IEEE Waves and Devices Phoenix Chapter: Space Communications
Bob Anderson 24 June 2010 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
2 Communications
TRANSMITTER RECEIVER
RECEIVER TRANSMITTER
COMMUNICATIONS DID THE RECEIVER RECEIVE THE SIGNAL? DID THE RECEIVER PROCESS THE SIGNAL CORRECTLY? DID I RECEIVE THE CORRECT TELEMETRY/DATA BACK?
3 Radio
Po
f AUDIO RF CARRIER AM MODULATED AM MODULATED (TIME DOMAIN) (FREQUENCY DOMAIN)
Po
f AUDIO PULSE CODE PCM PCM (TIME DOMAIN) (FREQUENCY DOMAIN)
4 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
5 Transponder
GROUND STATION TRANSPONDER
TRANSMITTER RECEIVER
RECEIVER TRANSMITTER
BENT PIPE TRANSPONDER TRANSMITS EXACTLY WHAT IT RECEIVES
6 Transponder
GROUND STATION TRANSPONDER
TRANSMITTER RECEIVER
RECEIVER TRANSMITTER
TWO WAY TRANSPONDER RECEIVES COMMANDS TRANSMITS SCIENCE DATA AND TELEMETRY
7 U.S. Space Program Timeline
NRL V2, SPUTNIK, EXPLORER, PIONEER, MERCURY Vanguard RANGER, GEMINI Space Programs (USA) APOLLO, LUNAR ORBITER, MARINER, SURVEYOR SKY LAB, PIONEER 10, MARINER 10, HELIOS VIKING, VOYAGER I, II, PIONEER VENUS, INTERNATIONAL SUN-EARTH, SOLAR MAXIMUM 1956-1962 1963-1965 1966-1967 1968-1969 1970-1975 1976-1980
TDRSS 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
8 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/HUYGENS LUNAR PROSPECTOR, DEEP SPACE I, STARDUST, MARS POLAR LANDER IMAGE, MARS ODYSSEY, GENESIS, CONTOUR, MARS EXPRESS MRO, JUNO, LRO, STEREO, DAWN (NEW HORIZONS), MARS LANDER 1981-1985 1986-1990 1991-1995 1996-2000 2001-2005 2006-2010
MRO, 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
9 Link Budget
E = + − b − − − − − M (dB ) EIRP (dBW ) Gr (dBi ) (dB ) R(dB bit / s) kT (dBW / Hz ) Ls (dB ) Lo (dB ) N o reqd
EIRP = Effective Isotropic Radiated Power, or Transmitted Power in dB-Watts Gr = Antenna Gain, dBi – referenced to isotropic Eb/No = Average energy per bit per unit of noise, required, dB R = Data rate, referenced to 1 bit/sec – dB-bit/sec kT = Boltzmann’s constant times temperature in Kelvins – (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
10 Link Budget
Source: Sklar, B., Digital Communications, Prentice Hall, NJ, 1988
11 Link Budget
Source: Sklar, B., Digital Communications, Prentice Hall, NJ, 1988
12 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
13 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.
SAA Source: NASA
14 Space Debris Problem
Source: National Geographic July 2010
15 Space Debris Problem
Source: National Geographic July 2010
16 Space Debris Problem
Source: National Geographic July 2010
17 Earth Satellite Communications
Geo-synchronous/stationary Weather Broadcast TDRSS Earth orbital IRIDIUM Scientific Study Space Station
18 Weather
GOES-8 Satellite and Weather Map (22,236 mi. High Orbit)
Source: NASA
19 TDRSS
Tracking and Data Satellite System (TDRSS)
Source: NASA/GD (Motorola)
20 TDRSS
Tracking and Data Satellite System (TDRSS)
Source: NASA
21 Iridium
Iridium Satellite (485 mi. High Orbit)
Source: Iridium/GD (Motorola)
22 Space Station
Space Station (181 – 189 mi. high Orbit)
Source: NASA/GD (Motorola)
23 Space Station
Space Station
Source: NASA
24 Space Station
Space Station
Source: NASA/JSC
25 Manned Missions Communications
Mercury Gemini Apollo Space Shuttle Space Station
26 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
27 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
28 Apollo
APOLLO COMMAND MODULE UNIFIED S-BAND TRANSPONDER
Source: SpaceAholic.com
29 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).
Source: SpaceAholic.com
30 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).
Source: SpaceAholic.com
31 Space Probe Communications
Early missions Sputnik Explorer Ranger Mariner Pioneer Surveyor Voyager I, II Magellan Galileo
32 Sputnik
Launched October 4, 1957; operated for 3 months
Source: University of Colorado Students for the Exploration and Development of Space
33 Vanguard I
Launched March 17, 1958; operated for 6 years ~ 2,200 days (first solar-powered satellite)
Source: NASA
34 Voyager
Voyager I,II
Source: NASA/JPL
35 Voyager
Voyager I,II
Source: NASA/JPL
36 Galileo
Galileo
Source: NASA/JPL
37 Magellan
Venus Radar Mapper (Magellan)
Source: NASA/JPL
38 Space Probe Communications
Cassini Mars Lunar Other probes
39 SDST
Small Deep Space Transponder (SDST)
Source: GD (Motorola)
40 Cassini
Cassini
Source: NASA/JPL
41 Cassini
42 Cassini
43 Cassini
44 Mars
Source: NASA/JPL
45 Mars
Source: NASA/JPL
46 Mars
Source: NASA/JPL
47 Mars
Source: NASA/JPL
48 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
49 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
50 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?
51 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.
52 Bob Anderson [email protected]
53 Q&A
54