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   missing from the computer system--is absolutely vital.

  

   In this case, the problem was exacerbated by the fact that NASA's

   field centres often competed with each other for projects. When a

   particular flight project came up, two or three centres, each with

   hundreds of employees, might vie for it. Losing control of the

   computers, and all the data, project proposals and costing, was a good

   way to lose out on a bid and its often

   considerable funding.

  

   This was not going to be a good day for the guys down at the NASA SPAN

   computer network office.

  

   This was not going to be a good day for John McMahon.

  

                            [ ]

 

   As the assistant DECNET protocol manager for NASA's Goddard Space

   Flight Center in Maryland, John McMahon normally spent the day

   managing the chunk of the SPAN computer network which ran between

   Goddard's fifteen to twenty buildings.

  

   McMahon worked for Code 630.4, otherwise known as Goddard's Advanced

   Data Flow Technology Office, in Building 28. Goddard scientists would

   call him up for help with their computers. Two of the most common

   sentences he heard were `This doesn't seem to work' and `I can't get

   to that part of the network from here'.

  

   SPAN was the Space Physics Analysis Network, which connected some

   100000 computer terminals across the globe. Unlike the Internet, which

   is now widely accessible to the general public, SPAN only connected

   researchers and scientists at NASA, the US Department of Energy and

   research institutes such as universities. SPAN computers also differed

   from most Internet computers in an important technical manner: they

   used a different operating system. Most large computers on the

   Internet use the Unix operating system, while SPAN was composed

   primarily of VAX computers running a VMS operating system. The network

   worked a lot like the Internet, but the computers spoke a different

   language. The Internet `talked' TCP/IP, while SPAN `spoke' DECNET.

  

   Indeed, the SPAN network was known as a DECNET internet. Most of the

   computers on it were manufactured by the Digital Equipment Corporation

   in Massachusetts--hence the name DECNET. DEC built powerful computers.

   Each DEC computer on the SPAN network might have 40 terminals hanging

   off it. Some SPAN computers had many more. It was not unusual for one

   DEC computer to service 400 people. In all, more than a quarter of a

   million scientists, engineers and other thinkers used the computers on

   the network.

  

   An electrical engineer by training, McMahon had come from NASA's

   Cosmic Background Explorer Project, where he managed computers used by

   a few hundred researchers. Goddard's Building 7, where he worked on

   the COBE project, as it was known, housed some interesting research.

   The project team was attempting to map the universe. And they were

   trying to do it in wavelengths invisible to the human eye. NASA would

   launch the COBE satellite in November 1989. Its mission was to

   `measure the diffuse infrared and microwave radiation from the early

   universe, to the limits set by our astronomical environment'.6 To the

   casual observer the project almost sounded like a piece of modern art,

   something which might be titled `Map of the Universe in Infrared'.