ISRO Chandrayaan-2 Vikram lander crash
India's Vikram lunar lander crashed onto the Moon's surface during its final descent, ending the primary landing objective of the Chandrayaan-2 mission.
The damage was public. The root cause was preventable.
India's Vikram lunar lander crashed onto the Moon's surface during its final descent, ending the primary landing objective of the Chandrayaan-2 mission.
What the software actually got wrong
ISRO's post-mission review found that the lander's braking algorithm allowed a larger-than-designed velocity and attitude deviation to build up during the fast descent phase, and the software's guidance logic could not correct for it before touchdown.
ISRO's post-mission review found that the lander's braking algorithm...
ISRO's post-mission review found that the lander's braking algorithm allowed a larger-than-designed velocity and attitude deviation to build up during the fast descent phase
Requs AI Edge Case flags this exact pattern at the requirements and architecture stage — before a single line of code implementing it exists — so the assumption behind it gets challenged while it is still cheap to fix.
The software's guidance logic could not correct for it...
the software's guidance logic could not correct for it before touchdown
Requs AI Software FMEA traces this failure mode back to the system-level hazard it feeds, tagging it against the Common Defect Enumeration so it surfaces in review instead of in the field.
Beyond code coverage and "shall" testing
Root causes like this one rarely show up in code coverage or requirements-compliance testing, because nobody wrote a requirement anticipating the specific edge case that broke. Requs AI Edge Case and Requs AI Software FMEA are built to surface exactly this class of overlooked failure mode — before the software is written.
Surfaces this before code exists
Identifies edge cases like this one at requirements and architecture time, using the Common Defect Enumeration to catalog failure patterns seen across hundreds of real-world software failures — including this one.
Connects the failure mode to the hazard
Traces this class of root cause directly to the system-level hazard it can produce, so a defect pattern like this one gets flagged during design review instead of after it ships.
Find the overlooked root causes before they ship.
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