Wednesday, April 05, 2006

Daedalus - The future that never was (2)

Who can forget the highly successful British manned space programme of the early seventies, just before that rash of creepy alien invasions?

Many wonderful spacecraft have been launched since then but a project to send a large ship to another star is still fires the imagination. It seems an impossible dream, yet just such a ship was seriously proposed on a cold night in London, over 30 years ago.

Project Daedalus, named for the mythical greek inventor who built is own wings, was the starship planned by the British Interplanetary Society in 1973, one of the first serious projects in designing a craft to reach the stars.

The B.I.S. had first studied possible space ship designs in the 1930s, 20 years before they became a reality. They invisioned that a mission like Daedalus could fly by the late 1990s.

Alan Bond argued that, not only did we have the ability to detect radio emmissions from alien civilisations, but we had (in 1973!) the capability to build an unmanned probe to reach a nearby star with existing technology, or logical extensions of it.

A public meeting in London on January 10, 1973 discussed the proposal, in the days when the question was 'how do we do it' not 'why bother at all?'

For the sake of simplicity the simplest mission, a stellar fly by, was chosen. The target was Barnard's star, 6 light years away, which could be reached in 30-40 years, allowing the engineers who had launched it to see it through.

Daedalus would be boosted to 15% of the speed of light and then coast to its destination, where it would have about 70 hours to study the system as it flashed through it. Slowing the craft to orbit Barnards star was not a possibility.

Various propulsion systems were discussed, including laser powered sails, fusion power and a version of the NERVA project already abandoned by the USA. The choice came down to the promising, but currently impractical interstellar ramjet, scooping up the tenuous hydrogen between the stars for fuel and nuclear pulse or internal confinement fusion. This, the favoured option, works by exploding 250 pellets of deuterium and helium-3 a second in a combustion chamber over an acceleration phase of four years. A magnetic field would stream the plasma behind the ship to propell it forward. The pellets would be ignited by high-power lasers or electron beams. Doubtless Greenpeace would have been picketing Pluto as it sped by.

The problems of interstellar radiation and transmitting the information back to Earth were discussed and committees set up to take the design further, work a dozen scientists continued up to 1978.

Daedalus first stage
The 3,500 ton Daedalus would be constructed in orbit, carrying 50,000 tons of fuel and 500 more of scientific payload. The first stage would fire for two years, taking the spacecraft to 7.1% of light speed, before being jettisoned. The second stage would fire for 1.8 years before being shut down to begin the 46-year cruise to Barnard's Star. Daedalus would carry 18 autonomous probes, equipped with artificial intelligence, to investigate the star and its planets. The 40-meter diameter engine of the second stage would double as a communications dish. On top of the second stage would be a payload bay containing the probes, two 5-meter optical telescopes, and two 20-meter radio telescopes. A 50-ton disk of beryllium, 7 millimeters thick, would protect the payload bay from collisions with dust and meteoroids on the interstellar phase during the flight, while an artificially-generated cloud of particles some 200 km ahead of the vehicle would help disperse larger particles as the probe plunged into the planetary system of the target star. En route, Daedalus would make measurements of the interstellar medium.

Daedalus Warden
Some 25 years after launch, its onboard telescopes would begin examining the area around Barnard's Star to learn more about any accompanying planets. The information would be fed to the probes' computers, which would be deployed between 7.2 and 1.8 years before the main craft entered the target system. Powered by nuclear-ion drives and carrying cameras, spectrometers, and other sensory equipment, the probes would fly past the planets looking for life or conditions favorable for biology.

It never happened of course, and 30 years later we're no closer to building such a probe. New techniquesNew have detected host of planets orbiting nearby stars and a rash of newly launched and proposed satellites could allow us to detect earth sized planets in the next few years. If we can find oxygen in a planets atmosphere, by analysing the light which passed through it, then we have found life.

Some of these projects (like the French COROT telescope) are late, whille the problems of the shuttle fleet and the much delayed, hugely expensive ISS have led to NASA slashing its funding of deep space scientific research.

Proposed for 2004, COROT is still to fly

The Stratospheric Observatory for Infrared Astronomy, a telescope already fully installed in a Boeing 747, has been cancelled, as has the Terrestrial Planet Finder, would have studied the formation of planets beyond our solar system. The mission to Europa, the most likely site of alternative life in our solar system, has gone, while the DAWN mission to explore the asteroid belt, after initial cancellation was revied after a public outcry. After already spending $257 million on it, it would have cost $14 million dollars to cancel. It cost just $73 million to revive.

The Kepler space telescope, delayed several times for fiscal reasons, will search for earth type planets around distant stars. NASA plans to delay the launch of the James Webb Space Telescope nearly two years, to 2013. The SIM planet finder has now been delayed to 2015, will it ever fly at all?

Mythical Greek inventor Daedalus (Daidalo - "cunningly wrought") built the the Labyrinth of Crete for Minos but, falling out of favour with his patron, was imprisoned in a high tower. Seeking to escape to his native Sicily he made wings of swan feathers, for himself and his son Icarus. They leapt from the tower and flew towards freedom but his impetuous son, defying his father's orders, flew too close to the sun. The wax holding his feathers melted away, his wings frayed and fell apart and Icarus tumbled to his death while his distraut father flew safely home.

How many of these brave ventures will get off the ground? How many will become nothing more than footnotes in history? Yet another project Icarus? How many of them will become the future that could have been? Let's get on with it!

Painting by Alan Reed

Daedalus specs from Bond, A., Martin, A. R., Buckland, R. A., Grant, T. J., Lawton, A. T., et al. "Project Daedalus." Journal of the British Interplanetary Society, 31 (Supplement, 1978).


Post a Comment

<< Home