The successful launch of Sentinel-1A in April 2014 signified the beginning of the dedicated space segment for the Copernicus Programme, the result of the partnership between the European Union (EU) and the European Space Agency (ESA). Sentinel-1A is the first of a long-term operational series of Earth Observation (EO) satellites to be launched by Europe that will complement the already well-established series of meteorological missions. For the first time, these missions will provide a continuous and long-term European capability for systematic observations of the Earth surface, its oceans and atmosphere to unprecedented accuracies, resolutions, and temporal coverage. If additional cost-effective missions could be flown together with these operational missions (including operational meteorological satellite series such as MetOp (Second Generation - SG) then the possibilities for meeting new Earth science and application objectives could be far-reaching e.g. fulfilling observational gaps, synergistic measurements of Earth system processes, etc. With this in mind, the ESA initiated three exploratory paper studies (known as the EO-Convoy studies). The aim of these studies is two fold: Firstly, to identify scientific and operational objectives and needs that would benefit from additional in-orbit support. Secondly, to identify and develop a number of cost-effective mission concepts that would meet these objectives and needs. Each EO Convoy study is dedicated to a specific theme, namely: Study 1- Ocean and Ice Applications, Study 2 - Land Applications and Study 3 - Atmospheric Applications. As a result of the Land study the following concepts have been selected and further investigated:

1. A passive C-Band SAR flying with Sentinel-1 comprises a single passive C-band SAR flying in formation with Sentinel-1. The aims of this mission include the monitoring of vegetation canopy height and changes over time to monitor deforestation and forest degradation as well as the monitoring of forest biomass and carbon changes based on canopy height changes (REDD+) and frequent terrain elevation and surface deformation monitoring e.g. volcanic and tectonic changes.
2. Multi-channel thermal infrared imager flying with Sentinel-2 (baseline) or Sentinel-3 (option) comprises a five-channel thermal infrared imager measuring in the 8 - 12 micron range. The aims of this mission include monitoring surface energy balance (land surface temperature, emissivity) and water status monitoring (evapotranspiration, water stress) of the continental sphere.
3. A thermal infrared / mid-infrared instrument flying with Sentinel-3 (baseline), Sentinel-2 (option) or JPSS (option) comprises a thermal infrared (10 - 12 micron) and mid-infrared (3 - 5 micron) instrument as the baseline. An instrument comprising only mid-infrared channels is also being considered as an option. The aims of this mission include monitoring the impact of fires and burn scars on the carbon cycle and atmospheric composition, observation of volcano thermal anomalies and the measurement of fire radiative power values. The baseline for this mission is to fly with Sentinel-3, however, two options were also considered: Sentinel-2 and the Joint Polar Satellite System (JPSS). JPSS, in particular, was identified as an interesting option for fire and thermal anomaly measurement due to its 13:30 Local Time of Ascending Node (LTAN).