April 21st, 1997 was a red letter day in the annals of space flight. On that day the cremated ashes of 1960s drug guru Dr Timothy Leary joined those of Star Trek creator Gene Roddenberry and 22 other individuals to be launched into orbit 340 miles above.
They were the lucky passengers in the inaugural "founders' flight" of the Earth View Commemorative Space Flight Service provided by a Houston-based space services company set up in 1994 to put people into space. The only drawback is you have to be dead to participate.
"We are still taking reservations for our second flight on October 25th," explains "perspectives liaison associate" for Celestis Inc, Paul Malecki. Betraying not a hint of irony, he explained that only a "symbolic portion" of each passenger - just seven grammes of ashes - is carried aloft. "An average sized person when cremated produces about six lbs of ashes and it would cost too much to launch all of this into orbit," he says. It was up to the deceaseds' relatives how the remaining ashes were put to rest.
"Seats" for the founders' flight, which cost a comparatively modest $3,300, were taken by a six-year-old Japanese boy, a truck driver, a restaurateur, "ordinary people", Mr Malecki says. Celestis, he adds, is the only company offering such a service.
Certainly being launched into orbit is a novel way to go, but is it a clever use of the space environment? Astronomers, space agencies and users of the skies hundreds of miles above including satellite companies would say no. At that altitude, the ashes of the 24 individuals are likely to remain in orbit for at least 50 years and possibly 100. The capsule carrying the remains not only runs the risk of colliding with other objects but also of being hit by other space junk, causing further debris and further risk of collision with satellites, space stations and flight crews walking in space.
The potential for harm is not just theory, explains the European Space Agency's co-ordinator on the issue of space debris, Prof Walter Flury. The first confirmed collision between an operational satellite, the French CERISE spacecraft and what was found to be a fragment of an ESA Ariane rocket launched in 1986, occurred on July 24th, 1996. The CERISE was crippled by the fragment, estimated to have been travelling at 50,000km per hour (about 30,000mph).
"The space environment is slowly degrading," Prof Flury believes. There are about 9,000 "large" objects - 20cm across and up - drifting in orbit and only about six per cent of them are useful, working satellites. The rest is just junk, he says.
Worse still, there are perhaps another 100,000 much smaller objects from a few centimetres across to bits no more than a few millimetres in size. While the large objects can be tracked using radar and telescopes, the small bits can't. And despite their size, any of these bits could cause catastrophic damage to anything else in orbit because they travel at "hypervelocity", speeds ranging from 30,000 to 50,000km/hour.
Dr Derek McNally, resident at the University of London Observatory and an expert on space debris, explains: "Space debris is a big problem and it is all increasing rapidly. We are putting things up at a speed of knots because of the development of communications satellites."
The European IUE satellite, recently shut down after 18 useful years in high altitude orbit, was thought to have been the victim of at least four debris impacts, says Dr McNally, a native of Belfast and a graduate of Queen's who became involved in the space junk issue while general secretary of the International Astronomical Union. In each instance control of the satellite was unexpectedly lost for a time. "They associated the loss of control with impacts," he adds.
The likelihood of impact in part depends how high up you are, explains Prof Flury. Low Earth Orbit is put at between 300km and 1,600km. The typical shuttle flight is at about 300km, the Mir space station orbits at 390km and the proposed International Space Station will sit at 450km. Many of the new small communications satellites are placed at 800km to 1,200km.
Space is not quite as empty as it might seem and residual atmosphere and gravity combine to "sweep" clean debris lower than about 800km in a matter of years. But generations will pass before debris at higher altitudes finally returns to burn up in the Earth's atmosphere.
Large orbiting pieces are a nuisance for astronomers when taking wide angle, slow exposure images of the night-time skies. The junk can reflect sunlight a few hours after sunset and before dawn, producing telltale tracks across the pictures.
This is only an annoyance. Scientists are much more fearful of a "cascade" effect in space. Fragments caused by explosions of left-over rocket fuel and by collisions make up almost half of all space junk. But fragments at hypervelocity can collide with other satellites and junk producing more fragments.
"This is a real concern for the future," Dr McNally says. "It is just manageable for the present, but we are on the fringe of it with the whole thing going exponential." And he adds: "It is quite impossible to clean it up. We are going to have to live with it."
Prof Flury agrees. "You cannot clean it up, what is there is there. The only thing is to avoid creating new debris. The first thing to do is to stop the break-ups." Space agencies are now much more careful with spent fuel, either venting it or burning it to prevent later explosions. And hatches and covers are no longer blithely jettisoned into the void.
"The debris moves in all directions so the idea of traffic lanes is not feasible," Prof Flury says. Use of the space shuttle to retrieve junk is also out. Each flight costs between $300-400million and there are 9,000 known large items. But things will get worse before they get better, he believes. A whole series of multiple launches of small communications and science satellites are either underway or planned. Over the next two years up to 300 satellites are due for launch, most of them with a useful lifetime of no more than a few years.
The communications satellites feed a demand for mobile phones and the science satellites also have a role, points out Prof Fleury. But he wonders about launching rockets so that someone's ashes can float in orbit. "It doesn't really make any sense to be adding to it," he concludes.