India’s First Sun Mission | Aditya-L1’s HEL1OS Captures First Glimpse Of Solar Flares

CHENNAI, Nov 8: India’s first solar exploratory mission spacecraft Aditya-L1, which is continuing its journey to land at the sun-earth L1 point, has captured the first glimpse of solar flares.
ISRO on Wednesday said the solar flares were captured by the L1-Orbiting X-ray spectrometer–HELIOS.

“During its first observation period from approximately 12:00 to 22:00 UT on October 29, 2023, the High Energy L1 Orbiting X-ray Spectrometer (HEL1OS) on board Aditya-L1 has recorded the impulsive phase of solar flares”, the Space Agency said in an upadate.
“The recorded data is consistent with the X-ray light curves provided by NOAA’s GOES.”
“Commissioned on October 27, 2023, HEL1OS is currently undergoing fine-tuning of thresholds and calibration operations. The instrument is set to monitor the Sun’s high-energy X-ray activity with fast timing and high-resolution spectra”, ISRO said.
“HEL1OS data enables researchers to study explosive energy release and electron acceleration during impulsive phases of solar flares” it added.

HEL1OS was developed by the Space Astronomy Group of the U R Rao Satellite Centre, ISRO, Bengaluru.
The High Energy L1 Orbiting X-ray Spectrometer (HEL1OS), is the hard X-ray spectrometer on Aditya-L1 Solar Mission by ISRO, operating in the wide X-ray energy band of 10 150 keV.
It is the harbinger of flaring activities on the Sun, with the ability to capture the early impulsive phase of the solar activity.
A solar flare is a sudden brightening of the solar atmosphere, which involves 1027 1032 ergs of energy release in tens of minutes.
Flares produce enhanced emission in all wavelengths across the electromagnetic spectrum radio, optical, UV, soft X-rays, hard X-rays and gamma-rays.
Flare emission consists of emissions from accelerated particles and hot plasma. Though solar flares have been studied in X-rays and gamma-rays for decades, the initial impulsive emission is very difficult to characterise and understand.
The impulsive hard X-ray emission has multiple spectral components which are highly time variable.
Further, the spectrum is very steep, the emission above 20 keV is typically several orders of magnitude (about a million times) lower than that of the emission below 10 keV. HEL1OS aims to overcome these difficulties by having a set of detectors specifically tuned to cater to different energy ranges and also provides very high spectral and time resolution measurements, ISRO said. .

The Science goals of HEL1OS are to study of explosive energy release, acceleration and transport of electrons during Solar flares using fast timing measurements and high resolution spectra.
Quasi-periodic Pulsations (QPPs) of hard X-rays during Solar flares to understand its connection with particle acceleration mechanisms.
It may be recalled that on September 19, AIDTYA-L1 spacecraft was given a perfect send off from the Earth Orbit, commencing its long voyage to the halo Lagrange-1 LI point, marking its journey lasting next four months to study the outer atmosphere of the most hot planet.
ISRO scientists had performed the Trans-Lagragean Point 1 Insertion (TL1I) manoeuvre of the spacecraft, which has commenced collecting scientific data at a distances greater than 50,0000 km from Earth.
The Trans-Lagrangean Point 1 Insertion (TL1I) maneuvre has been performed successfully and the spacecraft is now on a trajectory that will take it to the Sun-Earth L1 point, it said.
It will be injected into an orbit around L1 through a maneuver after about 110 days..
This is the fifth consecutive time ISRO has successfully transferred an object on a trajectory towards another celestial body or location in space.
The insertion into the Trans-Lagragean Point 1 Insertion (TL1I), signalled its stay in Earth orbit and commenced its voyage to the solar sphere after the successful fifth and final Earth bound orbit raising manouvere was performed at 0200 hrs early on September 19 morning.
From TLI1, the spacecraft will gradually proceed towards its final destination to study solar activities and its effect on space weather after a long voyage, signalling India’s second Space Odyssey after the Lunar Mission in a short span of time that made the galaxy of space faring nations to take note of India’s furtherance in global space programme.
ISRO had on Sep 19 said the fifth and final Earth-bound manouvre has been successful and it was injected into the TL1, as it started its voyage to the L1 point where it will be placed most likely in the first week of January, that will propel ISRO to become the first country to achieve the feat after the success of the more prestigious third Lunar Mission, when the Chandrayaan-3 made a soft landing on the moon’s South polar region.
Upon placing at L-1 point, the scientific objectives of Aditya-L1 mission includes, study of coronal heating, solar wind acceleration, Coronal Mass Ejections (CME), dynamics of solar atmosphere and temperature anisotropy.
ISRO used its workhorse launch vehicle PSLV for the mission that took off September two from the SHAR Range.
After a flight duration of 63 minutes and 20 seconds, Aditya?L1 spacecraft was successfully injected into an elliptical orbit of 235 km x 19,500 km around the earth from where the orbit was raised by firing the onboard propulsion motors.
PSLV-C57, in its 59th flight of PSLV and 25th mission using PSLV-XL configuration, took off from Second Launch Pad (SLP), SDSC, SHAR on September 2, and injected the Aditya-L1 spacecraft in a highly eccentric Earth bound orbit.
The spacecraft performed orbital maneuvers by using its LAM and will reach the Sun-Earth Lagrange point L1 (1.5 million kms from Earth, in a halo orbit) after a four-month long journey.
Of the total five Orbit raising manoeuvres, the first earth?bound manoeuvre was performed on September 3 and the second on September five and the third done on September 10 and the 4th on September 15.
After tfhe final manoeuvre on Sep 19 to raise its velocity ending its 16 days stay in the Earth-bound orbit, Aditya-L1 had underwent Trans-Lagrangian1 insertion manoeuvre, marking the beginning of its 110-day trajectory to the destination around the L1 Lagrange point.
As the spacecraft travels towards L1, it will exit the Earths’ gravitational Sphere of Influence (SOI). After exit from SOI, the cruise phase will start and subsequently the spacecraft will be injected into a large halo orbit around L1.
The total travel time from launch to L1 takes about four months for Aditya-L1.
Upon arrival at the L1 point, another manoeuvre binds Aditya-L1 to an orbit around L1, a balanced gravitational location between the Earth and the Sun.
Aditya L1 is the first Indian space-based observatory to study the sun from a halo orbit around first sun? earth Lagrangian point (L1), which is located roughly 1.5 million km from earth.
A satellite placed in the halo orbit around the L1 point has the major advantage of continuously viewing the Sun without any occultation/eclipse. This will provide a greater advantage of observing the solar activities continuously.
The satellite spends its whole mission life orbiting around L1 in an irregularly shaped orbit in a plane roughly perpendicular to the line joining the Earth and the Sun.
The strategic placement at the L1 Lagrange point ensures that Aditya-L1 can maintain a constant, uninterrupted view of the Sun. This location also allows the satellite to access solar radiation and magnetic storms before they are influenced by Earth’s magnetic field and atmosphere.
Additionally, the L1 point’s gravitational stability minimizes the need for frequent orbital maintenance efforts, optimizing the satellite’s operational efficiency.
Aditya-L1 will stay approximately 1.5 million km away from Earth, directed towards the Sun, which is about 1% of the Earth-Sun distance.
The Sun is a giant sphere of gas and Aditya-L1 would study the outer atmosphere of the Sun. Aditya-L1 will neither land on the Sun nor approach the Sun any closer.
Aditya-L1 is a satellite dedicated to the comprehensive study of the Sun. It has 7 distinct payloads developed, all developed indigenously–five by ISRO and two by Indian academic institutes in collaboration with ISRO.
Aditya in Sanskrit means the Sun. L1 here refers to Lagrange Point 1 of the Sun-Earth system. For common understanding, L1 is a location in space where the gravitational forces of two celestial bodies, such as the Sun and Earth, are in equilibrium.
This allows an object placed there to remain relatively stable with respect to both celestial bodies.
The spacecraft has seven payloads to observe the photosphere, chromosphere and the outermost layers of the Sun (the corona) using electromagnetic and particle detectors.
Using the special vantage point of L1, four payloads will directly view the Sun and the remaining three payloads will carry out in-situ studies of particles and fields at the Lagrange point L1.
ISRO said the suit of Aditya L1 payloads are expected to provide most crucial information to understand the problems of coronal heating, Coronal Mass Ejection, pre-flare and flare activities, and their characteristics, dynamics of space weather, study of the propagation of particles, fields in the interplanetary medium, etc.
For a two-body gravitational system, the Lagrange Points are the positions in space where a small object tends to stay, if put there. These points in space for a two-body system such as Sun and Earth can be used by the spacecraft to remain at these positions with reduced fuel consumption.
Technically at Lagrange point, the gravitational pull of the two large bodies equals the necessary centripetal force required for a small object to move with them.
For two-body gravitational systems, there are total five Lagrange points, denoted as L1, L2, L3, L4, and L5. The Lagrange point L1 lies between Sun-Earth line. The distance of L1 from Earth is approximately 1% of the Earth-Sun distance. (Agencies)