1. 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

2. 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

3. 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.

4. 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.

5. 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