Voyager's unlikely stowaway

Clean room etiquette, Voyager 1 and an unlikely stowaway ­– how a human fingerprint ended up leaving the solar system

We're all familiar with the concept of the clean room, and the importance of reducing sources of contamination to the lowest feasible levels. The modern clean room is an extremely sophisticated environment where bunny-suited operators minimise every conceivable impurity. This is a place where obsessive attention to detail is vital.

I'm not sure if this is significant, but most people I know who work in clean rooms have exhibited very different characteristics in their private lives. I don’t think I've ever seen so many untidy, poorly organised, but extremely well vacuumed living rooms and studies as in the homes of friends who spent their working hours in the aseptic chambers of chip fabs or bioscience research facilities.

I got to thinking about the subject last month with the widely-reported news that Voyager 1, a space probe launched in 1977, has travelled beyond our solar system. While much has been written and broadcast about this extraordinary machine and its less well known twin, Voyager 2 (which, bizarrely, was actually launched first), there is a clean room related anecdote that has not had much attention. I think it's time we put that right.

If you think levels of obsession with cleanliness are high in your laboratory, the fact is that few places are as anally-retentive about it as the space industry. Partly this is because of the potential for disaster that a single grain of grit could induce in a complex spacecraft, and partly it is a reflection of the vital necessity of not introducing contamination into the otherwise-pristine environments beyond Earth.

While this is entirely right and laudable, it might just possibly be futile. We know from meteorite studies that Earth and Mars regularly swap small lumps of each other, and it seems that the slow journey across the inner reaches of the solar system does not destroy organic molecules within those lumps.

Of rather more concern, at least as far as Mars is concerned, is that the American and European space agencies are not the only ones to have landed there. In the politically-charged space race of the 1960s and 70s, the Soviet Union put several collections of hardware on the surface in various states of disassembly, and nobody really knows how much attention was paid to the elimination of organic contamination on those probes before they left Baikonur.

I can guarantee that, should one of the present or future science labs on the red planet ever discover undeniable evidence of organic processes, that very same day we will hear from several experts stating categorically that this is nothing more than the yeasts from beneath some Russian technician's fingernails.

But should an alien intelligence ever encounter Voyager, they just might find some rather more deliberate contamination. After they have carefully studied the machinery, found the golden disks with our coded messages about life here, and used the helpful road map thoughtfully provided in order to navigate their invasion fleet, they might put the craft through a microscopic examination.

If the story told to me by a (then retired) very senior member of staff on the Voyager project is to be believed, on the lower edge of the rocket motor thrust cone they will find something unique: the remaining traces of a single human thumbprint.

I've cherished this story since it was revealed to me, in private, over several beers one evening during an otherwise rather dull engineering conference in the USA in the 1990s. I can’t tell you who it was, but I'm now confident that the story can be told without fear of causing any harm.

This individual had left the space programme and set up a new business in a high-tech industry, which is where I encountered him. It is entirely possible he was pulling my leg, but the circumstances make me doubt that and I think, on the whole, that I believe he really did what he said.

During the final inspection of the spacecraft in the clean room, shortly before it was hoisted aloft on a Titan rocket, he deliberately and overtly removed a glove and, in the presence of two or three witnesses, carefully placed his thumb on the cone. The otherwise sterile machine was thereby contaminated, but only temporarily. When the booster fired, any adhering molecules would be instantly and irrevocably sterilised. But they would leave a carbonised trace that might, just might, be detectable.

I think of this as rather like the cave paintings at places like Lascaux, where earlier hominids would blow pigment over their hands, placed against rock walls, to leave a handprint. It says "I was here", and is universally understood.

So there you have it. Along with the gold disk and the demonstration of 1970s Earth technology, Voyager carries a stowaway message of a very different and rather poignant kind. Think about that, next time you don the Tyvek suit.

By Russ Swan