What are the most important issues we have now in space exploration area? As we can see now space explorations are developing very rapidly and by doing this, it causes a lot of issues to solve. Humans have a lot of stuff to figure out to get closer to particular purpose and which one do you consider is the most important and must be solved the first?

Human hibernation.

How to limit space debris in LEO.

Ownership of extra-terrestrial resources and how conflicts in space are solved.

propulsion, propulsion, and... propulsion.
And breaking .

I think we would solve many issues (you said human hibernation?) if we knew how to go to mars in 45 minutes.

The biggest one has already been solved---was the moon made out of cheese.

mxaxai wrote:

How to limit space debris in LEO.

Ownership of extra-terrestrial resources and how conflicts in space are solved.

Yeah, the issue of space junk became very popular this time. Actually, it's not dangerous for humans on Earth but as I have already mentioned it's rather dangerous for spacecraft and for space companies who's spacecraft can collide and be damaged by space junk and whole mission can be under threat.

The big number of space junk can damage expensive spacecrafts The growing number of space items can lead to the state where he object density is so high that one collision is enough to generate a cascade effect, leading to further collisions. And now we are close to what is known as the ‘Kessler syndrome’, which represents a state where the object density is so high that one collision is enough to generate a cascade effect, leading to further collisions.

889091 wrote:

Human hibernation.

Human hibernation actually has a multitude of issues that not only make it (currently) impractical but outright undesirable (under any circumstance), for a number of reasons ranging from biological to social practicality to even moral/ethical. If long-term hibernation/"cryostatis" or even "generational ships" are required to make a journey, it either better be a one-way journey to a new planet to colonize or we'll likely conclude it not worth it.

The biggest issue is how the crew will miss time and events back on Earth and effectively get "out of sync" with the rest of society, which is actually a major problem. On the extreme end they would be more or less dedicating their entire lives to every second of space exploration, really becoming fleshy, "wet-ware" human-shaped space probes with advanced AI themselves. That's a lot to ask of any human, no matter how dedicated (fanatical, really) they insist they be. There's certain things about biology that a human won't be able to overcome no matter how fanatical they insist.

And that's assuming a completely "clean" absolute best-case method that doesn't involve biological modification of some sort, which just drags you further down the rabbit hole. The extreme suggestion I've seen (rather frequently, by actual scientists who should frankly know better or at least get their damn heads out of the clouds and touch base with reality once in a while) is to remove a person's consciousness from their bodies entirely and upload them as a "former wet-ware AI" into a space probe, where they would in fact become digital software for the rest of existence. The ethical, moral and practical considerations aside, this seems to just completely defeat the purpose of trying to send humans off-world in the first place. Occam's Razor dictates sending a probe with "dumb" AI is far more efficient and practical for what amounts to the same results.

Now there are those who suggest that society as a whole will eventually become digital software, and if that's the case the moral and ethical considerations shift, but that's outside the scope of this. But as I alluded to, a far more practical solution to this "issue" is to just continue to send probes with ever-advancing AI sophistication, up to a point, as there is a very hard limit of diminishing returns to which such a probe will benefit from such AI (in fact we're not too far off from that limit now). In the meantime, unless a society-wide digitization of all human consciousness occurs, it will be more practical to concentrate on faster-than-light travel, which according to a cursory Google search seems to be possible by scientists of accreditation, and work on ramping up the speed of probes with sub-lightspeed propulsion (say even up to anti-matter) so that we can at least get the data back in mere decades or even years instead of anywhere from centuries to the equivalent of the entire duration of human existence so far.

Otherwise, Mars or Venus is about as far as humans can go.

Another problem is the lack of superluminal communication and no real solution (yet) as to how that could be overcome. On a cosmic scale, light speed is pretty slow, meaning long communication delays even within a single solar system. Sure, if you develop FTL travel then the problem is mitigated somewhat by being able to physically send messages with some kind of traveling communications probe or by people traveling between places, but it's inconvenient and not always possible, and could still be rather 'slow' depending on how much faster than light one can travel.

Trololzilla wrote:

Another problem is the lack of superluminal communication and no real solution (yet) as to how that could be overcome. On a cosmic scale, light speed is pretty slow, meaning long communication delays even within a single solar system. Sure, if you develop FTL travel then the problem is mitigated somewhat by being able to physically send messages with some kind of traveling communications probe or by people traveling between places, but it's inconvenient and not always possible, and could still be rather 'slow' depending on how much faster than light one can travel.

Yeah, that`s a good point, we still have a large delayes in connection in space. For example, NASA`s scientists had a delay in connection around 7 minutes when the Perseverance rover was landing on the surface of the red planet.

You've already mentioned the problem of space debris, so I want to emphasize the fact that the government and private enterprises spend huge amounts of money on launches every year. I understand that building rockets and launch vehicles can't be cheap, but I think there are certain ways to save some money on it. I suppose reusability should become the main principle in aerospace engineering. We already have a reusable launch system designed by SpaceX, and it's great, but other space agencies must work on it. Btw, it also can help reduce the amount of space debris.