In the winter of 1973, the men and women of the British Interplanetary Society convened in London to engage in some lively interstellar discourse. The members' intent was to draw up a workable design for an extremely ambitious unmanned space probe, one capable of reaching a neighboring star system within fifty years. Moreover, they limited themselves to using only current and near-future technology, as this would allow the theories to be translated into practice one day if the concept proved feasible.
In order to reach even the nearest stars within the allotted fifty-year window, the thirteen scientists and engineers of the research group had a formidable task ahead of them. Their space probe would be required to accelerate to astonishing speeds, and it would need to weather the constant battering of particles from the soup of space debris known as the Interstellar Medium. In spite of these problems, in 1978 the organization presented a highly developed spaceship concept which may yet prove to be the model for future interstellar travel. It was called Project Daedalus.
Decades before Project Daedalus began, astronomer Peter van de Kamp began using photographic plates to measure extremely small variations in the position of one of our sun's nearest astronomical neighbors: Barnard's Star. In 1963 he announced that he had detected a perturbation in the star's movement, a wobble imparted on a star due to the tug of orbiting planets. Because of this distinction, the relatively close star-- only 5.9 lightyears away-- was selected as the destination for the Interplanetary Society's theoretical unmanned spaceship.
The project had three clearly stated guidelines:
The spacecraft must use current or near-future technology.
The spacecraft must reach its destination within a human lifetime.
The spacecraft must be designed to allow for a variety of target stars.
When the Society began their study, the fastest vehicle in existence was the Pioneer 10, a probe which was zipping through space at a brisk 51,810 kilometers per hour. Pioneer's journey to Jupiter was to last over a year and a half, but if it were to travel to Bernard's Star at such a speed, it would spend approximately 123,000 years in transit. Clearly the Daedalus would require an extraordinary propulsion system far beyond even the best technology of the time.
In order to accelerate sufficiently, the researchers envisioned the use of a two-stage nuclear pulse rocket. Similar to chemical rockets in basic principle, such rockets would create thrust by causing a very small explosions in a rapid series. Pellets comprised of deuterium and helium-3 would be bombarded by high-powered electron beams, thus triggering fusion and detonating the mass like a tiny nuclear bomb. These explosions would be repeated at a rate of two hundred and fifty per second, using a powerful magnetic field as the rocket's nozzle.
Using this principle, the Daedalus's first rocket stage would fire for two full years, consuming 46,000 tons of fuel to accelerate to about 76.6 million kilometers per hour. The Daedalus would then jettison the exhausted primary stage, shrugging off much of its size and weight as the second stage takes over. Just shy of four years after departure, the spaceship would expend the last of its fuel, and coast for the remaining distance at the ludicrous speed of 135 million kilometers per hour-- about 1/8 of the speed of light. By way of comparison, a vehicle traveling at that velocity could reach Jupiter from Earth in under five hours, or reach New York City from Paris in 0.156 seconds.
Though the scant, slow-moving particles of the Interstellar Medium are seldom larger than grains of rice, the millions of tiny, high-speed impacts would have a sandblaster effect upon the Daedalus. To combat this erosion damage, the Society members incorporated a beryllium deflection dome on the nose of the probe. Beryllium is a very lightweight metal with excellent thermal conductivity, making it ideal for the task. In addition, the Daedalus would be escorted by its own protective particle cloud, which would precede the spaceship at the same extreme speed, sweeping most larger objects out of the path. Any damage which occurred in spite of the protection would be repaired by a small army of "wardens," remote-controlled robots which serve the Daedalus master computer.
On approaching the halfway point, the Daedalus master computer would direct its pair of five-meter-wide optical telescopes towards the Barnardian System to take photographs to send back home. The massive, 40-meter-wide engine bell of the second stage would double as a radio dish, transmitting imagery and data towards our solar system-- the relatively bright star directly behind the ship. About two years later-- approximately twenty-seven years after the probe's departure-- the first close-up photos of Barnard's Star would finally reach the Earth. These images would reveal the exact positions of any attendant planets, allowing mission control to select points of interest.
Several years before completing the fifty-year journey to the star, the master computer would arouse its slumbering robotic passengers, and assign each a route based on earlier photographic findings. These eighteen sub-probes would then spring into action, breaking away from the mothership and darting off to their destinations powered by independent ion drives. Their cameras, spectrometers, polarimeters, and other instruments would make as many pictures and readings as possible while flying past planets at high speeds. As the sub-probes chatter away by radio, all data would be relayed back to Earth using the powerful transmitter on the mothership. Naturally many instruments would be tuned to search for evidence of life-harboring climates. Slowing down or stopping would be impossible since the fuel for braking rockets would increase the mission's weight budget too drastically, so the Daedalus and probes would have a relatively short time to make observations before zipping past the star system at over a million kilometers per hour.
Due to the Daedalus's massive size and environmentally hazardous fuel, it would almost certainly need to be constructed in orbit if the project were ever undertaken. The Helium-3 component of its fuel is scarce on Earth, but it is thought to be abundant in Jupiter's atmosphere. Therefore the Interplanetary Society suggested that the starship might first make a detour there in order to scoop up and store sufficient Helium-3 for the journey.
More recent data indicates that there are in fact no planets orbiting Barnard's Star, but the Daedalus design is flexible enough to apply to many other interstellar destinations. To this day, NASA considers the thirty-six year old research as a useful baseline study which addresses the problem somewhat effectively. The researchers at the British Interplanetary Society optimistically estimated that such a craft would be possible by the late 1990s, though they acknowledged that such a starship would still be prohibitively expensive without unprecedented international cooperation.
Technologies are gradually appearing and evolving which could one day bring Daedalus-- or something like it-- to fruition. But at some point in the 1980s, our culture's when-and-how optimism was smothered by why, and respectable scientists were urged to shelve their absurd ambitions for more practical pursuits. I say let the sticks have their mud... I want a massive interstellar space probe.