ISRO Plans GISAT-1A (EOS-05) Launch in September 2026

ISRO is planning to launch GISAT-1A (EOS-05) in September 2026, as a replacement mission designated F17. The planned launch is in focus as it follows the failure of GISAT-1/EOS-03 in 2021 and comes after recent PSLV launch failures.

GISAT Programme and Related Facts:

Dimension	Key Details
Developer	GISAT-1A is developed by the Indian Space Research Organisation (ISRO).
Satellite type and observation feature	GISAT is a Geo-Imaging Satellite designed for wide-area and near-continuous observation of the Indian subcontinent.
Observation coverage	GISAT-1A is intended to observe the Indian landmass for large parts of the day.
Applications	GISAT applications comprise flood monitoring, cyclone tracking, agriculture, forestry, and monitoring rapid changes on the Earth's surface.
Earlier mission failure	GISAT-1/EOS-03 is launched in August 2021 using GSLV Mk-II.
Earlier mission planned orbit sequence	GISAT-1/EOS-03 is supposed to first enter a Geosynchronous Transfer Orbit (GTO) and then move to a geostationary orbit.
Failure point and cause chain	The GISAT-1/EOS-03 mission fails when the cryogenic upper stage does not start, and the failure is linked to a valve leak that reduces pressure in the liquid hydrogen tank.
Cryogenic stage propellants	The cryogenic stage uses liquid hydrogen as fuel and liquid oxygen as oxidiser.
Orbit concept: GTO	Geosynchronous Transfer Orbit (GTO) is a highly elliptical orbit (170 km - 36,000 km) used as an intermediate orbit before reaching geostationary orbit.
Orbit concept: Geostationary	Geostationary orbit provides that a satellite appears fixed relative to a point on Earth, and it is particularly useful for continuous observation and communication.
Launch vehicles: stages	PSLV (4), GSLV Mk-II (3), and LVM-3 (3).
Launch vehicles: cryogenic stage presence	PSLV (No), GSLV Mk-II (Yes), and LVM-3 (Yes).
Launch vehicles: cryogenic engines	GSLV Mk-II (CE7.5) and LVM-3 (CE20).
Launch vehicles: GTO capacity	GSLV Mk-II (up to 2.5 tonnes) and LVM-3 (up to 4 tonnes).
PSLV–GSLV Mk-II commonality	PSLV and GSLV Mk-II share some design elements, including the S139 first-stage solid motor lineage, and share aspects of avionics, guidance, tracking, and separation systems.
Recent ISRO launch issues	Recent failures comprise PSLV-C61 carrying EOS-09 (May 2025) and PSLV-C62 carrying N1 satellite (January 2026), and both failures involve anomalies during the third stage.
Operational response to failures	ISRO subsequently has paused launches while failure causes are investigated.
NavIC linkage: mission intent	GSLV-F15/NVS-02 is intended to strengthen India's NavIC constellation.
NavIC service coverage and type	NavIC provides Positioning, Navigation and Timing (PNT) services over the Indian subcontinent.
NavIC constellation requirement	Following the NVS-02 problem, the constellation has only 3 satellites, whereas at least 4 are required for PNT services.
Upcoming related mission	NVS-03 is expected to be launched subsequently.
Human spaceflight linkage	LVM-3 is planned to be upgraded into a human-rated LVM-3, and it is intended to launch Indian astronauts under the Gaganyaan programme.