Background D/HSO Announcement of Opportunity (July 2011) in coordination with D/EOP soliciting scientific experiments for the International Space Station (ISS) relevant to Global Climate Change studies 16 Proposals were received from 309 science team members ESA Earth Sciences Advisory Committee (ESAC) recommended selection of the GEROS-ISS proposal for further study The GEROS-ISS experiment science objectives and requirements are elaborated with an International Science Advisory Group (SAG) Unique collaboration from three directorates, Human Space Operations (D/HSO), Earth Observation Programmes (D/EOP) and Technical and Quality Management (D/TEC) support the science, development and implementation of GEROS-ISS GEROS-ISS builds up from the solid experience gained in the definition, pre-developments and campaigns for the PARIS (Passive Reflectometry and Interferometry System) concept 3 studies on-going: One on Science requirements consolidation and 2 parallel phase A studies

Status of GEROS-ISS science activities ESA has run 3 SAG meetings (last one in July 2014) Meet-up with 9 top experts including the lead proposer of GEROS-ISS providing scientific advise to the Agency Approved Mission Requirements Document (MRD) detailing the science objectives and requirements ESA has released a science support activity “GNSS-R – Assessment of Requirements and Consolidation of Retrieval Algorithms (GARCA) Current status of the activity: Kicked-off on 1. November 2014, PM1 on 6 February 2015

Outcome of Phase A Identification of background and scientific issues to be addressed by the mission, considering the contribution of past and present activities in the field. It provides the justification for the mission, set within the post-2018/2019 time frame, and includes a review of the current scientific understanding of the issue in question while identifying the potential ‘delta’ that the mission could provide. Specific research objectives of the mission. Consolidation of mission requirements, including required geophysical data products and observational parameters, the need for observations from space and aspects of timeliness and timing of the mission. Definition and study of system elements, including the space and ground segments; and of the operations, calibration and data processing up to Level 1b. Description of the advances in scientific algorithms and processing, validation and assimilation techniques which may be required to meet the data product requirements.

Outcome of Phase A Comparison of expected versus required performance and ability to fulfil the research/observational objectives based upon the documented system concept. Documentation of maturity of the scientific user community in respect to planned use of the anticipated scientific products, the global context in terms of complementary missions as well as the operational or applications potential of the data products. Programmatics. It also addresses scientific and technical maturity, the development status of key technologies, risks, logistics and schedules.

Tentative dates for meetings Description Nominal Project Date PHASE-A GARCA Location ECE TAS-I GFZ KO (Kick-off) T0 5/12/2014 17/11/2014 1/11/2014 Telecon PM 1 T0+1.5 5/2/2015 4/2/2015 Contractor’s premises RR (Requirements Review) T0+3 6/2/2015 MRR (Mission Requirements Review) 25/3/2015 17/3/2015 ESTEC PM 2 T0+5 22/5/2015 29/4/2015 PDR (Preliminary Design Review) T0+6 9/6/2015 PMCR (Preliminary Mission Concept Review) T0+7 3/9/2015 8/7/2015 TAR (Test Acceptance Review) T0+9 24/9/2015 Webex PM 3 22/10/2015 8/9/2015 PM 4 T0+11.5 10/12/2015 10/11/2015 FR (Final Review) T0+12 18/11/2015 MCR (Mission Concept Review) T0+13.5 9/2/2016 26/1/2016 FR (Final Review with Final Presentation) T0+15 24/3/2016 1/3/2016