A collaborative mission between NASA and India’s ISRO (Indian Space Research Organization) is about to revolutionize our understanding of Earth’s shifting surface. The NISAR (NASA-ISRO Synthetic Aperture Radar) satellite, scheduled to launch in early 2025, promises to track changes in the land with unmatched precision, illuminating the subtle yet significant movements of earthquakes, volcanoes, landslides, and even structural changes in critical infrastructure.
A New Eye in the Sky For Earth’s Movements
Earth’s surface might seem stable, but much of it is in constant motion. Scientists have long relied on satellite and ground-based instruments to observe these shifts. NISAR, however, is poised to surpass previous capabilities, using dual radar systems—an L-band system from NASA’s Jet Propulsion Laboratory (JPL) and an S-band system from ISRO—that can measure ground movement down to fractions of an inch. This detailed, high-frequency data, collected every 12 days, could be transformative in helping us track and respond to natural and man-made disasters.
Satellite Technology Characteristics
- Dual Radar System:
- L-band (JPL): penetrates dense vegetation to detect ground motion.
- S-band (ISRO): complements the L-band with increased sensitivity.
- Frequency: Revisits nearly every land and ice-covered area twice every 12 days.
- Capability: Measures surface shifts down to fractions of an inch.
- All-weather Monitoring: Operates day and night, with cloud penetration for areas where optical instruments might fail.
This versatile radar system will be crucial in detecting early signs of geophysical hazards, such as volcanic eruptions or landslides, even in remote or densely vegetated regions.
Deciphering Earth’s Hidden Signals
Though NISAR won’t predict earthquakes, it offers essential insights into seismic activity. By examining fault lines globally, it can show which areas are likely to slip, causing earthquakes, and which may remain locked, building up seismic pressure. For example, Mark Simons from Caltech, the U.S. lead for NISAR’s solid Earth science, notes that in well-monitored areas like California, the data will refine risk assessments.
However, in less-monitored regions, like the Himalayan plate boundary—a seismic hotspot—the data could be groundbreaking, identifying previously unknown earthquake risks and adding depth to India’s earthquake preparedness.
The value extends to volcanic research too. Monitoring shifts in the landscape around a volcano can reveal the movement of magma beneath the surface. By observing these changes regularly, NISAR will aid scientists in detecting patterns and early warnings of volcanic eruptions, potentially helping communities take timely precautions.
Applications of NISAR Data in Earth Sciences
- Earthquake Monitoring:
- Identifies seismic hotspots and fault dynamics.
- Provides insights into locked faults and slip-prone areas.
- Expands monitoring to new regions like the Himalayan plate boundary.
- Volcanic Activity:
- Detects ground swelling or sinking around volcanoes.
- Assists in forecasting possible eruptions by monitoring magma movement.
- Offers a consistent data stream to detect long-term trends.
- Landslide Detection:
- Tracks slope stability to detect early signs of landslides.
- Crucial in areas with frequent heavy rains or seismic activity.
Watching over infrastructure: from levees to dams
Beyond natural phenomena, NISAR will also be a powerful tool in monitoring infrastructure. By establishing a baseline view of levees, dams, and other key structures, NISAR can alert engineers and authorities to changes that may indicate potential weaknesses.
For instance, a significant earthquake could trigger soil liquefaction around the levees of the Sacramento-San Joaquin River Delta in California. With over a thousand miles of levees, the satellite’s data will allow for targeted inspections of affected areas, saving time and resources while focusing attention on spots that need it most.
How NISAR Supports Infrastructure Resilience
- Baseline Mapping:
- Establishes “normal” conditions for levees, dams, and aqueducts.
- Allows early detection of deviations from the baseline.
- Targeted Inspections:
- Prioritizes inspection of areas showing unusual shifts.
- Reduces costs by limiting large-scale field surveys to affected spots.
- Post-Disaster Assessments:
- Assists in evaluating structural damage after events like earthquakes.
- Informs rapid response and recovery efforts by highlighting critical areas.
The NISAR mission, which is a pioneering collaboration, represents more than a technological milestone; it is a step towards a future where accurate and timely information will enable us to protect our landscapes and communities.
