Space
NASA-ISRO NISAR satellite
▪ NISAR = NASA-ISRO Synthetic Aperture Radar.
▪ Joint Earth Observation mission by ISRO and NASA.
▪ Launch date: July 30, 2025 from Sriharikota onboard GSLV Mk-II.
▪ Aim: To monitor earth’s surface changes like earthquakes, volcanoes, ecosystems, ice sheets,
agriculture, floods, and landslides.
Significance of NISAR
▪ First major Earth observation mission with dual-band radar (L-band + S-band).
▪ Can observe day/night, all-weather, through clouds, smoke, and vegetation.
▪ Tracks natural disasters, climate change, human impacts, and more.
▪ Data useful for scientists, policymakers, and disaster response agencies.
▪ ISRO contributed:
✓ I-3K spacecraft bus, S-band radar electronics.
✓ High-rate Ka-band telecom and high-gain antenna.
NASA contributed:
✓ Full L-band SAR system, 12-m antenna, 9-m boom.
✓ Onboard systems like GPS, recorder, avionics.
Scientific and Application Goals
✓ Solid Earth processes (e.g. earthquakes).
✓ Ecosystems and biomass monitoring.
✓ Ice dynamics (glaciers, ice sheets).
✓ Coastal and ocean processes.
✓ Disaster response.
✓ Applications like groundwater, dams, and infrastructure monitoring.
How does NISAR work?
▪ Uses Synthetic Aperture Radar (SAR) to bounce radar signals off Earth’s surface.
▪ Combines:
✓ L-band SAR (1.257 GHz) – detects deep ground movement & forest density.
✓ S-band SAR (3.2 GHz) – captures finer surface features (crops, water).
▪ Uses polarisation (horizontal/vertical) to distinguish between soil, crops, snow, etc.
India-Specific Use
▪ S-band focused on India – tracks biomass, soil moisture, and disaster zones.
▪ 240 km swath width with 3–10 m spatial resolution.
▪ Scans each area every 12 days.
▪ Damage proxy maps can be generated in under 5 hours during disasters.
General Science
Hepatitis
▪ India accounts for over 11.6% of the global burden:
✓ 29.8 million with hepatitis B.
✓ 5.5 million with hepatitis C.
▪ Cause: Viral (A, B, C, D, E) and non-viral infections.
▪ Major Threats: Types B & C cause most liver cirrhosis, cancer, and deaths.
▪ Transmission: Varies by type; includes contaminated food/water, blood, and mother-to-child.
▪ Prevention: Vaccines available for A & B; 4.5 million deaths preventable by 2030.
▪ WHO Goal: Reduce new infections by 90% and deaths by 65% (2016–2030).
▪ Symptoms: Often mild/none; include fever, fatigue, nausea, jaundice, dark urine.
▪ Complications: Chronic hepatitis, liver cirrhosis, cancer.
▪ Hepatitis D: Needs co-infection with B; more severe.
▪ Hepatitis E: Can cause acute liver failure, especially in pregnant women.
Global Hepatitis Report 2024
▪ Report Released By: World Health Organization (WHO).
▪ Highlighted India as one of the nations facing a significant burden of viral hepatitis, particularly Hepatitis B and C infections.
India’s Initiatives:
▪ National Viral Hepatitis Control Program.
▪ National Health Mission.
▪ India’s Universal Immunization Programme (UIP).
