appeared at that moment as if fate really was against Galileo. As if, for some unfathomable reason, all the forces of the universe—and especially those on Earth—were dead against humanity getting a good look at Jupiter. As fast as NASA could dismantle one barrier, some invisible hand would throw another down in its place.

Monday, 16 October, 1989
NASA's Goddard Space Flight Center, Greenbelt, Maryland

Across the vast NASA empire, reaching from Maryland to California, from Europe to Japan, NASA workers greeted each other, checked their in-trays for mail, got their cups of coffee, settled into their chairs and tried to login to their computers for a day of solving complex physics problems. But many of the computer systems were behaving very strangely.

From the moment staff logged in, it was clear that someone—or something—had taken over. Instead of the usual system's official identification banner, they were startled to find the following message staring them in the face:

"Worms Aginst Nuclear Killers!

Your System Has Been Officically Wanked.

You talk of times of peace for all, and then prepare for war."

Wanked? Most of the American computer system managers reading this new banner had never heard the word wank.

Who would want to invade NASA's computer systems? And who exactly were the Worms Against Nuclear Killers? Were they some loony fringe group? Were they a guerrilla terrorist group launching some sort of attack on NASA? And why `worms'? A worm was a strange choice of animal mascot for a revolutionary group. Worms were the bottom of the rung. As in `as lowly as a worm'. Who would chose a worm as a symbol of power?

As for the nuclear killers, well, that was even stranger. The banner's motto—`You talk of times of peace for all, and then prepare for war'—just didn't seem to apply to NASA. The agency didn't make nuclear missiles, it sent people to the moon. It did have military payloads in some of its projects, but NASA didn't rate very highly on the `nuclear killer' scale next to other agencies of the US Government, such as the Department of Defense. So the question remained: why NASA?

And that word, `WANKED'. It did not make sense. What did it mean when a system was `wanked'?

It meant NASA had lost control over its computer systems.

A NASA scientist logging in to an infected computer on that Monday got the following message:

deleted file <filename1>

deleted file <filename2>

deleted file <filename3>, etc

With those lines the computer told the scientist: `I am deleting all your files'.

The line looked exactly as if the scientist typed in the command:

delete/log *.*

—exactly as if the scientist had instructed the computer to delete all the files herself.

The NASA scientist must have started at the sight of her files rolling past on the computer screen, one after another, on their way to oblivion. Something was definitely wrong. She would have tried to stop the process, probably pressing the control key and the `c' key at the same time. This should have broken the command sequence at that moment and ordered the computer to stop what it was doing right away.

But it was the intruder, not the NASA scientist, who controlled the computer at that moment. And the intruder told the computer: `That command means nothing. Ignore it'.

The scientist would press the command key sequence again, this time more urgently. And again, over and over. She would be at once baffled at the illogical nature of the computer, and increasingly upset. Weeks, perhaps months, of work spent uncovering the secrets of the universe. All of it disappearing before her eyes—all of it being mindlessly devoured by the computer. The whole thing beyond her control. Going. Going. Gone.

People tend not to react well when they lose control over their computers. Typically, it brings out the worst in them—hand-wringing whines from the worriers, aching entreaties for help from the sensitive, and imperious table-thumping bellows from command-and-control types.

Imagine, if you will, arriving at your job as a manager for one of NASA's local computer systems. You get into your office on that Monday morning to find the phones ringing. Every caller is a distraught, confused NASA worker. And every caller assures you that his or her file or accounting record or research project—every one of which is 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