This drone footage was taken in 2019 over the site of Nan Madol, Pohnpei, Federated States of Micronesia during the planning phase of a LiDAR survey that led to the publication of Comer et al. 2019 (DOI: https://doi.org/10.3390/rs11182152).
The area surrounding the Nan Madol World Heritage Site shown in this video is characteristic of the types of coastal environments that we are studying. Here, our goal is to identify potential defensive structures and humanly altered terrestrial and aquatic landscape features that may have been constructed to enhance coastal and marine ecosystem productivity.
Introduction
Cultural Site Research and Management Foundation is pleased to announce the start of a new project in Micronesia: Multisensor Analyses of Pacific Island Migration and Societal Development. With funding from NASA’s Research Opportunities in Space and Earth Science (ROSES), this project will utilize a full suite of remotely sensed data collected by airborne and satellite platforms to study Pacific Island migration and societal development. This project will continue and complement the conservation work that we have been conducting at the site of Nan Madol, Pohnpei, FSM. For updates on our conservation project, please visit Nan Madol, Pohnpei, FSM: Sustainable Conservation Plan, AFCP.
NASA Research Opportunities in Space and Earth Science (ROSES): Interdisciplinary Research in Earth Science (IDS) Program
This project was selected as part of Subelement 6: Space Archaeology: Using the Past to Inform the Present and Future:
“It is widely recognized that current Earth system changes are strongly associated with changes in the coupled human-environment system, making the integration of human history and Earth system history a timely and important task. The IDS Space Archaeology subelement seeks to utilize existing remote sensing observations and data sources to discover archaeological evidence of human settlements. A secondary goal is to produce an integrated account and attribution of how changes in relevant environmental processes (e.g., climate, atmospheric chemistry and composition, ecosystem distribution, material and water cycle dynamics, biodiversity) have impacted human system dynamics (e.g., land-use systems, historical and pre-historical human settlement patterns, technologies, patterns of disease, patterns of language and institutions, conflicts and alliances). To achieve this ambitious goal, it will be necessary to integrate innovative remote sensing observations with perspectives, theories, tools and knowledge from a variety of disciplines spanning the full spectrum of natural and social sciences.
Cultures have blossomed, flourished, and then faded, sometimes abruptly, as societies have sought to optimize exploitation of the natural environment (climate, weather, physiography, hydrology, and biotic and mineral resources). A better understanding of how these cultures have flourished or transformed in response to local, regional, and global change is of profound significance to the present as societies grapple with possible adaptations to our changing world. In addition, past cultural practices often had profound impacts on the landscape by altering land-cover through land-use and modifying the hydrologic regime with associated potential consequences for biodiversity and climate. Thus, a better understanding of our past and how interactions between human and environmental systems have impacted and fed back into new, transformed societies might better inform current and future human-environmental interactions.”
Overview of Multisensor Analyses of Pacific Island Migration and Societal Development
The Pacific Islands, and in particular, islands in Micronesia, provide ideal laboratories in which to study how “environmental processes (e.g., climate, atmospheric chemistry and composition, ecosystem distribution, material and water cycle dynamics, biodiversity) have impacted human system dynamics (e.g., land-use systems, historical and prehistoric human settlement patterns, technologies, patterns of disease, patterns of language and institutions, conflicts and alliances),” as the NASA ROSES Space Archaeology announcement puts it. Here, dynamics such as sea level rise and temperature change clearly have had, and continue to have, profound effects on social and cultural trajectories. Our observations and conclusions in Micronesia will be relevant to environmental change and archaeology everywhere, especially in coastal regions, where environmental change can lead to large-scale population displacement and threaten infrastructure. Today as in the past, societies are forced to adapt to environmental changes; our understanding of the cycle of environmental change and societal adjustment, and especially how this is influenced by the pace of environmental change, can be greatly informed by linking archaeological and present-day landscapes to records of and observations of continuing environmental change in Micronesia.
We propose to use a full suite of remotely sensed data collected by airborne and satellite platforms: previously and newly collected airborne NIR and blue-green LiDAR, Landsat and Sentinel-2 (optical) and Sentinel-1 (radar), ICESat-2 (blue-green altimetry), and GEDI (infrared laser). Recently, by using LiDAR in the heavily vegetated environments at the Nan Madol World Heritage Site and adjacent Temwen island, a complex agricultural field system that was both unknown and unexpected was discovered (Comer et al., 2019). The form and sophistication of this system is a key to understanding the pattern and chronology of human occupation of islands in the Pacific. We fully expect to find and map other similarly informative archaeological landscapes, both on and offshore, at areas on Pohnpei and Yap where previous archaeological and ethnographic work suggest them to be present. This previous work found what might be thought of as scattered pieces of a puzzle; using airborne and satellite data, we intend to see the entire pattern of the puzzle, and moreover see it in the context of the environment that shaped it. That environment and environmental processes will be modeled using both optical and SAR satellite data. Moreover, we will utilize high resolution, fine-grained LiDAR data sets to inform the analysis of GEDI and ICESat-2 data in ways that will allow us to discern and differentiate archaeological landscapes. Satellites offer global coverage, while collecting airborne LiDAR, especially in remote regions such as those in the Pacific, is difficult to the extent of often being unfeasible. Success in detecting and characterizing archaeological landscapes, both terrestrial and bathymetric, using satellite LiDAR data would provide an enormously important new tool for archaeologists around the world.
Approximate Chronological Dispersal of Austronesian People across the Pacific (per Bellwood in Chambers 2008)
Short Description of Sensors
Airborne LiDAR: An airborne LiDAR system is a platform attached to an aircraft in flight that creates a point cloud model of the landscape. This method generates the most accurate and detailed digital elevation model (DEM). LiDAR (light detection and ranging) is an active sensor method by which distances (ranges) are measured by illuminating a target using laser light and recording its reflection with a sensor.
Landsat: Originally launched in 1972, the Landsat mission is a joint NASA/USGS venture and the longest-running satellite imagery acquisition program. Landsat-8 (the sensor of primary use for this project) imagery is multispectral, has 9 spectral bands and a 30-meter spatial resolution for Bands 1 – 7 and 9. Panchromatic band 8 has a 15-meter spatial resolution.
Sentinel-1: The Sentinel-1 mission includes two polar-orbiting satellites (that operate during the day as well as during the night) and produce C-band synthetic aperture radar (SAR) imagery. Like Sentinel-2, Sentinel-1 is a mission developed by the European Space Agency for the Copernicus initiative.
Sentinel-2: The Sentinel-2 mission includes two polar-orbiting satellites placed in the same sun-synchronous orbit, phased at 180° to each other. Its goal is to monitor variability and change in land surface conditions. The coverage limits are from between latitudes 56° south and 84° north. Sentinel-2 products are wide-swath, high-resolution, multi-spectral satellite images with 13 spectral bands (four bands at 10 m, six bands at 20 m and three bands at 60 m spatial resolution).
NASA’s ICESat-2 or the Ice, Cloud, and Land Elevation Satellite-2 aims to changes in elevation across the surface of the Earth using a photon-counting laser altimeter. As suggested by its name, the planet’s cryosphere will be the main priority for measuring elevation. In addition to generating detailed elevation data of ice sheets, glaciers, and sea ice, products related to land elevation and canopy heights will also be developed.
GEDI: Located on the International Space Station, the Global Ecosystem Dynamics Investigation (GEDI) lidar system produces high-resolution laser ranging observations of the 3D structure of the Earth, generating precise measurements of forest canopy height, canopy vertical structure, and surface elevation.