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ISRO missions

The Indian Space Research Organisation (ISRO) is flying its densest run of missions yet. EOS-05 has just become the first Indian Earth observation satellite to image from geosynchronous orbit, Aditya-L1 is returning solar results that bring flare forecasting within reach, and the missions being prepared run from a Venus orbiter to a lunar sample return. Prelims asks what each mission was first to do.

UPSC has asked

Prelims 2025: Axiom-4, SpaDeX and Gaganyaan as microgravity missions
Prelims 2022: the possible effects on the Earth of a major solar storm
Prelims 2018: the orbits of the IRNSS satellites
Prelims 2016: Mangalyaan, the Mars Orbiter Mission

The missions, and what each was first to do

Chandrayaan-3 made the first soft landing near the lunar south pole, on 23 August 2023.
Aditya-L1, ISRO's first solar mission, watches the Sun from a halo orbit around L1, the first Sun-Earth Lagrange point, about 1.5 million kilometres from Earth.
XPoSat is India's first X-ray polarimetry mission.
SPADEX (Space Docking Experiment) made India the fourth country to dock two spacecraft in orbit.
NISAR (NASA-ISRO Synthetic Aperture Radar), flown with the National Aeronautics and Space Administration (NASA) of the United States, is the first Earth observation satellite to carry radar in both the L and S bands.
GSAT-7R (CMS-03) is a communications satellite for the Navy.

Orbits, and what the images are for

Closer to Earth. Finer detail, but a satellite races past and sees a place only briefly.

Farther from Earth. A wide region watched continuously, in coarser detail.

Not to scale. Altitudes as given in The Indian Express, 5 September 2026.

A satellite in low Earth orbit sees fine detail, but its revisit time runs to days.
A satellite in geosynchronous orbit watches one large region continuously, in coarser detail, and spends fuel on station keeping.
Only a satellite in geostationary orbit appears fixed in the sky, while other geosynchronous orbits trace a path across it over the day.
What these satellites see feeds the Landslide Atlas of India, the monitoring of glacial lake outburst floods, and the National Database for Emergency Management 5.0.

How Aditya-L1 watches the Sun

Solar Ultraviolet Imaging Telescope (SUIT)

Images the Sun in near-ultraviolet light
Gave the pictures of the lower atmosphere where the brightenings appear

Solar Low Energy X-ray Spectrometer (SoLEXS)

Gave the low energy X-ray data

High Energy L1 Orbiting X-ray Spectrometer (HEL1OS)

Gave the high energy X-ray data

The three Aditya-L1 payloads the flare study combined, from The Hindu, 31 August 2026

From L1 the Sun can be watched without the Earth ever coming in the way.
A flare's radiation crosses to Earth in about eight minutes, so there is no useful warning once it has erupted.
Hours of notice would let operators safeguard satellites, astronauts and communication systems.

Geosynchronous orbit: An orbit at about 35,786 km whose period matches one rotation of the Earth.

Geostationary orbit: A geosynchronous orbit that is circular and above the equator.

Revisit time: How long a satellite takes to image the same place again.

Station keeping: Firing thrusters to hold a satellite's position against the pull of the Sun and Moon and the Earth's uneven gravity.

Lagrange point: One of five positions where the gravity of two large bodies and the motion of a small one balance, so a spacecraft keeps station with them; L1 lies between the Earth and the Sun.

Halo orbit: A looping orbit around a Lagrange point, held there by the balanced pull of two large bodies rather than by orbiting either one.

X-ray polarimetry: Measuring the direction in which X-rays vibrate, which tells astronomers about the magnetic fields and geometry of pulsars and black holes.

Solar flare: A sudden, intense burst of radiation from the Sun, released when magnetic energy stored above its surface is freed all at once.

Active region: A patch of the Sun with strong, tangled magnetic fields, where sunspots and flares occur.

What has happened

4 Sep 2026
A Geosynchronous Satellite Launch Vehicle (GSLV-F17) put EOS-05 up, the first Indian Earth observation satellite to image from geosynchronous orbit.
- Also called Geo Imaging Satellite 1A (GISAT-1A), it images chosen areas at frequent intervals for disaster monitoring, agriculture and forestry.
- It replaces GISAT-1, lost in 2021 when the cryogenic upper stage of its GSLV failed to ignite.
PIB, 4 Sep 2026: Prime Minister hails the launch of GSLV-F17 carrying EOS-05 (opens in a new tab)
31 Aug 2026
A study using Aditya-L1 found that a major flare is preceded, hours ahead, by small short-lived brightenings clustered where it later erupts.
- Repeated small releases of magnetic energy appear to destabilise an active region until a large flare breaks out.
- The brightenings show in the Sun's lower atmosphere, in SUIT images read together with both X-ray payloads.
The Hindu, 31 Aug 2026: New study captures Sun's early warning signs before solar flares (opens in a new tab)
13 Aug 2026
ISRO set out its recent and forthcoming missions as one list.
- The Venus Orbiter Mission is planned.
- Chandrayaan-4 is to bring a lunar sample back to Earth.
- LUPEX (Lunar Polar Exploration), also called Chandrayaan-5, is planned with the Japan Aerospace Exploration Agency (JAXA).
PIB, 13 Aug 2026: Recap of recent and upcoming ISRO missions (opens in a new tab)