Minimize FormoSat-7

FormoSat-7 / COSMIC-2 (Constellation Observing System for Meteorology, Ionosphere and Climate)

The FormoSat-7 / COSMIC-2 constellation (simply known as FS-7/C-2) is an international collaboration between Taiwan (NSPO) and the United States (NOAA) that will use a constellation of 12 remote sensing microsatellites to collect atmospheric data for weather prediction and for ionosphere, climate and gravity research. NSPO/NARL (National Space Organization/National Applied Research Laboratories) is the designated representative for Taiwan and NOAA (National Oceanic and Atmospheric Administration) is the designated representative for the U.S.

FormoSat-7 / COSMIC-2 is a follow-on mission to the FormoSat-3 / COSMIC mission to meet the RO (Radio Occultation) data continuity requirements of the user community. NOAA and NSPO intend to provide a high-reliability next generation satellite system.

The overall objective of FS-7/C-2 is to advance the capabilities of regional and global weather prediction (including severe weather prediction). The goal is to collect a large amount of atmospheric and ionospheric data primarily for operational weather forecasting and space weather monitoring as well as meteorological, climate, ionospheric, and geodetic research. It is expected to be a much improved constellation system consisting of a new constellation of 12 satellites for an operation mission.

The primary mission payload will be a TriG (third generation) GNSS-RO receiver and will collect more soundings per receiver by adding European Galileo system and Russia's GLONASS (Global Navigation Satellite System) tracking capability, which will produce a significantly higher spatial and temporal density of profiles. These will be much more useful for weather prediction models and also for the severe weather forecasting including typhoons and hurricane, as well as for the related research in the fields of meteorology, ionosphere and climate. 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12) 13) 14) 15)

The constellation is planned to be comprised of 6 satellites at 72º inclination, and 6 satellites at 24º inclination, which will enhance observations in the equatorial region over what is currently being collected with FormoSat-3 / COSMIC. This constellation configuration was chosen because it provides the most uniform global coverage, as shown in Figure 1. Figure 1 shows the global sounding (data point) distribution versus the various orbital inclinations that were considered. 16) 17) 18)

This constellation will produce nearly 12,000 sounding profiles per day, compared to the approximate 2,000 soundings per day currently produced by FormoSat-3 / COSMIC due to the ability of FS-7/C-2 to track three navigation systems’ signals (GPS, GLONASS, and Galileo) versus the ability of FormoSat-3 / COSMIC to track only one (GPS).

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Figure 1: Potential satellite inclinations vs. Global sounding coverage for FormoSat-7/COSMIC-2 (image credit: UCAR)

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Figure 2: Comparison of sounding distributions for FormoSat-3 / COSMIC and FormoSat-7 / COSMIC-2 (image credit: UCAR)

Responsibilities of FormoSat-7 /COSMIC-2 partner organizations:

NSPO shall be responsible for:

• acquisition, management, and deployment of satellites constellation

• development and management of mission operations

• modification and operations of the SOCC (Satellite Operations Command and Control) station and Taiwan’s TT&C station

• acquisition and management of the Taiwan data processing center.

NOAA shall be responsible for:

• acquisition and management of the GNSS-RO mission payload

• overall management of the data analysis, application, and distribution segment

• acquisition and management of the launch vehicle system

• acquisition and management of the ground receiving stations

• acquisition and management of the data processing centers in the U.S.

NOAA and NSPO shall be jointly responsible for the acquisition and management of the scientific payloads.

• Taiwan to provide: 12 spacecraft and integration of payload onto spacecraft, mission operations center, command & control station, and limited data recovery

• NASA providing: NRE (Non Recurring Engineering) for new sensor design

• USAF (US Air Force) to provide: Launch services for all 12 spacecraft and provide 12 AF payloads (2 per spacecraft) for 24º launch orbit

• NOAA to provide: 12 sensors, data recovery stations, command and control stations, payload data processing, and archival.

Table 1: Partnership responsibilities of the FormoSat-7/COSMIC-2 mission (Ref. 12)

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Figure 3: Collaborative framework of the FormoSat-7(COSMIC-2 joint mission (image credit: NSPO, NOAA) 19) 20)

Functions

FormoSat-7 / COSMIC-2 mission

FormoSat-3 / COSMIC mission

Mission

- Establish an operational mission for near real-time numerical weather prediction
- 8,000 (threshold) profiles per day (the goal is 10,000)

- Demonstration of near real-time numerical weather prediction
- 1,600~1,800 profiles per day

Spacecraft

- NSPO will provide 12 satellites for the joint mission and a spare satellite in space depending on the launch vehicle capability.
- NSPO will integrate new GNSS P/L provided by JPL & perform P/L system Integration & Test at NSPO

- NSPO defined system requirements
- NSPO & Orbital designed the spacecraft
- UCAR provided the P/L suite
- EDU and FM1 I&T at Orbital
- FM2 to FM6 I&T at NSPO

Mission P/L capabilities

GPS / GALILEO / GLONASS tracking capabilities

GPS tracking capability

Launch vehicle provision

NOAA will provide 2 dedicated launches into selected orbits and inclinations

Use the US Air Force Minotaur L/V through UCAR’s acquisition

Ground system

NOAA’s strategy is to use U.S., European, Asian, and polar ground networks

Use of the USN ground stations for the first 2 years, and then service provision by NOAA's ground stations for the following 3~5 years

Operations

High degree of automated ground system for a minimum of a 12 satellite constellation

6 satellite constellation operations

Data processing

- TACC (Taiwan Analysis Center for COSMIC) Upgrade
- CDAAC Upgrade
- GPS-ARC II

TACC & CDAAC Implementation
GPS-ARC Initiation

Table 2: Comparison of functions allocated in FormoSat-7(COSMIC-2 and FormoSat-3/COSMIC constellations (Ref. 2)

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Figure 4: System architecture of FS-7/C-2 (image credit: NSPO, NOAA) 21)

The project plan is to launch 2 rockets (Minotaur-4 or Falcon-9) with 6 satellites on each rocket. They will be launched and then positioned into their final orbits (nominally 800 km altitude for the 72º inclination orbit and 520 km altitude for the 24º inclination orbit).

The original FormoSat-3 / COSMIC mission had an operational concept of allowing for one data downlink per orbit. The plan for FS-7/C-2 is to allow for 2 data downlinks per orbit, which will considerably reduce the data latency. Consequently, FS-7/C-2 will require more satellite ground stations for receiving the data. As with FormoSat-3 / COSMIC, the data collected by FS-7/C-2 will be downlinked to the tracking station, then transmitted to the COSMIC processing center CDAAC (COSMIC Data Analysis and Archive Center) in Boulder, CO, as well as to the Taiwan processing center TACC (Taiwan Analysis Center for COSMIC) for processing.

The processed products will then be provided to the NOAA GTS (Global Transmission System) for distribution to the worldwide weather prediction centers. Command and control for the FS-7/C-2 constellation will continue to be provided by the NSPO SOCC (Satellite Operations Control Center). Payload operational configurations will continue to be managed by a joint effort between UCAR (University Corporation for Atmospheric Research) and JPL (Jet Propulsion Laboratory) with NOAA and NSPO concurrence for updates and changes.

Item

First launch of 6 spacecraft

Second launch of 6 spacecraft

Mission objectives

To be achieved after FOC (Full Operational Capability):
8,000 atmospheric sounding profiles per day
45 minute data latency

Mission constellation

6 satellites (each of 215 kg wet estimated mass)

6 (or 7) satellites (each of 215 kg wet estimated mass)

Mission orbit

Inclination ~24.5-28º
Mission altitude of ~ 520-550 km, circular orbit

Inclination ~72º,
Mission altitude of ~ 720 km, circular orbit

GNSS RO payload

TriG receiver (NOAA/JPL)

TriG receiver (NOAA/JPL)

Science payload

- 2 band Radio Beacon scintillation instrument
- VIDI (Velocity, Ion Density and Irregularities) instrument

Taiwan furnished payload

Launch vehicle

EELV-like new LV, carrying 6 satellites

Minotaur-4 or Falcon-9 carrying 7 satellites (including 1 spare)

Launch schedule (expected)

2016

2018

Max daily average data latency

45 minutes

Communication architecture

SFTP (Scalable Fault-Tolerant Protocol) multicast via VPN (Virtual Personal Network) Internet

Ground stations

There shall be sufficient ground stations to meet the data latency requirement

Primary Data Processing Centers

US-DPC (UCAR) and Taiwan-DPC (TACC)

Mission duration

10 years

Table 3: Baseline mission requirements of FS-7/C-2 (Ref. 13)

Status of project in 2011 (Ref. 6):

• The U.S.-Taiwan agreement that is the authorizing document for the FormoSat-7 COSMIC-2 program was signed by both parties in May 2010.

• The Joint Program Office held the FDR (Feasibility Design Review) in May 2010 and the MDR (Mission Definition Review) in August 2010.

• The SRR (System Requirements Review) is scheduled for April 2011, the PDR (Preliminary Design Review) for June 2011, and the CDR (Critical Design Review) for September 2011.

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Table 4: FormoSat-7 program master schedule (Ref. 20)

Function

FormoSat-7 design

FormoSat-3 design

Spacecraft bus reliability

>0.66 for 5 years

>0.68 for 2 years

Spacecraft mass

~215 kg (wet)

61 kg (w/ propellant)

Attitude control performance

3-axis linear control
Roll/Yaw/Pitch:±1º (3σ)
Attitude knowledge: better than 0.05º (3σ), all axis GPS bus receiver x 1

3-axis nonlinear control
Roll/Yaw: ±5º (1σ), Pitch: ±2º (1σ)
GPS bus receiver PL x 1

Data storage

Bus: > 256 MByte
Science: >2 Gbit

128 MByte

Avionics architecture

Centralized architecture, radiation - hardness

Distributed architecture, (multiple avionics boxes)

Electrical power

10 % power margin
Lithium-ion battery
Voltage based algorithm

10 % power margin
Ni-H2 battery
dMdC charging algorithm

Payload interface

Mission PL: TriG
Science PL: VIDI & RF beacon

Primary PL: GOX
Secondary PL: TIP, TBB

Table 5: FormoSat-7 enhanced satellite design

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Figure 5: Illustration of the FS-7/C-2 constellation orbits (image credit: NSPO, NOAA)

Legend to Figure 5:

• Launch No 1: 6 satellites to be launched at low inclination (~ 24.5-28º) and separated by 60º when complete cluster constellation deployment. This inclination provides a better coverage over equatorial and low latitude regions.

• Launch No 2: 6 satellites to be launched at high-inclination-angle (~72º) and separated by 30º when complete final constellation deployment. The higher inclination provides better high latitude coverage.

 


 

Spacecraft:

On Sept. 6, 2012, NSPO awarded a contract to SSTL (Surrey Satellite Technology Ltd., UK) to built 12 minisatellites for the FormoSat-7/COSMIC-2 program. The spacecraft bus contract kick-off ceremony was held at NSPO (National Space Organization) and co-chaired by Dr. Guey-Shin Chang, Director General of NSPO, and Sir Martin Sweeting, Executive Chairman of SSTL. 22) 23)

The first phase is to deploy 6 satellites, each carrying an advanced GNSS receiver, to low-inclination-angle orbits. The launch is targeted in 2016.

Under the contract, SSTL will design and manufacture satellites for the FormoSat-7 program at its facilities in Guildford, UK, with the payloads being produced by NSPO's partners in the USA. NPSO will be responsible for the integration of the majority of the spacecraft at its facilities in Taiwan. The spacecraft design phase is already underway and SSTL is tailoring a new 200 kg platform to the mission requirements.

Spacecraft design: The FS7/C-2 constellation will need to use the same mission control and mission operations ground system network as is being used for the FORMOSAT-3 system. The heritage baseline employed for the spacecraft is the SSTL-100 bus, which has been used on numerous previous missions, and has most recently flown on the UK-DMC2 and Deimos-1 mission. This avionics set provides a large degree of redundancy commensurate with mission lifetimes beyond 5 years. This bus is modified in some areas according to mission specific requirements. 24) 25)

The propulsion system is based on heritage space components, and uses a monopropellant hydrazine system. Four thrusters are employed in order to permit spacecraft attitude control during propulsive maneuvers. Larger reaction wheels are employed to provide adequate control authority. Finally, star cameras are included to improve the attitude knowledge in support of the scientific payloads. One efficiency saving has been implemented by sharing capabilities cross the redundant OBCs (On-Board Computers) and redundant star camera processors, resulting in the need for just three computers. The resulting spacecraft avionics block diagram is shown in Figure 6.

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Figure 6: FormoSat-7 spacecraft systerm block diagram (image credit: SSTL, NSPO)

 

As of 2013, several launchers are still under consideration which require different spacecraft designs (Ref. 24):

1) S/C design for the Minotaur-IV launch option: The most constraining situation is provided with the Minotaur-IV of OSC. The following layout defines the spacecraft configuration for a launch option with the Minotaur-IV launch vehicle.

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Figure 7: Preliminary design of theFS-7/C-2 spacecraft and payload accommodation with the Minotaur-IV selection (image credit: NSPO, SSTL)

Spacecraft size (stowed)

963 (L) mm x 621 (W) mm x 2257 (H) mm

Launch mass (wet)

215 kg

Total power / OAP ( Orbit Average Power)

325W / 325-205W

Attitude control

3-axis linear control
Pointing knowledge <0.07º (3σ)
Pointing control < 1º (3σ)

Orbit control (propulsion)

Hydrazine monopropellant system, ~140 m/s

Navigation

GPS receiver

Communications

S-band TM/TC, 32 kbit/s uplink, 2 Mbit/s downlink

Design life

5 years, > 66%

Availability

> 95%

Launch compatibility

Minotaur-IV

Payload support

>2 Gbit data storage, 40 kg mass, 95 W OAP (Orbit Average Power)

Design Features

- Dual redundant avionics
- Batch launch compatible
- Constellation compatible

Table 6: Spacecraft specification with the Minotaur-IV selection

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Figure 8: FS-7/C-2 Minotaur-IV compatible design of the launch configuration (image credit: NSPO,Ref. 25)

 

2) S/C design for the EELV-Grande launch option: This launch configuration provides a much more generous mass and volume allocation for the platform avionics. A more conventional design can be accommodated in this selection, without the need for extensive mass optimization and miniaturization.

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Figure 9: FS-7/C-2 ESPA-Grande compatible design of the launch configuration (image credit: NSPO, SSTL)

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Figure 10: Schematic view of a FS-7/C-2 spacecraft configuration with the EELV-Grande selection (image credit: NSPO, SSTL)

Spacecraft size (stowed)

1 m x 1.25 m x 1.25 m

Launch mass (wet)

290 kg

Spacecraft power

225 W

Attitude control

3-axis linear control
Pointing knowledge <0.07º (3σ)
Pointing control < 1º (3σ)

Orbit control

Hydrazine monopropellant system, ~140 m/s

Navigation

GPS receiver

Communications

S-band TM/TC, 32 kbit/s uplink, 2 Mbit/s downlink

Design life

5 years

Availability

> 95%

Launch compatibility

EELV-Grande

Payload support

>2 Gbit data storage, 40 kg mass, 95 W OAP

Design Features

- Dual redundant avionics
- Batch launch compatible
- Constellation compatible

Table 7: Spacecraft specification with the EELV-Grande selection

 

Launch: The FORMOSAT-7 program is intended to consist of 2 launches (of 6 satellites each) which are planned to take place in 2016 and 2018, respectively. The launch provider is NOAA.

Orbit:

• First launch: Six satellites will be positioned in a low inclination orbit at a nominal altitude of ~550 km with an inclination of 24.5-28º. Through constellation deployment, they will be placed into 6 orbital planes with 60º separation.

• Second launch: Six satellites will be positioned in a high inclination orbit at a nominal altitude of ~750 km with an inclination of 72º. Through constellation deployment, they will be placed into 6 orbital planes with 30º separation.

 


 

Sensor complement: (TriG-RO, VIDI, RF Beacon)

TriG-RO [Tri-GNSS (GPS+ Galileo+GLONASS) Radio Occultation receiver]

NASA/JPL (Jet Propulsion Laboratory) is developing a next-generation GNSS space science receiver, the TriG receiver. The receiver will upgrade the capabilities offered by the current state of the art BlackJack/IGOR GPS science receivers in order to meet NASA’s decadal survey recommendations. This includes the ability to track not only GPS, but additional GNSS signals, including Galileo, CDMA GLONASS and Compass.

Most of the low level signal processing will be done inside multiple reconfigurable FPGAs, which can be updated post-launch to track new in-band GNSS signals as they become available. TriG will greatly increase the amount and quality of data by employing digital beamforming to direct multiple simultaneous high-gain beams at GNSS satellites.

With this new architecture and the availability of Galileo, GLONASS and Compass signals, many more occultations will be observed each day. The TriG receiver will have two processors, one for performing POD (Precise Orbit Determination), and the other dedicated to occultation and other science applications. The science processor will run Linux and can be programmed by scientists in a high-level scripting language, putting the scientist in the driver’s seat when it comes to onboard processing of science data. 26)

TriG technology demonstration: As part of the NASA Instrument Incubator program, JPL developed a prototype of the TriG receiver, namely TOGA (Time-shifted, Orthometric, GNSS Array), and demonstrated dual processor coupling, multi-frequency beamforming, and L5 tracking of both Galileo, GPS, and WAAS L5 signals. 27)

The TriG receiver is a NASA funded instrument. The hardware development is at Moog Broad Reach (formerly Broad Reach Engineering), the software development and complete end-to-end testing is at JPL. 28) 29) 30) 31) 32) 33)

• TriG includes the POD (Precise Orbit Determination) and RO (Radio Occultation) functionalities other than the capability of tracking existing and future GNSS signals. TriG receives all L-band GNSS signals (GPS, Galileo, GLONASS, Compass) and DORIS.

- TriG has separate science processor and the navigation processor (dual processor architecture)

- TriG possesses higher SNR compared to its previous generation receivers

- TriG is tolerant to a total ionizing dose of 40 kRad.

• TriG design is based upon heritage derived from the BlackJack/IGOR receivers that flew on numerous missions with successful operation.

• NASA is scheduled to receive the “in place delivery” of the first fully tested EM (Engineering Model) by early summer of 2013.

• A second EM (with higher Navigation processor throughput capability) is also being built for NOAA in support of the COSMIC -2 program. The NOAA EM is upgraded to allow two additional RF down-converter cards and up to 16 antenna inputs to include surface reflection sensing capability and receiving DORIS signal.

Instrument mass, power

~6 kg, 50 W

Instrument volume

30 cm x 30 cm x 20 cm

Antenna inputs

8 channels

GNSS Real-time Navigation Processor

- Acquires and tracks GNSS signals
– Sets realtime clock
– Generates position, velocity and time
– Outputs time-tagged phase/range/SNR
– Sends navigation data to Science Processor

Science Processor

– Schedules Ionospheric/Atmospheric occultation profiles
– Extracts 1 ms phase/range/amp
– Formats observables

Data volume

200 MByte/day

Table 8: Preliminary overview of TriG GRO instrument parameters

For a full-up occultation receiver the spacecraft would also have to accommodate a fore and an aft occultation antenna (2.5 kg each) and a POD antenna (1 kg) with their attendant fields of view, and cables between the antennas and the receiver.

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Figure 11: Architecture of the TriG instrument (image credit: JPL)

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Figure 12: Conceptual view of the TriG GNSS-RO instrument elements (image credit: JPL)

RFDC = RF-downconversion array

 

TriG performance features: 34)

• Support for GPS CA, L1 and L2 Semi-Codeless, L2C, and L5

• Supports from 1 to 16 antennas

• Supports POD (Precision Orbit Determination), cm level positioning, mm/sec level velocity

• Supports RO (Radio Occultation) science for weather and climatology

• Supports Reflections science applications (in development).

The TriG receiver requires more capable antennas than those flown on missions such as COSMIC. To maximize the number of ionospheric and atmospheric profiles, the TriG receiver will be capable of tracking legacy and new GPS signals such as L5, L2C and L1C; GLONASS CDMA and Galileo E1 and E5a. 35)

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Figure 13: Photo of the TriG instrument with seven 3U slot cPCI chassis (image credit: Moog Broad Reach)

Navigation Processor Features

RO-Science Processor Features

• PPC603r Processing Platform using RogueOS

• 128 kB of System EEPROM (with TMR)

• 1 GB of System NAND Flash (with TMR)

• 256 MB of System SDRAM (with EDAC)

• 384 MB of Sample SDRAM (no EDAC)

• On-orbit Reconfigurable DSP FPGA

• Spacecraft communication

- 3 RS422 UARTs

- 2 SpaceWire Ports

- 4 RS422 pulse/s outputs, 1 LVDS pulse/s output

• Ethernet interface for GSE communication during code development

• IBM750FX Processing Platform using Linux OS

• 128 kB of System EEPROM (with TMR)

• 1GB of System NAND Flash (with TMR)

• 256 MB of System SDRAM (with EDAC)

• 1GB of Buffer SDRAM (no EDAC)

• Spacecraft communication

- 3 RS422 UARTs

- 2 SpaceWire Ports

- 4 RS422 pulse/s outputs, 1 LVDS pulse/s output (generated by RO-Science DSP)

• PCI interface for backplane communication with RO-Science DSP board

• Ethernet interface for GSE communication during code development

Table 9: Summary of dual processor architecture

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Figure 14: Schematic view of the TriG instrument receiver (image credit: NASA/JPL, Garth Franklin)

In 2013, Moog Broad Reach completed the TriG HW development in collaboration with NASA/JPL and has delivered the EM (Engineering Model) HW platform to Jet Propulsion Laboratory. 36)

 

VIDI ((Velocity, Ion Density and Irregularities) instrument

The USAF (U.S. Air Force) is partnering in FormoSat-7/COSMIC-2 and will provide two space weather payloads that will fly on the first six satellites: RF Beacon transmitters and VIDI (Velocity, Ion Density, and Irregularities) instruments.

VIDI is a space weather instrument of AFRL (Air Force Research Laboratory), Kirtland AFB, Albuquerque, NM. The VIDI instrument includes three packages: 37)

• IVM (Ion Velocity Meter) sensors, aperture plane and associated electronics

• SPLP (SSAEM Planar Langmuir Probe), sensors, aperture plane and associated electronics

• DCPU (Data Combiner/Power Unit) interface box.

All sensors are ram-facing. The IVM can measure the electric field perpendicular to the magnetic field and the ion motions parallel to the magnetic field through measurement of the ion drift velocity vector. Two sensors are part of the IVM package, the RPA (Retarding Potential Analyzer) and a DM (Drift Meter), which together provide data to determine the total ion concentration, the major ion composition, the ion temperature and the ion velocity in the spacecraft reference frame.

The SPLP is designed to measure absolute ion density, ion density fluctuations, and electron temperature. The SPLP has two independent sensor heads: an IT (Ion Trap) and a SP (Surface Probe). The Ion Trap is responsible for absolute ion density and density fluctuation measurements at sample rates up to 1 kHz for the identification of scintillating regions. The Surface Probe primarily measures electron temperature but also provides electron density, spacecraft potential and if necessary can perform the ion density fluctuation measurement. The power and data interface for IVM and SPLP is provided by the DCPU. It provides a single electronic interface between the spacecraft bus and the VIDI sensors.

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Figure 15: Illustration of the VIDI-IVM instrumentation (image credit: USAF AFSPC SMC/WMA, Ref. 21)

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Figure 16: Illustration of the VIDI-SPLP instrumentation (image credit: USAF AFSPC SMC/WMA)

 

RF Beacon instrument:

The RF Beacon includes the sensor electronics and antenna. The RF Beacon will transmit a coherent signal at frequencies in the UHF, L-band and S-bands. Ground receivers will intercept the signals and derive information on ionospheric scintillation.

• The ITT antenna design is a cylinder of 25 cm in diameter and 29.1 cm tall.

• The SRI RF beacon antenna unit will be set of 3 nested quadrafilar helix antennae, with outermost and largest element (UHF) to be ~ 14 cm in diameter and 23 cm high, and mounted on a circular base plate/ground plane approximately 25 cm in diameter. The complete antenna unit has a volume of 25 cm x 25 cm x 35 cm.

 


 

Ground segment:

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Figure 17: Overview of COSMIC-2 operational processing (image credit: UCAR, NSPO)


1) Nick L. Yen, Chen-Joe Fong, Kendra L.B. Cook, Peter Wilczynski, “Future Low Earth Observation Satellite - Radio Occultation Mission,” 2011, URL: http://www.eumetsat.int/.../pdf_conf_p59_s1_01_yen_v.pdf

2) Nick Yen, “FormoSat-7 /COSMIC-2 Joint Plan and Current Progress,” OPAC-2010 (Occultations for Probing Atmosphere and Climate-2010), Joint OPAC-4, GRAS-SAF & IROW-1 Climate Workshop, Graz, Austria, September 6-11, 2010 URL: http://www.uni-graz.at/opac2010/pdf_presentation/opac_2010_yen_nick_presentation49.pdf

3) Dave Ector, Lidia Cucurull, Pete Wilczynski, “Plans for a 12 Satellite GNSS RO Constellation (COSMIC-2/FORMOSAT-7),” OPAC-2010 (Occultations for Probing Atmosphere and Climate-2010), Joint OPAC-4, GRAS-SAF & IROW-1 Climate Workshop, Graz, Austria, September 6-11, 2010 URL: http://www.uni-graz.at/opac2010/pdf_presentation/opac_2010_ector_dave_presentation08.pdf

4) “Status and Strategies for COSMIC-II Planning,” UCAR, Oct. 2008, URL: http://www.cosmic.ucar.edu/~kuo/Retreat-08/COSMIC-II-Planning.ppt

5) Dave Ector, “COSMIC-2 Update,” Nov. 4, 2010, URL: http://www.cosmic.ucar.edu/retreat_2010/presentations/Thu_Morning/COSMIC_2_Retreat_10.pptx

6) Kendra L. B. Cook, Peter Wilczynski, Chen-Joe Fong, Nick L. Yen, G. S. Chang, “The Constellation Observing System for Meteorology Ionosphere and Climate Follow-On Mission,” 2011 IEEE Aerospace Conference, Big Sky, MT, USA, March 5-12, 2011

7) Nick L. Yen, Chen-Joe Fong, Chung-Huei Chu, Jiun-Jih Miau, Yuei-An Liou, Ying-Hwa Kuo, “Global GNSS Radio Occultation Mission for Meteorology, Ionosphere & Climate,” URL: http://www.intechopen.com/download/pdf/pdfs_id/6844

8) Lidia Cucurull, Dave Ector, Estel Cardellach, “An overview of the COSMIC follow-on mission (COSMIC-II) and its potential for GNSS-R,” GNSS-R Workshop, Barcelona, Spain, October 21-22, 2010, URL: http://congress.cimne.com/gnss-r10/frontal/presentaciones/139.pdf

9) Bill Schreiner, C. Rocken, X. Yue, B. Kuo, P. Wilczynski, D. Ector, R. Fulton, “Follow?On Radio Occulta0on Constella0ons for Meteorology, Ionosphere and Climate: Overview of Currently Planned Missions, Data Quality and Coverage, and Poten0al Science Applica0ons,” 2010 Space Weather Workshop, Boulder, CO, Apr 27?30, 2010, URL: http://www.cosmic.ucar.edu/groupAct/references/SWW-Apr30-2010-Schreiner.pdf

10) C.-J. Fong, D. Whiteley, E. Yang, K. Cook, V. Chu, B. Schreiner, D. Ector, P. Wilczynski, T.-Y. Liu, N. Yen, “Space and ground segment performance and lessons learned of the FORMOSAT-3/COSMIC mission: four years in orbit,” Atmospheric Measurement Techniques, 4, pp. 1115–1132, June 2011, URL: http://www.atmos-meas-tech.net/4/1115/2011/amt-4-1115-2011.pdf

11) http://www.nspo.org.tw/2011/tw/download/info/NSPO_EDM_2011.pdf

12) Bill Schreiner, C. Rocken, X. Yue, B. Kuo, D. Mamula, D. Ector, “GNSS Radio Occultation Constellations for Meteorology, Ionosphere and Climate: Status of the COSMIC and Planned COSMIC-2 Missions,” 2011 Space Weather Workshop, Boulder, CO, USA, April 26-29, 2011, URL: http://www.swpc.noaa.gov/sww/SWW_2011_Presentations/Friday_830/SWW-Apr-2011-Schreiner.pdf

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14) Nick L. Yen, Chen-Joe Fong, G.-S. Chang, “Approaching the First Global Radio Occultation Operational Mission Using Constellation LEO Satellites,” Proceedings of the 2012 EUMETSAT Meteorological Satellite Conference, Sopot, Poland, Sept. 3-7, 2012, URL: http://www.eumetsat.int/.../pdf_conf_p61_s1_08_yen_v.pdf

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The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates.