The world faces an ever-present risk of infectious disease outbreaks, whether naturally occurring, accidental, or intentionally introduced. Rapidly detecting these biological threats and providing early warning is critical for mounting effective responses to mitigate their impacts. However, current biosurveillance capabilities have significant gaps and limitations. Emerging satellite technologies offer powerful new tools that could revolutionize how we detect and monitor biological threats on a global scale.
The Need for Enhanced Biosurveillance
Infectious diseases continue to pose major risks to human health, agriculture, and the environment worldwide. The COVID-19 pandemic and recent outbreaks of avian influenza highlight the immense challenges in rapidly detecting and responding to disease events. Identifying outbreaks before widespread effects occur allows for proactive interventions rather than scrambling to react after an outbreak has already taken hold.
Biosurveillance – the process of gathering, integrating, analyzing and communicating information related to threats to human, animal, or plant health – aims to provide early warning of potential outbreaks. However, current biosurveillance systems have limited ability to detect outbreaks in their earliest stages. Most rely on public health reporting of clinically apparent cases, meaning the outbreak may already be underway by the time it is noticed. Gaps also exist in monitoring diseases in livestock, wildlife and the broader environment.
To address these shortfalls, a new paradigm in biosurveillance is needed – one that leverages cutting-edge technologies to detect subtle signs of emerging biological threats before clinical cases appear. This is where satellite remote sensing holds immense potential.
The Promise of Satellite Biosurveillance
Satellites offer a unique vantage point to monitor the Earth’s environment in a comprehensive yet efficient manner. Satellite instruments can detect changes in environmental conditions over vast geographic areas on a frequent basis without the limitations of ground-based monitoring. A growing array of increasingly sophisticated sensors are being deployed on satellites, opening up new possibilities for biosurveillance applications.
Some of the most promising tools for satellite biosurveillance include:
- Hyperspectral imaging: Hyperspectral sensors measure reflected energy across a wide range of the electromagnetic spectrum, well beyond what the human eye can see. This allows detection of subtle changes in the spectral signatures of vegetation, water, and other environmental features that may indicate early signs of disease.
- Thermal infrared: Thermal sensors can measure the temperature of the Earth’s surface and atmosphere. This could enable detection of changes in the thermal signatures of plants, animals, or human populations that may be early indicators of infection.
- Synthetic aperture radar: SAR sensors actively emit microwave energy and measure the backscattered signal, enabling high-resolution imaging day or night and in any weather conditions. SAR could be used to detect changes in soil moisture, ocean surface patterns, or other environmental conditions relevant to disease ecology.
- Atmospheric sounding: Sounders measure the vertical profiles of temperature, moisture and chemical composition of the atmosphere. This could allow detection of changes in atmospheric gases that may be produced by diseased plants or animals.
By integrating data from multiple sensor types and satellite platforms, it may be possible to develop “spectral fingerprints” that can diagnose specific pathogens or disease states from orbit. Machine learning algorithms could be trained on satellite data coinciding with known disease events to identify the telltale signs of an emerging outbreak.
Realizing the Vision: A Roadmap for Development
Achieving a robust satellite biosurveillance capability will require a sustained research and development effort bringing together expertise from multiple disciplines. Key elements of this roadmap include:
Identifying Detectable Signatures
A critical first step is determining what disease-relevant environmental changes can realistically be detected from space. Research is needed to characterize the “normal” baseline fluctuations in spectral and environmental parameters across different ecosystems and seasons. Controlled studies should then examine how specific pathogens or disease states alter these baselines to identify potential indicators to monitor from satellites.
Improving Sensor Capabilities
Ongoing improvements in satellite sensor technologies will be essential to enable biosurveillance missions. Priorities include developing hyperspectral and thermal sensors with higher spatial and spectral resolutions, increased sensitivity, and wider geographic coverage. Constellations of small satellites offer a promising approach to achieve the needed temporal revisit rates in a cost-effective manner.
Advancing Data Analytics
The sheer volume of satellite data poses a “big data” challenge for biosurveillance. Continued advancements in high-performance computing, cloud storage and machine learning will be critical to process and interpret this data deluge. Novel algorithms need to be developed and validated for automated change detection, anomaly identification, and diagnostic classification from multi-sensor satellite data streams.
Integrating Data Streams
Satellite data will be most powerful when integrated with information from other biosurveillance sources, including public health reporting, veterinary surveillance, and environmental monitoring networks. Seamless data integration platforms and analysis tools should be developed to fuse these disparate data streams and extract actionable biosurveillance alerts.
Engaging Stakeholders
For satellite biosurveillance to have real-world impact, the information must get into the hands of public health officials, agricultural agencies, and others responsible for outbreak response. Sustained engagement with these stakeholder communities is needed to understand their information requirements, data standards, and communication protocols. Collaborative pilot projects demonstrating the utility of satellite tools for specific biosurveillance needs can build support.
Challenges and Limitations
While the potential of satellite biosurveillance is immense, several challenges will need to be overcome for operational implementation:
- Sensitivity and false alarms: The ability to reliably detect the subtle signatures of early-stage disease outbreaks from space remains to be proven. False positive detections could undermine confidence in the system if not managed properly.
- Data access and sharing: Mechanisms will be needed to ensure timely access to relevant satellite data for biosurveillance purposes while respecting the data rights of satellite operators. Standards for secure data sharing between countries will also be critical for a global system.
- Resource requirements: Deploying and operating the satellite constellations and ground systems needed for global biosurveillance will require substantial financial investments and international coordination. Sustaining funding and support for this mission may be a challenge.
- Ethical and societal implications: The ability to conduct global disease surveillance from space raises important questions about privacy, data security, and societal acceptance. Proactive efforts will be needed to address these valid concerns through appropriate policies and public outreach.
Despite these challenges, the potential benefits of satellite biosurveillance for global health security are too great to ignore. With sustained research and development, international collaboration, and stakeholder engagement, this vision could become a reality within the next decade.
Summary
The increasing threat of infectious disease outbreaks demands new tools for early warning and situational awareness. Satellite remote sensing offers a powerful approach to fill critical gaps in current biosurveillance capabilities. By harnessing a growing array of satellite sensors and advanced data analytics, it may soon be possible to detect subtle signs of emerging disease threats anywhere on Earth.
Realizing this vision will require a multi-disciplinary effort spanning the Earth science, public health, and aerospace engineering communities. While challenges remain, the potential benefits for global health security are immense. With the right investments and coordination, satellite biosurveillance could provide a revolutionary new tool to help prevent the next pandemic.