The HyspIRI mission, as recommended to NASA in 2007 by a committee of the Space Studies Board of the National Research Council (NRC), aims to detect responses of ecosystems to human land management and climate change and variability. In recommending HyspIRI as a medium-sized mission, the committee combined concepts for an “Ecosystem Function” mission from a study panel on land-use change, ecosystem dynamics, and biodiversity, and a “Mission to Observe Surface Composition and Thermal Properties” from the solid-Earth hazards, natural resources, and dynamics panel. They also included objectives related to human health, climate variability and change, and coastal and inland water quality. Key challenges for the team studying HyspIRI included establishing the scientific compatibility of measurement requirements and demonstrating the feasibility of meeting those requirements within the proposed mission class and time-frame. Requirement compatibility is addressed with broad-based science workshops (in 2008, 2009, and 2010; http://hyspiri.jpl.nasa.gov/), and with analyses carried out by a science study group and a concept study team. Showing feasibility involved team engineering exercises to develop reference point designs for two instruments and the mission as a whole, complemented by simulations of global data coverage and quality.
Results/Conclusions
The HyspIRI science study group and workshops developed a set of science-driven questions and subquestions, answerable using a visible-to-short-wave-infrared (VSWIR) imaging spectrometer, a multispectral thermal infrared (TIR) imager, or combined data from both. Themes of particular importance in ecology included: pattern and spatial distribution of ecosystems and their components; ecosystem function, physiology, and seasonal activity; biogeochemical cycles; changes in and responses to disturbance; ecosystem and human health; wildfires; coastal, ocean, and inland aquatic environments; and ecosystem function and diversity. Important unknowns included interactions with changing climate and land use. Answering a number of the questions requires global measurements of terrestrial and shallow aquatic ecosystems, over seasonal to inter-annual time scales. There exist sun-synchronous orbits compatible with both TIR (5-day) and VSWIR (3-week) requirements for repeat observation, and terrestrial and shallow aquatic requirements for illumination. Within the 50-75 m range of spatial resolutions suggested for the Ecosystem Function mission, a nominal ground-sampling distance of 60 m offers sufficient resolution to quantify composition and diversity using high-quality reflectance spectra, while permitting frequent opportunities for observing the vegetated terrestrial and shallow aquatic surface of the Earth, using existing technologies.
