For many years, I've wanted to see Heinlein's last Hugo award winning novel converted to a movie. Seeing the plucky Loonies fight off the hamfisted Terran Federation would be definitely very enjoyable. Recently, however, I've come to see some major problems with the novel as a movie.
The first relates to a major issue in the novel - the low gravity of the Moon. It figures in many aspects of the storyline. The inhabitants of the Moon are permanentally adapted to the one sixth gee, and can't return to earth for any sort of normal existence. When the Federation lands troops on the moon to suppress the revolt, the troops are hampered by their inexperience, and the Loonies use this to their advantage. In any adaptation of the novel, the gravity should figure in every scene, not just a few. Depicting the low gravity is very difficult.
The movie Gravity did show zero gee very well, and for the full length of the movie. However Cuaro only had to show one person moving in zero gee- not whole families, riots and battles. The one sixth gravity would be quite the hindrance of translating the novel and it has to be shown.
Another issue is that Heinlein told us about a revolt on the moon, but did not show it. Much of the preparation of for the rebellion is laid out in expository pages. Heinlein, master that he was, got away with it, but it won't work for a video art form. The directory could opt for numerous montage scenes, but that gets old fast.
Heinlein also glossed over several character issues. He shows a long discussion with Manny and Stuart Lajoie to enlighten the reader as to the social status of females and the social heirarchy on Luna. He skips later scenes when Lajoie becomes entranced with Manny's family, and not only figures out what's going on, but joins the rebellion as soon as he's informed. In a later scene Manny complains that many of Prof's friends spoke down to him during the time when Luna was preparing for invasion. But this was never shown. The first the reader hears of it is when Manny complains about it.
The obvious solution for these two issues is of course to write more material. Introduce more characters and show them joining the rebellion and what it means. Let us see Lajoie get swayed by Wyoming Knott, watch his face as he puts clues together and figures out whats going on. Show the progression of the revolt from the formation of the cell system, to the gang rape and riots that resulted with the Loonies overthrowing the local authorities. This of course would mean not a movie, but a full HBO or Netflix style series. Maybe show three seasons, one season for the insurgency, one for the rebellion and one for fighting the invasion forces.
Finally their are several major plot holes that need to be resolved. The first involves the various tricks Mycroft plays on the occupying forces. Unlike 1965, computers are now prevalent in society. The first thing Alvarez would think of would be computer viruses or back doors allowing access to the mainframe. As the local computer consultant, they would heavily scrutinize Manny. Perhaps some sort of LeCarre sting could be worked out to redirect attention to some one else - a very smart computer scientist on the Fed's payroll, but it would still be difficult. Alvarez would know what was happening, he just couldn't prove it. He may even campaign for a total reboot that would destroy Mycroft.....hmmm that could lead to a heist episode where Manny has to download Mycroft to a portable disk drive. Okay, maybe this plot hole could be fixed, but the writers would have to spend some time on it.
The second major plot hole involves sending convicts to the moon to do the Fed's farm labor. With a long waiting list for colonizing Mars, I don't think it would be difficult to find volunteers to colonize the moon. Why send dangerous convicts who would more like as not drag their heels and try to sabotage every project? The moon is only three seconds from the earth- many tasks could be done by drones monitored from earth. The idea doesn't make sense.
Also, consider the whole 'farming wheat on the moon to resolve a hunger crises on earth' scheme. Heinlein was only guessing at the amount of Lunar water, but we now know there isn't very much. The lunar regolith lacks carbon and nitrogen, vital necessities for any agricultural endeavors. Any scheme to send convicts to the moon to farm food for earth would just be met with a puzzled look and the question, "Why not just build more prison farms in Nebraska and Alabama?"
A plot point about the rebellion was the Loonies had to revolt or face a severe ecologic crisis as they mined the last of their water. They would not even be able to feed themselves, let alone the teaming masses of India or China. With all the current emphasis on sustainability, I'm not sure how no one would notice that the Moon is running out of water, carbon and nitrogen. The scheme in the later part of the novel where an indigenous Lunar authority increases grain shipments would be utterly ludicrous.
The idea of the descendants of convicts on the moon revolting against outside authority certainly touches part of the human spirit, but making a movie from Heinlein's book presents far too many problem. It's a shame though, because I'd love to see it.