Which of the following correctly describes the NISAR mission?

Question

Which of the following correctly describes the NISAR mission?

1. A. NASA-only mission for ultraviolet astronomy
2. B. Optical imaging mission for exoplanet detection
3. C. ISRO-only mission for X-band radar mapping
4. D. Joint ISRO–NASA mission using L and S-band radar (Correct answer)

Correct Answer

Option D — Joint ISRO–NASA mission using L and S-band radar

Detailed Solution & Explanation

The correct answer is Joint ISRO-NASA mission using dual-band radar.

Key Points

• NISAR stands for NASA-ISRO Synthetic Aperture Radar, so it is a joint mission, not the work of either agency alone.
• It carries two radar frequencies: an L-band instrument from NASA and an S-band instrument from ISRO — the first satellite to use dual-band SAR of this kind.
• It is a radar mission, not optical or ultraviolet, which rules out the remaining options.

Additional Information

• Being radar-based, NISAR images through cloud, rain and darkness, giving consistent coverage that optical sensors cannot match.
• It flies in a polar sun-synchronous orbit, surveying nearly all the Earth's land and ice roughly every 12 days to track deformation, ecosystems and ice-sheet change.
• Applications include monitoring earthquakes, landslides, glacier movement, soil moisture, crop growth and coastal erosion.
• ISRO's other headline collaborations and missions: Chandrayaan-3 (2023 lunar south pole landing), Aditya-L1 (solar observatory at L1) and Gaganyaan (crewed spaceflight).