IEEE Waves and Devices Phoenix Chapter: Space Communications

IEEE Waves and DevicesPhoenix Chapter:

Space Communications

Bob Anderson24 June 2010

2

Introduction

� Why communicate?� Must control the spacecraft/experiment

� In human spaceflight, lives depend on it

� Must track the craft� Ranging (distance/position)� Relative speed (Doppler effect)

� Collect science data� Usually the purpose of the mission in the first

place

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Communications

TRANSMITTER RECEIVER

TRANSMITTERRECEIVER

COMMUNICATIONSDID THE RECEIVER RECEIVE THE SIGNAL?DID THE RECEIVER PROCESS THE SIGNAL CORRECTLY?DID I RECEIVE THE CORRECT TELEMETRY/DATA BACK?

4

Radio

AUDIO RF CARRIER AM MODULATED(TIME DOMAIN)

AM MODULATED(FREQUENCY DOMAIN)

Po

f

PULSE CODEAUDIO PCM(TIME DOMAIN)

PCM(FREQUENCY DOMAIN)

Po

f

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TT&C

� Telemetry Tracking and Command (TT&C)� Monitor received telemetry

� Health and mode analysis

� Perform tracking� Distance and position measurements� Doppler measurements – spacecraft velocity

� Send commands� Command the spacecraft for attitude, position, and

miscellaneous functions

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Transponder


TRANSMITTERRECEIVER

BENT PIPETRANSPONDER TRANSMITS EXACTLY WHAT IT RECEIVES

GROUND STATION TRANSPONDER

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Transponder


TRANSMITTERRECEIVER

TWO WAYTRANSPONDER RECEIVES COMMANDSTRANSMITS SCIENCE DATA AND TELEMETRY

GROUND STATION TRANSPONDER

8

U.S. Space Program Timeline

NRL V2, SPUTNIK, EXPLORER, PIONEER, MERCURY

RANGER, GEMINISpace Programs(USA) APOLLO, LUNAR ORBITER, MARINER, SURVEYOR

SKY LAB, PIONEER 10, MARINER 10, HELIOSVIKING, VOYAGER I, II, PIONEER VENUS,INTERNATIONAL SUN-EARTH, SOLAR MAXIMUM

1956-1962 1963-1965 1966-1967 1968-1969 1970-1975 1976-1980TDRSS I, SPACE SHUTTLE

GD (Motorola) contributions

VOYAGER, NASA STDN

S-BAND SPECIAL TEST EQUIPMENT, MARINER MARS

APOLLO TRANSPONDERS, LUNAR ORBITER

RANGER AND MARINER TRANSPONDERS, APOLLO STUDY

JPL X-BAND, RANGER AND MARINER TRANSPONDERS

Vanguard

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U.S. Space Program Timeline

MAGELLAN, GALILEO, HUBBLE SPACE TELESCOPE, ULYSSES

Space Programs MARS OBSERVER, CLEMENTINE, SOHO(USA)

SPACE STATION, NEAR, MARS GLOBAL SURVEYOR, MARS PATHFINDER, CASSINI/HUYGENSLUNAR PROSPECTOR, DEEP SPACE I, STARDUST, MARS POLAR LANDER

IMAGE, MARS ODYSSEY, GENESIS, CONTOUR, MARS EXPRESSMRO, JUNO, LRO, STEREO, DAWN (NEW HORIZONS), MARS LANDER

1981-1985 1986-1990 1991-1995 1996-2000 2001-2005 2006-2010MRO, JUNO, LRO, STEREO, DAWN (NEW HORIZONS), MARS LANDER

GD (Motorola) contributions

SDST, CASSINI, MARS ODYSSEY, STARDUST,SPITZER SPACE TELESCOPE, MARS ROVERS, DEEP IMPACT, MERCURY MESSINGER, MARS EXPRESS

DST, TDRSS IV, SPACE STATION, NEAR, MARS GLOBAL SURVEYOR, MARS PATHFINDER, CASSINI/HUYGENS,DEEP SPACE I, STARDUST, MARS POLAR LANDER, MARS ODYSSEY

IRIDIUM, MARS OBSERVER, SOHO

JPL DSN 3, MAGELLAN, GALILEO, HUBBLE SPACE TELESCOPE

JPL DSN, TDRSS II, III

10

)()()/()/()()()()( dBLdBLHzdBWkTsbitdBRdBN

EdBiGdBWEIRPdBM os

reqdo

br −−−−−

−+=

Link Budget

EIRP = Effective Isotropic Radiated Power, or Trans mitted Power in dB-Watts

Gr = Antenna Gain, dBi – referenced to isotropic

Eb/No = Average energy per bit per unit of noise, r equired, dB

R = Data rate, referenced to 1 bit/sec – dB-bit/sec

kT = Boltzmann’s constant times temperature in Kelv ins – (dBW/Hz)

Ls = Path loss, dB – proportional to (4pd) 2

Lo = All other losses, dB (rain, solar effects, etc .)

Source: Sklar, B., Digital Communications, Prentice Hall, NJ, 1988

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Link Budget


12

Link Budget


13

Van Allen Radiation Belt

Discovered by Explorer I and II in

1958 under direction of Dr. James Van Allen.

A satellite shielded by 3 mm of aluminum in

an elliptic orbit (200 by 20,000 miles) passing through the radiation

belts will receive about 2,500 rem (25 Sv) per

year. Almost all radiation will be

received while passing the inner belt. 25 Sv =

25 J/kg.

The inner belt is 60 to 6,200 miles high

Source: NASA

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South Atlantic Anomaly

The South Atlantic Anomaly (SAA) refers to the area where the Earth's inner Van Allen radiation belt comes closest to the Earth’s surface. This leads to an increased flux of energetic particles in this region and exposes orbiting satellites to higher than usual levels of radiation. The effect is caused by the non-concentricity of the Earth and its magnetic dipole, and the SAA is the near-Earth region where the Earth’s magnetic field is weakest.

Source: NASASAA

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Space Debris Problem

Source: National Geographic

July 2010

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July 2010

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July 2010

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Earth Satellite Communications

� Geo-synchronous/stationary� Weather� Broadcast� TDRSS

� Earth orbital� IRIDIUM� Scientific Study

� Space Station

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Weather

GOES-8 Satellite and Weather Map (22,236 mi. High O rbit)Source: NASA

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TDRSS

Tracking and Data Satellite System (TDRSS)Source: NASA/GD (Motorola)

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TDRSS

Tracking and Data Satellite System (TDRSS)Source: NASA

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Iridium

Iridium Satellite (485 mi. High Orbit)Source: Iridium/GD (Motorola)

23

Space Station

Space Station (181 – 189 mi. high Orbit)Source: NASA/GD (Motorola)

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Space Station

Space StationSource: NASA

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Space Station

Space StationSource: NASA/JSC

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Manned Missions Communications

� Mercury

� Gemini� Apollo

� Space Shuttle� Space Station

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Manned Missions

� GD (Motorola) supported various phases of Apollo program� Unified s-band transponder� Command module unified amplifier

� Functional communications link that carried astronauts’ pictures and voice from the Moon’s surface back to Earth

28

Apollo

Apollo Command Module Unified S-Band Transponder (manufactured by Motorola, Inc., Military Electronics Division, Scottsdale, Ariz.). The Unified S-Band Transponder was the only method of exchanging voice communications, tracking, biomedical, and ranging, transmission of pulse code modulated (PCM) data and television, and reception of uplinked data from Mission Control once the Apollo Command Module was outside a range of 1500 nautical miles and line of sight from Manned Space Flight Network (MSFN) ground stations strung around the Earth (within that range, VHF was available). The term "Unified" is applicable because the communications system combined the functions of (signal) acquisition, telemetry, command, voice, television and tracking on one radio link. The Unified S-Band Equipment (USBE) onboard the Apollo Command Module, Lunar Module, Lunar Rover were absolutely critical to the successful execution of the Apollo program; and reliability was assured through the implementation of full redundant, heavily tested design.

Source: SpaceAholic.com

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Apollo


APOLLO COMMAND MODULE UNIFIED S-BAND TRANSPONDER

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Apollo


The location of artifacts discussed in this when installed in their native environment (within the Block II Apollo Command Module). This profile depicts the Lower Equipment bay where the majority of the spacecraft telecommunications subsystem electronics were housed). For reference the Astronauts feet (when laying in the crew couch) are oriented towards the Equipment bay).

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Apollo


Motorola Corporation News Bureau release photograph of Apollo Command Module Unified S-Band Equipment (USBE) Transponder - the release reads: "The two-way radio on the Apollo Command Module requires less power to communicate with Earth from the vicinity of the Moon then the power used by the light bulbs in your refrigerator. The small unit, produced by Motorola Government Electronics Division, is the only communications link with the Apollo Command Module crew has with Earth from beyond 30,000 miles away providing all voice contact, TV pictures and mission data. Lovely Motorola technician Mandy Biondi shows the sophisticated unit which has functioned perfectly on every mission." (Image courtesy Motorola/GDAIS).

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Space Probe Communications

� Early missions� Sputnik� Explorer� Ranger� Mariner� Pioneer� Surveyor� Voyager I, II� Magellan� Galileo

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Sputnik

Source: University of Colorado Students for the Exploration and Development of Space

Launched October 4, 1957;

operated for 3 months

34

Vanguard I

Source: NASA

Launched March 17, 1958;

operated for 6 years ~ 2,200 days

(first solar-powered satellite)

35

Voyager

Voyager I,IISource: NASA/JPL

36

Voyager

Voyager I,IISource: NASA/JPL

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Galileo

GalileoSource: NASA/JPL

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Magellan

Venus Radar Mapper (Magellan)Source: NASA/JPL

39

Space Probe Communications

� Cassini

� Mars� Lunar

� Other probes

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SDST

Small Deep Space Transponder (SDST)Source: GD (Motorola)

41

Cassini

CassiniSource: NASA/JPL

42

Cassini

43

Cassini

44

Cassini

45

Mars

Source: NASA/JPL

46

Mars

Source: NASA/JPL

47

Mars

Source: NASA/JPL

48

Mars

Source: NASA/JPL

49

Mars

� Panoramic Camera (Pancam): for determining the mineralogy, texture, and structure of the local terrain

� Miniature Thermal Emission Spectrometer (Mini-TES): for identifying promising rocks and soils for closer examination and for determining the processes that formed Martian rocks. The instrument is designed to look skyward to provide temperature profiles of the Martian atmosphere.

� Mössbauer Spectrometer (MB): for close-up investigations of the mineralogy of iron-bearing rocks and soils.

Source: NASA/JPL

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Mars

� Alpha Particle X-Ray Spectrometer (APXS): for close-up analysis of the abundances of elements that make up rocks and soils.

� Magnets: for collecting magnetic dust particles. The Mössbauer Spectrometer and the Alpha Particle X-ray Spectrometer are designed to analyze the particles collected and help determine the ratio of magnetic particles to non-magnetic particles. They can also analyze the composition of magnetic minerals in airborne dust and rocks that have been ground by the Rock Abrasion Tool.

� Microscopic Imager (MI): for obtaining close-up, high-resolution images of rocks and soils.

� Rock Abrasion Tool (RAT): for removing dusty and weathered rock surfaces and exposing fresh material for examination by instruments onboard.

Source: NASA/JPL

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Future of Space Communications

� Laser technology� Currently used in some communications � Advantages include extremely fast speed� Disadvantages include attenuation

� New and improved modulation techniques� Improved efficiency� Less power� Sub-space communications?

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Conclusion

� Why Do We Explore?

� From the time of our birth, humans have felt a primordial urge to explore -- to blaze new trails, map new lands, and answer profound questions about ourselves and our universe.

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Bob Anderson

[email protected]

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Q&A

Documents

IEEE Waves and Devices Phoenix Chapter: Space Communications