It is the 22nd Century and the population of the Earth has reached eighteen billion, with more millions scattered throughout space in the solar system, but the thirst to expand the human race even farther afield into the stars remains. One problem is finding the energy for this amount of people, so a solution has been arrived at in orbit of the planet Jupiter: it will be the subject of a scientific reaction that turns its vast resources into the fuel we need to continue existing in the universe. At the forefront of this endeavour is the scientist Dr. Eiji Honda (Tomokazu Miura), living on a station above the Jupiter atmosphere, but not everyone is happy about his plans, indeed there is a certain group of environmentalists keen to put a stop to them by means of violence...
Sayonara Jupiter, also known rather childishly as Bye-Bye Jupiter, was the Japanese Toho studio's attempt to cash in on the international appetite for big screen science fiction that had really been kicked off by Star Wars, though in Japan effects-filled space opera was hardly a new phenomenon, and this was more in that tradition. Five years in production and self-consciously portentous in tone, this was meticulously planned to the last detail, which was a pity as when it finally reached cinemas the general audience reaction was to dismiss it as terminally silly, which to be fair it was, a case of a project going ahead with such enthusiasm that nobody thought to pause and ponder if what they were doing made any sense or not.
As it was, that international release was less a blockbuster and more of a whimper, the title languishing in obscurity except in Japan, eclipsed by Toho giving in to popular pressure and bringing back Godzilla the following year, a film that did indeed make it to foreign cinemas while Sayonara Jupiter was consigned to the dustbin of "nice idea, but no thanks". It wasn't as if the budget hadn't been up to the demands of the imagination, as you could tell there had been a load of money spent on it, the chief issue was that it was simply darned daft, so intent in making a grand statement on mankind enduring through the hardship of the future that its enthusiasm for packing in the relevant points, even down to the smallest details, sent it careering off the rails of reason.
Take the scene where we are introduced to Dr. Honda: he meets an old pal, Captain Kinn (Ron Irwin), whereupon such is their delight at their reunion that they proceed to beat each other up, Police Academy 2 gag style. Then there's the environmentalists who are a religious colony who spend the whole movie arseing around on a beach as if they were a multiracial gang of Frankie Avalons and Annette Funicellos, listening to their mentor Peter (Paul Tagawa) sing songs accompanying himself on the guitar, much in the way Silent Running would have been if Douglas Trumbull had gone insane during production. They do other things, such as worship a dolphin called Jupiter, which comes to a bad end when someone leaves the ocean gate open and a shark gets in, chomping him and having to be hilariously despatched with explosives and an outboard motor.
It's not just the space hippies the scientists have to combat, as Captain Kinn's excursion to find out what has happened to the past couple of deep space probes meets a sticky end himself as he and his craft as pulled apart by an approaching black hole. Now it is imperative the Jupiter project go ahead, though the precise deduction behind this remains bafflingly obscure, it'll work out because, um, it's science, no further explanation necessary. Complicating an already bloated experience is Honda's old girlfriend Maria (Diane Dangely, as wooden as the rest of the Westerners) who after three years apart from her whips off their clothes and gets down to a space age form of intercourse which involves both of them having such a spiritual bond that they float around the universe in the buff for what seems like fifteen minutes of your precious time. Whatever good intentions Sayonara Jupiter had are abandoned in ludicrous sequences such as that, leaving laughter the sole reaction; it is kind of compelling to see so much blown on so ridiculous a plot, inevitable laser battles and all. Music by Kentaro Henado.