1 / 29

X-Ray WFI Mission

X-Ray WFI Mission. Communications Ron Vento Blake Lorenz 16 – 20 April 2012. Topics. Overview Functional Configuration Driving Requirements and Assumptions L-2 Orbit, Mission Timeline, and S/C Attitude Selected Configuration and Rationale Antenna information

vida
Download Presentation

X-Ray WFI Mission

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. X-Ray WFI Mission Communications Ron Vento Blake Lorenz 16 – 20 April 2012

  2. Topics • Overview • Functional Configuration • Driving Requirements and Assumptions • L-2 Orbit, Mission Timeline, and S/C Attitude • Selected Configuration and Rationale • Antenna information • Data Rate, Time, and Quantity • Signal Margin Summary • Cost/Mass/Power Summary • Acronyms • Backup

  3. Overview • Ka-Band for X-ray Wide Field Imager (WFI) mission science and data dumps via DSN 34 meter • Data dumps at 20 Mbps • One 7.6 minute contact per day require to dump data (assumes 10% peak data – an “average” mission day). • A full day of peak data would require a 35 minute contact • S-Band TT&C (Telemetry, Tracking & Command) via HGA to DSN 34 meter • 2 kbps command • 8 kbps telemetry • S-Band TT&C via omni to DSN 34 meter • 1 kbps command • 2 kbps telemetry • Ranging for orbit determination • 60 minutes per day required for transfer phase; 30 minutes per day on orbit • S-Band thru TDRSS for launch and LEO critical events • 1 kbps command • 1 kbps telemetry

  4. Functional Configuration decrypter S S/Ka-band Transponder Hybrid Diplexer S S-Band omnis PA switch K S decrypter S C&DH PA Diplexer S switch S/Ka-band Transponder Hybrid S switch ISOLATOR SWITCH Ka-band TWTA S / Ka HGA Triplexer K Ka-band TWTA

  5. Functional Configuration 1 kbps Tlm 1 kbps Command (Launch & LEO) TDRS Ka-band: 20 Mbps Telemetry S-band: 8 kbps Tlm 2 kbps Command & Ranging 34M MOCC White Sands complex DSN Command Command Housekeeping Science & Hskpg

  6. Driving Requirements & Assumptions • Launch: 2021 • Nominal Orbit: Earth-Sun L-2 orbit (Lagrange or libration point ) • ~800,000 km to 1.2 Mm Halo and/or Lissajous orbit • Attitude: Stellar pointing • Orbit determination via DSN ranging • Ranging required • One 60 minute period/day during transfer orbit • One 30 minute period/day when on orbit • Timing requirement of 0.001 seconds at L2 • Latency: 72 hours for nominal data • Telemetry BER: 10-6 • “Low Nominal” raw instrument data rate: 44.1 kbps • Peak science collection rates 10 percent of the time: 354.1 kbps • RF communications - observations continue during downlink • Disposal plans – Same as Grating Mission (1 m/s delta-V at EOL)

  7. Driving Requirements & Assumptions • X-ray Imaging Mission • Class B • L-2 Orbit • ~6 m Focal Length • 3 years Mission life • 5 year goal • Launch on EELV • Launch Date – 2021 • Payload (pass through) • Three ~1 m diameter X-ray Flight Mirror Assembly (FMA) • Three Wide Field Imager (WFI) Instrument Flight Mirror Assembly (FMA) –3X Wide Field Imager -3X WFI Instrument

  8. L-2 Orbit 800,000 km amplitude L-2 Orbit with 180 day period L-2 Earth-Sun angle: 7 to 34º Lunar Orbit L-2 Transfer Trajectory E Earth- L2 Distance: 1.5 x 106 km To Sun Courtesy - JWST Max Range: 1.8 x 106 km • L2 800,000 km semi-major axis halo orbit • 0% solar or lunar obscuration throughout 10 years • Essentially the same orbit as JWST

  9. X-ray WFI Mission Timeline Transfer Trajectory Insertion (TTI) at L + 25 to 120 minutes Launch (L) at T0 After outgassing: Jettison / Open Flight Mirror Assembly Covers, Calibrate w/ Celestial Targets then start Science Ops Open Instrument Covers and Gate Valves LV Separation: TTI + 5 minutes ELV Dispersion Corrections at TTI + 24 hours EOM Disposal: Establish Power Positive Attitude First Mid-Course Correction: TTI + 16 days Commence Instrument Aliveness Checks Spacecraft full power on Commence Observatory Checkout Instrument internal background measurements Second Mid-Course Correction: TTI + 60 days At L2, continue with Science Ops L2 Orbit Insertion (L2OI) TTI + 100 days Launch (L) at T0

  10. X-ray WFI Mission Timeline

  11. X-ray WFI – Pitch, yaw, roll from L2

  12. Science Data Rates

  13. Selected Configuration & RationaleKa-Band • Ka-band used for data dumps • Two DSN S/Ka-Band transponders • Two 10 watt Ka-Band TWTAs • Data will be LDPC rate ½ encoded • (If rate 7/8 encoding is used a 15 Watt TWTA will be needed ) • QPSK modulation will be used for Ka-band (Residual carrier for S-band when ranging) • Gimbaled 0.5 M dual frequency high-gain antenna • On the Earth pointed axis • Transmit data rate of 20 Mbps to DSN 34 meter • Multiple rates can be included if lower or higher rates are needed • A 30 minute contact is required every day for ranging. • 95% rain availability is assumed • Redundancy, except for the antenna systems • 8 minutes required to transmit data simultaneous with the 30 min ranging contact • Even 24 hours of peak data can be accommodated during a 30 minutes ranging contact with an additional ~5 minutes

  14. Selected Configuration & RationaleS-Band • S/Ka-band communications using DSN 34 m • S-Band for TT&C • 5 watts RF using 5 watt power amplifiers via omnis or the HGA • Use omnis • 2 kbps telemetry • 1 kbps command • Use HGA • 8 kbps telemetry (rates up to 250 kbps are achievable) • 2 kbps command • Use TDRSS for launch and LEO critical events • 1 kbps command • 1 kbps telemetry • Ranging: One hour contact per day during transfer orbit and one 30 minute contact per day when on orbit, alternating between north and south Earth station locations

  15. X-ray WFI Ka- / S-band Antenna

  16. Data Rate, Time and Quantity • Data Storage: 54 Gbits for 2 days low nominal plus one full day “peak”

  17. Link Margin Summary TDRSS guarantees support with a margin of >0 dB S-Band return links use residual carrier (worse case) for ranging.

  18. Component Summary

  19. DSN Support • Launch and early orbit • Continuous tracking for the first 48 hours • DSN 34M/Transfer orbit (100 days to orbit) • Two 30 minute contacts/day • 24 hour support before and after each mid course corrections (Two corrections planned) • Orbit insertion, continuous support • DSN 34M/ Mission orbit • One 30 minute contact /day • The peak data can be accommodated during a ranging contact with an additional 5 minutes • Pre-pass time: 45 minutes • Post-pass time: 15 minutes

  20. Total RF Communication Costs • Total RF mission costs for 5 years: $15.1 M (Excludes FTEs) • RF Communication Links • Launch and early orbit: $155 k • SN TDRSS costs: $55 k • 2 hours SSA support: $15 k • Documentation: $40 k • DSN 48 hours support: $100 k • DSN 34M/Transfer orbit: $601.9 k • 0ne hour contact/day: $345.3 k • 100 days to orbit • Two mid course corrections: $171 k • Orbit insertion: $85.6 k • DSN 34M/ Mission orbit: $4.55 M / 5 years • One 30 minute contact /day: ($910 K/year) • Spacecraft RF Hardware cost: $9.76 M

  21. Acronyms

  22. . Back-up Slides Ka-band (HGA) to 34 meter (at 20 Mbps) S-band (HGA) to 34 meter S-band 34 meter to HGA S-band omni to 34 meter S-band 34 meter to omni TDRSS return link (SSAR) TDRSS forward link (SSAF)

  23. Ka-Band (HGA) to 34m BWG

  24. S-Band (HGA) to 34M BWG

  25. S-Band 34 M to S/C HGA

  26. S-Band 34 M to S/C omni

  27. S-Band S/C omni to 34 M

  28. S-Band S/C omni to TDRSS

  29. S-Band TDRSS to S/C OMNI

More Related