Today's e-mail:

Quick! Settle a bar bet for me. What was the cheapest yet most financially successful science fiction movie ever? Beer is riding on your answer!

I write a weekly column and you want your answer quickly? I think you are fundamentally misapprehending the nature of the column, my friend.

Be that as it may, the answer to this one is pretty simple: It's almost certainly Star Wars, which was made in the mid-'70s for a budget of about $11 million and which in its initial release earned more than $300 million domestically, with an extra $160 million or so tacked on during its re-releases in 1982 and 1997. Adjusted for inflation, it cost about $45 million in today's currency to make and has earned some $1.4 billion, which is a return on investment of more than 30 to 1. This doesn't even factor in international grosses, which is hard to find a reliable number for, particularly those dating back to the original release.

Neck and neck with Star Wars would be E.T. The Extra-terrestrial, made for $10.5 million in the early '80s and raking in $435 million in its various releases. If you adjust for inflation, the return on investment ratio is again something close to 30 to 1. Purely on domestic numbers, E.T. might be slightly ahead of Star Wars in terms of cheapness to success, but I'm going to make the unilateral decision to give the overall crown to Star Wars because I suspect it grossed more internationally, once adjusted for inflation, or at the very least will once Lucas releases the planned 3D version sometime in the near future.

But this isn't actually an interesting question to me. A really interesting question would be: When was the last time a really cheaply made science fiction film became a blockbuster hit? Science fiction films clutter up the top of the annual box office each year, of course. Right now, Transformers, Captain America, and Rise of the Planet of the Apes are in 2011's top ten. But these films cost $195 million, $140 million, and $93 million, respectively, to make. When was the last time a science fiction film that cost as little as Star Wars to make landed in the top ten of a year's box office -- or at least made $100 million at the box office?

The answer: Since the turn of the millennium, no science fiction film costing $45 million or less to make has cracked the annual top ten, and only one such film has made more than $100 million: 2009's District 9, which cost $30 million to make and grossed $115 million domestically. Before that, you have to go all the way back to 1986, when Star Trek IV: The Voyage Home, made for about $21 million ($41 million adjusted), brought in $133 million domestically, and a year before that, when Back to the Future, off a $19 million ($38 million adjusted) production budget, grossed $210 million in North America.

Think about that: In a quarter of a century, just one inexpensive science fiction film has been a genuine $100 million blockbuster at the box office.

It's not that cheaply made science fiction films aren't being made; this year alone has seen Paul ($40 million), Source Code ($32 million), and Apollo 18 ($5 million). Sometimes these even do decently -- Source Code and Apollo 18 made back their budgets and then some, and Paul came close to breaking even. Other cheaply made science fiction films have become cult hits and launched careers: The $23 million Pitch Black put Vin Diesel on the map in 2000, and the $45 million Galaxy Quest has become the beloved This is Spinal Tap of the science fiction world. Cloverfield cost $25 million and become the center of an Internet sensation.

The question today is whether a cheaply made science fiction film can capture the attention of enough moviegoers to become a genuine blockbuster. District 9 shows it is indeed possible, if the film is innovative, not stupid, and especially when Peter Jackson is your producer. But likely? No. As with many other genres of film, from a sheer numbers perspective, if you want the big grosses, you have to commit the big bucks to the production. This of course runs the risk of going badly for you (see Green Lantern and Cowboys & Aliens from this year), but correlation strongly suggests: No green, no glory.

For all that, I would love to be surprised more often by cheap, great science fiction breaking out and making it big. To put it another way: I hope it's not another 25 years before we get another District 9.