NASA Office of Logic Design

NASA Office of Logic Design

A scientific study of the problems of digital engineering for space flight systems,
with a view to their practical solution.

Usage of this WWW Site

Intended Audience

This www site is designed for engineers involved with digital logic technologies for space flight applications.  As such, there are papers, reports, test data, and various types of technical information.  This is a research site and posted material is believed to be of good quality.  While not all of the content is generated by NASA GSFC, we will not post data that we have doubts about.

Site Construction and Policies

This www site is constructed with the aims of making it useful to the adult professional and in compliance with all of the various rules, regulations, laws, statutes, circulars, and other documents that are supposed to be followed.  The www site is kept simple with no frills or fancy features for easy, safe visits.  Most of the items are either simple text, .jpg or .gif pictures, or .pdf files.  These are all standard and they should give you no problems.  I try to make all of the files backward compatible so that upgraded browsers and readers are not required.  Some items are also presented in their native format (e.g., .ps, .doc, .ppt) for your convenience.  In a few instances, I could not successfully make .pdf files so the native files or scanned documents are the only ones that appear.  The material here is either in the public domain or published with the permission of the authors.  No plug-ins are required and there are no java script programs, flash animation, etc.  There is a minimum of sound and video.  We do have some good space clips now on-line as well as video of interesting and useful talks.

Material on this site is free for your use.  This is the official NASA policy


I try to keep the text a reasonable size so that all visitors can easily read the material.  Where possible, all files are less than 100 kbytes to make access via a phone line (that's how I access it most often) reasonable.  If you need assistance accessing any material on this www site, please send me an e-mail at the address listed on the bottom of any page and we will work to satisfy your needs.

External Links

Most of the pointers/links are to material on this site.  Sometimes, particularly when the material is not free for copying, there will be pointers out of this www site.  I can not control other www sites so the material may be moved or taken over by another company who purchased the domain name; please browse with care and note where links are before clicking.  You are solely responsible for your www surfing.   At the bottom of each page you will find my e-mail address.  In the event that you need any help accessing material, you have identified any mistakes in implementing our policy, or you have comments of any sort, please send an e-mail and to the best of our ability and resources the problem will be promptly resolved.

Interpretation of Data

However, it is important that any data on the site be interpreted appropriately.   That is the job of an expert.  A "quick look" is not sufficient.   For example, if a part is tested to X krads(Si) in the total dose chamber, that by no means implies that the part is good to that or any other level.  Often parts are tested to failure or to investigate a parameter of interest.  For reliable operation of a part, it is mandatory that a proper and thorough analysis be performed by an appropriate expert and that the test conditions and parameters are well understood.

The radiation expert will apply the proper Radiation Design Margin (RDM), your program's reliability requirements, and take into consideration the test conditions, sample size, and dosimetry.

Extrapolating data sets, of course, can be hazardous.  Additionally, ignoring any deviation in a parameter may not be wise.  For example, although leakage currents can be low during a total dose test, the part can still be subject to failure.   Please see this chart, for an example:


It has been shown for some parts, that functional failure occurs just before the small, sudden rise in current.  Functional failures have been detected by in situ functional tests.

Interpret your data carefully!!!!!!!!!!!!

Additionally, there are often multiple data sets pertaining to a lot of parts.   All data should be reviewed, carefully, and not used in isolation.

Lastly, assuming that one lot of parts will be similar to another is poor engineering.  Many of the devices that are tested are of commercial origin and are not controlled for radiation hardness.

Other factors should be considered as appropriate.  The above is not intended to be an exhaustive list.

Plugins and Readers

Many files are in Adobe Acrobat .pdf format.  If you need software to read them, please go here: Adobe Acrobat Reader.

If you need viewers for .doc or .ppt files, please go here: Microsoft Office - Converters and Viewers - Microsoft Office.

In summary, one must be careful interpreting data.  The data on this www site is provided for your use.  In general I do not certify parts for any particular mission or environment.  I instead will refer you to a radiation effects or parts specialist near you.

Good luck!


Home - NASA Office of Logic Design
Last Revised: February 03, 2010
Digital Engineering Institute
Web Grunt: Richard Katz