GPS Radio Occultation Hosted Payload on Iridium NEXT ? ‚ GPS Radio Occultation Hosted Payload on Iridium NEXT ... Ka Band service, ... Iridium Operations manages deployment

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  • GPS Radio Occultation Hosted Payload on Iridium NEXT

    Fourth COSMIC Data Users Workshop, Boulder CO

    October 29th, 2009

    Dr. Om P Gupta

    Iridium Communications Inc.

  • Iridium Communications Inc. Transaction with Greenhill completed in September, 2009.

    Iridium Communications Inc is listed on NASDAQ (Ticker Symbol: IRDM)

    Satellite voice and data solutions for enterprise & government

    The only provider offering 100% worldwide coverage

    ~347,000 subscribers(1)

    Anchor U.S. DoD customer 23% of 1H09 revenue(2)

    Iridium network complements terrestrial wireless solutions

    Most of the earths surface is not served by terrestrial wireless systems

    Expanding portfolio of products & services sold via a broad distribution network

    Data services growing rapidly

    Unique, resilient mesh satellite architecture - 66 LEOs & 7 in-orbit spares


    (1) At 6/30/09(2) Includes direct and indirect DoD revenues and revenues from certain other governmental entities through the DoD gateway

  • NEXT Constellation Iridium NEXT (NEXT) is planned to replace current

    satellite fleet starting in 2014

    Final NEXT launch completed by end of 2016 Current fleet is expected to provide commercially

    acceptable service through transition to NEXT

    NEXT is planned as a constellation of 66 cross-linked LEO satellites and 6 spares

    Maintains Iridiums unique architecture: True global coverage, low latency, providing real time

    transmission of data from anywhere on Earth

    Compatibility with current fleet eases network transition

    NEXT advantages: Higher data rates up to 1.5 Mbps (L-Band), ~10 Mbps

    Ka Band service, and other new services

    Designed to host secondary payloads Expands capacity to 3 MM plus subscribers


    Constellation 66 SVs in 6 planesOrbit Polar at 780 kmInclination 86.4oPeriod 101 min per orbit

  • Hosted Payload Opportunity on NEXT Hosted payloads missions deployed on NEXT provide following key benefits:

    One-of-a-kind solution for entities seeking global coverage/data from remote sensors and earth/climate observation instruments hosted on NEXT satellites

    Unprecedented spatial and temporal coverage with 66 hosted payloads Real-time data transmission from hosted payload in space to a user on ground Cost-effective A fraction of the cost of dedicated satellites using Public-Private Partnership (PPP) Possibility of longer mission life for hosted payload, through 8-10 year satellite design life of SVs;

    and long term mission continuity; SV replenishment and follow-on constellations are needed for business reasons offering future opportunities for additional hosted payload deployments

    Significant interest from government bodies, international agencies and industry in sharing NEXT global networked communications infrastructure

    Iridium and its team of expert partners have completed several technical feasibility studies of possible missions including GPSRO, Altimetry, ERB, Ocean Color, Solar Irradiance, and more, demonstrating compatibility with NEXT

    Window of Opportunity to commit to hosted payload on NEXT extends till the PDR planned for in 2011


  • Specifications

    Weight 50 kg

    Payload Dimensions 30 x 40 x 70 cm

    Payload Power 50 W average (200 W peak)

    PayloadData Rate

  • 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

    Iridium NEXT Hosted PayloadsDecision Time Line











    Start Date

    Hosted Payload Interface

    Specification Released

    Hosted Payload Interface

    Specification Finalized

    Feasible Study Window

    Mission Decision Window

    Hosted Payload Selection, I&T, Qual Test, Integration with SV, Launch

    Mission Launch Window




    Iridium Proprietary and Confidential


    Optimum program start by PDR in 2011 to meet first launch window Flexibility declines with CDR in 2012


  • GPSRO Mission on NEXT Feasibility Study

    A detailed feasibility study has been completed for GPSRO mission, consisting of sensor surveys, sensor design trades, optimum orbital configuration and NEXT accommodation analysis

    GPSRO RF Interference between GPS L1 and Iridium L-band transmit was considered a key issue, and it has been studied in detail and solutions established

    A solution using 12 GPSRO sensors (GPS/Galileo) on NEXT was demonstrated as providing an optimal data set for measuring global atmospheric temperature and humidity profiles in REAL TIME Over 14,000 soundings per day possible with 12 sensors Using these GPSRO sensors, electron content of ionosphere & density profiles

    measurements for space weather application is also possible in REAL TIME

    NEXT GPSRO solution would enable real-time input to weather models, and ability to grow the amount of data input over time

    Target Applications include Tracking extreme weather events Weather now-casting and forecasting Seasonal variations; climate variability; hydrologic cycle


  • Survey of GPSRO Receivers Broad Reach Engineering

    Pyxis RO Based on IGOR/JPL Blackjack development IGOR has long history in RO

    GRACE, SAC-C, CHAMP Most recently flown on FORMOSAT-3 and COSMIC

    Thales Alenia Space Topstar RO

    Based on Topstar 3000 G2 satellite navigation GPS receiver Low cost receiver with only one POD and one RO antenna

    ROSA NG Based on LAGRANGE and Topstar 3000 GPS navigation

    receiver ROSA developed for Italian Space Agency


    Based on GRAS RO mission launched on ESAs MetOp-1 GRAS-2 to have reduced size, power, smaller RO antennas

    than GRAS



    TOPSTAR 3000 G2




  • Interface with NEXT SV

    GPSRO sensor assemblies consisting of the following were studied Receivers One or two RO antennas in +/- velocity directions One or two POD antennas 60 degrees off Zenith

    Iridium NEXT design enables accommodation of the GPSRO antenna and all associated electronics

    GPSRO sensor mass is relatively small compared to 50 Kg limit, which makes it possible to host

    Additional secondary payload missions on the same SV provided total mass and data rate constraints for the combined missions are met

    For example, GPSRO mission may be combined with Altimetry, ERB, or and Ocean Color on the same SV


  • Sensor Quantity and Capability

    Study established that sensors on more satellites will produce more evenly distributed geographic coverage than more RO antennas

    24 satellites provide more even distribution than twelve over a shorter period of time

    Technically, 24 satellites with only one aft-looking RO antenna are marginally better

    Analysis also included GPS and GPS/Galileo options

    Twelve dual RO antenna sensors capable of receiving GPS and Galileo signals for RO provide optimum results


  • Sensors on 12 Satellites - Occultation

    12 Sensors on NEXT, 24 hours, GPS and Galileo14,250 Occultation


  • This work carried out by Iridium/Lockheed team to study a potential RF interference issue between GPS L1 and Iridium L-band

    A conceptual but detailed analysis has established that, under worst operating conditions, this interference can be mitigated for 99.7% of duration in 2016, dropping to 99.2% of duration in 2025

    Multiple methods were identified that can contribute to mitigating this interference, but in this analysis only a few were needed

    Others can be explored during actual implementation phase of a GPSRO mission on NEXT to achieve an optimum performance

    GPSRO RF Interference Analysis

    Lockheed Martin Space Systems Company Copyright 2009 12

  • GPS RO L1 measurements are expected to have an excellent probability of success on Iridium NEXT SV

    Establishing low noise in GPS L1-band is key; L2, L5 GPS bands are separated much more in frequency than L1 is from Iridium

    NEXT; noise situation should be better farther away

    Certain design criteria need to be met for success, some features already inherent to the SV structure and GPS receivers Factors with positive impact:

    High isolation (~48 dB) from physical spacing between MMA and GPS RO antennas GPS spread spectrum operation: inherently anti-jam Broad band noise is the least effective of all jammers Low MMA noise level from higher order inter-modulation products

    Favorable results were obtained in comparing Iridium NEXT noise level to criteria from various sources JPL noise floor prediction Stanford tests for GPS accuracy impairment NTIA tests for GPS impairment China Lake tests for GPS jamming susceptibility

    GPSRO RF Interference Analysis Summary

    Lockheed Martin Space Systems Company Copyright 2009 13

  • Concept of Operations and Data Handling Iridium Operations manages deployment and operation of the Iridium System

    Enables sensor command and data path to an MPLS cloud Has the capability to turn off the sensor to preserve the Iridium mission

    Sensor Operations manages sensor including: Sensor targeting and model updates Updating software or firmware Data stream management (pull or push from the MPLS cloud) Anomaly resolution

    Data Processing Center receives data str