CAPCOM
CAPCOM or 'CAPsule COMmunications' refers to the astronaut or Mission Control staffer in charge of communications. CAPCOM is also the name of the audio link between Mission Control and the Habitat.
Alternative forms of communication include AUXCOM and sign language over the video feeds.
Contents
Implementation
The Habitat and Mission Control CAPCOMs communicate over a closed-circuit telephone system, which is the main audio link between the Habitat and MC supplemented by radio headsets as available. Buzzers are used to call a CAPCOM to the phone when their counterpart needs to contact them.
Radio transmissions for the complete communication system between EVA astronauts and the habitat. There is currently no way for Mission Control to communicate directly with the EVA astronauts.
During Daedalus the telephone system was under repair and redevelopment, so two networked computers using Windows NetMeeting were used in place of the telphones for all but one night of the mission.
Prior to 2004-05 radios were used exclusively for CAPCOM with no telephone system.
Location
In the Brahe, the CAPCOM phone is located on the Airlock side of the Interlock, while the Mission Control CAPCOM phone is located beside the CorelCam console.
In the new CAPCOM system developed in 2009-10 by Chris Hawthorne, Matt Farkas-Dyck, and Stefan De Young with help in construction from Nevin Hotson, each of the Airlock, Hotlab, Interlock, Longhouse, and Command and Control have a CAPCOM telephone located on a wall in that module. There is also a handset located in the Simulator Loft, and the system can communicate over the VPN to Mission Control at Lisgar in the Sim Office.
Closed-Circuit Telephone Systems
A telephone junction box usually has four wires, of which the Green and Red wires carry content. If the red and green wires of two telphones are wired in parallel with a power source, they will be able to communicate. This is the most basic CCTS setup, and was employed in the Brahe.
.--\/\/-.----.
| | |
_ | |
--- { } { }
| | |
._______|____|
Where {} represent telephone jacks.
With appropriate voltage, this system could be scaled to any number of telephones wired in parallel.
The simple addition of a single-pole single-throw switch in series with a telephone, would allow the Simulators to disable it from talking to the circuit, as such:
.--\/\/-.----.
| / /
_ | |
--- { } { }
| | |
._______|____|
Where the / are the switches.
The system deployed in the Hawking III employs all of the principles discussed above, but expands the system to employ two separate circuits. The first circuit is an inter-Hab circuit, and the second is a Hab-MC circuit. All phones on the same circuit will be able to talk to each other. The simulators will be able to disable each phone from either circuit individually, with the exception of the phone in the Simulator Loft and the connection to the VPN. However, to accomplish the equivalent effect, the simulators could disable all phones in the Habitat from the Hab-MC Circuit.
Each circuit has its own power supply and resistor to act as a load in case no phones are attached. The MC Phone is wired directly into the MC Circuit, whereas each Habitat phone is wired to a double-pole double-throw switch that will allow it to choose which circuit it will connect to.
HABITAT ~ MC
.--\/\/-- \-< ^ >-/ -.--\/\/--.
| | | |
_ | | _
--- { } { } ---
| | | |
| | | |
|___________< ^ >_____|________|
Where the {} are telephone jacks, \ / are single throw switches, and <^> are double throw switches.
In the actual system, there are five telephones that duplicate the example phone that is connected to the double throw switch. Only one is shown here for clarity.
The final design, which is being implemented for the 2009-10 Mission is a modified version of the above circuit that uses only one power supply.
.--\/\/---< ^ A
| |
| { } P (Phone)
| |
.--\/\/---< ^ B
| |
_ |
--- |
|_________<< C
Apologizing for the complete unclarity of the above circuit diagram, it attempts to show that the circuit is split into two parallel systems right after the power supply with the switches wired so that they will choose between one of the two systems as opposed to one of two circuits in the earlier version of the circuit.
If the bottom of the double pole double throw switch appears as below, then each prong will be wired to the appropriately labeled wire in the above diagram.
A< >C P< >P B< >C
Analogue to Digital
Mission Control was run from the Sim Office at Lisgar during Daedalus as opposed to being run from 440 Albert. In order to pass data to and from the simulation facilities at 440 Albert, the OCDSB provided a Virtual Private Network.
It was discovered that by connecting a Whetstone Bridge to the closed-circuit telephone system with a phantom telephone represented by a mini cable taking the place of the fourth resistor in the Bridge, a signal could be passed to the computer.
However, a solution to have the line-out from a computer to the telephone system was not discovered prior to Daedalus, and the CCTS system was not deployed for that Mission.
Buzzers
The Buzzer system envisioned to accompany the new telephone system had a buzz box in each room of the Habitat that contained a telephone. Each buzz box contained:
- 1 9V Buzzer (25mA)
- 1 2V Green LED (10mA)
- 1 2V Yellow LED (10mA)
- 1 single throw, single pole, momentary switch
Signals ran to and from each buzz box along the Green and Brown CAT5 components in the cables that were already running the Telephone system along their Purple and Orange components.
In the simulator loft a card sends resistor modulated voltage to the buzz box along the green solid and brown solid. Voltage returns along the green and brown stripe wires. The brown stripe wires are all connected to Pin 10 of a parallel port, and the green stripes are individually connected to the collector of an NPN transistor. The base of each transistor is powered by Pins 2 thru 6 of the parallel port.
This setup allows the Habitat to Buzz Mission Control by throwing the switch in the buzz box, and Mission Control to buzz a single room in the Habitat by entering a command on the keyboard corresponding to the Pin 2 thru 6 on the parallel port (this is handled in software).
Events during Daedalus
The buzzer system was not ready for Mission Daedalus. Prior to liftoff, all of the buzz boxes were installed in the Habitat. The card in the simulator loft was completed after takeoff, and during the first test, it was discovered that the buzzers sounded whether or not the transistors were activated by the software. This may be due to a short in the wiring. The ability of the Habitat to buzz MC was not verified.
It was suggested that the Buzzers be used as a Master Alarm in order to not waste the pre-Daedalus time that went into them. However, they were not used for this purpose.
During the final night of Daedalus, the astronauts were forced to evacuate C&C due to decompression. This meant that there was no means of communicating with the Astronauts.
Chris Hawthorne put out a remarkably successful last-ditch effort to get the telephones working to re-establish communications, while Stefan De Young attempted to sound the buzzers to get the attention of the astronauts towards the telephones.
The ploy worked, however, it was observed that every time the buzzers were sounded, there was a visible arc across the contacts of each transistor. In addition, Mr. De Young was electrocuted many many times.
After the disaster was successfully resolved, the buzzers were not sounded again for the rest of the Mission for fear of harming the buzzer system.
