4.2.1 Ground  SegmentCommunications Architecture

  Even  as larger and more ambitions space projects for space exploration are planned,  one essential requirement for the success of every space mission remains.  Clear and constant communications can and often do mean the difference  between life and death.  Without a good communications system, many multi-billion  dollar missions would never get off the ground.  Communications help the scientists and ground control crew on Earth to  receive and process data and to control and upload commands to the various  satellites, probes and astronauts during the course of their missions.  But as with all essentials, there are certain drawbacks or problems that  come with using current technology.  The main problem with current communications over large distances is the fact that  there is always a time lag involved.  For our mission to Mars, there would be an approximately 20-30 minute time lag.  There is no current method of reducing this time, however there is a  method to circumvent the problem, through the use of simultaneous transmissions  and other such methods.  Another major problem is the line of sight problem.  Most transmitters and receivers work on the line of sight and need to be  in direct view of the other in order to work.  To get around this problem, our mission will deploy a  satellite into a polar orbit, which will then always have a line of sight with  the existing TDRSS or deep space satellite networks around the Earth.  As the Mars-Sat will not be in constant line of sight of the Mars Base,  the use of burst transmission will deal with constant communication problem.

Purposes of the Ground Control  Communications

-To monitor and archive all incoming data and  information during the course of the mission and set aside for future study.

-To aid the crew throughout their mission by  ensuring that they are always apprised of any problems noticed during their  mission and notified of possible solutions. An example of the usefulness of this was the Apollo 13 mission.

-For the crew of the MMVS to have contact with  Earth during their mission, so that the can communicate problems that they  encounter.

-For the crew to communicate with other people  and their loved ones, for psychological reasons.

-To upload newer data and software for the MMVS  crew to use.

-To enact safety and/or abort protocols in the  event that the mission fails and the crew is incapable of helping themselves.

-To transmit new missions and expand on older  missions, for more detailed investigations of the surface of Mars.

Ground Segment Architecture

TDRSS/Deep  Space Satellite Network: To receive/transmit data from the MMVS and the Ground  Antennas, and maintain line of sight communication with the MMVS crew.

Antenna System: To transmit and receive data  from the TDRSS and Mission Control. The antenna tracking system will also be used to act as a feedback to control the  position of the antennae.  The antenna system also has many other functions.

Communications Signal Processing: To encode and decode the data being  transferred and to convert it into the appropriate format for transfer to and  from the MMVS and the Ground Control Segment.

Data  Recovery Equipment: The process of conditioning the demodulated data before  transmitting the information and insuring that no vital information is lost.

Data Flow Control and Routing Interface: Handling data requests and data  path orders to Ground Control.

Preamplifiers: Amplify the  weak signals received from the spacecraft and send them to the transceiver.

Mission Control Center: To analyze data and maintain control over every aspect  of the MMVS mission while maintaining  constant communication with the crew.  The Mission Control Center has many different aspects:

Telemetry, Tracking and Control: To receive data and use it to study the  mission objectives and the current mission profile and direct it to greater  success. To verify and send  commands and solutions to problems to the crew of the MMVS.

Data Simulation and Processing Center: To process and compile all  incoming data and ascertain what new commands need to be sent.

Archiving Center: To store data and reference data against previous  missions, so NASA scientists can study and use data in research.