Satellites die when a vital part fails, when propellant or power runs out, or when the launch or an early manoeuvre goes wrong.
Space is harsh, and an uncrewed satellite cannot be repaired. A single small fault can end a mission. India's own satellites give clear examples of each way it happens.
IRNSS-1H was meant to replace a failing navigation satellite. Its PSLV launch on 31 August 2017 failed, and the satellite never reached a working orbit.
NVS-02 reached its transfer orbit safely on 29 January 2025, but a loose electrical connection stopped the pyro valve on its engine's oxidiser line from opening. Without its engine, it is stranded in a 170 × 37,785 km orbit instead of its planned one. ISRO said its other systems were healthy and that it was working out ways to use it for navigation from that orbit. ISRO's committee recommended changes to make the pyro system more reliable; these were applied to CMS-03, launched on 2 November 2025 by LVM3-M5, whose pyro systems worked.
Each first-generation IRNSS satellite carried three rubidium atomic clocks. All three on IRNSS-1A had failed by January 2017. The satellite kept flying, but a navigation satellite without a clock cannot do navigation. The same month, ESA reported clock failures on Europe's Galileo satellites too. In 2026 the problem reached IRNSS-1F: ISRO says its atomic clock stopped on 13 March 2026, three days after it completed its 10-year design life.
Radiation is a quieter threat. NASA notes that small MEMS gyros are prone to radiation damage and to single-event upsets, where one charged particle flips a bit in the electronics.
ISRO's Mars Orbiter Mission most likely ran out of propellant. Unable to hold the pointing needed for power, it went silent after a long eclipse in April 2022, after about eight years at Mars.
Solar panels also fade. NASA lists radiation, ageing and contamination as the causes of solar cell degradation over a mission.
Find NVS-02 in the list and compare its orbit with the circular ones of its neighbours — it is alive but in the wrong place. Open the NavIC tracker
Engineers fight random failures with redundancy. If one unit survives the mission with probability r, and the satellite works as long as at least one of n identical units works, the probability of success is
R = 1 − (1 − r)ⁿ
Illustrative: r = 0.9.
This is why IRNSS satellites carried three clocks. But the formula assumes failures are independent. If all units share a design flaw, a manufacturing batch or an environment, they can fail together, and the real R is close to r. Losing all three clocks on IRNSS-1A is the signature of such a common cause.
NVS-02 shows the same trap in wiring. Its pyro valve had a main and a redundant firing path. ISRO's Apex Committee concluded that at least one connector contact disengaged in each path. Two paths through one kind of connector are not fully independent. ISRO's fix, flown on CMS-03 in November 2025, aimed to improve the redundancy and reliability of the pyro system.
A useful habit is to sort failures by phase:
Designers attack each phase differently: testing for launch, careful checks of one-shot devices like pyro valves, redundancy for random failures, and margins for wear-out.
The firing signal did not reach the pyro valve on the oxidiser line of its orbit-raising engine, most likely because a connector contact disengaged in both the main and backup paths, so the engine could not fire.
Backups help only when failures are independent. If all units share a cause — a design flaw or the same connector type — they can all fail together.
Launch: IRNSS-1H, lost when its PSLV launch failed in August 2017. In orbit: IRNSS-1A, whose three atomic clocks all failed.