There's a lot that is tackled in Planetes and what it has to tell, it succeeds quite well with covering. The series offers a realistic take on the many details and issues of a future where man has begun to expand its civilization in space with the main focus on the debris workers who have to clean up the remains of abandoned or damaged satellites, space stations and spaceships that are drifting around Earth's orbit. The physics and conditions of space are portrayed believably with the weightlessness of space when in orbit with no gravity and low gravity when moving around on the moon. There's focus on the negative effects of being in space for long periods of time on both the physical and mental conditions of the body through characters Nono-chan, Gigalt and one of the major characters at one point. The ordeals of living in space are also delved into with oxygen being enough of a precious resource where smoking is heavily prohibited in most areas (which Fee the captain has to deal with regularly) and enough preparations made with astronauts when away from a ship, space station or the lunar city (wearing a diaper, amount of available oxygen, signal flares, etc...)
Many issues are tackled throughout the series regarding the time in which it is portrayed such as the socio-economic divide between corporate executives and lower-level workers, pollution in space, the need for developed nations to expand their resources through expansion in space without allowing underdeveloped nations any gain from it and terrorism in opposition of space expansion. The morality of these issues is grey as each character and faction within the series responsible for the issues faced are fleshed out enough where you see they have justifications for what they are doing and there are both positives and negatives to the actions and decisions that are made.
Speaking of characters, Planetes does quite well at delving into the backgrounds, mentalities and ordeals faced by many of the show's characters as they each come to terms with some dilemma they face as a result of being in space or a moral issue. From major characters like Hachimaki coming to grips with his purpose of being in space and slowly warming up to newbie Ai to secondary ones like Edelgard having a dark past that pushes her to retain a professional mindset, you'll be amazed by just how much the show covers with its large cast of characters.
If there's one element to the series that I have a bone to pick with, it would be the comedy. The show does start off as a bit of a light-hearted comedy shown through the antics of two of the Debris Section's bosses and an episode featuring some unemployed workers in an apartment complex dressed as ninjas. The comedy to the series tended to be hit-or-miss for me as I found the more subtle examples of humor such as Fee's cigarette withdrawals to be funny than the blatant examples shown through the two goofball bosses. Fortunately, the comedy is downplayed as more focus is put on the character developments and morality issues as the series progresses.
Overall, Planetes was quite the watch for me special thanks to the future setting its set in being realistically close to our time than most other sci-fi titles plus delivering plenty of focus on morality issues and character ordeals. You'll definitely enjoy this title if you are into sci-fi anime.