lagrangian Point 1 Insertion (TL1I) maneuvre performed on September 19, 2023. Team
 Nigar Shaji - Project director 
 Sankarasubramanian K - Principal scientist of the mission

See also 

 Lagrange point
 Solar space missions
 Solar Orbiter
 Parker Solar Probe
 ISRO

References

External links 

 ISRO page for Aditya-L1

Satellites of India
Spacecraft launched by India in 2023
Missions to the Sun
September 2023 events in India
Space probes launched in 2023