Ah, okay. So probably:
terraforming begins → this structure is built → ice caps melt → Mars is renamed to Aqua
Looks like that to me as well. Maybe it’s dialectical? 迷うことないわよ?
That was my only guess as well…
迷うことはないわよ I think, hence the “a” sound in what she says.
Ah, that makes sense! Adding the は back in definitely explains the sound.
Lots of it seems to be underwater too, so that was how I interpreted it as well - looks like it got more flooded than expected!
Ooh, I like this interpretation. It fits well with Aika’s admonishment over embarrassing speeches on the next page 
oh I just saw your spoilered bit too!
I think I only noticed because the shot really framed her shoes… but I totally agree with @Belthazar - the Aria boots look super comfy in comparison!
Don’t mind me coming in 24hrs later and still trying to get my 2c worth in
らしい is a bit like ようです meaning “apparently” or “it seems that”, so this fragment of sentence means but it seems humans can’t enter
See the first lot of example sentences here: ～らしい(rashii)【JLPT N3 Grammar】 | 日本語の例文
I think of it as “almost as if” or “almost identical to”
I think all your other questions were answered?
The remains of colonisation structures from the time when Aqua was still called Mars.
This makes sense, although if they were able to create an atmosphere first (as the ruined buildings don’t look like your typical built to survive no atmosphere dwellings) then perhaps rerouting of water led to the current situation where older buildings are submerged.
I suspect a full plausible backstory is not likely to emerge any time soon!
Aye. Amano-sensei establishes often enough that there is a backstory, but never quite covers it in enough detail to completely hammer down the specifics, either in the distant backstory or the recent backstory.
That said, one of the anime-only episodes features Akari travelling back in time, again via cat-based means, to a point where the planet already had atmosphere and residents, but no water (or Neo Venezia). I don’t rightly recall whether they mentioned the name “Aqua” during the episode, though - I might have to rewatch it.
Makes sense! I was considering something related to the word “colonization” as well, but I couldn’t find the right words.
Yeah I doubt it too. Doesn’t seem like the kind of manga/story that would give a full backstory. Often it’s better to just let your readers speculate about that kind of thing.
@Belthazar Sorry for constantly calling you out, but I think from now on anyone talking about about future stuff from the manga or anime (even vague stuff like how well something is or is not fleshed out) should be put it in blurred text or a hidden section. I made this mistake just a few days ago and spoiled something for Nath, and the general point is that none of us knows what details (large or small) would bother one person or another. So I think it’s best to play it safe by putting any reference to stuff from future material in hidden sections.
Speaking more personally now, a lot of the enjoyment I get out of reading is being able to speculate about what might happen. So if I’m constantly being told what things may or may not happen or to what extent they will happen, it can largely ruin the experience for me.
/rant
Thank you! In all the excitement over くらい I totally forgot about that question!
I would not overthink it too much. People are free to correct me, but Aria doesn’t look like a hard scifi story 
probably neither the author thought about this (at least at this point)
I try not to! 
But I grew up on sci-fi not anime, and I can’t help myself.
We should read Planetes next to see some hard sci-fi!
Gosh, that’s a jump into the past! I honestly remember zero of the plot (I vaguely remember it was about rubbish in space). I wonder how challenging it would be… probably a chunk above aria 
I just watched the anime recently and loved it. I also bought the manga, but in English, which I plan to read soon. I agree that it would probably be much harder than Aria.
Does anybody else sometimes find it hard to know who is speaking? I often can’t tell from the speech bubbles which character is supposed to be talking, and have to kind of read ahead a panel or two to get the context in order to work it out (sometimes they helpfully call each other by name, of course ). Just wondering whether (assuming it’s not just me) that’s a general manga issue, or specific to Aria…
Yes it happens to me too sometimes. I try to understand the speech pattern of the characters (for instance, Aika uses a less formal way of speaking, Alicia (?) uses a quite polite way of saying things, etc.). It’s quite common in manga, and even more in light novels. I don’t know if this is as common in general though (ie. novels).
Anyway: confusing.
I would say it’s more of a general problem when you (general “you”) don’t fully understand what you’re reading. It happened fairly often when I was reading Kiki, and even happens very rarely when reading a book in English. But the more you understand, the better you’ll be at following the context and picking up on different speaking patterns that each character has.
For Aria in particular, I can’t say I’ve had this problem. Have you started picking up on their speaking patterns? For example, when Akari and Aika are speaking, Aika sometimes says things with a slight accent or used わ, whereas Akari generally speaks “normally” and never uses わ.