Assessments to Prepare and De-Risk Technology Developments - Characterisation of a Liquid Crystal on Silicon Based Laser Beam Steerer for Applications in Free Space Optical Satellite Communications in Low Earth Orbit. 

Optical satellite communications play an increasingly important role in a number of space applications. However, if the system concept includes optical links to the surface of Earth, the limited availability due to clouds and other atmospheric impacts need to be considered to give a reliable estimate of the system performance. An OGS network is required for increasing the availability to acceptable figures.

Low Earth orbit (LEO) is experiencing a renaissance thanks to increasing commercialisation of space. The opportunities provided by small satellites are enabling diminutive companies and startups, in particular, to make a significant impact on the space economy. Small satellites have played a vital role in this revolution and they have a unique ability to bring around new products and services at short timescales and for relatively low-cost.

The population of non-operational objects in the space environment is raising, increasing concern about the safety of operations for current and future space activities. In this respect, space agencies and in particular ESA with its ESA/ADMIN/IPOL (2014) have established policies to mitigate space debris creation. Please refer to the compendium of space debris mitigation standards adopted by states and international organizations, [RD.5], for additional information. This basically implies that satellites in LEO and GEO shall perform an End Of Life (EOL) disposal with a reliability of 90%.

The ISOTROP project was a response to the ESA ITT "Impact of Spaceborne Observations on Tropospheric Composition Analysis and Forecast", AO/1- 6845/11/NL/AF. The general aim is to assess the benefit of the LEO+GEO satellite system for the understanding of local to regional scale tropospheric composition with a focus on Europe. The ISOTROP consortium involved researchers from the European institutes CNRS-GAME, TNO, NILU, FMI, and was led by KNMI.

The project summarized here was conceived to support the definition of applications, products and user requirements, as well as the hardware design and ground processing design of a companion satellite mission which will carry aboard a "passive" radar working in tandem with the Argentinian L-band radar developed by CONAE and denoted as SAOCOM. The primary objective (i.e., science driver) of the SAOCOM companion satellite mission (SAOCOM-CS) is forest tomography, which will be carried out by exploiting small baselines between active and passive systems (order of km) changing with time.

Generally speaking DIAMS has been an opportunity to secure the feasibility of the IOD in technical, programmatic and financial terms. More specifically DIAMS has allowed to define the end-to-end mission concept for this IOD, covering the design of various associated segments : Space Segment (Payload, Platform), and Ground Segment. Both interest and programmatic aspects have also been consolidated.

- On the technical plane :
Both the requirements and the design of the system have been refined to validate the IOD concept :

The overall objective of this study is to assess constellations of two pairs of satellites for the retrieval of time-variable gravity field information for best quality scientific monitoring of mass distribution and transport in the Earth system. Before embarking on this study the geodetic community and space agencies have come to realize that weaknesses in current single-pair gravimetric satellite missions such as GRACE or GRACE-FO (to be launched in 2017) would significantly be alleviated by having a second GRACE-type pair in space simultaneously.

There is a need to achieve optimal cost effectiveness from remote sensing missions. Concurrently, a key scientific need in remote sensing is to address the spatial and temporal resolution of atmospheric measurements. Improved temporal resolution observations of the atmosphere – and importantly a reduced latency between observation and delivery to the user – can directly improve weather forecasting services.

The simulations of the long term evolution of the space debris population, under realistic assumptions, show how the driving factor in the future environment will be mostly the breakup of large spacecraft and rocket bodies in LEO.