Indian Space Program: News & Discussions

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In almost every other GSLV Mk-2 launch something or the other goes wrong.

ISRO's 100th mission hits a thruster snag, desired orbit not achieved​

The launch happened on board the GSLV-Mk 2 rocket.

"But the orbit raising operations towards positioning the satellite to the designated orbital slot could not be carried out as the valves for admitting the oxidizer to fire the thrusters for orbit raising did not open," the space agency said in an update to the GSLV-F15 mission on its website.

The satellite is orbiting the Earth in an elliptical Geosynchronous Transfer Orbit (GTO) which is not suitable for the navigation system.

"The satellite systems are healthy and the satellite is currently in elliptical orbit. Alternate mission strategies for utilising the satellite for navigation in an elliptical orbit are being worked out," ISRO said.

After the GSLV rocket placed the satellite in the GTO, the solar panels on board the satellite were successfully deployed and power generation was nominal.

According to the Indian Space Agency, communication with the ground station has been established.

The launch on board the GSLV was successful as all the stages performed flawlessly and the orbit was achieved with a high degree of precision.
 

ISRO's 100th mission hits a thruster snag, desired orbit not achieved​

The launch happened on board the GSLV-Mk 2 rocket.

"But the orbit raising operations towards positioning the satellite to the designated orbital slot could not be carried out as the valves for admitting the oxidizer to fire the thrusters for orbit raising did not open," the space agency said in an update to the GSLV-F15 mission on its website.

The satellite is orbiting the Earth in an elliptical Geosynchronous Transfer Orbit (GTO) which is not suitable for the navigation system.

"The satellite systems are healthy and the satellite is currently in elliptical orbit. Alternate mission strategies for utilising the satellite for navigation in an elliptical orbit are being worked out," ISRO said.

After the GSLV rocket placed the satellite in the GTO, the solar panels on board the satellite were successfully deployed and power generation was nominal.

According to the Indian Space Agency, communication with the ground station has been established.

The launch on board the GSLV was successful as all the stages performed flawlessly and the orbit was achieved with a high degree of precision.
We should have implemented the RLV program for a similar type of scenario, which is to capture the satellite with a robotic arm and send it back to earth to troubleshoot or send an astronaut to repair it in the space itself. We have seven NavIC satellites, which are out of order now.



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Historic First: India’s Solar Ultraviolet Imaging Telescope (SUIT) onboard Aditya-L1 Captures Unprecedented Solar Flare Details

February 28, 2025

Aditya-L1, India’s first dedicated space based solar mission, has made a ground-breaking observation from its scientific payloads- capturing the first-ever image of a solar flare ‘kernel’ in the lower solar atmosphere, namely the photosphere and the chromosphere, in the images recorded in the Near Ultra-violet (NUV) band. This observation and associated scientific results marks a major step in understanding the Sun’s explosive activity and its impact on Earth.

Aditya-L1 mission was launched on September 2, 2023 by ISRO PSLV C-57 rocket. On January 6, 2024 the spacecraft was successfully placed in a large halo orbit around first Earth-Sun Lagrange Point known as Lagrange Point L1. The L1 point is 1.5 million kilometres away from Earth towards the Sun. The special vantage point L1 allows the spacecraft to continuously observe various solar activities without any eclipse and occultation’s. Its advanced instruments, including Solar Ultraviolet Imaging Telescope (SUIT), Solar Low Energy X-ray Spectrometer (SoLEXS), and High Energy L1 Orbiting X-ray Spectrometer (HEL1OS), work together to detect and analyse solar flares from Near Ultra-violet (NUV) wavelength to soft and hard X-rays. SUIT payload is developed by Inter University Centre for Astronomy and Astrophysics (IUCAA) in close collaborations with various ISRO Centres. SoLEXS and HEL1OS payloads are developed by U Rao Satellite Centre (URSC), Bengaluru. SUIT can capture high-resolution images in 11 different waveband in NUV of the full solar disk or a specific region on the solar disk of scientific interest depending upon the scientific requirements. As different radiations of different wavelength leave the solar atmosphere from different height/layers, it allows scientists to study multiple layers of the Sun’s atmosphere to study their coupling and dynamics. SoLEXS and HEL1OS instruments monitor solar X-ray emissions, which help detecting the solar flare activity. This collaborative approach and joint data analysis from different instruments of Aditya-L1, gives scientists a complete picture of how solar energy moves through different layers of the Sun.

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Figure: Aditya-L1 spacecraft in clean room with location of SUIT payload

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Figure: The image of SUIT payload

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Figure: Illustration of Lagrange points of Sun-Earth system and location of Aditya-L1 (schematic image, not drawn to scale)

What is a Solar flare?

A solar flare is a sudden and intense burst of solar energy from the Solar atmosphere. The phenomena is caused by Sun’s magnetic field. The magnetic field of the Sun is very dynamic in nature. Sometime they suddenly snap and release intense burst of energy – like a powerful, short flash. The energy is released in the form of light/radiation and high energy charged particles.

How Aditya-L1 study the Solar flares?

During solar flare (as well as before the occurrence of solar flare) that particular region of the Sun generating flare becomes brighter in UV and X-ray. Aditya-L1 instruments such as SUIT, SoLEXS and HEL1OS can study these brightening and associated flash of radiation in greater details. This provides a detail picture of various phenomena related to Solar flares. It is to be noted that atmosphere of the Earth blocks these harmful radiations from the Sun to reach to the ground. Therefore, such study can be only made from space.

What did researchers observe from SUIT on-board Aditya-L1?

On February 22, 2024, the SUIT payload onboard Aditya-L1 observed an X6.3-class solar flare, which is one of the most intense categories of solar eruptions. The unique feature of this observation was that SUIT detected brightening in NUV wavelength range (200-400 nm) —a wavelength range never observed before in such greater detail (See Figure below). These observations confirm that the energy released from the flare spread through different layers of the Sun’s atmosphere. This provides new insights into the complex physics responsible for these massive solar explosions.

One of the most exciting revelations in this observation is that the localized brightening captured in the lower Solar atmosphere corresponds directly with an increase in the temperature of plasma in the Solar corona at the top of the solar atmosphere. This confirm the linkage between flare energy deposition and associated temperature evolution. This finding also validates long-standing theories while offering new data that will help to reshape our understanding of physics of solar flare.

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Figure: Observation of the flare as obtained from various SUIT filters.
Top figure: This figure shows the observations in SUIT narrow band NB04 filter, 280 nanometre (nm) wavelength, which shows the flaring region and the sunspot. The blue box shown in this figure mark the Region of Interest (RoI) of this observation. The region marked with white dashed box shows the region that was used for subsequent analysis by other filters of SUIT payload.

Bottom figure: The size of the images shown here corresponds to the white box region shown in the top figure for detail analysis. SUIT observed two bright kernels in various channels marked by arrows. The appearance of these bright kernels in NB02 and NB05 is highly interesting as these two filters observe the solar photosphere, which is lower than the chromospheric emissions Magnesium II and Calcium II. This implies that the effect of this flare affected the layers below the chromosphere. The images are taken in various narrow band (NB) filters of SUIT and are shown with various numbers in the figure. These corresponds to the wavelengths 214 nm (NB01), 276 nm (NB02), 279 nm (NB03), 280 nm (NB04), 283 nm (NB05), 300 nm (NB06), 388 nm (NB07), 396 nm (NB08).

Historic First: India’s Solar Ultra-violet Imaging Telescope (SUIT) onboard Aditya-L1 Captures Unprecedented Solar Flare Details
 
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SPADEX UNDOCKING SUCCESSFUL

March 13, 2025

The SPADEX satellites were successfully docked on January 16, 2025. ISRO has now accomplished the pivotal operation of undocking of SPADEX satellites in the very first attempt on 13th March 2025 at ~09:20 Hrs. The undocking of the satellites took place in 460 km circular orbit with 45-degree inclination. The satellites are now orbiting independently and their health is normal. With this, ISRO has now successfully demonstrated all the capabilities required for rendezvous, docking and undocking operations in a circular orbit.

The in-orbit performance of the docked satellites was extensively analysed and an immediate opportunity was found to be feasible from March 10, 2025 till March 25, 2025. The entire operations were monitored through ground stations located at Bengaluru, Lucknow and Mauritius.

Having accomplished this major mile stone of undocking, further experiments with satellites are planned in the coming days.

Exhaustive ground simulations and analysis were the cornerstone of achieving the undocking in the first attempt itself. Various tests replicating on-orbit conditions were meticulously planned and carried out in preparation for the earliest opportunity for undocking operations.

ISRO has now successfully demonstrated space docking technology using two small satellites. It is a cost-effective experiment through which, India has achieved space rendezvous, docking and post docking control technologies.

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On-board images of SPADEX undocking

SPADEX UNDOCKING SUCCESSFUL
 
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Cryogenic Upper Stage (C25) for LVM3 flagged off to Sriharikota

March 15, 2025

Secretary, DOS/Chairman, ISRO flagged off the Cryogenic Upper Stage (C25) of ISRO’s LVM3 launch vehicle on March 15, 2025, from the ISRO Propulsion Complex (IPRC), Mahendragiri, to the launch complex at Sriharikota. The Directors of ISRO Propulsion Complex (IPRC), Liquid Propulsion System Centre (LPSC), and Satish Dhawan Space Centre (SDSC SHAR) also participated in the flag off ceremony. This stage has been integrated at ISRO Propulsion complex, Mahendragiri and is earmarked for the fifth operational mission of LVM3 (LVM3-M5) under a commercial agreement between NSIL and AST & Science, LLC to launch their BlueBird Block 2 satellite. The stage was designed and developed by Liquid Propulsion Systems Centre (LPSC) during the development of the LVM3 launch vehicle and the stage is powered by the indigenous high thrust Cryogenic Engine (CE20) with a propellant loading of 28.5 tonnes.

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Cryogenic Upper Stage (C25) for LVM3 flagged off to Sriharikota
 
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