Questions and Answers

DISCOVERER stands for DISruptive teChnOlogies for VERy low Earth oRbit platforms. A project about the radical redesign of earth observation satellites to operate at significantly lower altitudes, the benefits (e.g. higher resolution imagery and smaller lighter payloads) of doing so, but also the challenge of overcoming the increases in atmospheric drag.

DISCOVERER is highly innovative as it will open up a new low altitude flight regime for EO satellites. Current approaches to improve EO platforms focus on incremental improvement on proven technology (e.g. larger optics, more precise attitude determination and control, higher bandwidth communications) in order to increase image resolution and downlink data rates. However these platforms are fundamentally limited by their operational altitude.

DISCOVERER, in contrast, envisages a radical redesign of these platforms to operate at lower altitudes. For example, a VLEO platform orbiting at 300km could obtain the same resolution imagery as the current state-of-the-art WorldView-4 satellite, but with payload cost savings due to a telescope aperture less than half the diameter (or one quarter the area).

Key is to overcome or use the atmospheric interaction with the satellites, developing aerodynamic materials which reduce the effect of drag on the satellites and enable new aerodynamic control concepts atmosphere breathing electric propulsion to compensate drag and new economically beneficial satellite configurations to use all these technologies.

To our knowledge, there is no other ongoing research effort in our field anywhere in the world which pursues the same ideas as DISCOVERER, or would produce comparable data quality and quantity at the same extraordinary speed. It is our ambition to completely eliminate the lifetime limitation of EO platforms for sustained operation at significantly lower altitudes with the ultimate goal of reducing cost whilst achieving the same or even better resolution pictures and shorter revisit times.

We’re developing the enabling technologies and concepts for aerodynamic satellites which operate in a new orbital regime and at lower cost.  Being closer to the surface of the Earth benefits not only remote sensing applications, but also has potential impact on broadband and communications applications.

Satellite earth observation data is already used for the general public in many areas. Data from very low earth orbit can be used for intelligence and security, for supporting our response to disasters, for maritime surveillance, for civil protection, land management and precision agriculture. The aim of the project is to obtain this data at lower costs whilst also placing the European industry at the forefront of this rapidly growing sector. It is also an exciting opportunity for the partners to work with colleagues across Europe to help develop the next generation of earth observation satellites.

Markets with large demands for high resolution images will benefit such as defense, infrastructure, location based services or disaster management. In particular, there is demand from infrastructure and value added services such as civil engineering and location based service that monitor real-time information like traffic. Reducing the costs of how we get this imagery will have an impact throughout the value chain.

The current TRL  of material aerodynamic characterisation for VLEO satellites and for active aerodynamic control is at best at around TRL1 or less, and the proposed activities aim to move this to TRL5. The concept of atmosphere-breathing electric propulsion will be taken forward by designing, building and testing intakes and thrusters with the ambition to experimentally demonstrate, in a relevant environment, the feasibility of these concepts, and will prepare for operational use and wide-scale marketing of the new technology. Due to the experience and capability of the DISCOVERER partners, these developments in the timeframe of the project are entirely plausible. If successful, DISCOVERER will have a highly foundational effect. With the innovative breakthroughs it aims to deliver, VLEO platforms will become commercially viable for Earth observation thanks to unlimited orbital lifetimes and reduced costs. They will set new standards for civilian Earth observation applications, delivering better value remote sensing for flagship EC programmes such as Copernicus.

This requires novel and foundational research to identify and develop low-drag materials which specularly reflect the incident gas, in satellite aerodynamic control, and in atmosphere-breathing electric propulsion. An experimental wind tunnel will be developed, built and operated. It will provide a unique, world-leading infrastructure for studying rarefied-gas aerodynamics and will enable the identification and characterisation of low-drag materials. Furthermore, the test satellite will be the first wholly devoted to the study of spacecraft orbital aerodynamics and will validate the performance of the most promising low-drag materials in the VLEO environment, and demonstrate aerodynamic attitude and orbit control manoeuvring.

DISCOVERER will be developing a facility to replicate the atmospheric flow experienced by satellites in very low Earth orbits to test aerodynamic materials. We’ll also be validating the performance of the most promising materials, as well as aerodynamic control concepts, on a small satellite to be launched in early 2020.  And we’ll be demonstrating the atmosphere breathing electric propulsion.

Traditional satellites fly at higher altitudes 600km-800km to avoid atmospheric drag. This project is looking at very low orbit between 100km-450km. Key benefit is the reduction in size and therefore cost of the satellite and therefore in obtaining the Earth observation data.

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