Space Debris — Revision Notes

⚡ 30-Second Revision

Detect, assess, prevent, dispose. Debris is human-made and no longer useful. Alerts are predictions, not collisions. Passivation manages stored energy; disposal changes the end-of-life situation; removal intervenes on existing objects. For fixed mass, double speed means four times kinetic energy. Keep report date, data year and target year separate.

2-Minute Revision

A catalogue is limited by sensing and identification. Operational payloads, debris and natural micrometeoroids are different categories. Collision feedback can increase long-term risk, but a scenario is not an instantaneous universal catastrophe.

Low-orbit disposal and geostationary relocation involve different conditions. A graveyard orbit still contains the object. India declared its debris-free mission intent on 16 April 2024 with a 2030 goal.

ISSAR-2025 was released on 8 April 2026; ESA's 2026 report appeared on 14 September with data through end-2025. Evaluate completed practices and outcomes, not labels alone.

5-Minute Revision

Calculate the energy ratio for the same mass at 10 km/s and 5 km/s: four. Explain why that does not fully determine damage. Next, distinguish a detection, an alert, an assessment and a manoeuvre. Describe an object that is passivated but remains in orbit, then contrast a higher disposal orbit with re-entry. Finally, label 2025 as a reporting period, 8 April 2026 as an ISRO release date and 2030 as a goal. State what evidence would be needed before claiming the goal had been achieved.

Vyyuha Quick Recall

PDR: Passivate stored energy; Dispose at end of mission; Remove existing objects. Each verb names a different result.