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Answers Your Questions

From: Bary D. Ridenour, of Windcrest TX
To: Paul Dye, flight director for the orbit 2 team


Question: What is the method used to prechill the external tank prior to loading fuels? In MCC, I've noticed orange plasma display at the positions, what is their function?

Answer: Thanks for the question, Bary. The short answer to your question about chilling down the External Tank is that we actually use a small amount of the cryogenic propellants to dothat. Prior to the main fueling, the launch team pumps a small amouont of the propellants into the tank and let that cool down the materials of the tank prior to the main fueling. Detailed information on the ET is available at the following URL: http://www.ksc.nasa.gov/shuttle/technology/sts-newsref/et.html#et

The orange display panels are called "DVIS Keysets". DVIS is the Digital Voice Intercommunications Subsystem, which is the equipment we use to talk to one another on console. The keysets are the end user piece of equipment on a massive, custom built intercom system that connects everyone on console with people supporting thier mission on any console position at JSC as well as other NASA centers. Each keyset has a touch sensitive plasma display with three columns and eight rows of channel "buttons", giving us the ability to listen to as many as 24 voice channels at a time. There are ten pages of 24 channels, providing the ability to have 240 different channels (called "loops" or "conferences") configured on a keyset. A fourth column of "buttons" provides controls to change pages, volume and reconfigure individual "buttons".

The typical use for a front room controller is to have the flight director loop and one or more discipline specific loops active at a time, with the ability to talk on one at a time while monitoring the others. The controller would discuss technical issues with his/her back room support personnel and relay and pertinent information or recommendations to the flight director. They would also be monitoring the air-to-ground ("A/G") loops at all times to be able to quickly respond to the flight director concerning crew questions, and to not talk on the flight director loop ("FD1", or "ISS FD1") while the crew was talking.

Different pages would be configured for different types or phases of operations, with many of the same loops configured on multiple pages, but some unique ones required for specific functions (test or sim versus mission support, or ascent/entry versus on orbit support, as examples).

DVIS replaced the original "VIS" (Voice Intercommunications Subsystem) from the Gemini/Apollo/Early Shuttle programs in the early to mid 1990's. The VIS system had 36 hard contact buttons individually wired to a patch frame on the first floor of the building 30 complex at JSC. In order to reconfigure a button, the wiring had to be changes on the patch frame (unsoldered and re-soldered in a new location) and the button label had to be replaced. Each DVIS keyset has a single fiber-optic cable connecting it to the system (in the same room as the patch frame), but can be reconfigured in real time by the user from a menu selection of over 700 conferences.

An effort is currently underway by the Consolidated Space Operations Contract (CSOC)to replace the DVIS system, as well as voice systems at Marshall, Goddard and Kennedy space centers, with a common, commercially available voice system. The new system will probably be somewhat less capable than DVIS, but will be much more cost effective to operate and maintain, and will allow better communications between centers. Sometime over the next two years the orange panels will be replaced by this new system.

Thanks again for your question, and please continue to monitor the mission.

Bill Foster
Ascent/Entry Ground Control Officer "GC"


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Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 04/07/2002
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