Launching a robotic probe to another star is on a completely different scale to launching a probe to the farthest-most reaches of the solar system.
As the nearest star is over 4 light-years away, we’d have to become accustomed to multi-year communications delays -- the unmanned interstellar vehicle being sent would need to be a “multi-probe,” able to explore multiple environments autonomously.
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Collectively the star probe is more likely its own space exploration program, launched as a package on a transport system, which for Project Icarus is a fusion rocket. However, fusion rockets do not scale well and have a minimum size typically of hundreds of tons.
As we’re sending a whole exploration program to another star system, that’s not a major issue, but it does require doing things differently -- it will be a paradigm shift in our approach and thinking of how to explore space. No single space-launch is sufficient to place the vehicle in orbit and no fusion rocket can lift hundreds or thousands of tons of fuel and vehicle into space.
The “Firefly” z-pinch fusion rocket design (as discussed in a previous Icarus Interstellar guest article), designed to fly to Alpha Centauri in 100 years, will have a mass of around 1,500-3,000 tons with payload, and will need to carry about 19 times its own dry-mass in deuterium fuel (the fuel used in the Firefly’s fusion processes). Thus about 30,000-60,000 tons of machinery and fuel may need to be launched into orbit.
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