India’s space program will proceed its busy 2023 with the launch of its first solar research mission, Aditya-L1, on Saturday. Liftoff, aboard the country’s Polar Satellite Launch Vehicle (PSLV) XL rocket, is predicted at 11:50 Indian Standard Time (06:20 UTC) from the Satish Dhawan Space Centre.
Aditya-L1 will probably be the primary mission conducted by the Indian Space Research Organisation (ISRO) that is devoted to studying the Sun. Sure for the Earth-Sun L1 Lagrange point, it would even be the primary Indian spacecraft to operate at this location. ISRO expects the mission to contribute to global research into the Sun, with a deal with space weather and the solar wind.
Key science objectives for the mission are to assist increase understanding of the phenomena of coronal heating, or how the Sun’s corona – its outer atmosphere – has a far higher temperature than the surface of the Sun itself, and study how the corona accelerates the solar wind. Other major objectives include understanding how solar flares and coronal mass ejections are initiated, studying the dynamics of the Sun’s atmosphere, and monitoring the distribution and anisotropy (lack of uniformity by direction) of particles within the solar wind.
Saturday’s launch comes just ten days after ISRO celebrated one other major milestone with the successful landing of its Vikram probe on the Moon as a part of the Chandrayaan-3 mission. With the agency having already carried out the primary successful launch of its latest Small Satellite Launch Vehicle rocket earlier this 12 months, and now gearing up for the primary uncrewed test flight of its Gaganyaan crew capsule in early 2024, that is a very important time for India in space.
Aditya-L1 carries a set of seven instruments that will probably be used to review the Sun. The spacecraft was constructed in-house at ISRO and has a mass of 1,475 kilograms. It is predicted to operate for a minimum of five years. The foremost instrument is the Visible Emission Line Coronagraph, which was built by the Indian Institute of Astrophysics to review the Sun’s corona and coronal mass ejection events. It uses an internally occulted reflective coronagraph to dam direct light from the Sun itself to permit its detectors – including an imager, a multi-split spectrograph, and a polarimeter, to watch the corona.
The Solar Ultraviolet Imaging Telescope was developed by the Inter-University Centre for Astronomy and Astrophysics. Its purpose is to make observations of the complete disc of the Sun at near-ultraviolet wavelengths — allowing for study of the photosphere and chromosphere, in addition to measuring fluctuations in the quantity of ultraviolet light radiated by the sun.
ISRO’s U R Rao Satellite Centre has contributed a pair of x-ray imaging payloads to the mission: the Solar Low Energy X-ray Spectrometer (SoLEXS) and the High Energy L1 Orbiting X-ray Spectrometer (HEL1OS). These will probably be used to assist study solar flares, with SoLEXS observing soft, or lower-energy, x-ray emissions and HEL1OS focussing on hard, or high-energy, emissions.
Aditya Solar Wind Particle Experiment (ASPEX) was built by the Physical Research Laboratory at Ahmedabad to review the solar wind in an effort to unlock a greater understanding of processes throughout the Sun. It consists of two sensors: the Solar Wind Ion Spectrometer, which will probably be used to detect and measure protons and alpha particles; and the Suprathermal and Energetic Particle Spectrometer, which is able to detect higher-energy ions.
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Aditya-L1 atop PSLV C57’s fourth stage, shortly before being enclosed within the payload fairing. (Credit: ISRO)
The Plasma Analyser Package for Aditya (PAPA), developed by the Vikram Sarabhai Space Centre’s Space Physics Laboratory, may even contribute to Aditya’s study of the solar wind. PAPA consists of a Solar Wind Electron Energy Probe and Solar Wind Ion Composition Analyser to record the flux, density, and composition of electrons and ions within the solar wind, helping to construct an in depth record of how these vary over time.
By studying particles within the solar wind with ASPEX and PAPA, the Aditya mission may give you the option to validate theories about how wave-particle interactions might play a job within the processes of solar wind acceleration and coronal heating.
The ultimate instrument aboard Aditya, the Magnetometer, will measure the magnetic fields in situ on the spacecraft’s location. Two sets of sensors are mounted on a six-meter deployable boom, with one set at the top of the boom and the opposite halfway along it, providing two sets of measurements.
ISRO will use its PSLV rocket to deploy Aditya-L1 into an initial low-Earth orbit. From here, the spacecraft will, under its own propulsion, perform a series of maneuvers to put itself right into a halo orbit across the Earth-Sun L1 Lagrange point. Lagrange points are locations in space where the gravitational pull of two celestial bodies are in equilibrium, allowing objects to stay at, or orbit, the purpose with minimal station-keeping.
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Aditya’s journey to the Earth-Sun L1 point. (Credit: ISRO)
The Earth-Sun L1 point is situated directly between the Earth and the Sun, at about 1.5 million kilometers from Earth. Placing solar research missions at L1 ensures their view of the Sun won’t be interrupted by Earth while ensuring the spacecraft also stays relatively near Earth for communications and data downlink.
Upon arrival on the L1 point, Aditya will join 4 other spacecraft currently operating at L1: the joint NASA-ESA Solar and Heliospheric Observatory, NASA’s Advanced Composition Explorer and Wind missions, and the National Oceanic and Atmospheric Administration’s Deep Space Climate Observatory. Aditya will probably be the primary Indian spacecraft to operate at L1 and is predicted to succeed in its final orbit across the Lagrange point about 125 days after launch.
To deploy Aditya-L1, essentially the most powerful version of the PSLV rocket, PSLV-XL, will probably be employed. This can be a four-stage launch vehicle employing each solid and liquid-fuelled propulsion, able to placing payloads of as much as 1,750 kilograms right into a 600-kilometer Sun-synchronous orbit or 1,425 kilograms to a geosynchronous transfer orbit.
The rocket that may carry Aditya into orbit has been designated with flight number PSLV C57, and will probably be the fifty-ninth PSLV rocket to fly. The rocket is ISRO’s workhorse, carrying out nearly all of the agency’s satellite launches in addition to occasional business missions. It first flew in September 1993 and had – prior to Saturday’s launch – carried out 55 of its missions successfully, with two failures and one partial failure resulting from an off-nominal orbit. PSLV’s last 17 missions have all been successful.
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PSLV C57 leaving the assembly constructing for the launch pad. (Credit: ISRO)
Saturday’s launch will happen from the Second Launch Pad on the Satish Dhawan Space Centre (SDSC) on Sriharikota, a barrier island within the Bay of Bengal. First utilized in 2005, this launch pad has hosted PSLV, Geosynchronous Satellite Launch Vehicle (GSLV), and GSLV Mk.III (also generally known as Launch Vehicle Mark 3) launches and is certainly one of two pads available for PSLV missions, together with the nearby First Launch Pad. SDSC has been the positioning for all of India’s orbital launches up to now.
PSLV’s first stage is powered by an S-138 solid rocket motor. Depending on the configuration, as much as six PS0M-XL solid rocket motors might be attached as boosters to enhance its thrust, with PSLV-XL using the complete set of six. Once Saturday’s countdown reaches zero, the primary stage will ignite, followed by the primary two pairs of boosters at T+0.42 seconds and T+0.62 seconds. Climbing away from the SDSC, PSLV will ignite the ultimate pair of boosters around 25 seconds into flight. Separation of the ground-lit boosters will occur across the 70-second mark, while the air-lit boosters will separate about 92 seconds into the mission.
About 108 seconds after liftoff, the primary stage can have exhausted all of its propellant and can burn out. The spent stage will probably be jettisoned, and the vehicle’s second stage will take over. Designated PS2, or PL40, the second stage is powered by a single Vikas engine burning hypergolic liquid propellants. Its fuel is UH25, a mix of three parts unsymmetrical dimethylhydrazine to at least one part hydrazine hydrate, while its oxidizer is dinitrogen tetroxide. This propellant combination might be stored at room temperature and ignite easily without the necessity for complex ignition systems on the vehicle; nonetheless, also they are toxic and highly flammable. The Vikas engine itself is derived from the Viking engine used on early versions of the European Ariane series of rockets.
PSLV’s second stage burn is predicted to last about two and a half minutes. While the second stage is firing, the rocket will enter space, and shortly afterward will shed its payload fairing. The fairing, which ISRO calls a “heat shield,” helps to guard the satellite and preserve the rocket’s aerodynamic profile during its ascent through the atmosphere, but is not any longer needed once PSLV reaches space and is discarded to scale back the rocket’s weight.
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PSLV C57 with Aditya-L1, prior to launch. (Credit: ISRO)
The third stage, or HPS3, will ignite shortly after the second stage has shut down and separated. This solid-fuelled stage consists of an S-7 motor which is able to burn for roughly 70 seconds. After burnout, the mission will enter a coast phase because the rocket climbs towards its apogee – or the very best point on its trajectory. Third stage separation will happen during this coast, leaving PSLV’s fourth stage to finish the insertion of Aditya into its initial orbit.
The fourth stage is able to completing multiple burns to perform complex satellite deployments, ensuring payloads might be delivered to specific goal orbits or, on multi-satellite missions, allowing satellites with differing orbital requirements to be accommodated. This stage, generally known as PS4, has a pair of small engines burning monomethylhydrazine and mixed oxides of nitrogen (MON-3 – a mix of three% nitric oxide and 97% dinitrogen tetroxide). Once the fourth stage has accomplished its burn, Aditya-L1 will separate to start its own journey to L1.