Prepared by ESA Copernicus Team Reference EOP-CO/SSS3/REQ/00001 Issue 1 Revision 0 Date of Issue Status Approved Document Type RP Distribution COM

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Requirements

for the

Sentinel Small Sat (S^3) – Challenge

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Table of Contents 1 Introduction ................................................................................................................4 2 Background ................................................................................................................4 3 Objective of the Sentinel Small Sat (S^3) Challenge...................................................4 4 Implementation ..........................................................................................................4 5 Requirements .............................................................................................................5

5.1 Mission Requirements.........................................................................................5 5.2 Launcher Interface Requirements .........................................................................5 5.3 Ground Segment Requirements ............................................................................5 5.4 Debris mitigation Requirements ...........................................................................6 5.5 Quality Assurance & Safety Requirements ...........................................................6

6 Planning .....................................................................................................................6 7 Financial & Contractual aspects .................................................................................6 8 Communication and Outreach ....................................................................................7

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1 Introduction The purpose of this document is to provide the objectives, requirements and implementation arrangements for the Sentinel Small Sat (S^3) Challenge. 2 Background In recent years, a large number of private companies have started to develop and deploy constellations with hundreds of satellites providing new infrastructure with innovative Telecommunication and Earth Observation (EO) capabilities. These new systems are designed to leverage the latest technological advancements and evolve quickly over time in a more risk-taking approach and, hence, are likely to impact existing and planned traditional space infrastructure. Traditional development approaches have proven successful in generating high quality and highly reliable products. Nevertheless, innovative satellite design, development and operations approaches may facilitate the exploitation of the technological advancements achieved by the earthbound consumer IT industry. Stimulating the adoption of such approaches could foster growth and boost competitiveness of the European aerospace industry. The main factor fuelling this revolution is the rapid development and high integration of miniaturised technologies (electronics, sensors, MEMS, RF devices), and a similar development in remote sensing technologies could lead to very light satellites with higher capabilities and lower costs. Moving the space development cycle towards the IT model, driven by a huge effort in terms of R&D and resources, may actually kick-start a new era of innovation in space. The Copernicus Programme supports the advent of the innovation wave in Europe by ensuring a continuous supply of high quality data in an open and free manner for users for decades to come. 3 Objective of the Sentinel Small Sat (S^3) Challenge The S^3 Challenge goal is to stimulate innovative satellite design, testing and manufacturing solutions leading to small missions complementary, or providing added value, to current Sentinel family missions (see Annex I). 4 Implementation The S^3 Challenge will be proposed as part of the 2017 ESA Challenge within the Copernicus Master Prize. The Copernicus Master Prize is an ideas competition, aiming at young and innovative entrepreneurs making use of Earth Observation Copernicus data. The goal of the ESA Challenge within the Master prize is to obtain "out-of- the-box" ideas for the benefit of the commercial use of EO data, by anticipating disruptive changes to current market conditions and technologies. The S^3 Challenge winner is planned to be launched on the Small Satellite Mission Service (SSMS) proof-of-concept flight on Vega currently foreseen by end of 2018.

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The final aggregate configuration for the SSMS proof-of-concept flight will be taken into account when selecting the S^3 Challenge winner. The main milestones of the S^3 Challenge are illustrated in Annex II. 5 Requirements

5.1 Mission Requirements Sentinel Small Sat missions shall be complementary or provide added value to current Sentinel family missions. The Sentinel Small Sat mission shall include both the space segment infrastructure and the ground segment infrastructure (e.g. flight operations, payload data acquisition, product description, processing and distribution). Main parameters regarding the Sentinel missions are reported in Annex I to this document. Further information is available at https://sentinels.copernicus.eu.

5.2 Launcher Interface Requirements The proposed Sentinel Small Sat mission shall comply with the “Small Spacecraft Mission Service, User Manual for SSMS Proof of Concept Flight on VEGA”, DC/BD/ST/CDU N17-003 Issue 1, Rev. 0, Feb. 2017. Sentinel Small Sat missions using CubeSats shall be compatible with the CubeSat standard [CubeSat Design Specification, revision 13, California Polytechnic, 20 February 2014] and foresee the provision of a deployer compliant with the CubeSat standard, for example supplied by the following companies:

• ISIS • ECM • Astrofein • TYVAK • Toronto University Deployers • D-Orbit

Mathematical models supporting Mission Analysis activities foreseen by the SSMS Proof of Concept Flight shall be provided to launch service provider by March 2018.

5.3 Ground Segment Requirements The implementation of the Data Processing function shall be compatible with a Cloud type-computing environment and to the maximum extent based on open source software. The proposed mission shall comply with the free and fully open Copernicus Data Policy. As a baseline the proposal shall assume an autonomous ground segment including all functions (flight operations, payload data acquisition, processing and distribution). ESA

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may provide support to the processing and distribution of the data of the proposed Sentinel Small Sat mission. For related descriptions, the ESA Copernicus Sentinels On-Line (technical web site) provides the necessary information and is accessible through the following link https://sentinels.copernicus.eu.

5.4 Debris mitigation Requirements The Sentinel Small Sats shall fully comply with the ESA debris mitigation policies (ESA-ADMIN-IPOL(2014)2 - Space Debris Mitigation for Agency Projects).

5.5 Quality Assurance & Safety Requirements The following documents may be used to support the Product and Quality Assurance activities by the developers: Tailored ECSS Engineering Standards for IOD CubeSat Projects, ref. TEC-SY/128/2013/SPD/RW, issue 1, revision 3, 24 November 2016. Product and Quality Assurance Requirements for IOD CubeSat Projects, ref. TEC-SY/129/2013/SPD/RW, issue 1, revision 2, 05 October 2016. 6 Planning The Sentinel Small Sat mission shall be designed, developed, tested and delivered for launch within 12 months of the prize award date and in any case by the SSMS Proof of Concept Flight on Vega required delivery date. The mission shall be a hands-off programme for ESA. The proposers are free to engage the support of other agencies or institutions to ensure the degree of project oversight they consider useful. Under no circumstances ESA shall be held responsible for the completion or accomplishments of the mission or any consequential situations or events. 7 Financial & Contractual aspects The winner of the Sentinel Small Sat (S^3) challenge shall be awarded 1 MEuro and provided with one launch service free of charge. ESA shall decide on an incremental payment plan based on the procurement plan by the bidder. The team behind the winning proposal will be asked to sign a contract with ESA which will serve to identify the rights and obligations of the team towards ESA, in particular the way the funding is disbursed to the team. For this purpose ESA’s General Clauses and Conditions for Contracts shall apply [http://www.esa.int/About_Us/Law_at_ESA/Highlights_of_ESA_rules_and_regulations]

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8 Communication and Outreach Proposals shall include a plan for innovative (including social media) communication and outreach solutions to be implemented throughout the entire S^3 lifecycle (from design to operation). The goal will be to inform through story telling and share the excitement and innovative spirit leading to the birth of the first Sentinel Small Sat mission.

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Annex I

Sentinel Missions

Sentinel missions are part of the GMES/Copernicus Space Component (CSC). The CSC includes a space segment and a ground segment. The space segment is composed of the Sentinel-1,-2, -3, -5 Precursor, and -6 satellites, the Sentinel-4 and -5 payloads, and the Copernicus Contributing Missions (CCMs). The ground segment is composed of the Sentinels Payload Data Ground Segments (PDGS), the Flight Operation Segment (FOS), the Data Access System, and the Collaborative Ground Segment. Space Segment Mission fact sheets for each Sentinel are provided at the end of this Annex. The Sentinel launch manifest is reported below. Sentinel-1A Launch – 3 April 2014 Sentinel-2A Launch – 22 June 2015 Sentinel-3A Launch – 16 February 2016 Sentinel-1B Launch – 25 April 2016 Sentinel-2B Launch – 6 March 2017 Sentinel-3B FAR – October 2017 Sentinel-4A delivery to MTG – Nov 2019 Sentinel-4B delivery to MTG – Q3 2020 Sentinel-5P Launch – June 2017 Sentinel-5A AR – June 2019 Sentinel-5B delivery to MetOp-SG – Q3 2020 Sentinel-5C delivery to MetOp-SG – Q4 2021 Sentinel-6A FAR – Apr. 2020 Sentinel-6B FAR – Q2. 2025

Ground Segment Payload Data Ground Segment The Payload Data Ground Segment (PDGS) is a distributed ground segment that uses existing facilities, infrastructure and expertise to support Sentinel missions and provide access to CCMs. The multi-mission PDGS provides the generic elements (archives, interfaces, catalogues, networks, user services, etc.) for the Sentinels and through the Data Access Integration Layer, overall data delivery monitoring, multi-mission order handling, etc. The PDGS also includes Sentinel-1, -2 and -3 specific elements such as algorithms and processors, modules related to the customisation/adaptation of mission planning, user services and facilities for acquisition, archiving, and dissemination and calibration/validation functions.

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These mission-specific elements are integrated into the configured multi-mission infrastructure which will be deployed in the operational centres. Flight Operations Segment The Flight Operations Segment (FOS) of the CSC is the collection of software and hardware needed to monitor and, if required, modify flight operations of the Sentinels. All commands to the Sentinels originate from the FOS, and all telemetry from the Sentinels flow through the FOS. The FOS provides commanding of the Sentinels for communications and, as needed for commissioning and contingency operations, uplink observation plans, scripts and command sequences that are used to execute most operations. The FOS also uplinks flight software when changes are required. The FOS controls the execution of the observation plan and coordinates commands and data needed to maintain the spacecraft in its orbit. The FOS receives all telemetry data from the Sentinels, real-time engineering telemetry and analyzes recorded engineering telemetry to ensure health, safety, and performance of the spacecraft. CSC Collaborative Ground Segment The CSC Collaborative Ground Segment, with non CSC-funded functions and elements, provides supplementary access to Sentinel Missions data either through specific data acquisition services (e.g. Quasi-Real-Time), or specific data products. Mission Management and Operations Sentinel operations are performed in accordance with the Sentinels High-Level Operations Plan (HLOP) document available on-line at: https://sentinels.copernicus.eu/documents/247904/351367/Sentinel+High+Level+Operations+Plan Routine operations start after the commissioning and ramp-up phase of the Sentinels. Sentinel-1A & -1B and Sentinel-2A, have started Routine Operations. The up-to-date Sentinel-1 observation scenario is available online at: https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-1/observation-scenario The detailed Sentinel-1 observation plan in the form of acquisition segments is published at: https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-1/observation-scenario/acquisition-segments The detailed Sentinel-2A observation plan in the form of acquisition segments is published at: https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-2/acquisition-plans

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Regular Sentinel-1, -2A, 3A mission status reports are released weekly on Sentinel Online (available at sentinels.copernicus.eu). Sentinel Data Dissemination The data access system through which ESA disseminates Copernicus Sentinel products is constantly evolving to remain in step with the growing user demand and data volumes. In its current configuration, the data access system consists of 4 logical data hub instances through which users can access Copernicus data (i.e. Sentinel core products):

• the Open Access Data Hub (SciHub) - open to everybody, on the basis of self-registration;

• the Copernicus Services Data Hub (CopHub) – open to the Copernicus Services and EU institutions;

• Collaborative Data Hub (ColHub) - open to GSC and Copernicus Participating States, following signature of a CollGS agreement with ESA;

• the International Access Hub (IntHub) – open to international partners, following signature of a technical arrangement with ESA.

The underlying data hub software (DHuS) is managed within an open source framework in order to respond efficiently to new user requirements and allow re-use of the software by various stakeholders. The latest version of the DHuS open source is available online at https://github.com/SentinelDataHub/DataHubSystem. The DHuS software is being progressively adopted by several stakeholders, e.g. Member States, International partners and Industry. Data Access Copernicus Contributing Missions The data offer and information for data access are presented on the CSCDA web portal (http://spacedata.copernicus.eu). The status of CORE datasets implementation and data delivery as well as the quota consumption per project within additional datasets is published at https://spacedata.copernicus.eu/web/cscda/data-provision-status.

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Copernicus Sentinel-1 Project Data Sheet

Sentinel-1 Mission Objectives: European polar orbiting radar observatory providing continuity of SAR data for operational applications. These services include applications such as:

• Monitoring sea ice zones and the arctic environment

• Surveillance of marine environment • Monitoring land surface motion risks • Mapping of land surfaces: forest, water

and soil, agriculture • Mapping in support of humanitarian aid

in crisis situations

Mission Profile: • Sentinel-1A Launch: 3 April 2014

With a Soyuz launcher from CSG (Kourou) • Sentinel-1B Launch: Early 2016 • With a Soyuz launcher from CSG (Kourou) • 7 years lifetime (consumables for 12) • Sun-Synchronous orbit @ 693km • Inclination: 98.18 deg. • Mean LST: 18:00 at Ascending Node • 12-days repeat cycle, 175 orbits/cycle • 96 hrs operative autonomy • Maximum eclipse duration:19 minutes

Spacecraft Platform: • 3 axis stabilized, yaw/pitch/roll steering (zero Doppler) • 0.01 deg attitude accuracy (each axis) • Right looking flight attitude • 10 m orbit knowledge (each axis, 3σ) using GPS • Spacecraft Availability: 0.998 • S/C Launch Mass: 2300kg (incl. 130 kg fuel) • Solar Array Power: 5900W (End-of-Life) • Battery Capacity: 324 Ah • Science Data Storage Capacity: 1410 Gb (End-of-Life) • Communication Links:

• S-Band TT&C Link: TC at 64kbps, and TM at 128kbps/2Mbps • X-Band Payload Data Downlink at 520Mbps • Optical Downlink for Payload Data Relay through EDRS at

520Mbps

C-Band SAR Payload: • Centre frequency: 5.405 GHz • Polarisation: HH, HV, VH, VV • Incidence angle: 20º – 45º • Radiometric accuracy: 1 dB (3σ) • NESZ: -22 dB • PTAR: -25 dB • DTAR: -22 dB Four nominal operational modes designed for inter-operability with other systems: • Strip map Mode with 80 km swath and

5x5 metre (range x azimuth) spatial resolution

• Interferometric Wide Swath Mode with 250 km swath, 5x20 metre (range x azimuth) spatial resolution and burst synchronisation for interferometry

• Extra-wide Swath Mode with 400 km swath and 20x40 metre (range x azimuth) spatial resolution

• Wave Mode with 5x5 metre (range x azimuth) spatial resolution leap-frog sampled images of 20x20 km at 100 km along the orbit, with alternating 23° and 36.5° incidence angles.

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COPERNICUS Sentinel-2 Project Data Sheet

Sentinel-2 Mission Objectives: The Sentinel-2 twin satellite system will systematically acquire high resolution images from Land with unprecedented revisit between -56deg and +84deg. Its fields of application are vegetation (agriculture and forestry), human inhabitancy, and their interactions. User products: • Level1c ortho-rectified Top Of Atmosphere

reflectance, archived systematically, provided as 100km x 100km tiles. This product includes the parameters for reflectance to radiance conversion.

• Prototype Level2a ortho-rectified Bottom Of Atmosphere reflectance “tool box”, including cloud screening and atmospheric corrections.

System: • 7.25 years nominal in orbit lifetime

(consumables for 12years) • Sun-Synchronous orbit @ 786km • Mean LST: 10:30 at Descending Node • 5 days global geometric revisit (2 satellites) • 15 days of operative autonomy. Multispectral Instrument Payload: Push broom Multi Spectral Imager, using a three mirrors anastigmatic SiC telescope concept: • Separate VNIR and SWIR detection chains • 13 multispectral channels: between 400 nm

and 2300 nm • Spatial resolution: 10m, 20m, 60m • Spectral resolution: 1nm – 180 nm • Observation mode: ~40 min/orbit, nadir

pointing • Radiometric accuracy: < 5 % • Radiometric resolution: 12 bits • Geo-location: < 20m (3) • Swath: 290Km • Mass: 290kg • Power consumption: 250W • Data rate: 490Mbits after on-board

compression

Spacecraft: • AOCS: 3 axis stabilised (on-board attitude

knowledge <10rad (2 ) • Launch mass: 1200 kg (117kg of N2H4

included, 60kg of margin) • Power: 7.2m2 solar array, 1700W EOL • 2.4 Tbits of on-board mission data storage • 2Gbits TM/TC storage • Authenticated TT&C at S band: 64kb/s up

with authenticated/encrypted commands, 2018Kb/s down

• X-band Data transmission at 520Mb/s (8psk) Launch Vehicle: • VEGA and Rockot: launch capability of

1225Kg at 786km Optical Communication Payload: • Optical Communication Payload for mission

data relay through EDRS: 600Mb/s transmission capability for Sentinel-2.

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COPERNICUS Sentinel-3 Project Data Sheet

Sentinel-3 Mission Objectives: Sentinel-3 is dedicated to operational oceanography & global land applications, providing 2 days global coverage Earth observation data (with 2 Satellites) for sea and land applications with real-time products delivery in less than 3 hours. Acquire data to feed ocean/atmosphere models and to derive global land products and services. • Sea/land colour data, in continuation of Envisat/MERIS. • Sea/land surface temperature, in continuation of

Envisat/AATSR. • Sea surface and land ice topography, in continuation of

Envisat altimetry. • Along-track SAR for coastal zones, in-land water and

sea ice topography. • Vegetation products by synergy between optical

instruments. Mission Duration: A series of satellites, each designed for a lifetime of 7 years, shall be launched to provide an operational service over 15 to 20 years. Furthermore, two satellites shall operate at any time to fulfil the mission requirements.

Mission Orbit: Type: Frozen, sun-synchronous low earth orbit Repeat cycle: 27 days (14+7/27 orbits per day) Average altitude: 814.5km over geoid Mean solar time: 10h00 at descending node Inclination: 98.65o Launcher: Rockot/Plesetzk (S3B) Spacecraft Configuration: Launch mass: 1250kg Stowed dimensions: (H)3710 mm (W)2202 mm (L)2207mm Attitude control: Gyroless, 3 axis stabilised platform with 3

star tracker heads, 4 reaction wheels and magnetic off-loading. Geodetic pointing and yaw stearing

Orbit control: 8x1N hydrazine thrusters for in-plane and out-out plane manoeuvres. 130kg hydrazine tank capacity 3 meter accuracy real-time onboard orbit determination based on GPS and Kalman filtering

Power: 2.1 kW rotary wing with 10 m2 triple junction GaAs European solar cells. Ion battery, 160Ah

Communications: 64kbps uplink, 1Mbps downlink S-band command and control link (with ranging). 2x280Mbps X-band science data downlink 384 Gbit solid state mass memory

Autonomy: Position timeline and on-board sun ephemeris for >2 weeks nominal autonomous operations.

Payload: OLCI: Ocean and Land Colour instrument Swath: 1270km, with 5 tilted cameras Spatial sampling: 300m @ SSP Spectrum: 21 bands [0.4-1.02] μm Radiometric accuracy: 2% absolute, 0.1% relative SLSTR: Sea and Land Surface Temperature Radiometer Swath: 180rpm dual view scan, 750km (backwards) and

1420km (nadir) Spatial sampling: 500m (VIS, SWIR), 1km (MWIR, TIR) Spectrum: 9 bands [0.55-12]μm Noise equivalent dT: 50mK (TIR) at 270K SRAL: SAR Radar Altimeter Operation frequency: dual C and Ku bands Radar measurement modes: LRM and SAR Pulse Repetition Frequency (PRF): 1923.87 Hz and 17.8

kHz Tracking modes: Closed-loop and Open-loop Total range error: 3cm MWR: MicroWave Radiometer (SRAL wet troposphere correction by co-located measurements) Operation frequency: dual 23.8GHz 36.5GHz Radiometric accuracy: 3K absolute, 0.6K relative POD: Precise Orbit Determination Ground processing of GPS data with enhancement through Laser Retro-Reflector and DORIS (CFI) Final accuracy: 3cm (after processing)

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Sentinel-5 Project Data Sheet

Sentinel-5 Mission Objectives: The Sentinel-5 mission covers the needs for continuous monitoring of the atmospheric chemistry at high temporal and spatial resolution from a low-Earth orbit. The main data products will be O3, NO2, SO2, HCHO, CO, CH4 and aerosol optical depth, enabling services addressing global air quality monitoring and composition-climate interaction. Mission Profile: The Sentinel-5 UVNS instrument will be embarked on the MetOp-SG satellite A. Global coverage is achieved with a daily revisit time.

Instrument Coverage: The Sentinel-5 UVNS instrument is a high resolution spectrometer, covering the following wavelengths bands:

• ultraviolet (270-370 nm), • visible (370-500 nm) • near-infrared (685-773 nm) • short-wave infrared (1590-1675 & 2305-

2385nm) The instrument consists of 5 spectrometers, in a push-broom configuration with a 108° instantaneous Field-of-View. The spatial resolution is about 7 km at Nadir and the spectral resolution ranges between 0.25 nm for the longest wavelengths and 1.0 nm at the shortest wavelengths. Instrument Elements: The instrument is composed of the following units:

• the Instrument Optical Module which contains the optical and detection part

• the Detection Support Electronics • the Instrument Control Subsystem.

Instrument Characteristics: • Allocated Mass = 292.5 kg • Allocated Mean Power = 250 W • Data Rate during acquisition = < 20

Mbps • Mission reliability = > 0.75 @ 7.5

years Flight Acceptance Review: Sentinel-5 PFM shall be ready for launch with MetOp-SG A1 in 2021 Sentinel-5 FM2 shall be ready for launch with MetOp-SG A2 in 2028 Sentinel-5 FM3 shall be ready for launch with MetOp-SG A3 in 2035 Flight Operations & Payload Data Processing (and Dissemination): EUMETSAT (Darmstadt, Germany)

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COPERNICUS Sentinel-5 Precursor Project Data Sheet

Sentinel-5p Mission Objectives: European polar orbiting UV-VIS-NIR-SWIR spectrometer payload providing continuity of atmospheric chemistry data at high temporal and spatial resolution with increased frequency of cloud-free observations for the study of tropospheric variability. Provides measurements of: UVN:

• Ozone • NO2 • SO2 • Formaldehyde • Aerosol

SWIR: • CO • CH4

NIR: • Clouds and surface albedo.

Mission Profile: • 7 years lifetime • Sun-Synchronous orbit @ 824km • Inclination: 98.730 deg. • Mean LST: 13:30 at Ascending Node • 16-days, 227 orbits repeat cycle • 72 hrs operative autonomy. TROPOMI Payload: UV-VIS-NIR-SWIR push-broom grating spectrometer. UVN module provided as a national contribution by the Netherlands: • Number of channels: 4 • Spectral range: 270-500 nm, 675-775 nm,

2305-2385 nm • Spectral resolution: 0.25-1.1 nm • Observation mode: nadir pointing, global

daily coverage, 7*7 km2 ground pixel • Radiometric accuracy: ~ 2 % • Mass: 200kg • Power consumption: 120 W average • Data Volume: 140 Gbits/orbit.

Spacecraft Platform: Astrobus L 250 M from ASTRIUM 3-axis stabilised with yaw steering Mono-propellant hydrazine propulsion. Spacecraft Launch Mass: ~ 900 kg. Spacecraft Power: 1500 W (EOL) 430W average power consumption. Science Data Storage Capacity: 480 Gbit (EOL) using flash-memory technology. Communication Links: S-Band TT&C, 64 kbit/s uplink, 128 kbit/s-1 Mbit/s downlink with ranging and coherency X-Band Science Data, 310 Mbit/s downlink OQPSK. Launch Vehicle: ROCKOT. Indicative FAR date: April 2016

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COPERNICUS – Jason-CS/Sentinel-6 Project Data Sheet

AMR-C (Climate-quality microwave radiometer – NOAA/JPL contribution):

3 channels.

GNSS POD Receiver (heritage from Sentinel-3b) provides GNSS measurements for Precise Orbit Determination.

DORIS enables precise orbit determination, as well as providing on-orbit position to the satellite attitude control.

Laser Retroreflector Array (NOAA/JPL contribution) enables tracking by ground-based lasers.

TriG Receiver for Radio Occultation (NOAA/JPL contribution) uses GNSS measurements for RO. Spacecraft Based on CryoSat with deployable solar-array extension flaps; most electronics mounted on nadir plate acting as radiator; GaAs solar arrays, with 850 W minimum (end of life); 2x108 Ah Li-ion batteries. Attitude: 3-axis stabilised local-normal pointing; mono-propellant propulsion system for deorbiting and orbit maintenance. - Dimensions (flight configuration) 5.13 m x 4.17 m x 2.35 m - Dimensions (stowed configuration) 5.13 m x 2.47 m x 2.35 m - Mass 1440 kg (wet) - Power 891 W average consumption - Data volume: order of magnitude 1200 Gbit/day - on-board storage by SSR 496 Gbits (beginning of life)

Launch Vehicle US launcher baseline (Falcon-9, Atlas-4 or Antares) procured by NASA-JPL/KSC.

Flight Operations Mission control for LEOP and IOV from ESOC. Commissioning and routine operations from EUMETSAT. Two operational ground stations, at Fairbanks and Kiruna (to be confirmed)

RF Links - X-band data downlink: 150 Mbps at 8.090 GHz - S-band TTC link: 16 kbps uplink,32 kbps downlink

Payload Data Processing Data processing and dissemination at EUMETSAT and NOAA.

Jason-CS/Sentinel-6 Mission To provide continuity of the reference, high-precision ocean topography service after Jason-3.

Mission Duration • 6 months commissioning • 5 year operational mission.

Mission Orbit • Type: LEO, non sun-synchronous • Repeat cycle: 10 days • Mean altitude: 1336 km • Inclination: 66°

Spacecraft and Payload Spacecraft design based on CryoSat-2, with necessary adaptations for the higher, mid-inclination orbit, harsher radiation environment, increased payload and space debris mitigation.

Instruments Poseidon-4 (SAR Radar Altimeter):

• Interleaved mode providing conventional pulse-width limited and SAR altimetry simultaneously (only the pulse-width limited data recorded over land)

• Possibility of following a built-in digital elevation model for improved tracking over land; • Separate SAR and pulse-width limited modes possible as fall-back.

Annex II Page 1

Annex II

S^3 Main Milestones

1 April 2017 => Sentinel Small Sat (S^3) Challenge call opens 30 June 2017 => S^3 Proposal Submission Deadline 21 July 2017 => S^3 best proposals short-list 26 July 2017 => S^3 final evaluation team meeting October 2017 => Master Prize Awards ceremony March 2018 => S^3 Math Models delivered to launcher End 2018 => Launch