Centre for Earth Observation Instrumentation

CEOI initiates another five EO instrumentation projects

The Centre for EO Instrumentation has approved the funding for another five instrumentation projects to be carried out by teams from UK industry and academia.  The projects were won under open competition and selected against criteria to further technological capability in line with UK EO science priorities. 

Use of reflected GPS signals to measure the ocean surface state

This project investigates a new prototype instrument that exploits signals from GPS/GNSS navigation satellites reflected from land, ice and ocean.  By analysing the reflected signal with an instrument flying on a separate small satellite, it is possible to derive important scientific data on the nature of the reflecting surface and the atmosphere, such as the sea-surface roughness or soil moisture content.  The project will develop a flexible multi-channel receiver for reflected GNSS signals for surface sea-state measurements.  It is led by SSTL working with the University of Surrey, the University of Bath and the National Oceanography Centre, Southampton

Science and operational need 

The scientific usefulness of GNSS signals for Earth Observation is already well established e.g. for atmospheric sounding to measure tropospheric temperature, pressure and humidity. GNSS signals also prove their worth for Earth Surface Reflectometry. In an experiment from an SSTL satellite in 2003, GPS signals reflected off the Earth surface were used to yield geophysical information about the scattering properties of the ocean, ice and land surfaces.

GNSS signals reflected from the ocean contain information about both sea surface height (altimetry) and ocean roughness (sea state and scatterometry). Ocean roughness impacts many areas of ocean and atmospheric science and is important for operational ocean and weather forecasting.  Air-sea exchanges of gases, for example, are controlled by surface roughness, so that better sampling would have a direct impact on our understanding of the magnitude and distribution of atmospheric carbon dioxide (CO2) uptake by the ocean.  There are important applications in the prediction of high winds, dangerous sea states, risk of flooding and storm surges.

Project objectives 

The objective of this project is to develop a new prototype instrument that can be applied to both Earth surface reflectometry (ocean, land and ice) and atmospheric sounding together with the consolidation of the science case. Evolving from the successful GNSS-R receiver flown on UK-DMC satellite, the new prototype will incorporate a new multi-channel frontend receiver for both GPS and Galileo signals on two frequencies. It will have re-configurable processing capabilities to allow processing and data collection in real time. Space flight opportunities for this instrument are identified both through SSTL’s own satellite-launching capability and through ESA as an approved addition to a future operational mission (SMOS-ops) to measure soil moisture and ocean salinity.

Contact point for further information:  Dr Martin Unwin, SSTL

TIDAS – Thermal Infra-Red Detector Array System

Spectrometry is one of the most important assets of passive remote sensing systems since it is the ability to observe spectra of top of the atmosphere radiance which provides the most detailed information on atmosphere composition. This project will address the deployment of detector array technology to meet the challenge of building thermal infra-red Fourier transform spectrometers for future EO mission opportunities.

The Astrium led team has started work to develop a 2-dimensional thermal infra-red (IR) detector array system and on-board signal processing unit, targeted at IR sounding instruments for future meteorological and climate missions. The project makes use of the signal processing capability developed by Astrium for sophisticated telecommunications payloads. The team includes Selex Galileo for detectors, University of Leicester as the science lead and RAL to provide a laboratory high spectral resolution FTS.

Science and operational need 

Two fundamental aspects of NERC strategy will directly benefit from infra-red spectral sounders delivering information on the Earth’s atmosphere: the Climate System and Earth System Science challenges. Infra-red nadir and limb sounders can provide fundamental observations of the anthropogenic and natural greenhouse gases, as well as many related species. In particular, infra-red systems are excellent for measuring height-resolved profiles of water vapour, ozone, methane and CFC-related species.  Provision of long-term data sets for these gas concentrations is key for climate and climate-feedback studies.

Project objectives 

The study will develop a demonstration of a 2-d thermal infra-red detector array system and associated on-board signal processing unit.  The use of a 2-d detector array with simultaneous spectral acquisition offers improved spatial discrimination of fine scale processes. The study will explore the technical challenges required to fully exploit an array detector, including enhancements to the detector read-out electronics and the on-board data processing to accommodate the large volume of data generated by an array detector.  The study partners have key expertise in NERC climate science, Fourier transform spectrometry, thermal infra-red detector arrays, fast electronics and on-board processing brought together in a new team.

Contact point for further information: Dr Alex Wishart, Astrium.

Use of Hollow Waveguide Technology for high resolution spectroscopy

Monitoring of air quality and emissions from space is a vital goal for human health and for our understanding of climate change. A major step forward would be provided by sub-city scale observation from space or from high altitude platforms (cf. CEOI HAP project).  The combination of very high spatial resolution with high spectral resolution would enable observation of altitude-resolved concentration profile information, well-suited to the monitoring of tropospheric trace gases relevant to air quality (e.g. O3, CO, NO2) or to composition-climate interactions (e.g. H2O, O3, CH4, CO2).

The Rutherford Appleton Laboratory is leading work to develop a new concept in very high resolution spectroscopy, by developing a Laser Heterodyne Radiometer (LHR). This is a passive radiometer which uses a low-power, highly-stable quantum cascade laser to modulate the incoming optical beam. The most recent work approved for funding is for a study to investigate use of hollow waveguide technology developed by QinetiQ Ltd for a space-qualified instrument.

QinetiQ have developed an approach to optical and laser systems manufacture which is the optical equivalent of the electronic printed circuit board (PCB). In this approach, hollow waveguides formed in the surface of a dielectric substrate are used to guide light through a circuit of discrete optical components. The waveguides and the alignment slots for the components are created in the substrate using precision computer controlled milling techniques. The technology provides a fundamentally new way of manufacturing compact, low mass, low cost optical systems which have excellent performance and are robust to misalignment in harsh vibrational and thermal environments.

For this seedcorn project, the focus is on demonstrating and studying the concept of hollow-waveguide-based heterodyne optical mixing. This demonstration is the first and crucial step toward the full optical integration of the radiometer. Three activities will be undertaken:

• the development of a hollow waveguide board for heterodyne mixing
• the assessment of mixing performance using quantum cascade lasers
• the implementation and demonstration of a full laser heterodyne radiometer based on hollow waveguide mixing board.

The LHR represents a truly new technology with high potential for EO applications, and which has never been deployed in space. The proposed work will be a significant step forwards towards a fully integrated laser heterodyne radiometer.

Contact point for further information: Dr Damien Weidmann, STFC/RAL

MISRlite - Multi-angle Infra-red Stereo-Radiometer 

In the Earth Sciences Decadal Survey carried out by the US National Research Council, tropospheric winds are identified as “the number one unmet measurement objective for improving weather forecasts”. Current and planned methods for measuring winds from space have limitations in their ability to provide full global coverage at sufficient spatial resolution, in both day and night. Proposed missions such as NASA’s WindCam could dramatically increase the number of accurate measurements of cloud-top heights and winds, especially when compared against the proposed Doppler lidar wind measurements (from for example, ADM-AEOLUS). However they would still be limited to measurements from cloud-top surfaces in daylight.

This CEOI  project being undertaken by a team at the Mullard Space Science Laboratory (MSSL) of University College London will explore a concept known as MISRlite. It is based on the MISR (Multi-Angle Imaging Spectro-Radiometer) instrument on the NASA Terra satellite but using a single set of optics and no in-flight calibration. It will explore the optical and sensor design issues associated with building an instrument incorporating linear pushbroom technology, preferentially using uncooled thermal IR system of very low mass. It will permit cloud-top height and wind measurements to be made both day and night.  Such instruments carried on a constellation of some 3 micro-satellites will provide daily coverage and with 12 micro-satellites will provide synoptic 6-hourly coverage.

Contact point for further information: Jan-Peter Muller, UCL/MSSL

Air Quality Monitoring from High Altitude Platforms

The aim of this seed-corn study is to provide an assessment and roadmap for the development of sensor and platform technology for High Altitude Platforms (HAP’s).  HAP’s present an intermediate step to a space flight opportunity for air quality measurements (e.g. MTG and post-EPS), and could enable early high-priority science to be obtained relating to such space missions, as well as potentially offering an unrivalled observation platform for regional science and monitoring in their own right.

Science and operational need

  By maintaining a roughly stationary position with respect to the ground, HAP’s provide an observing platform for both the surface (e.g. cities) and the atmosphere (e.g. pollution). This novel application of technology promises to revolutionise traditional remote sensing by providing near-continuous observations, excellent spatial resolution, low operating costs, and long mission life, giving the prospect of dedicated platforms covering environmental "hotspots". The ability to recover payloads easily from HAP’s also offers a test-bed for the development of EO spaceborne instrumentation. As well as rapid deployment, HAP’s can provide benefits of close range (hence high resolution), high data capacity, and flexible configuration.  HAP’s could fill a distinct niche as a low cost technology between global-monitoring EO satellites and in-situ terrestrial systems.

Project objectives 

In this study, we propose to assess the preliminary design for such a system.  The main project objectives are:

• To define the key requirements for an air quality monitoring service that addresses public environmental interests (e.g. pollution “hotspot” monitoring, emergency support, legislation enforcement).
• To define the suite of technology and integration required to support this service, and to establish how the technology will meet the requirements.
• To assess how this technology may subsequently be developed into a space flight opportunity for air quality measurements.
• To secure funding to help design / develop a prototype flight demonstrator in a second CEOI study phase or through direct NERC funding of HAP’s.

The new technology material for an airship application is a skin that needs to have an extremely low porosity to helium as there is no means of topping up for any losses.  It must also be extremely light due to the vast area of the envelope.  There is plenty of experience with solar cells at this altitude, but fuel cell and electrolyser technology would have to be adapted for these flight conditions. 

The study kicked off in January 2009, and has a duration of 12 months.  The study is led by Astrium Ltd, with University of Leicester and Lindstrand Technologies Ltd.  Other partners would likely be involved in a later implementation, but inputs to this seedcorn study from external partners are also welcome.

 Contact point for further information: Dr Tony Sephton, Astrium Ltd ( This e-mail address is being protected from spam bots, you need JavaScript enabled to view it )