AAE450 Senior Spacecraft Design Dorrie Byford Dorrie Byford Week 7: March 1 st, 2007 Communications Group Leader / Autonomous Rendezvous / Integration Team / Website Designer Dish Diameter, Power, Mass, and Volume for all Vehicles and Satellites

AAE450 Senior Spacecraft Design Dorrie Byford Highlights of Analysis Transfer Vehicle –1 x 4.75 m dish, 1 x 1.5 m dish –14.25 kW 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

AAE450 Senior Spacecraft Design Dorrie Byford IMLEO / IVLEO Comm Satellites –2.74 mt – 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

AAE450 Senior Spacecraft Design Dorrie Byford Back-up Slides

AAE450 Senior Spacecraft Design Dorrie Byford 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.

AAE450 Senior Spacecraft Design Dorrie Byford Comm Spreadsheet Dorrie Byford *Could not get TC traj dimensions from Chris Bush in time.

AAE450 Senior Spacecraft Design Dorrie Byford 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).

AAE450 Senior Spacecraft Design Dorrie Byford 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.

AAE450 Senior Spacecraft Design Dorrie Byford Info on Comm Data Sheet (cont) 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).

AAE450 Senior Spacecraft Design Dorrie Byford Info on Comm Data Sheet (cont) 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.

AAE450 Senior Spacecraft Design Dorrie Byford Info on Comm Data Sheet (cont) 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.

AAE450 Senior Spacecraft Design Dorrie Byford Info on Comm Data Sheet (cont) 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).

AAE450 Senior Spacecraft Design Dorrie Byford Transfer Vehicle Earth to 75% of Total Distance 75% Distance to Mars

AAE450 Senior Spacecraft Design Dorrie Byford TV Back-up & Other Traveling Vehicles

AAE450 Senior Spacecraft Design Dorrie Byford Satellite Info This table was used to create the estimates for the satellite’s masses and volumes. (see following graphs)

AAE450 Senior Spacecraft Design Dorrie Byford Graph to Estimate Sat Mass

AAE450 Senior Spacecraft Design Dorrie Byford Graph to Estimate Sat Volume

AAE450 Senior Spacecraft Design Dorrie Byford References comm.html