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Title: Communication Architectures for Future Lunar Missions


1
Communication Architectures for Future Lunar
Missions
  • Brian.Gosselin_at_NASA.gov
  • Code 567, Microwave and Communication Systems
    Branch

2
Where Code 567 Fits at NASA
  • Member LESWG Steering Committee for
    Communications.
  • Works closely with Microwave Instrument Branch
    (Code 555) to support science missions. Past
    missions MAP and COBE.
  • Antenna range in building 19
  • Host several Electromagnetic software tools on
    server.
  • In-house design and development of flight
    hardware.
  • Support ISAL with expertise in areas such as Data
    Compression.
  • Engineers co-located with Code 450 (including
    White Sands) to support near-earth communications
    (lt 2,000,000 km includes Lunar, L1, L2).
  • Engineers working directly for Constellation at
    JSC to lead communications for CEV and
    exploration.
  • Work with other centers and JPL as part of
    various working groups.
  • Responsible for communications subsystems on
    almost every Goddard Spacecraft development (IMDC
    -gt On-orbit).
  • Some direct funding from NASA HQ for technology
    developments.

3
(No Transcript)
4
Specific Lunar Milestones from Roadmap
  • Launch and mission support of LRO 2008
  • Begin Lunar pre-cursor missions TBD??
  • Begin Lunar Human missions 2018

5
LRO Routine Operations Support
  • LROs routine support requirements include
  • 30 minutes of S-band tracking per 113 minute
    lunar orbit
  • Range measurements
  • Range rate measurements
  • Commanding
  • Realtime housekeeping telemetry
  • 600 Gbits per day of Ka-band downloads
  • Recorded science data
  • Recorded housekeeping telemetry
  • CCSDS CFDP protocol with loop closed via S-band

6
Comm. for LRO Mission
  • LRO uses basic S-Band Communications System
    almost identical to 1960s Lunar Orbiter missions
    which provided reconnaissance for selection of
    Apollo landing sites.
  • New Ka-Band downlink service for LRO enables high
    data rates at 100 Mbps from near-side of moon to
    earth. These assets should be available after
    LRO.
  • Goddards Role for LRO Comm
  • Code 567 is responsible for implementation of the
    LRO spacecraft communications subsystem hardware
    and has some responsibility for installation of
    Ground Network Hardware.
  • The NASA Ground Network (GN) managed by Code 450
    is responsible for fulfilling LROs operational
    communications and navigation support on the
    earth.

7
Enabling Ka-Band Support for LRO
  • LRO has funded installation of 18 meter antenna
    as part of new dedicated S/Ka-band terminal at
    White Sands.
  • Code 567 is developing new Ka-band component
    technologies for LRO spacecraft
  • RF Modulator developed in-house by 567 for SDO.
  • Traveling Wave Tube Amplifier developed for Glenn
    Research Center by L3.
  • High Gain Antenna (Dual S/Ka Bands) developed
    in-house by 567.

8
18-meter Antenna for LRO
WS1 Foundation being poured at WSC in May, 2006
First 18-meter antenna reflector and riser under
construction at the vendor in early 2006
18-meter antenna riser in the foreground compared
to a 13-meter antenna riser
9
Space Communication Architecture Working Group
(SCAWG).
  • Recommendations for Space Communication
    Architecture (SCA) for 2005-2030 were developed
    by the SCAWG.
  • SCAWG consisted of members from NASA Centers and
    JPL.
  • Final report available from the website
    http//www.spacecomm.nasa.gov
  • SCAWG did not focus on cost and funding issues,
    and report mostly provides a basic foundation.
  • Several follow-on working groups have since
    expanded upon details from this report.

10
Basic Recommendations of the SCAWG Report
  • Baseline architecture for missions in the Lunar
    vicinity is
  • Lunar Relay Satellite (LRS) Element
  • First Available for Robotic Lunar Exploration and
    then evolves to more than 1 satellite
  • Ground-based Earth Element (GEE)
  • Requires visibility towards earth.
  • Lunar Surface Segment to support Lunar Outpost
    region with Lunar Communications Terminal (LCT)
  • provides Wide Area Network (WAN) service and acts
    as an access point to the LRS and navigation
    beacons.

11
2nd Space Exploration Conference Dec 2006 Lunar
Architecture Overview by Tony Lavoie
Lunar Communication Terminal (LCT) provides tower
for surface-surface communications
12
Lunar Relay Element - Key Attributes
  • Lunar Exploration Robotic Phase
  • Small dedicated relay satellite in frozen,
    elliptical orbit
  • Primary mission is meeting requirements for
    robotic missions to Permanently Shadowed Regions
  • Secondary focus on technology/operational
    demonstrations to support future human phase
    needs including Constellation C3I
    Interoperability capability
  • DSN 2-way ranging Doppler used for navigation
  • Robotic Landers demonstrate Autonomous Landing
    and Hazard Avoidance Technology (ALHAT)
    capability for precision landing
  • Robotic rovers use autonomous tracking on surface
  • May be aided by relay satellite and Lander beacon
  • Lunar Exploration Human Phase
  • Two relay satellites in frozen, elliptical orbit
    provide communication services with 60
    availability to polar outpost and periodic
    coverage of entire surface for robotic and human
    sortie missions
  • Spacecraft designed and provisioned for extended
    operations
  • Full compliance with Constellation C3I
    Interoperability Specification
  • Use SN signal formats
  • Use Code Division Multiple Access (CDMA) to
    support simultaneous communications between
    Constellation elements
  • Lunar Communication Terminal (LCT) provides tower
    for surface-surface communications
  • DSN plus relay satellites provide 2-way ranging
    Doppler for navigation
  • Lunar Surface Access Modules (LSAM) use ALHAT
    capability aided by DSN relay satellites for
    precision landing
  • Surface rovers use autonomous tracking aided by
    relay satellites and LCT (when in view) on
    surface
  • May be aided by surface beacons

Lunar Architecture Team (LAT) Phase 1 Point Of
Departure design. LAT Phase 2 will study lower
cost alternatives including co-hosted
communications payloads on science orbiters.
ALHAT is funded by ESMD (not on SCaN Technology
List)
13
SCAWG Report -Trade-offs for possible Lunar Relay
Deployments
14
Final Thoughts for Planned Lunar Communications
to Support Science Missions
  • LESWG Steering Committee strives to be a resource
    for inserting communications needs for future
    science missions into the current planning
    discussions.
  • Goddard has a major role in defining and
    implementing future lunar communications through
    its work on CEV, LRO, and existing Near-Earth
    Assets (GN and SN).
  • The Lunar Architectural Team (LAT) will be
    releasing a report in Aug. 07 which will provide
    recommendations for new communication assets such
    one or more Lunar Relay Satellites.

15
Lunar Quiet Zone Considerations
  • ITU Radio Regulation - Section V Radio
    astronomy in the shielded zone of the Moon
  • 22.22 8 1) In the shielded zone of the Moon31
    emissions causing harmful interference to radio
    astronomy observations and to other users of
    passive services shall be prohibited in the
    entire frequency spectrum except in the following
    bands
  • 22.23 a) the frequency bands allocated to the
    space research service using active sensors
  • 22.24 b) the frequency bands allocated to the
    space operation service, the Earth
    exploration-satellite service using active
    sensors, and the radiolocation service using
    stations on spaceborne platforms, which are
    required for the support of space research, as
    well as for radiocommunications and space
    research transmissions within the lunar shielded
    zone.
  • 22.25 2) In frequency bands in which emissions
    are not prohibited by Nos. 22.22 to 22.24, radio
    astronomy observations and passive space research
    in the shielded zone of the Moon may be protected
    from harmful interference by agreement between
    administrations concerned.
  • 31 22.22.1 The shielded zone of the Moon
    comprises the area of the Moons surface and an
    adjacent volume of space which are shielded from
    emissions originating within a distance of 100
    000 km from the centre of the Earth.

16
Lunar Quiet Zone Considerations (continued)
  • IAU Resolution B16 recommendation that
    radiocommunication transmissions in the SZM be
    limited to the 2-3 GHz band and a TBD identified
    band (1GHz wide) for future operations on a
    time-coordinated basis between the radio
    astronomy and lunar communication systems.
  • The ITU-R Recommendation RA.479.5 (Protection of
    frequencies for radioastronomical measurements in
    the shielded zone of the Moon) stated that ALL
    frequencies below 2 GHz in the SZM should be
    accessible (protected for use by) to radio
    astronomy and that that higher frequencies (e.g.
    range above 25 GHz) would be most acceptable to
    radio astronomers for transmission on the Moon.

17
Lunar Quiet Zone ConsiderationsSummary
  • Allowances have been granted for the CEV and any
    future Lunar Relay Satellites to use S-Band (2-3
    GHz) and the Near-earth Ka-Band (gt25 GHz).
  • Current CEV planning is also for emergency voice
    communications at UHF frequencies.

18
On-going Goddard Technology Developments that
will benefit future science missions
19
GSFC Communications, Standards and Technology Lab
(CSTL) Demonstration
  • Dave Israel/Code 567
  • Willie Thompson/Code 567
  • Jane Marquart/Code 582
  • Greg Menke/Code 582/RSC
  • 22 January 2007

20
Introduction
  • GSFC Flight Software and RF Systems Laboratory
    elements combined to create an end-to-end
    IP-based communications testbed.
  • Current configuration for the new GSFC
    Communications, Standards and Technology
    Laboratory (CSTL) in Building 25.
  • First demonstrations in June 2005
  • Single spacecraft to ground station
  • Incorporated Cisco Embedded Space Router
  • Second demonstrations in November 2006
  • Additional hop to second spacecraft
  • Based on Constellation C3I Interoperability
    Specification
  • Attendees included CEV Comm Lead with Lockheed
    Martin Communications team, C3I Communications
    and Networking teams, Communications and Tracking
    Network personnel

21
Communications Scenario Relayed Communications
Orion
Orion voice/videoLSAM command/voice
Orion command/voice LSAM command/voice
Orion command/voiceLSAM voice/videoLSAM
telemetry/files
Lunar Surface Access Module (LSAM)
Orion voice/videoOrion telemetry/filesLSAM
voice/video LSAM telemetry/files
Orion command/voice LSAM command/voice
MCC
Ground Station
Orion voice/videoOrion telemetry/filesLSAM
voice/video LSAM telemetry/files
22
FY07 CSTL Activities
  • Software Defined Radio Functions
  • Coherent mode operations (Point A and Point
    B)
  • Low Density Parity Check (LDPC) Coding
  • Link Layer framing (AOS)/Channel Coding
  • Adaptive Power Control
  • Networking Functionality
  • Delay/Disruption Tolerant Networking (DTN)
  • Other hardware demonstrations (CCA, spacewire)
  • Applications
  • Core Flight Executive (CFE) upgrade / LRO
    Applications
  • Asynchronous Messaging Service (AMS)
  • Ground Implementations
  • Space Link Extension (SLE)
  • Interface with GMSEC

23
Summary
  • The use of Software Defined Radios in the testbed
    allow for investigations that require
    modifications inside the radio, such as coding
    and modulation trade studies
  • The integration of the RF development Lab and
    Flight Software Lab forms an ability for complete
    end-to-end testing and demonstrations
  • The testbed capabilities and flexibility provide
    a location for testing and demonstration to
    support
  • Standards development and testing
  • Technology development and testing
  • Constellation/C3I trade studies
  • Comm and Track Network studies
  • Testbed is a significant Goddard asset for the
    development of reliable communication systems
    that can enable new Lunar science applications
    (such as sensor-webs).

24
High Performance Data Compression
  • Benefits
  • Provides quick look/telescience capability
  • Allows direct broadcast in real time
  • Technology Features
  • Implements new CCSDS Image Data Compression
    Recommendation (122.0-B-1)
  • RT ASIC implementation offers real-time operation
    gt 20 Msamples/sec
  • Applicable to push-broom and frame data
  • Adjustable compression ratio from lossy to near
    lossless or lossless with integer transform
  • Easy interface with CCSDS packet data structure
  • Embedded bit string for progressive decoding
  • Large input data dynamic range (4-16 bits/sample)
  • No need to design coding tables, no need for
    upload
  • Technology Development
  • 2 flight ASICs under development at CAMBR/I.
    Idaho, baselined for MMS mission

Original Image
Reconstructed at ratio 201
Contact Pen-Shu Yeh (301)286-4477,
pen-shu.yeh-1_at_nasa.gov, Goddard Space Flight
Center
2006
25
Rad-hard Ultra Low Power 32-bit ColdFire Processor
  • Features
  • 32-bit Rad-Hard RISC microprocessor from General
    Dynamics Space Division
  • Low-power 1.6 watt at max freq. 65 Mhz, 3.3 V
  • MIPS 60 MIPS at 65 Mhz
  • High-quality open source S/W tools available
    compiler, debugger, ..
  • Used on various NASA missions
  • Ultra Low Power ColdFire Processor
  • Utilize Rad-Hard-by-Design technique and
    Ultra-Low-Power technique
  • Projected power savings gt 401
  • First microprocessor at Ultra Low Power
  • Provides heritage/experience for other
    microprocessors to be developed at ULP
  • Implementation technology 0.18µ CMOS/SOI at
    commercial foundry
  • Developed by GSFC and CAMBR/U. Idaho

26
Onboard Re-configurable Processing With Field
Reprogrammable Processor Array Chip (FPPAC)
  • Benefits
  • Off-loads computation intensive tasks from CPU
  • Allows on-board run-time re-programmability for
    different applications
  • Technology Features
  • One chip with 16 processing elements with
    programmable connectivity
  • Implemented in radiation tolerant 0.25
    micron CMOS with SEU/SEL immunity and TID gt
    200krad
  • Simulator software developed in GUI/C,
    Matlab
  • Low power consumption estimated 800 MMAC/3
    watts
  • Prototype chip fabricated
  • Testbed in design
  • Multi-chip reconfigurable computation platform
    with reconfigurable memory module under study
  • Target Applications
  • Sensor read-out correction (flat-fielding)
    with bad-data replacement simulated
  • 3x3, 5x5 convolution/filtering simulated
  • Discrete Fourier Transform simulated
  • Pixel processing in local neighborhood
    simulated
  • Onboard cloud detection simulated
  • Interferometry processing for wavefront control
    in progress

16 Processing Elements in one chip
MMAC Million Multiply-And-Accumulates
Contact Pen-Shu Yeh (301)286-4477,
pen-shu.yeh-1_at_nasa.gov
27
LOW DENSITY PARITY CHECK CODES
  • Features
  • Near Shannon Capacity performance
  • About 1 dB away from the Shannon Limit _at_ 10-5 BER
  • Very high minimum distance, as much as dmin66
  • No error floor above 10-10 BER
  • Outperform Reed-Solomon(255, 223) by 2.5 dB _at_
    10-5 BER
  • High Rate Encoding
  • Code Rate 0.822 or 0.875
  • Very Simple Encoder Structure
  • Cyclic Encoder (Serial division)
  • Very High Speed (Basically a serial shift
    register)
  • Low power (low gate counts)
  • Fast Decoder
  • Highly parallel architecture
  • Very fast iterative convergence
  • Regular structure (one basic processing unit is
    replicated in entire design)
  • Technology Flight Encoder ASIC at gt 1 Gbps and
    matching decoder H/W by CAMBR/U. Idaho

Contact Wai Fong (301) 286-8165,
wai.h.fong_at_nasa.gov
28
FLIGHT BASEBAND MULTI-MODULATOR
  • Features
  • Filtered OQPSK, GMSK, 8-PSK TCM CCSDS Bandwidth
    Efficient Modulation Schemes from CCSDS standards
  • Additional 16 QAM, 8-PSK (non-CCSDS)
  • Selectable Modulation Schemes (can be changed in
    Flight if designed to do so)
  • User can tailor baseband modulation filter to
    suit their requirements
  • Table of predefined Filter coefficients are
    available to select among predefined CCSDS Filters
  • Bandwidth efficiency can range from 2.0, 2.25,
    2.5, 2.75, 3.0 and 4 Bits/Symbol/Hz
  • Architecture has serial or parallel inputs
    allowing great interfacing flexibility and High
    throughput rates
  • Rad-tolerant ASIC developed at CAMBR/U. Idaho gt
    300 Mbps throughput

Lossless Compression Board
Contact Wai Fong (301) 286-8165,
wai.h.fong_at_nasa.gov
29
Code 567s Current Work
  • Code 567 is both a Microwave group and a
    Communications group.
  • Provide Goddard Code 400 spacecraft projects with
    engineering expertise for implementation of
    communication subsystems.
  • Example LRO spacecraft communications subsystem.
  • Provide resident engineering expertise to Code
    450 to support the Near-Earth Space Network (lt
    2,000,000 km) which consists of the TDRSS
    project, NASAs Space Network (SN), and Ground
    Network (GN).
  • Many Code 567 employees are matrixed to work
    directly for Code 450.
  • Support construction a LRO ground station at
    White Sands, NM.
  • Develop new space communication technologies to
    develop components not available from industry.
  • Examples Ka-Band components, High Gain Antennas.
  • Work closely with GRC to implement their
    technologies.
  • Receive direct funding for technology
    developments from NASA HQ.
  • Provide engineering support for implementation of
    Laser Communications. Work closely with Code
    554, 450, and MIT Lincoln Labs.

30
Code 567s Current Work (continued)
  • Develop new standards and protocols for space
    communications
  • Provide expertise and leadership to CCSDS
    working groups.
  • Work closely with 580 and GRC to develop
    communications standards through test-beds and
    define Software Defined Radio standards.
  • Support Code 555 (Microwave Instrument Branch)
    and their customers from Code 600 with antenna
    ranges, microwave labs, test equipment, microwave
    CAD tools, and personnel on as-needed basis.
  • Example Anechoic Indoor Antenna Range in
    Building 19 which measured performance of
    instruments such as MAP and COBE.
  • Support proposal activities at IMDC ISAL
    sessions.
  • Provide engineering expertise to NASA Centers and
    Code 450 in support of Constellation and other
    exploration planning activities.

31
(No Transcript)
32
Microwave Anisotropy Probe
Set-up of the 93 GHz RF Leakage Test Around the
Sun Shade System
33
Microwave Systems Branch FacilitiesGoddard
ElectroMagnetic Anechoic Chamber Antenna
Measurements from 400 MHz to 100 GHz
Automated Test Control and Data Visualization
MAP Reflector Engineering Unit in the GEMAC
34
Graphical Simulation of Edge-slot Antenna
Performance
35
Graphical Simulation of Edge-slot Antenna
Performance
36
Considerations when Proposing Future Lunar
Science Missions
  • Lunar Communications is an extension of existing
    Near-earth communication assets and can support
    relatively high data rates.
  • Human Exploration requires extensive upgrades to
    communications infrastructure for supporting lots
    of data (HDTV, Bio-telemetry) on a 24-7 schedule.
  • Pre-cursor missions may have benefit from Lunar
    Relay Satellite, but scheduled implementation is
    not well defined.
  • Pre-cursor missions will benefit from the
    extensive amount of technology developments and
    engineering which has already occurred to design
    several robust communication options.
  • LRO is a good example for baseline performance
    that can be achievied
  • Goddard has Mission Design capabilities through
    the IMDC which includes support from Code 567.
  • Code 567 has a major role in defining
    communications for the moon, and can provide
    mission design trade-offs.

37
Additional Technologies
38
Contents
  • Uplink Arraying
  • X-Ray Pulsar Navigation
  • Networking
  • Programmable Communication Systems
  • Spacecraft RF Technology
  • Optical Communication Technology

39
Uplink Arraying
Recommendation Develop uplink arraying
technology and prove the concept with appropriate
flight demonstration.
  • The concept is to use small aperture antennas in
    arrays into a transmit beam. This uplink
    transmit array may provide more cost-effective
    mission support, enable simpler spacecraft
    receivers, and provide more robust support in
    emergencies.
  • Has been demonstrated for near Earth
    applications, but the deep space requirement is
    more difficult.
  • Extremely large distances
  • Atmospheric conditions
  • Duration and accuracy

1. Analysis and Simulation
  • Far-field phase control via local measurements
  • adaptive tracking algorithms
  • differential modulation

2. Experimental verification
  • LEOS and spacecraft demos
  • operational arraying
  • demonstration

40
X-Ray Pulsar Navigation
  • Recommendation Complete the XNAV demonstration

41
Networking
  • Recommendations
  • 1.  An integrated test and validation capability
    is needed to experiment with network-centric
    mission operations, including measuring
    performance in degraded and emergency modes.
    Actual flight testing is highly desirable.
  • 2.  Further technology development investment is
    required to fully realize the benefits of
    building on the Internet protocol base and
    development model. In particular, the
    architecture will require the rapid maturation of
    the core DTN protocols from their current
    moderate TRL to flight readiness (a high TRL). In
    parallel there is a need to quickly advance
    supporting DTN protocols (e.g., security and
    multipoint delivery) from their current low TRL
    status.
  • 3. An enhanced time code format and distribution
    capability should be developed to support
    establishment of a single solar system-wide time
    distribution standard.

42
Programmable Communication Systems Software
Defined Radio
Notional Software Defined Radio Architecture
  • Recommendations
  • Develop open architecture for hardware and
    software.
  • Research radio components needed to improve
    performance such as higher data rates.

43
Flight SDRs Tailored to Mission Needs By Module
Library Selections
44
Spacecraft RF Technology
  • Recommendation Fund RF technologies needed for
    higher data rates for deep space distances.
  • Technologies include
  • High Power Sources (i.e. kW TWTAs)
  • Large Mesh and Inflatable Antennas
  • Power Efficient Modulation Techniques
  • Will Provide the capability to support Gbps data
    return from Mars, using large antennas, high
    power transmitters, and bandwidth efficient
    modulation, assuming effective ground apertures
    roughly equivalent to a single 70-m antenna.

45
High Power Sources
  • Ka band transmitters to greater than 1KW with
    over 100X increase in data rate. While
    high-capacity (gt100 kW) TWTAs are currently
    available for terrestrial applications, but
    kilowatt tubes are not yet space qualified. The
    concept to enable the greater than 1 kW power is
    well understood.

46
Large Mesh and Inflatable Antennas
  • Large antennas enable over 50X increase in data
    rate. Areal density of future Ka Band antennas
    may be below 1 kg/m2 including support
    mechanisms.
  • Large deployable mesh antennas, up to 12 meters
    in diameter are currently flying in commercial
    applications and larger ones are planned, however
    these are at lower frequencies. Mesh antenna
    technology is currently in the seventh generation
    of development and manufacturers are confident
    that Ka-band antennas will be available shortly.
  • Inflatable antenna technologythe potential
    leader in low-mass density aperturesis newer and
    continues to be developed.

47
Optical Communication Technology
  • Recommendation Invest in optical communications
    technology leading to a series of proof of
    concept flight demonstrations.
  • Compared with RF communications that requires
    large antennas and heavy feed systems, optical
    communications can possibly be implemented with
    lower mass and reduce the user burden for the
    same data rates as RF.
  • Technical challenges
  • space qualified sensitive detectors
  • efficient and stable sources (amplifiers and
    lasers)
  • large, lightweight spacecraft telescopes
  • electro-optical mechanical devices for beam
    pointing and steering systems.
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