If we ever come across traces of an advanced alien civilization like the one featured in "Prometheus," the new semi-prequel to the "Alien" movie series, our first course of action should not be to send them a shipload of human meat. Instead, send in the robots.

At least that's the prescription from Seth Shostak, senior astronomer at the California-based SETI Institute. "Would you indeed load up a starship with alien fodder and send it out?" he asked me. "Of course you wouldn't, because we don't know how to do that."

Sure, the crew of the starship Prometheus starts out in the year 2089, when we can assume that fusion power has solved our energy woes. But there's no chance that we'd be able to mount an interstellar trip by then, unless Spock and his pals from the planet Vulcan beam down and show us how. Even assuming that an ion-powered starship like the Prometheus could somehow get to other stars in a realistic (and relativistic) time frame, Shostak said he wouldn't send the humans on the first expedition to LV-223, the scene of the action in "Prometheus." 

"I think what you'd probably do is load up a spacecraft with sensors of all types, radio receivers, cameras, spectrometers, anything you can take up, essentially make it a Mars Viking mission, and just have it radio back what it finds," he said. "That's a heck of a lot less dangerous, and beyond that, it's a lot easier, because you don't have to put all this life support stuff and these cantankerous hominids on the rocket."

Even better, you could have that spaceship peopled by androids like David (played by Michael Fassbender in the movie), who basically steals the show in "Prometheus" anyway. That way, you avoid the ickiness of having monsters incubate inside human wetware, as they did in the original "Alien."

"If you can design an android that can do all the things that they do in these films, why is it that they haven't gone one step further and just replaced us with the androids?" Shostak asked. "Machinery can evolve much more quickly than biology. It's funny that they all get stunted at just the level where they're mostly helpful and occasionally malevolent."

Of course, without all that human cantankerousness and ickiness, you don't have much of a space horror movie. And be assured, there's plenty of both in "Prometheus." There's also a little real-life science in the movie, thanks in part to Kevin Hand, deputy chief scientist for solar system exploration at NASA's Jet Propulsion Laboratory. Hand served as a consultant on the film, and one of the first things he learned is that you should never let scientific qualms get in the way of a good movie.

"Being a scientist working with filmmakers, you have to keep in mind that the story comes first," Hand told me. "The science is a way to motivate certain elements and provide aspects of the plot. As long as you go in with that understanding, as a scientist, you can let your guard down a bit and not be constrained — which is different from our normal day-to-day scientific metabolism."

With that in mind, here are five themes in the movie that include a twist of scientific realism:

Habitability: Early into his involvement, Hand gave film director Ridley Scott and his team a tutorial on the different environments in our own solar system, ranging from steaming-hot Venus to cold, dry Mars and ice-covered Europa and Enceladus. The setting for the movie, LV-223, is a moon that orbits a giant planet in its parent star's habitable zone. That's similar to the fictional moon in the movie "Avatar," which orbits a Jupiter-like world named Polyphemus. It might also be similar to the theoretical moons circling 55 Cancri f, a planet detected about 41 light-years from Earth.

Hand noted that LV-223 is habitable in the Earthlike sense, meaning that it has an atmosphere and could conceivably support life at the surface. But he thinks that most livable environments are less like Earth and more like Europa, a Jovian moon that is thought to have a miles-deep ocean of water hidden beneath its forbidding surface ice. "Much of the habitable real estate in the universe might be within these ocean worlds that are covered with ice," Hand said. By his reckoning, Earth would be the peculiar planet.

Panspermia: I hope I'm not giving anything away when I say that "Prometheus" touches on the theme of panspermia — the idea that the building blocks of life, if not life itself, can be transferred from one planet to another. It's a great sci-fi theme, but it's not necessarily science fiction. Some theorists have proposed that life could have gotten its start on Mars, which was warmer and wetter billions of years ago, and then hitchhiked its way to Earth on the debris thrown up from a meteor blast. Or life could have come to Earth from farther out in the cosmos, borne by an impacting comet.

Hand pointed out that NASA's Kepler mission has detected thousands of potential planets in just one little patch of sky. That leaves plenty of opportunities for finding life out there, and plenty of opportunities for life to make its way here.

"Here we are on Earth, a planet in a solar system around a star that is 4.6 billion years old, which seems like an incredibly long period of time to us," Hand said. "But the universe is 13.7 billion years old. So there was a lot of time before the solar system even came about, 8 billion years or so of the history of the universe, during which many forms of life, many advanced civilizations, could have come and gone. They could still be there now, or they could have died off billions of years ago."

Propulsion: The Prometheus starship uses an ion propulsion system that gives a nod to the real-life ion drives used by probes such as the Dawn spacecraft, which is currently in orbit around the asteroid Vesta, Hand said. "The spacecraft that they're using is a much more advanced version of that kind of propulsion, but it's got a link to our current mode of exploring the solar system," he said.

It's unlikely that ion propulsion will be able to provide the power and maneuverability that Prometheus has anytime soon, and certainly not by 2089. But ion drives could offer a good option for interplanetary or interstellar flight. Their hallmark is slow but steady acceleration, starting out with as much force as it takes to hold up a piece of paper. Unlike chemical rocket engines, ion propulsion drives keep going, and going, and going, building up a figurative head of steam. Some experts suggest that nuclear or solar electric ion propulsion will provide the oomph for eventual missions to Mars.

Mapping: In the film trailer, there's a scene where the away team tosses out a few flying robotic spheres that scan the underground caverns with lasers and send back mapping data. Hand said he couldn't take total credit for that idea, but the robo-balls are based on the same principle that Stone Aerospace is using to design real-life submersible robots capable of observing and mapping subglacial lakes in Antarctica or, perhaps eventually, on Europa. "I mentioned some of that work to the artistic team," Hand recalled. There's just one big difference: The real-world robot, known as the Deep Phreatic Thermal Explorer, or DEPTHX, will be "going through underwater environments on Earth as opposed to exploring alien spaceships," Hand said.

Terraforming: At one point in the movie, Prometheus' away team finds out that they can take off their helmets and breathe the air inside an underground cavern. Hand was asked to come up with a plausible explanation for that plot point, and he proposed that an alien civilization could easily come up with a nuclear-powered device that electrolyzes water to produce oxygen. Heck, even we puny humans are thinking of ways to use rock-eating microbes to make Mars more livable. It won't happen overnight ... but maybe it could happen by 2089, if we play our cards right.

"Prometheus" focuses on an expedition to go after to the aliens, but what if the aliens were of a mind to come after us? Should we lie low, as famed physicist Stephen Hawking has suggested? Unfortunately, it's too late for that, Shostak said.

"For any society that could come here to do nasty things to us ... it's very easy to show that they could pick up all the stuff we've been sending out since the Second World War. In fact, they could pick up the lights of New York City," he said. "In a sense, we've already told the aliens we're here. The idea that it might be dangerous if we found some planet over there, so don't send them anything ... it's too late. That's not to say it might or might not be dangerous. We have no idea. But it's too late. It's silly to worry about it, because it would require that you lay low not just for the weekend, but forever. Forever! That would so cramp the sorts of things that our descendants could do, that I don't think that policy would have legs."

And if the aliens really do come after us? If they have the capability to project their firepower over a distance of light-years, forget what you saw in the movie "Battleship." We're toast.

More about the search for alien civilizations:

• Expert doubts alien visitors would terrorize us
• Queen of SETI retires from research
• City lights could point to E.T.
• What if E.T. thinks we're evil?
• What would you ask E.T.?
• Cosmic Log archive on aliens

More Hollywood reality checks:

• Reality check on 'Hunger Games' tech
• Invisibility and other 'Harry Potter' technologies
• 'John Carter' and the real-life Martian quest
• Virtual actor takes over in 'Tron: Legacy'
• Apollo 18 in fiction and fact
• 'Avatar' and the future of 3-D moviemaking
• Reality check for 'Star Trek' tech

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.