LG 204 Communications System Amit Patel ASTE 527

Amit PatelDec 15, 2008Communications Issues of Current DSN Many of the current DSN assets are obsolete or well beyond the end of their design lifetimes The largest antennas (70m diameter) are more than 40 years old and are not suitable for use at Ka-band where wider bandwidths allow for the higher data rates required for future missions Current DSN is not sufficiently resilient or redundant to handle future mission demands Future US deep space missions will require much more performance than the current system can provide Require ~ factor of 10 or more bits returned from spacecraft each decade Require ~ factor of 10 or more bits sent to spacecraft each decade Require more precise spacecraft navigation for entry/descent/landing and outer planet encounters Require improvements needed to support human missions NASA has neglected investment in the DSN, and other communications infrastructure for more than a decade Compared to 15 years ago, the number of DSN-tracked spacecraft has grown by 450%, but the number of antennas has grown only by 30% There is a need to reduce operations and maintenance costs beyond the levels of the current system

Amit PatelDec 15, 2008Communications 70m Goldstone Antenna Upgrades needed Change to 30GHz Ka- Band

Amit PatelDec 15, 2008Communications Performance Upgrade for Next Generation DSN 4

Amit PatelDec 15, 2008Communications Need Higher Data Rates 4

Amit PatelDec 15, 2008Communications High Bandwidth due to Intrinsically High Carrier Frequency Reduced Component Size as compared to Electronic Counterparts Ability to Concentrate Power in Narrow Beams Very High Gain with relatively Small Apertures Reduction in Transmitted Power Requirements Advantages of Higher Frequency

Amit PatelDec 15, 2008Communications Basic Concept TDRSS or TSAT Satellites 10 Gbps links at 3 Ghz To Whitesands Ground Teminal, etc

Amit PatelDec 15, 2008Communications LG204 Communications System For Earth-Moon link communication 2 X 12m mesh tracking antenna Solar Arrays sized at for 4m by 14m for 30kW solar power Output power on HPA (High Power Amplifier) X W total ie., 250W on each HPA Power receiver from microwaves For Moon to lunar orbit communication link 2m tracking mesh antenna - 10W Omni - X 3 For lunar surface local communication Omnis Laser communication links to observatories - 12in aperture X 3 - high bandwidth

Amit PatelDec 15, 2008Communications Command Module Link Laser Link 2 to observatory Laser Link 1 to observatory Omni High Gain Mesh Antenna To Earth LG204 Communications System Gimbaled Solar Arrays

Amit PatelDec 15, 2008Communications Lunar Environment Considerations Absence of significant atmosphere On Earth, have to deal with Absorption, Turbulence and Link Availability Path absorption losses minimal Spreading Loss dominant loss mechanism No Beam Wander, Scintillation, etc. No Weather (Clouds, Rain, Fog)

Amit PatelDec 15, 2008Communications Link Budget Block Diagram Moon-to-Earth Optical Data Link

Amit PatelDec 15, 2008Communications 2m Antenna on Lunar Surface Antenna Diameter = 2m Frequency = 70 Ghz Lambda = m Loss free space = dB Gain (dBi) = 40.1 dB Received signal power (C) = Available (C/No) = Power = 10 Watts Required (Eb/No) (bit energy/Noise power density) = 8 Max Bit rate supported = Gbps

Amit PatelDec 15, 2008Communications Experimental Technology Inflatable Antenna Combines traditional fixed parabolic dish with an inflatable reflector annulus Redundant system prevents “all-or-nothing” scenarios Based on novel shape memory composite structure High packing efficiency Low cost fabrication and inflation of an annulus antenna Overall surface accuracy 1 mm Negligible gravity effects Elimination of large curve distortions across the reflector surface (i.e. Hencky curve) 2

Amit PatelDec 15, 2008Communications General Horizon Formula The general horizon distance formula is X = (h^2 + 2hR)^1/2, where X is the distance to the horizon R is lunar radius = km h is height of the observer/transmitter above ground Distance from Malapart to Shackleton = 150km Distance from Shackleton to Schrodinger = 300km Peak to Peak (8km) = 334km Peak to Ground = 164km Horizon Distances For The Moon Observer height h, mHorizon distance X, km

Amit PatelDec 15, 2008Communications Line-of-Sight To Earth Mons Malapert Shackleton Schrodinger 110km 300km 120km 150km

Amit PatelDec 15, 2008Communications Data Rates Forward Link Requirements Data Type (Reliable Channel) Data RatesElement Speech 10 kbpsAstronaut Digital Channel 200 bps Astronaut Digital Channel 2 kbps Transport / Rover / Base Data Type (High Rate Channel) Data Rates Element Command Loads 100 kbps Transport / Rover / Base CD-quality Audio 128 kbps Astronaut Video (TV, Videoconference) 1.5 Mbps Astronaut Return Link Requirements Data Type (Reliable Channel) Data Rates Element Speech 10 kbps Astronaut Engineering Data 2 kbps Astronaut Engineering Data 20 kbps Transport / Rover / Base Video 100 kbps Helmet Camera Video 1.5 Mbps Rover Data Type (High Rate Channel) Data Rates Element High Definition TV 20 Mbps Astronaut Biomedics35 Mbps Astronaut Hyperspectral Imaging 150 Mbps Science Payload Synthetic Aperture Radar 100 Mbps Science Payload

Amit PatelDec 15, 2008Communications Aggregated Data Rates Aggregated Return Link Requirements (Reliable Channel) User Channel Content # of Channels Channel Data Rate Total Data Rate Base Speech 4 10 kbps 40 kbps Base Engineering1 100 kbps100 kbps Astronaut Speech 4 10 kbps 40 kbps Astronaut Helmet Camera kbps 80 kbps Astronaut Engineering 4 20 kbps 80 kbps Transports Video Mbps 6 Mbps Transports Engineering 4 20 kbps 80 kbps Rovers Video Mbps 36 Mbps Rovers Engineering kbps 480 kbps Aggregate 43 Mbps (High Rate Channel) UserChannel Content # of Channels Channel Data Rate Total Data Rate Base HDTV 1 20 Mbps 20 Mbps AstronautBiomedics435 Mbps140 Mbps Transports HDTV 1 20 Mbps 20 Mbps Transports Hyperspectral Imaging Mbps 150 Mbps Rovers Radar Mbps 100 Mbps Rovers Hyperspectral Imaging Mbps 150 Mbps ObservatoriesHyperspectral Imaging3150 Mbps450 Mbps Aggregate 1030 Mbps

Amit PatelDec 15, 2008Communications Block Diagram of System 5

Amit PatelDec 15, 2008Communications Block Diagram of Antenna 5

Amit PatelDec 15, 2008Communications Communication signal flow between spacecraft and Earth for free-space optical communication links. 3

Amit PatelDec 15, 2008Communications Problems Dust Electrostatically attaches to surfaces Atomically sharp, abrasive Wide range of particle distribution size Lunar Line-of-Sight Very rough terrain Other Radiation and Solar Flares, Temperature Swings Micrometeorites (and not so “micro”) Antenna Pointing Accuracy Optical Libration – Needs to be accounted for.

Amit PatelDec 15, 2008Communications Further Studies Laser communications Large towers Inflatable Antennas

Amit PatelDec 15, 2008Communications Future 1km Tower To Shackleton and Schrodinger

Amit PatelDec 15, 2008Communications Conclusion Reliable and Sturdy communication system is critical for lunar operations High data rate transfer is vital for the successful buildup of a lunar base. Greater bandwidth and data rate transfers creates many possibilities for the future People will be watching lunar activities in the highest quality video, which will lead to much greater interest in space

Amit PatelDec 15, 2008Communications References 1. RF and Optical Communications: A Comparison of High Data Rate Returns From Deep Space in the 2020 Timeframe, W. Dan Williams, Michael Collins, Don M. Boroson, James Lesh, Abihijit Biswas, Richard Orr, Leonard Schuchman and O. Scott Sands An Overview of Antenna R&D Efforts in Support of NASA’s Space Exploration Vision, Robert M. Manning ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/ _ pdf ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/ _ pdf 3. Development of an End-to-End Model for Free-Space Optical Communications, H. Hemmati tmo.jpl.nasa.gov/progress_report/42-161/161H.pdf 4. A Vision for theNext GenerationDeep Space Network, Bob Preston, JPLLes Deutsch, Barry Geldzahler 5. NASA Ground Network Support of the Lunar Reconnaissance Orbiter, Steohen F. Currier, Roger N. Clason, Marco M. Midon, Bruce R. Schupler and Michael L. Anderson. sunset.usc.edu/GSAW/gsaw2007/s6/schupler.pdf 6. Using Satellites for Worldwide Tele-health and Education – The Gates Proposal. P.Edin, P. Gibson, A. Donati, A. Baker Architectural Prospects for Lunar Mission Support. Robert J. Cesarone, Douglas S. Abraham, Leslie J. Deutsch, Gary K. Noreen and Jason A. Soloff Communications Requirements for the First Lunar Outpost, Timothy Hanson' and Richard Markley. ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=465752

Amit PatelDec 15, 2008Communications BACKUP

Amit PatelDec 15, 2008Communications 12m Antenna Link from Moon to Earth Antenna Diameter = 12m Power = 30kW power array = 240W front end Frequency = 3 Ghz Lambda = 0.01m Loss free space = dB Gain (dBi) = 30.7 dB Received signal power = Available (C/No) = Required (Eb/No) (bit energy/No) = 8 Max Bit rate supported = Gbps

Amit PatelDec 15, 2008Communications Moon - to - Earth Distances and Associated Propagation Losses Minimum: 364,800 km (Propagation Loss = dB) Nominal: 384,00 km (Propagation Loss = dB) Maximum: 403,200 (Propagation Loss = dB)

Amit PatelDec 15, 2008Communications Transmitter Power, nm 0 dBW Transmitter Antenna Gain, 1 m Dia dBi Transmitter Optical Losses dB Space Propagation Losses dB Losses in Vacuum 0 dB Spatial Pointing Losses dB Receiver Antenna Gain, 1 m Dia dBi Receiver Optical Losses dB Spatial Tracking Splitter Losses dB Receiver Sensitivity 84.0 dBW Link Margin 17.9 dB Assume: 100 Mbps, 10-6 BER Link Budget Calculation

Amit PatelDec 15, 2008Communications Solar Power Requirements

Amit PatelDec 15, 2008Communications Mars -.38AU = 56,847,240 km 1

Amit PatelDec 15, 2008Communications Schematic of S-band and Ka-Band Antenna 5

Amit PatelDec 15, 2008Communications Formula’s Used Lambda = speed of light / frequency Loss free space = 20*LOG10(4*PI*Distance_m/lambda) Gain (dBi) = 0.7*20*LOG10(PI*Antenna_Dia_m/lambda) Received signal power (C) = Pt*Gt*Lfs*Gr Available (C/No) = C-Noise Density Noise Density = K*T Required (Eb/No) (bit energy/Noise power density) = 8 Max Bit rate supported = 10^(0.1*(C- (Eb/No))) /10^6