Guidance, Navigation, and Control
Section 4.3.1.
Home Tour Join! Contents Team News Catalog Search Comm

Computer Redundancy

Geoffrey Landis

Continuing the line of thought about computers, the shuttle runs three identical computers, with the output states compared at each calculation. If one is at odds with the other two, this is flagged to the pilot's attention, so the pilot can take that one off-line.

Originally the computers were supposed to take off-line the one that was wrong, but the astronauts very energetically informed the shuttle designers that they did not want to fly a shuttle where the computers can shut themselves off.

In addition to this, there is a 4th computer ready as a back-up if one of the three is turned off.

In addition to that, there is a different backup computer, with different hardware and independently-written software that can be put on-line in case of a problem which is generic to type. All of this with 1976 technology! (upgraded since the first flights, though)

We might want to think about how much backup we want. With current technology, shuttle-level backup won't incur a heavy mass penalty, and the extra spare processing power will always be useful when not in a failure mode.

Guidance, Navigation, and Control

Home Tour Join! Contents Team News Catalog Search Comm
ASI W9600866r1.1. Copyright © 2004 Artemis Society International, for the contributors. All rights reserved.
This web site contains many trade names and copyrighted articles and images. Refer to the copyright page for terms of use.
Maintained by ASI Web Team <>.
Submit update to this page. Maintained with WebSite Director. Updated Sat, Aug 28, 1999.