Launching of the earliest missions to our nearest stellar neighbors may come even in the lifetime of the reader today, though they may not reach their destinations after generations. In our TMP timeline, this is a likely possibility during the Asgard phase of development as the combination of advancing artificial intelligence, self-healing/repairing systems, and new methods of propulsion emerge with the expanding pursuit of solar system development.
Such early missions will most certainly be similar to today’s scientific missions to the outer solar system, based on robotic spacecraft of modest -though still much larger than current- scale and comparable design. The difference will be in the autonomy of their control systems and the scale and sophistication of their communications systems as the vastness of interstellar distances will leave these machines on their own to deal with the situations they encounter on their long journeys.
The first of these are likely to be ‘gravity probes’ that exploit the slingshot effect of intercepts with multiple planetary bodies to supplementarily accelerate the spacecraft to as great a velocity as possible before it travels off to its extrasolar target. In effect, using the whole solar system as a kind of engine to amplify the potential of its own limited propulsion. Some such spacecraft may be designed to repeat this process in a simplified manner at their stellar destination in order to propel themselves from one star to another. This may eventually be used as the basis of so-called Von Neumann probes (which we will discuss in another section) that seed solar systems with the mechanisms to develop and exploit their resources for replication and restocking of the probe as it sails on to star after star. Though for these early starships it will be a challenge simply to withstand the rigors of a single journey and maintain the most basic communication with our own solar system.
Later generations of interstellar probes may exploit increasingly powerful propulsion to achieve higher initial velocities for their journeys. Large fusion powered vessels -similar to the BeamShips common to the Asgard era or the [Daedalus/Icarus] concepts currently speculated- may be employed. Or perhaps large solar/magnetic sails relying on vast solar-orbital laser/maser systems.
The temptation of whole new solar systems to explore and develop may -especially after initial contact by probes- compel the pursuit of manned missions before we have means of propulsion capable of any significant fraction of the speed of light. In the original TMP, Marshal Savage imagined some spacefaring communities choosing to brave the very protracted journey to our nearest stellar neighbor in ‘generation ships’ -a common trope in science fiction. Savage imagined the same techniques used to make asteroids into comfortably habitable settlements being used to create such vessels, the vast hollowed bodies providing the raw materials to sustain their inhabitants for generation after generation while providing a mini-world sufficiently vast to present no hardship for their traveller. We can still envision such spacecraft deriving from the same application of EvoHab technology to asteroid mining and settlement. Such vessels would most certainly employ the propulsion approach of gravity probes as well as using their own vast engine systems to accelerate their great masses.
But given the pace of technical advance we anticipate across the Asgard era, the passengers of such generation ships face the risk of being well overtaken by progressively faster generations of spacecraft before they arrive. And there is an open ethical question of whether it is fair to future generations unborn to be committed to a journey not of their choosing. But then again, we could ask the very same question of ourselves today as we blindly experiment with our Earth’s environment and the very real fates of generations unborn.