NASA has initiated a new study for the Surface Biology and Geology (SBG) Designated Observable, identified in the 2018 National Academies’ Decadal Survey entitled, “Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space.” This document presented a clear vision for the combined roles of visible to shortwave infrared imaging spectroscopy and multispectral or hyperspectral thermal infrared imagery in addressing: terrestrial and aquatic ecosystems and other elements of biodiversity, geology, volcanoes, the water cycle, and applied sciences topics relevant to many societal benefit areas.

A Research and Applications (R&A) team has been developed to include four working groups: algorithms, calibration and validation, applications, and modeling. A parallel team is envisioning candidate architectures for implementing observing system concepts, exploring capabilities from program of records and recent opportunities.

Designated Observable Description Implementation
Surface Biology and Geology Earth surface geology and biology, ground/water temperature, snow reflectivity, active geologic processes, vegetation traits, and algal biomass Hyperspectral imagery in the visible and shortwave infrared; multi- or hyperspectral imagery in the thermal IR

In addition to the most and very important priorities defined in the decadal survey, there are a number of other priorities that are also being tracked and the extent to which they are met is being assessed. A key aspect of the architecture study is to determine the extent to which any given architecture meets all, most or some of the objectives derived. It is anticipated that some of these objectives will be met through international and private sector partnerships.

1 Introduction
Evolution in the Copernicus Space Component (CSC) is foreseen in the mid-2020s to meet priority user needs not addressed by the existing infrastructure.

Growing expectations about the use of Earth observation data to support policy making and monitoring puts increasing pressure on technology to deliver proven and reliable information. Hyperspectral imaging today enables the observation and monitoring of surface measurements (geo-biophysical and geo-biochemical variables) due to the diagnostic capability of spectroscopy provided through contiguous, gapless spectral sampling from the visible to the shortwave infrared portion of the electromagnetic spectrum.
This will support the generation of a wide variety of new products and services in the domain of agriculture, food security, raw materials, soils, biodiversity, environmental degradation and hazards, inland and coastal waters, and forestry. These are relevant to various EU policies, that are currently not being met or can be really improved, but also to the private downstream sector.

2 Mission requirements
The observational requirements of CHIME are driven by the primary objectives i.e. agriculture, soils, food security and raw materials, and are based on experience, state-of-the art technology and results of previous hyperspectral airborne and experimental spaceborne systems. They were drafted by an international group of experts in reflected in the Mission Requirement Document. These baseline observational requirements consider trade-offs and dependencies between parameters such as spectral resolution and radiometric performance.
Currently the main mission objectives require a contiguous spectral coverage between 400 and 2500 nm, a spectral sampling interval about 10 nm, a spatial sampling interval in the range of 20 – 30 meters and a geometric revisit time of 10 to 15 days at an equator nodal crossing time between 10:30-11:30.

4 CHIME Phase A/B1 activity
Based on the analysis of observation requirements and identification of preliminary system concepts two parallel CHIME Phase A/B1 contracts were kicked off in early 2018.

As a result of CHIME Phase A, parametric analyses identifying the critical parameters and defining a set of performance requirements corresponding to the optimum in cost vs. benefits for a number of proposed mission concepts were provided.

4 Data Products, Usage and Access
As far as end user products are concerned, considering that many of the applications exploiting hyperspectral data rely on surface reflectance spectra, atmospheric and geometrically corrected surface reflectance are requested as the main data product to be distributed to users by the mission core ground segment.
The main features of this Level-2A product are:
- Bottom-of-Atmosphere reflectance pixel-level information.
- Ortho-rectified geometry including the usage of a Digital Elevation Model;
- Appended pixel classification (side product from the atmospheric correction process) allowing to distinguish opaque clouds, thin clouds, cloud shadows, vegetation, etc.
Additionally, access to Level-1B and Level-1C products are required to give the possibility to advanced users to perform their own atmospheric correction.

5 Synergies and International Context
In terms of potential for synergies with other missions and especially with Sentinel-2, a hyperspectral mission would be complementary to Sentinel-2 for many fields of application, and in particular for vegetation-related and land cover mapping applications.
There are also other planned hyperspectral missions aiming for hyperspectral image data.
The recent Decadal Survey prioritised the hyperspectral Surface Biology Geology (SBG) mission as “designated” mission to perform observations considered essential to the overall NASA programme.
Further, the Environmental Mapping and Analysis Program (EnMAP) for an imaging spectrometer mission is in Phase D production for a 2020 launch by the DLR.
The PRISMA (PRecursore IperSpettrale della Missione Applicativa) is a hyperspectral Italian Space Agency programme with a planned 2019 launch.
The Japanese Hyperspectral Imager Suite (HISUI) will be deployed in a non sun synchronous orbit aboard the International Space Station in the 2019 time-frame, following the VNIR ‘DLR Earth Sensing Imaging Spectrometer’ (DESIS), which was deployed onto the ISS in June 2018.