UPSC Prelims Practice Questions — Mexico City is sinking so fast, it can be seen from space

Q1. Within the NASA-ISRO Synthetic Aperture Radar (NISAR) mission that recently mapped extreme land subsidence in Mexico City, which one of the following organisations developed the S-band Synthetic Aperture Radar payload carried on the satellite?

  • A. NASA Jet Propulsion Laboratory
  • B. Indian Space Research Organisation
  • C. European Space Agency
  • D. Japan Aerospace Exploration Agency

Q2. In the context of the NISAR satellite's observations of Mexico City, the term 'Synthetic Aperture Radar Interferometry (InSAR)' most accurately refers to which of the following?

  • A. Combining radar signals from two satellites flying in close formation to widen the imaging swath
  • B. Measuring small ground-surface displacements by comparing the phase of radar signals from repeated satellite passes over the same area
  • C. Using the intensity of radar backscatter to classify different types of land cover and crops
  • D. Emitting ground-penetrating radar pulses to directly image the depth and shape of subsurface aquifers

Q3. With reference to the NISAR satellite as compared with earlier civilian Synthetic Aperture Radar missions, consider the following statements: 1. NISAR is the first satellite to carry two SAR instruments operating in two different frequency bands on the same platform. 2. On NISAR, the L-band SAR payload has been developed by ISRO while the S-band SAR payload has been developed by NASA. 3. NISAR is designed to observe almost the entire land and ice surfaces of the Earth every 12 days. Which of the statements given above is/are correct?

  1. NISAR is the first satellite to carry two SAR instruments operating in two different frequency bands on the same platform.
  2. On NISAR, the L-band SAR payload has been developed by ISRO while the S-band SAR payload has been developed by NASA.
  3. NISAR is designed to observe almost the entire land and ice surfaces of the Earth every 12 days.
  • A. 1 and 2 only
  • B. 1 and 3 only
  • C. 2 and 3 only
  • D. 1, 2 and 3

Q4. The NASA-ISRO Synthetic Aperture Radar (NISAR) satellite, whose data was used to map rapid subsidence in Mexico City, was launched on which one of the following dates?

  • A. 30 July 2023
  • B. 30 January 2024
  • C. 30 July 2025
  • D. 30 January 2026

Q5. According to the NASA-ISRO analysis of NISAR data on Mexico City, which one of the following is identified as the primary driver of the extreme land subsidence observed in the city?

  • A. Movement along the boundary of the North American and Cocos tectonic plates
  • B. Excessive groundwater extraction causing compaction of the ancient lakebed aquifer beneath the city
  • C. Accelerated sea-level rise in the adjoining Gulf of Mexico
  • D. Repeated ash loading from the nearby Popocatépetl volcano