· · · Aerospace Engineering reports

Participation of Dutch industries and institutes in future development activities of the Lunar European Demonstrator Approach has been focused on simulation and teleoperation concepts. Some studies have been initiated on the implementation of new technologies in teleoperation: Virtual Reality and Telepresence. An evaluation of state-of-the-art Virtual Reality and Telepresence technologies is given, and the factor time delays in teleoperations and the way to deal with it have been studied and discussed. Main conclusions are: • Use of Virtual Reality techniques might be used in a limited number of applications. At this moment astronaut training appears to be the only application. Use of Head Mounted Display systems here might form a part of the total training effort. • Use of Telepresence techniques for remote operations such as in Lunar telerobotics is only possible when drawbacks due to occurring time delays are reduced by using advanced technologies. Use of Head Mounted Displays here is possible, if there are enough means to display the images to the rest of the remote operations team. • Application of Virtual Reality and Telepresence techniques in The Netherlands is limited compared to the USA and some other ESA partners. Use of Virtual Reality for training seems to be technically more feasible in The Netherlands than use of Telepresence for remote operations.

This document describes the results of research activities related to critical issues of the FA^ffi mission, carried out by NLR. FAME constitutes a dedicated infrastructure, consisting of a space segment and a ground segment, for the global monitoring of forests. The space segment is a single-mission satellite carrying a Synthetic Aperture Radar sensor. Recorded SAR data are transmitted directly to the ground over a low-rate data channel and received by multiple low-cost end-user stations. The work covered by this report comprises the following subjects: • Applicability of operational and future payloads for global forestry monitoring. • Data rate reduction techniques. • Orbit analysis.

Effective global forest monitoring can be achieved by means of Earth Observation techniques. The most promising technique in this respect is the synthetic aperture radar (SAR) technique. Due to the high percentage of cloud cover in tropical and temperate regions SAR offers excellent opportunities to monitor the forests. Requirement studies in the past have discovered that requirements from users focus on five aspects: the availability of data, the accessibility of data, the affordability of data, the timeliness of data and thematic aspects. On the basis of these requirement aspects a concept was developed which emphasises an end-to-end small space mission approach. This approach is characterised by a complete integration of the groundand space segment, rather than treating them separately. The concept is based on two key-elements: decentralised, low-cost reception and processing capabilities and a low-frequency SAR. This paper presents the initial concept, and its elements, based on work performed within the National Space Technology Programme.

This paper describes the conceptual design of a synthetic aperture radar (SAR) sensor operating at P-band frequency (435 MHz). It is part of the FAME (Forest Assessment and Monitoring Environment) initiative for the realisation of a global operational end-to-end service to allow forests to be monitored at national and sub-national level. The system will cover all the global forest areas at least three times a year, providing timely information on deforestation and forest degradation processes at a resolution of 50 - 100 m. SAR processing and product generation are fully decentralized activities carried out by low-cost end-user stations. For standardisation and cost reasons the SAR data downlink is compatible to the NOAA HRPT link, with a data vthroughput capacity of 614 kb/s. This limited data rate imposes a hard constraint on the instrument requirements. In order to achieve sufficient radiometric resolution, data buffering as well as data compression and basic SAR processing on-board the satellite are foreseen.