[geijoenr]

Definitely a common sense step in the right direction. Humans going anywhere beyond the moon using chemical propulsion seems quite problematic due to all the unsolved issues related to radiation and micro-gravity.

Now talking speculative fiction, the real breakthrough will come if we figure out a way to induce acceleration without an action-reaction process. Just an energy source, and no propellant. Being able to sustain 1g for a few months on a heavy spacecraft means interstellar travel (proxima centaury) would be within grasp.

[Kim_Bruning]

Meanwhile, having engines that have higher specific impulse helps quite a bit as well. That is to say: a nuclear engine needs less propellant to provide the same amount of delta V (actual work). Since the majority of a rocket's mass is in the propellant, this scales non-linearly.

A nuclear rocket is a big improvement over chemical rockets already.

[eddsh1994]

How does your initial point of 1g for a few months on a heavy spacecraft lead to traveling 4.246 light years? Genuine question!

[gpm]

It would take 6 years to get there (earth time) or 3.6 years (spacecraft time) if you could have constant 1G acceleration (in the opposite direction for the second half of the journey).

https://cosmicreflections.skythisweek.info/2019/09/04/space-...

[brnt]

In fact, you could get anywhere in the universe in your lifetime/timeframe, if you could maintain the 1g acceleration.

[dmitrybrant]

> without an action-reaction process. Just an energy source, and no propellant.

Unfortunately, in our universe, momentum is conserved.

[mr_toad]

If you could somehow convert mass into a beam of photons then the mass loss would be tiny compared to the momentum.