Summary of SPECTRA mission
Scientific Background
Understanding the interactions between terrestrial ecosystems (in particular vegetation) and the atmosphere is a central requirement to address issues such as climate change, the greenhouse effect and environmental degradation. The release of carbon dioxide into the atmosphere by human activities is recognised as one of the main drivers of climate change. Its partial sequestration by the biosphere in the form of net ecosystem productivity has prevented even more drastic changes in the short term and provides a possible mechanism to counteract excessive releases as foreseen by the Kyoto Protocol.The scientific objective of the SPECTRA mission is to describe, understand and model the role of terrestrial vegetation in the global carbon cycle and its response to climate variability under the increasing pressure of human activity.
Research objectives
Bridging the gap between observations at the local scale and parameterisations at the regional scale leading to a robust description of biosphere processes at the global scale. The SPECTRA mission aims at providing biome specific parameterisation of processes in the biosphere determining the terrestrial component of the Carbon Cycle.
Providing detailed and precise measurements of vegetation amount and conditions with a spatial resolution sufficient to characterise individual vegetation types and assess the role of the terrestrial component of the carbon cycle. SPECTRA will provide measurements of albedo, leaf area index, fraction of photo-synthetically active radiation, vegetation cover fraction, leaf chlorophyll-, water- and dry matter content, leaf and soil temperature and the fraction of living/dead biomass at a spatial resolution consistent with ground measurements.
Learning how to incorporate heterogeneity of terrestrial vegetation in global Earth system models.
Improving the accuracy of global estimates of carbon fluxes, based on SPECTRA data with input from existing and future sensors offering a lower spatial resolution, but frequent global coverage.
Observational requirements
| Observational requirements | |
|---|---|
| Spectral coverage | 450-2350 nm |
| 10.3-12.3 micron | |
| Spectral resolution | 10 nm; 0.5 micron |
| Spectral calibration | 1 nm; 0.1 micron |
| Radiometric accuracy | 2%; 1K |
Mission elements
The SPECTRA mission combines global access with high spatial, temporal and spectral resolution angular data. The scientific objectives of the mission require observations with high temporal frequency. SPECTRA will thus focus on obtaining frequent data over an ensemble of regions, which are representative of all major Earth biomes. They comprise research sites where intensive experiments and monitoring are carried out. The mission aims at integrating local measurements and the SPECTRA observations through data assimilation at the regional scale. This is achieved with the following mission elements:
Space segment
Single satellite pointable along-track (for Bi-directional Reflectance measurements) and across-track (for global Earth access) carrying a VNIR/SWIR imaging spectrometer combined with TIR imaging radiometer.
Ground segment
Satellite operation+control and provision of data products covering 10 Geo-biophysical variables.
Field segment
Consisting of ± 100 well documented regions (changeable) representative of all the Earth’s biomes associated with large programmes (e.g. IGBP, WCRP) and maintained by research teams.
System concept
| System concept | |
|---|---|
| Mass | 850 kg |
| Power | 650 W |
| Data rate | 8.5 Gbit/Orbit |
| Orbit | Sun-Synchronous - polar |
| Height | ± 670 km |
| Lifetime | 5 years |
| Launcher | Rocket |