Environmental information about the polar regions is required to support a broad range of scientific and operational activities. Drivers of information requirements include a range of regulations, standards, and policies (such as the new Polar Code) aimed at ensuring safety of life and mitigating negative environmental impacts.

Given the remote and inhospitable nature of the vast polar regions, earth observation and other space-based technologies can provide information that is detailed, comprehensive, cost effective, and not available from any other source. This information can support monitoring and analysis of issues relating to the environment, safety, and sustainable development.

The Polaris User Needs and High-Level Requirements Study was the first of a number of activities planned as part of the ESA Polaris Initiative. It reviewed user requirements for polar environmental information, considered current and proposed sources of such information from space-based and in-situ sensors, evaluated the information gaps and the impact of filling those gaps with new integrated products and services, and provided a preliminary discussion of the considerations that will shape new satellite missions to fill the gaps.

The study examined seven main mission capabilities that were chosen to fill existing and future information deficiencies:

• Dual and Tri-Band Synthetic Aperture Radar (SAR)
• Bistatic Interferometric SAR
• Automatic Identification System (AIS) with
• Next-Generation Altimeter
• LEO Optical
• HEO Optical

These mission capabilities were evaluated for contribution to each of five impact categories:

• Economy
• Safety
• Environment
• Society
• Knowledge

Not surprisingly, a large number of polar user communities are interested in monitoring variations of frozen water (sea ice, river and lake ice, glaciers and ice sheets, icebergs, and snow). Because of the ability of SAR sensors to see through cloud and in darkness (both of which are common at high latitudes), and their ability to penetrate ice and snow to see below the surface, SAR is the best sensor for monitoring polar frozen water. Different SAR frequencies reveal different information, and therefore there are benefits to having more frequencies available. As a result, the analysis found tri-frequency SAR to have the greatest impact of the mission capabilities examined, followed by dual-frequency SAR.

For observing things other than frozen water, optical sensors are superior to SAR, although they are obstructed by darkness and cloud. The results show multi-spectral optical sensing to have the greatest impact in environmental applications involving the monitoring of the atmosphere, land cover, vegetation, and ocean colour.

The ability to determine surface topography is important in a number of application areas. Although such information can be acquired in a number of ways, interferometric SAR offers the best combination of vertical resolution and wide-area coverage compared to alternative altimeter options.

The choice of which missions to pursue will depend upon the potential impacts, analysed in this study, but also critically on their costs. The mission design considerations and costs have been examined in a parallel study: “Future Mission Concepts for Polar Regions”.