How do you fly a space mission to another star? Over the next five years a group of specialists tries to come up with a theoretical study of such a mission. The name of this study is Project Icarus...

30 years ago a theoretical study was undertaken by the British Interplanetary Society (BIS) about a flyby mission to Barnard's star 5.9 light years away. The study was called Project Deadalus and it remains one of the most complete studies of interstellar travel to date.

Rather than retorting to mere science fiction this study tried to comply with well established science and with technology which should be available near term (meaning over the next few generations). Another requirement was that the vast distance to another star should be covered within a human lifetime or better yet within a working lifetime.

What resulted was a 54,000 ton two stage vehicle powered by Deuterium/Helium 3 nuclear fusion and which could travel at 12% the speed of light. (Compare this to the ISS with about 400 tons at speed of 0.0026% the speed of light and you can see that in order to travel over astronomical distances you better get used to astronomical numbers!)   

Recently a symposium was held in London by the British Interplanetary Society together with the American Tau Zero Foundation to review Project Deadalus in light of the advances made in science and technology over the past 30 years and to inaugurate a follow-on study aptly named "Project Icarus - son of Daedalus". This new study is expected to last about five years and shall result in a credible mission scenario to yield useful scientific data from another star.

This last point is important. With Project Daedalus a mere flyby of a star at 12% the speed of light was assumed. Slowing down to go into orbit around another star was deemed impossible due to the large amount of energy needed. But by the time mankind is ever able to build starships like that big space interferometers with huge apertures will allow to study nearby stars in considerable detail while the limited size of telescopes being carried by a spacecraft to another star means that you have to be very near and stay there for a longer time in order increase scientific knowledge.

We can expect significant advances in science and technology over the next few generations but one thing will likely remain the same: You will always have to make a convincing case to get the necessary funding for your project. Simply zipping past a star at full speed as kind of a flag waving exercise with very little scientific gain will not do.

So Project Icarus will try to slow down the spacecraft at the destination. They plan to retain nuclear fusion as the power source. (I should mention that Laser driven light sails have been proposed for interstellar travel as an alternative. This does hold some promise but the studies done so far have not been quite as extensive as Project Daedalus.)  

Of course there is much more to designing a spacecraft than coming up with a suitable propulsion system. You need reliable power and computer systems which can work without maintenance over the 50 year mission lifetime. Current interplanetary spacecraft already operate for one or two decades and possess a certain amount of artificial intelligence and fault tolerance. But they also rely on contacts with a mission control center which will be very difficult if you are a few light years away.

Another daunting problem which usually gets glanced over in studies about interstellar flight is how to achieve the precision navigation necessary for such a mission. And of course you have to communicate your science results over interstallar distances which likewise will be a challenge.

Rather than designing all systems exclusively for the one-off flight to another star it would be an advantage if whatever is needed for this flight turns out to also benefit "local" transport (meaning space travel within our solar system). This would help spread the enormous costs of such a project over a number of commercial ventures.

Which star should you select as a target? To be of particular scientific interest it should be a star with a planetary system - preferably one which holds some promise of possible life. 30 years ago extra-solar planets were only a hypothesis. But now they are discovered at an ever increasing rate. Long before Icarus would ever be able to leave our solar system we should have an accurate overview of the planetary systems in our neighbourhood.

But if nobody today will ever live to see an interstellar space mission like the one proposed by Icarus why bother to do such a study at this moment? In our world today we worry almost exclusively about short term day-to-day problems. We have to do this in order to stay alive. But taking a more long term global approach might help us answer the question why we should stay alive in the first place...

If you would like to follow the progress of Project Icarus over the next few years you can have a look at the project website.