Documents don&#x27;t usually preserve themselves.  Paper lasts a long time if left in an attic or a closet but can be lost if the wrong person &quot;cleans up&quot;.  Electronic documents are much more fragile.  Media decays or otherwise becomes unreadable.  If data is saved in proprietary formats and the reader hardware or software is lost, then it&#x27;s much the same as degaussing.<p>IIRC a large set of moon landing data was lost when somebody set the tapes down on a heater and left them there too long.<p>Not moon-landing related, but Yellow Magic Orchestra (YMO), the very first group to use a Roland TR-808 drum machine, was unable to read the original masters because they were recording using a cutting-edge digital format for which there are no readers.<p>Preserving digital data for the long term is hard.<p>Disclaimer: Library and Info Sci degree with archives coursework.