aae450 senior spacecraft design dorrie byford dorrie byford week 7: march 1 st, 2007 communications...

AAE450 Senior Spacecraft Design

Dorrie Byford

Dorrie ByfordWeek 7: March 1st, 2007

Communications Group Leader / Autonomous Rendezvous / Integration Team / Website Designer

Dish Diameter, Power, Mass, and Volume for all Vehicles and Satellites


Dorrie Byford

Highlights of Analysis• Transfer Vehicle

– 1 x 4.75 m dish, 1 x 1.5 m dish– 14.25 kW + 1.25 kW = 15.5 kW– .25 mt + .15 mt = .4 mt

• Earth Taxi / Mars Taxi– 1 m dish x2– 1 kW x2– .15 mt x2

• All Other Space Traveling Vehicles– 1.5 m dish x2– 1.25 kW x2– .15 mt x2

VehicleMax Xmit

Time to MarsMax Xmit

Time to Earth(min) (min)

Transfer Vehicle 40 2838 22


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IMLEO / IVLEO

• Comm Satellites– 2.74 mt– 123.49 m^3 (stowed)

• GPS Satellites– 1.74 mt– 55.32 m^3 (stowed)

• Sat totals:– Power: 44 kW– Mass: 18 mt– Volume: 730 m^3

CAD by: Steve Kassab


Dorrie Byford

Back-up Slides


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Link Budget Analysis

• A budget analysis was performed for every vehicle to ensure complete coverage during the entire mission. Power and dish size were optimized by increasing transmission time. A table of maximum transmission times can be found on the next slide. Link budget analysis for each vehicle follows.


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Comm SpreadsheetDorrie Byford

*Could not get TC traj dimensions

from Chris Bush in time.


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Info on Comm Data Sheet

• Video– Traveling Vehicles

• Transfer Vehicle– Since the crew will be in the Transfer Vehicle the most, I

allotted one video feed per crew member plus one in the common area. This high HD video requirement is what drove up the power estimates and dish size.

• Taxi Capsule– The crew spends very little time in this vehicle, and it is

very small, so only one video feed was allotted. Also, because of the vehicle’s constant proximity to a planet, the power requirements and dish size remain low (not much distance to transmit over).


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Info on Comm Data Sheet (cont)

• Video– Mars Vehicles / Structures

• All vehicles and structures on Mars require very little power. This is because the satellites in Mars-stationary orbit are only 20,462 km away.

• These structures and vehicles also will not require a satellite dish. Instead they will have a transmission antenna similar to that on an aircraft.


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• Diameter– Traveling Vehicles

• Vehicles Requiring Video– The Transfer Vehicle and Taxi Capsule require video to meet

mission requirements. The diameters of the TV dish is the largest because it has the most data to transmit over the farthest distance. The TC dish is still small in size because of its proximity to the planet.

– The TV also has a smaller antenna for voice/data/telemetry/commanding. This serves as an emergency communication system. The TV will always be able to transmit directly back to Earth using this dish (does not need to be bounced off of any satellites unless there is no line of sight).


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• Diameter– Traveling Vehicles

• Vehicles Not Requiring Video– These vehicles are equipped with a dish to allow for

data/telemetry/commanding. There will be two identical dishes on each vehicle; one as prime and one as back-up. The second will require little power (only thermal) since it will not nominally be in operation.


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• Power– All power requirements were derived using the Link

Budget Analysis found in future slides.• Mass/Volume

– Mass and volume, where applicable, were estimated by finding a trend in historical data (see future slides). A value of “<<“ means that the value is so small (< .01 mt for mass) that the number is negligible. For volumes with a “<<“, the dish will be stored inside the vehicle, thus not adding to the IVLEO.


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• Percentage– Transfer Vehicle

• For the TV, the percentage indicates at what point the vehicle changes from transmitting to Earth to transmitting to the Gangale sats. When the TV departs Earth, for the first 75% (distance) of the trip, all communication is sent back to Earth and then forward to Mars and other vehicles, if necessary. At the 75% point, all comm is sent through the Gangale sats and then bounced back to Earth. This is necessary to reduce the size and power requirement of the dish on the vehicle.

– Other Vehicles and TV Back-up Comm System• The other vehicles and the TV’s back-up comm system with values

of 100/38 can communicate directly to Earth 100% of the trip, but can communicate directly to the Gangale sats only during the last 38% of the trip.

– These percentages are what drive the max transmit time for each vehicle (seen in previous slide).


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Transfer VehicleConstantsk -228.6 dBW/KHzSystem Noise Temp 150 KEta 0.55SNR_req 9.6 dBLother 3 dB

InputMargin 3 dBTransmitter Power 14250 WFrequency 8 GHzData Rate 2632090 bpsPropogation Path Length 293400000 kmTransmitter Diameter 20.000 m

Intermediate StepsSNR_avail 12.6 dBTransmitter Gain 61.886 dBG/T 27.640 dBLfs 279.861 dB

OutputReceiver Diameter 4.751 mReceiver Gain 49.401 dB

Constantsk -228.6 dBW/KHzSystem Noise Temp 150 KEta 0.55SNR_req 9.6 dBLother 3 dB




Earth to 75% of Total Distance 75% Distance to Mars


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TV Back-up & Other Traveling Vehicles

Constantsk -228.6 dBW/KHzSystem Noise Temp 150 KEta 0.55SNR_req 9.6 dBLother 3 dB





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Satellite Info

Satellite Dish size Mass (In Orbit) Volume (Stowed)Apstar 1 2.2 0.726 46.6Bonum-1 2.54 1.747 11.78Anik-F1 2.4 3.015 28.56Anik-F2 2.16 3.805 94.32Galaxy III-C 2.85 2.873 77.09Galaxy XI 2.4 2.775 77.748NSS-8 2.4 3.8 326.92PAS 1-R 2.4 3.059 80.1Spaceway 1 2 3.832 55.49XM-1 5 2.95 69.3AsiaSat 4 2.72 2.275 69.02Astra IH 2.7 2.48 59.9Astra 2A 2.72 2.47 59.9Astra 2C 2.72 2.494 59.9DirecTV 1R 2.72 2.304 38.88Galaxy IV 2.4 1.709 29.16Galaxy VII 2.4 3.71 29.16Galaxy VIII 2.72 4.326 29.16Galaxy X 2.72 4.663 57.35Horizons 1 2.72 2.63 57.35JCSAT 8 2.2 1.6 41.8MSAT 6.8 1.716 324.19Palapa-C 2.16 1.775 191.36TDRS H 4.88 1.781 305.06Anik C 2.16 0.563 41.33Astra 2D 2.17 1.816 46.6Brasilsat B 3.65 1.052 143.56BSAT-1 2.17 0.723 46.6ChinaSat7 2.2 0.734 47.14eBird 2.16 0.888 46.32Galaxy 376 1.8 0.709 42.57MEASAT 2.16 0.886 48.37Morelos 2.16 0.647 41.77Palapa-B 2.16 0.692 41.63SBS 2.16 0.54 41.33Sirius 3 2.16 0.815 48.66Telestar 3 2.16 0.653 40.16Thaicom 2.16 0.723 41.04Thor II 2.16 0.647 48.66Westar IV 2.16 0.582 40.16Thuraya 16 3.2 106.88Thuraya II 16 3.2 82.69

• This table was used to create the estimates for the satellite’s masses and volumes. (see following graphs)


Dorrie Byford

Graph to Estimate Sat MassMass vs Dish Size

y = 0.7963Ln(x) + 1.1864

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 2 4 6 8 10 12 14 16 18

Dish Size (m)

Mass

(mt)


Dorrie Byford

Graph to Estimate Sat VolumeStowed Volume vs Dish Size

y = 58.416Ln(x) + 17.604

0

50

100

150

200

250

300

350

0 2 4 6 8 10 12 14 16 18

Dish Size (m)

Stow

ed V

olum

e (m

^3)


Dorrie Byford

References• http://www.boeing.com/defense-space/space/bss/programs.html• http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts-jsc-

comm.html

aae450 senior spacecraft design dorrie byford dorrie byford week 7: march 1 st, 2007 communications...

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