Prof. Maria T. Zuber (PAS), Presidential Advisor for Science and Technology Policy and E. A. Griswold Professor of Geophysics at MIT; Co-chair of President Biden’s Council of Advisors on Science and Technology

Introduction

As humanity confronts the escalating challenges of climate change, resource depletion, food and freshwater availability and environmental degradation (cf. Steffen et al., 2015), space technology will play an increasingly central role in constructing solutions to maintain a sustainable planet. From monitoring Earth’s weather and climate, to optimizing agriculture, to making more efficient use of resources, to communicating environmental conditions and threats, space-based technologies offer opportunities to foster a more sustainable future. By leveraging capabilities of satellites, sensors, communications, precise positioning systems, radiation-resistant semiconductors and computation, it is possible to observe, collect, analyze and disseminate information regarding the state of the planet. Such information can be used to develop informed strategies to protect and preserve the Earth for current and future generations. This contribution provides a sampling of applications based on past and current Earth-orbiting spacecraft and concludes with discussion of emerging technologies that are accelerating progress.

Earth Observation and Monitoring

Weather: One of the longest-standing contributions of space technology to sustainability is weather monitoring. From the 1960 launch of the first weather satellite, NASA TIROS-1 (Television Infrared Observation Satellite) (Stroud, 1961), satellites equipped with advanced sensors have continuously orbited our planet, collecting data that is used to understand and manage environmental changes. Satellites like the National Oceanic and Atmospheric Administration GOES (Geostationary Operational Environmental Satellites) (Schmit et al., 2017) and Japanese Himawari (Bessho et al., 2016) series provide real-time data on atmospheric conditions including cloud cover, water vapor, smoke, dust and aerosols, land and sea surface temperature and space weather. These satellites help to forecast weather patterns, detect and monitor storms, and provide data for aviation route planning.

Space-based monitoring also provides continuous observations of incoming (solar) and outgoing (thermal) radiation. Satellites like NASA’s Clouds and the Earth’s Radiant Energy System (CERES) (Wielicki et al., 1996) measure these energy fluxes at the top of the atmosphere, allowing scientists to quantify changes in Earth’s energy budget over time. These measurements have revealed an increasing imbalance, with more energy being trapped in the Earth system than escaping to space, primarily due to increasing greenhouse gas concentrations (Loeb et al., 2021).

Soil Moisture: The Soil Moisture Active Passive (SMAP) satellite (Entekhabi et al., 2010; Chan et al., 2018) plays a critical role in monitoring soil moisture levels worldwide. This data is essential for understanding drought conditions, improving agricultural productivity, and managing water resources more effectively. By providing detailed maps of soil moisture, SMAP helps farmers optimize irrigation, reducing water waste and promoting more sustainable agricultural practices.

Water and Ice Mass Transport: The Gravity Recovery and Climate Experiment (GRACE) (Tapley et al., 2004; Famiglietti & Rodell, 2013) and GRACE-FO (Follow-On) (Kornfeld et al., 2019)) missions minute temporal changes in Earth’s gravity from which changes in water reservoirs, including ice sheets, glaciers, and underground aquifers can be inferred. GRACE data have been instrumental in tracking the loss of ice mass in Greenland and Antarctica, as well as the depletion of groundwater in major aquifers, both of which have critical implications for sea-level rise and water security.

Sea Level Rise: Space geodetic observations provide validation of climate models that make predictions of phenomena such as sea level rise (cf. Nerem et al., 2016). Moreover, gravity, combined with sea surface altimetry, permits assessment of how much sea level rise is due to continental runoff vs. thermal expansion of the oceans associated with rising global temperatures. This is essentially an exercise in isolating mass vs. volume change of seawater. GRACE/GRACE-FO, for example, measure mass transport from continental ice sheets to the oceans (Rignot et al., 2011), while satellite altimeters, such as the TOPEX/Poseidon (Fu et al., 1984) or Jason (e.g., Pujol et al., 2016) satellites, provide information on volume change associated with thermal expansion and land runoff (Cazenave et al., 2018).

Greenhouse Gas Monitoring from Space: CO₂ and Methane

Greenhouse gas monitoring from space has become an essential tool in the global effort to understand and mitigate global warming. Among greenhouse gases, carbon dioxide (CO₂) and methane (CH₄) are of particular concern due to their abundance and warming potential. Space-based monitoring provides a comprehensive and continuous means to track these gases, providing information on sources, distribution and trends.

Carbon Dioxide (CO₂) Monitoring: Carbon dioxide is the primary greenhouse gas responsible for the anthropogenic greenhouse effect. Monitoring CO₂ from space enables scientists to quantify emissions, understand natural carbon sinks, and assess the effectiveness of climate policies. NASA’s Orbiting Carbon Observatory-2 (OCO-2) (Crisp et al., 2017; Eldering et al., 2017), launched in 2014, provides information on the spatial and temporal variability of CO₂, particularly in regions where ground-based observations are sparse. The satellite’s ability to detect small variations in CO₂ levels allows identification of specific emission sources, such as urban areas and power plants. Additionally, data from OCO-2 supports climate models that predict impact on global temperatures of future atmospheric CO₂ levels.

Methane (CH₄) Monitoring: Methane, although present in smaller quantities than CO₂, is a more potent greenhouse gas, with a global warming potential approximately 28 times that of CO₂ over a 100-year period. Methane emissions come from both natural sources, such as wetlands, and anthropogenic sources, including agriculture; fossil fuel extraction, production, transportation; and waste management.

The European Space Agency’s Sentinel-5P satellite, equipped with the TROPOspheric Monitoring Instrument (TROPOMI) (Veefkind et al., 2012; Hu et al., 2018), provides high-resolution measurements of atmospheric methane that permit detection of emissions from specific sources such as oil and gas facilities, coal mines, and landfills. This capability is essential for implementing and verifying mitigation strategies aimed at reducing such emissions.

Other satellites, such as the Japanese Greenhouse gases Observing SATellite (GOSAT) (Yokota et al., 2009) and the ongoing MethaneSAT mission (Jacob et al., 2016; Hamburg et al., 2021) by the Environmental Defense Fund (EDF), contribute to the global effort to monitor methane. These missions complement each other by providing data at different spatial resolutions and temporal coverage, ensuring a comprehensive understanding of global methane dynamics.

Resource/Land Management and Optimization

Space technology plays a crucial role in optimizing the use of Earth’s resources. Precision agriculture (Mulla, 2013), for example, relies on satellite data to guide farmers in making informed decisions about planting and fertilization. By analyzing data from satellites like Landsat, which provides detailed imagery of the Earth’s surface, farmers can monitor crop health, assess soil conditions, and identify areas that require intervention (Gitelson et al., 2012). This approach not only contributes to improving crop yields but also reduces the environmental impact of farming by minimizing the use of water, fertilizers, and pesticides.

Similarly, space-based systems are essential for sustainable fisheries management (Kourti et al., 2005). Satellites such as the European Space Agency’s Sentinel-1 use synthetic aperture radar (SAR) to monitor illegal fishing activities, track fishing vessels, and assess fish stocks (Mazzarella et al., 2017). By providing real-time data on the location and behavior of fishing vessels, these systems help enforce regulations, protect marine ecosystems, and ensure the long-term viability of fish populations.

International Collaboration and Global Sustainability

Space technology facilitates international collaboration, which is vital for global sustainability efforts. Initiatives such as the United Nations’ Sustainable Development Goals (SDGs) increasingly rely on space-based solutions to monitor progress and achieve targets (Bensi et al., 2021). For example, satellite data is used to track deforestation rates, monitor global water quality, and improve disaster response efforts (Tralli et al., 2005). Collaborative projects like the International Space Station (ISS) also serve as platforms for researching and developing sustainable technologies.

The Future

Sustainability solutions will increasingly be informed and aided by space-based technology due to ongoing advances that are driving down the cost of orbital assets, providing a more ubiquitous presence, and facilitating communication and analysis.

Launch costs: The emergence of innovative companies in the rocket business such as SpaceX, Blue Origin, and Rocket Lab has contributed to substantial decreases in launch costs (Jones, 2018) that are opening the space frontier, at least in Low Earth orbit (LEO).

SmallSats and CubeSats: Miniaturization of satellite technology including thrusters, altitude control, computing and communication systems are enabling more frequent and inexpensive launches and result in improved temporal and spatial coverage. For example, the NASA TROPICS (Time-Resolved Observations of Precipitation structure and storm Intensity with a constellation of SmallSats) (St. Germain et al., 2021) was the first agency science mission implemented with CubeSats and provided high-resolution microwave observations of storm intensity, precipitation, and thermal structure relevant to improving storm forecasts.

Sensors: Advances in sensor technology, for example, in optical, hyperspectral and thermal infrared imaging, Synthetic Aperture Radar (SAR), Global Navigation Satellite System (GNSS) reflectometry, laser altimetry and LIDAR sensing, provide higher resolution and higher sensitivity observations of water quality, vegetation health, deforestation, land deformation, soil moisture, sea level, snow depth and weather and climate monitoring.

Communications: Space communications will play an expanding role in the global exchange of sustainability information, enabling the monitoring, analysis, and dissemination of data related to environmental and social sustainability. By facilitating real-time data transmission across vast distances, space-based communication systems such as Starlink (Shotwell & Venkatesh, 2020) support a wide array of sustainability initiatives, from climate monitoring to disaster response and agricultural management.

The role of space communication in providing information to remote and under-served communities, where access to traditional communication infrastructure may be limited (Loboguerrero et al., 2018) is worthy of special mention. Satellite-based communication systems can deliver vital information on, for example, weather forecasts, agricultural best practices, health and education, and disaster preparedness to these communities.

Advances in laser communications hold the promise of greatly increasing bandwidth over current radio systems. NASA’s Lunar Laser Communication Demonstration (LLCD) (Boroson et al., 2009) was NASA’s first system for two-way communication using a laser instead of radio waves. LLCD featured a pulsed laser beam that transmitted data over the 239,000 miles between lunar orbit and Earth with a downlink rate of 622 megabits per second (Mbps).

Data Integration and Cloud Computing: Combining data from multiple sensors and satellites with ground-based data provides an increasingly holistic picture of environmental changes, allowing for better decision-making and predictive modeling. Advances in cloud computing enable the storage, processing, and sharing of large datasets from satellite observations that facilitates real-time data analysis and broader access to satellite data.

Artificial Intelligence and Machine Learning: AI and ML algorithms are increasingly being used to process and analyze enormous volumes of satellite data. AI enhances the ability to detect patterns, predict environmental changes, automate the monitoring process and sort through vast data sets.

Space Resources: In the distant future, solar system objects may provide resources needed on Earth (Anand et al., 2012; O’Rourke & Jansen, 2020). For example, the potential for off-world mining of asteroids, some of which are rich in minerals and metals, presents the possibility of reducing the strain on Earth’s finite resources. While still in the conceptual stage, such efforts could in principle revolutionize resource management, though such solutions are high risk due to technical complexity and prohibitive costs.

In the near term, space exploration will drive innovation in sustainable technologies, for example in improved components such as radiation-tolerant chips. And efficiency, resource recycling and waste reduction in space can lead to breakthroughs that can be applied on Earth.

Conclusion

Space technology offers powerful tools that contribute to advancing sustainability on our planet. By harnessing the capabilities of satellites and space exploration, we can monitor environmental changes, optimize resource use, and develop innovative solutions to the climate change and other challenges to the human condition. As civilization continues to explore space, it is essential to ensure that technological advancements contribute not only to our knowledge of the universe but also to the protection and preservation of our home planet.

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