In the early 1970s, as the Apollo missions to the Moon were coming to a close, there were plans to explore even further into the Universe. Not simply to Mars, or even the outer solar system, but a mission to another star. It became known as Project Daedalus.
Project Daedalus was hugely ambitious. In order to reach Barnard’s star within 50 years, Daedalus would rely upon nuclear fusion rather than chemical rockets. Pellets of deuterium and helium-3 would be detonated 250 times a second, and the plasma exhaust would be directed away from the rocket by a magnetic field. As a two-stage rocket this would accelerate the ship to 12% of the speed of light.
To gather the 50,000 tonnes of fuel necessary for the journey, there were plans to harvest helium-3 from the atmosphere of Jupiter using hot air balloons. The helium-3 could also be mined from the lunar surface. Construction of the spacecraft itself would require the development of new materials capable of surviving a range of temperatures from 1,600 K to the cold of deep space. Since there would be no crew for the mission, robotic technology would need to be developed to explore the Barnard system.
Needless to say, the Daedalus mission never got off the ground. It was so ambitious that it was intended more as a proof of concept rather than a mission feasible for its time. But the project inspired later ideas for interstellar missions, and when the first human spacecraft reach the stars their success will be based in part on the efforts of wild ideas like Project Daedalus.
As we focus more practical ideas on a return to the Moon and a mission to Mars, it’s worth keeping in mind that big dreams like Daedalus can spur us to keep pushing the envelope of what is possible.