In the conventional system approach, image stability requirements are met constraining the platform and instruments to a very quiet thermo-mechanical environment. Major limitations come from the difficulties to develop low noise reaction wheels and the huge mass penalty of a cold gas micropropulsion solution. For the GEO-HR mission, which targets 6-10 m spatial resolution from GEO, an active line of sight control is considered as a candidate solution.

Payload data transmitters in Earth Observation (EO) missions are moving from X-band to K-band (i.e. 25.5 to 27 GHz), where the downlink data rates can be increased due to the four times higher availability of bandwidth than in X-band. In addition, an interest is certainly growing in the field of small-size satellites and cube-sats. Therefore, there is a need to reduce the size/mass of the K-Band transmitter while increasing the DC-to-RF efficiency in order to relax the constraints of the thermal management systems at platform level.

The use of optical (laser) feeder-links for next generation telecommunication satellites is receiving strong interest from commercial telecommunication providers because it will soon not be possible to support the projected growth in bandwidth using radio frequency bands (e.g. Ka-band). Moving to higher radio frequencies such as the Q/V or W-bands does not dramatically improve available bandwidth, while it increases atmospheric attenuation to a level comparable with the laser communication bands. Cloud coverage can be mitigated by site diversity, namely by using multiple (e.g.

Radio Frequency Interference (RFI) impact heavily on a wide variety of space applications/services belonging to different areas, such as Telecommunications, Navigation and Earth Observation. Despite the huge number of interfering signal types, a preliminary classification of Interference may be performed according to the nature of interfering sources: - Intentional interferences. The transmitting events are deliberately performed for attacking other systems (e.g., jamming, spoofing, etc.); - Unintentional interferences.

The possibility to acquire and track signals for which the PRN code is not public (e.g. as for Galileo Public Regulated Service or any other non-public GNSS service) is of high interest in order to be able to assess, with real field signal, new acquisition and tracking techniques that otherwise can only be assessed with a full GNSS receiver with access to those PRN codes. In this context, the recovery of the unknown PRN codes from low-noise signal recordings (e.g.

The Ka-band frequency (35 GHz) is becoming increasingly attractive for spaceborne remote sensing applications. Unlike other radar bands, the Ka-band enables the development of compact high resolution interferometric instruments and embarking the payloads on a single platform. This creates unique new opportunities in Earth observation science and civil security applications, for instance in monitoring the changing cryosphere, generating high resolution maps of ocean currents and ship and vehicle detection.

Intentional and unintentional electromagnetic transmission can interfere with various space-borne receiving systems. Generally, such occasions are called Radio Frequency Interferences (RFI). Reports of RFI problems can be found from many space application domains that use radio receiving systems: Satellite navigation services (such as the Galileo service), telecommunications, Earth Observation, or satellite telemetry, tracking and commanding services.

The Doherty concept has proven to be a very effective technique for designing amplifiers, which maintain a high efficiency over a wide range of operating conditions. This technique is extensively used in terrestrial applications like base stations where power efficiency is getting more and more attention. Power efficiency is also of concern for space and the Doherty concept could certainly help in designing more efficient PAs. Ka-band is now being considered for mobile services that could offer very high capacity as compared to the existing ones at L-band.

The straylight characterisation and verification of EO instruments are quite challenging due to the stringent requirements regarding straylight and radiometric accuracy typically set for such instruments. The straylight verification generally requires an input source as an extended black (Lmin)/white(Lmax) scene with a very sharp and high contrast transition between the dark/bright region. The realisation of such a source is not straightforward as it requires careful design so as not to introduce additional straylight by its own.

Background and justification:

•The railway simulation testbed is an essential tool / capability needed to support validation of GNSS receiver technologies / techniques / integrity algorithms for safety-related applications in railway

•Testbed complements field testing allowing conditions that are statistically unlikely to be observed in the field to be simulated in a highly controlled and repeatable environment

Achievements and status: