Houston, they have a problem. Lots of problems, as a matter of fact.

In the alternative universe of Apollo 18, the small-budget, high-concept thriller that opened Friday at theaters and drive-ins everywhere, it’s 1974 – two years after Apollo 17, which most of us have long assumed was the final Apollo mission – and three NASA astronauts are on a top-secret voyage to the moon.

While Lt. Col. John Grey (Ryan Robbins) steers the Liberty command module in orbit around the moon, Cmdr. Nathan Walker (Lloyd Owen) and Capt. Benjamin Anderson (Warren Christie) descend to the surface in their Freedom lunar module to install what they think are radar scanners. (At least, that’s what they’ve been told by NASA – and NASA surely wouldn’t lie, right?)

Unfortunately, Walker and Anderson find a Soviet spacecraft – and the corpse of a Soviet cosmonaut – near their landing site. Worse, they soon discover why that cosmonaut is very seriously deceased.

Borrowing heavily from the playbook used by the makers of The Blair Witch Project, Paranormal Activity and other “found footage” flicks, director Gonzalo López-Gallego and screenwriter Brian Miller contrive to make audiences believe that Apollo 18 isn’t just your garden-variety B-movie hocus-pocus, but rather a documentary culled from hours and hours of recently declassified footage pertaining to a purported ’74 moon mission that ended badly for all parties involved.

The illusion is sustained with surprising persuasiveness, thanks to the efforts of technicians who shrewdly use variegated visual styles —blurry black-and-white video, shaky handheld camerawork, static-interrupted transmissions from inside spacecraft and aboard lunar rovers, faded-color home movies and “official interviews” — to simulate the look of documentaries about ‘60s and ‘70s NASA missions.

Indeed, the flickering black-and-white stuff supposedly shot in the Apollo 18 spacecraft and on the moon itself is especially effective. If you’re old enough to remember Walter Cronkite anchoring live coverage of Neil Armstrong’s giant leap for mankind, or even if you’ve just watched archival footage on The History Channel, you can’t help being impressed by what this movie’s behind-the-scenes craftsmen have wrought.

Trouble is, all of this handiwork is employed to support an all-too-familiar scenario — U.S. astronauts encounter unfriendly life forms on the dark side of the moon— that dates back to those bygone days when John Agar and Kenneth Tobey were tangling with extraterrestrials on drive-in double bills.

It’s undeniably amusing to watch and listen while these fictional spacemen anxiously converse with Houston mission controllers — and, yes, more than a tad unsettling to learn that the folks back in H-Town haven’t been totally truthful about the mission they’re controlling — but Apollo 18 ultimately comes across as nothing more than a gimmicky trifle that, judging from early box-office reports, isn’t likely to draw massive audiences to megaplexes.

If you really want to see real astronauts boldly going where, alas, man hasn’t gone for nearly 40 years, you’d do better to track down a DVD (or, better still, a Blu-Ray) of For All Mankind, Al Reinert’s superb 1989 documentary that edits a single, composite space-flight narrative, paradigmatic of all the NASA moon missions, from footage obtained in the space administration's extensive archives. It's a linear story — beginning with the anxious minutes before liftoff, culminating with a splashdown — that is absolutely seamless in its construction.

Some of the imagery is astonishing, even shocking. The seemingly endless moment of ignition, as the rocket rises slowly, almost reluctantly, from the launch pad. The spectacular astronaut's view of the rocket's lower stage, as it is blown off into space. The first glimpse of a massive blue marble in a sea of black — the Earth, seen from a vantage point most humans can only dream of obtaining.

Other scenes are hilarious — surprisingly so, given the media-manufactured image of astronauts as bland technocrats. There's a spirit of frat-house horseplay in some shots aboard the spacecraft. There's an air of joy-riding giddiness to the long-distance drives along the lunar surface. And when one astronaut suddenly lifts his voice in robust song — ''While strolling on the moon one dayyyyyy . . .'' -- it's impossible to keep from laughing out loud.

Even funnier is an earlier moment back home on Earth, as the astronauts trek toward the launch pad. An unseen, unidentified NASA employee thrusts her arm into camera range, waves and chirps: ''Y'all take care, now!''

Reinert underscores his imagery with haunting music by Brain Eno — and commentary by the actual Apollo astronauts. They are never identified by name as they recall their pre-flight jitters and on-the-moon impressions, but their words — simple, tinged with amazement and humility — are unforgettable.

One Apollo alumnus remembers pausing on the moon during the standard operational procedures, just to marvel at where he was standing. (''Do you know where you are?'' he asks himself.) Another astronaut says he was greatly relieved to look up from the launch pad and see the moon directly overhead: ''I knew we were pointed in the right direction.'' It's a priceless moment in a peerless movie.

Of course, to be fair, For All Mankind benefited from having a bigger budget for on-location filming than Apollo 18 ever could. But Reinert’s Oscar-nominated tour de force also offers much more compelling drama than López-Gallego and Miller’s faux-documentary feature.