Millions of miles away on Mars, in a barren crater just north of the equator, a rover is wandering around, carrying a gold-coated gadget the size of a toaster. The machine inhales the Martian air and strips away contaminants. It splits the atmospheric gas into constituent parts, takes what it needs, and then reassembles that blend to create something that is in very short supply on Mars: oxygen. Real, breathable oxygen, the kind you took in as you read these sentences.

After a bit of analysis, the machine puffs out the oxygen, harmlessly releasing the molecules into the Martian environment. The act makes this very sophisticated toaster, situated in the belly of NASA’s Perseverance rover, the closest thing to a small tree on Mars.

And according to the researchers behind the little machine, it’s a pretty good tree. Every time they’ve run it, the Mars Oxygen In-Situ Resource Utilization Experiment—MOXIE, for short—has successfully converted Martian air, which is almost entirely made of carbon dioxide, into oxygen gas. “We’re not far from being able to produce oxygen at the rate that would sustain a human being,” Michael Hecht, a planetary scientist at MIT’s Haystack Observatory who leads the project, told me. “A small dog would be just fine at the rate that we produce.”

[Read: What would a dog do on Mars?]

MOXIE is a clever chemistry experiment. It is also a remarkable event in the history of space exploration. If human beings want to build a long-term home on Mars, they’ll have to make use of the planet’s natural resources instead of lugging everything they need all the way from Earth. “We have to be able to live off the land,” Jennifer Heldmann, a NASA scientist who works in this futuristic field—known as in situ resource utilization—told me. “This is the first time that we’ve been able to test and demonstrate the technology to do that.”

And oxygen is wonderfully versatile. Not only would it sustain humans on a planet that their lungs weren’t designed for, but it could also be combined with other compounds to produce rocket fuel so that they could return to Earth. On Mars, we’re the aliens. We’d need to invent all kinds of stuff to give future astronauts a chance to survive there, let alone live comfortably. It is almost sci-fi-ish to think about, but by tinkering with Mars’s atmosphere, we—as in humankind—have managed to figure out at least one piece of that endeavor.

The MOXIE experiment whirred into action in February of last year, after Perseverance touched down and started working toward its prime mission: collecting rocky samples that could contain the tiny imprints of long-dead Martian life. MOXIE had its own work cut out for it. The Martian atmosphere is so thin that, compared with our own, it’s almost a vacuum. “I like to say we’re making oxygen out of thin air,” Hecht said. “If you were a Martian, you would think that those of us on Earth are fish swimming around in a thick soup of atmosphere.”

[Read: We’ve never seen Mars quite like this]

Mars also experiences far more dramatic shifts in its atmospheric conditions. Daytime and nighttime temperatures can vary by about 212 degrees Fahrenheit (100 degrees Celsius). The air shifts as well, thinning out during the warm days and becoming denser during the cold nights. Swings in air pressure occur seasonally, too. During Martian winters, some of the atmosphere condenses into frost and settles over the poles, reducing the air pressure across the rest of the planet. During Martian summers, air pressure ticks up. All of these factors influence the amount of carbon dioxide in the atmosphere—MOXIE’s main snack.

To see how MOXIE would fare, engineers powered up the instrument during different times of day and different seasons. They found that “the most difficult time to collect carbon dioxide is in the middle of the day, in the middle of the winter, when it’s both warm and the pressure is low,” Hecht said. “And the easiest time is the middle of the night in the middle of the summer, when the pressure is high and the temperature is low.” But during every run, the machine worked, spending an hour churning out oxygen.

The team has yet to deploy MOXIE during dawn or dusk, though, when “the density of the air is changing, and the temperature is changing rapidly,” Hecht said. Engineers are concerned that the sudden shift in the presence of carbon dioxide could damage the instrument as it draws the gas in. Hecht says they’ll do some testing with a lab version of MOXIE on Earth first, but they’re confident that they can get their little lunch box to work under these conditions, too.

[Read: Mars’s soundscape is strangely beautiful]

Other groups of scientists are thinking about how to make oxygen factories for future Mars missions; one team recently devised a method for generating oxygen from carbon dioxide with the help of plasma. And other researchers are thinking deeply about how to use additional resources on Mars, such as the ice deposits just below the planet’s surface. Future astronauts could mine the frozen water and purify it for everyday use. They could also steal the water’s hydrogen molecules and put them toward the work of getting home. “You can make methane, which is a rocket propellant,” Julie Kleinhenz, a NASA research engineer who studies in situ resource utilization and is not involved with the MOXIE project, told me. “You could fully refuel an ascent vehicle with methane and oxygen just by using resources on Mars, through processes that are pretty well understood.” Some basic items, such as spacesuits and toilets, will have to come over from here. But if you can make something on Mars, you can reduce the heavy baggage that makes it more difficult to blast off from Earth.

The team behind MOXIE imagines a future in which a scaled-up version, capable of doing the work of hundreds of trees, hums away on the surface of Mars, working around the clock. The factory would be launched ahead of a human mission, so that there would be plenty of oxygen reserves by the time astronauts arrive. That future is still many years away; NASA says the earliest that it could land astronauts on the red planet is sometime in the early 2040s. Elon Musk wants to go much earlier than that with SpaceX, but even the space billionaire will face the same constraints that would make a Mars trip difficult (funding, physics, the cosmic radiation between here and there). A mega-size MOXIE would be just one item on a very long packing list. But MOXIE has a certain concreteness to it that feels thrilling even now. It is the kind of detail that makes a human base on Mars seem a tiny bit more realistic. Imagine, decades from now, an engineer sitting at a console, inhaling air derived from an alien atmosphere, and telling one of her staff: “Hey, Steve, we’re getting some weird MOXIE readings—can you go check it out?”

What exactly do we mean by alone when we ask if we’re alone in the universe?  

The search for extraterrestrial life is one of astronomy’s grandest projects. But the search is more multifaceted than anyone casually intrigued by aliens might realize. At its core lies the question of what version of life we are seeking. On Earth, and presumably beyond, life exists on a spectrum of forms and capacities. But for the purposes of tracking it down in the cosmos, it can be lumped into two somewhat crude categories: “dumb life” and “smart life.” Dumb life consists of things such as microbes and plants that can proliferate across a planet but are unlike humans as self-conscious, technological thinkers. Smart life consists of creatures like us that build planet-spanning technologies.    

With deep apologies to microbes, plants, and even elephants for the ham-fisted nomenclature, this distinction between dumb and smart life matters because each can be detected in a different way. Given the mind-wilting distances between stars, even our most advanced tools for surveying far-off worlds won’t be delivering on-the-ground pictures of alien pine trees or anteaters anytime soon. Instead, we must look for indirect signatures of life when surveying a planet. First, there are biosignatures, such as the presence of oxygen and methane in the atmosphere. These are gases that might only be found together because a biosphere—the collective activity of all life on a planet—keeps them there. Second, there are technosignatures. The presence of complex industrial chemicals in the atmosphere or the reflected glint of massive solar-panel deployment would tell astronomers that a technologically capable species like us inhabits that distant world.

To maximize our chances of discovering life, the ideal would always be to scour a planet for both signatures. But astronomers have a big universe to explore and only so much time and money to do the exploring. With projects requiring decades to bear fruit, scientists must choose their shots carefully. (The James Webb Space Telescope, humanity’s newest and most powerful observatory, cost roughly $10 billion, which tells you something about the resources at play.) So far, in the search for extraterrestrial life, dumb life has won out. With healthy funding from NASA, astronomers have made astonishing progress over the past 20 years articulating what kinds of biosignatures might exist on alien worlds. This progress has been remarkably rewarding, but it could come with a cost. Could we be missing out on the promise of smart life?

[Read: Looking for solar panels on distant planets]

It’s worth remembering that the first scientific search for extraterrestrial life was a search for extraterrestrial intelligence, i.e., SETI. In 1960, the astrophysicist Frank Drake launched Project Ozma, an experiment using radio telescopes to search for signals from chatty high-tech civilizations. Back then, no one could even imagine a way to search for trees or insects or microbes on distant planets orbiting distant stars; no one even knew if such planets existed. Although for decades SETI remained the only game in town in the search for life, it always suffered from a giggle factor. More than once, congressional representatives used “the search for little green men” to whip NASA for wasting tax dollars. As a result, radio SETI’s funding suffered. The field has lived on life support for most of the past 40 years (though recent funding via the private Breakthrough Listen effort has helped).

Meanwhile, in 1995, the search-for-life-game changed forever. The first planet orbiting another sun-like star was discovered, and astronomers realized that they could directly detect biosignatures by observing starlight passing through an exoplanet’s atmosphere. The development of this technique, called “atmospheric characterization,” has been one of the major successes of NASA’s astrobiology program. Astronomers recently ranked a space-based “life-finder” telescope as one of their top funding priorities in a once-in-a-decade survey of the field. Amid the clamor of biosignatures, technosignatures have often seemed like afterthought, if they have come up at all.

The allure of biosignatures is clear. Many astronomers start out assuming that biosignatures will be more prevalent than technosignatures. After all, you can’t have a civilization-building species evolve on a planet before life does. And from Earth’s history—our only reference point on life’s path—it’s clear that basic forms of life have been around far longer than technology. Earth was sporting biosignatures for all the universe to see more than 3 billion years ago. Only over the past century or so have we begun dressing ourselves in technosignatures. That means there have been technosignatures on Earth for less than 0.00001 percent as long as there have been biosignatures. From this perspective, technosignatures might seem like mere icing on the cake of detectable life.  

There is, however, another dimension to the question that a simple evolutionary progression fails to recognize. A new study, led by Jason Wright of Penn State University to which I contributed as part of a NASA-funded technosignature-research group, have laid out the argument that astronomy is overlooking the value of technosignatures. The problem with biosignatures is that they’re forever tied to their biospheres, i.e., their planets. Biosignatures have no way to leave their biosphere of origin. And, for that matter, if all life were to disappear from Earth tomorrow, most of Earth’s biosignatures would disappear quickly too. For example, the oxygen in our atmosphere all comes from the planet’s life. If that life went extinct, atmospheric oxygen would react back into rocks and disappear quickly on the scale of deep time.

To detect a biosignature, in other words, we have to find a fully functional biosphere. But we don’t really know how long biospheres generally last. Ours has, thankfully, persisted for more than 3 billion years. But there are many ways a biospehere might die, including the loss of the planet’s atmosphere from solar winds or a really big asteroid impact. Once the biosphere goes, the biosignatures likely go with it.

Technosignatures have no such constraint. Consider the fact that the solar system is already full of Earth’s technosignatures. There are more than 10 spacecraft orbiting Mars or on its surface right now. And that’s just one planet. Hundreds of other spacecraft are out there traversing the sun’s spaceways. We have even blasted five craft entirely out of the solar system and into the interstellar domain. Every one of these machines we’ve sent into space constitutes a material technosignature—an artifact—in its own right. More important, all of the active ones are sending radio signals into space. These signals are weak, but each still constitutes a technosignature that some other species conceivably could detect.  

[Read: Seriously, what’s making all these mysterious signals in space?]

Unlike biosignatures, technosignatures move and endure. The Apollo 11 moon lander will be sitting on the moon for millions of years because there’s no wind or water to erode it away.  Projecting forward, if we were to cover a fraction of the moon with solar panels and then succumb to some civilization-crashing accident, those panels might still be visible to alien observers long after we disappeared. Meanwhile, in our own search for life, imagine an interplanetary civilization that has freighters routinely moving between worlds. Engine-exhaust plumes, tight-beam laser communications, even waste disposal, if the alien civilization burned its garbage, might show up as a signal—a signature—that we could detect on Earth. All of these technosignatures could be transmitted far from the alien civilization’s home world (let’s call it a “technosphere”). An alien civilization might even use uninhabitable worlds in its solar system to host its industry or energy generation. Such “service worlds,” as my colleagues and I call them, would only generate technosignatures, because no biosphere would be present.

Technosignatures could also be prolific. A single civilization and its technosphere could produce millions or even billions of individual objects that each could create detectable technosignatures. Imagine a civilization that is thousands or millions of years older than our own. Not only might it routinely create legions of artifacts that emit technosignatures; it might also create more technospheres. Unlike biospheres, technospheres can reproduce themselves via intentional space settlement. By these measures, imagining what distant civilizations might invent through advanced technologies, humanity so far might hardly even count as smart life.

There is plenty to argue about here. On a specific level, for instance, a critic might respond that biospheres can also reproduce via panspermia, the process when a chunk of microbe-bearing rock gets blown into space via an asteroid impact and then lands on another fertile world. Calculations show panspermia may be relatively rare occurrences even in the best of circumstances, however. Meanwhile, a single space-faring civilization could seed the entire galaxy with new technospheres as it settled ever more distant worlds. That said, this all is speculation. We have yet to discover extraterrestrial life, so we have no idea what true ratio of smart to dumb life exists out in the cosmos. Advanced civilizations may well be so exceptionally rare that the odds are still in dumb life’s favor. I wouldn’t bet on this; but then again, so much remains undiscovered.

One misconstrued takeaway from our group’s research could be that the priority in life hunting should now shift to technosignatures. That is not, however, what we concluded. Instead, in reviewing the past biases and future possibilities, we came to see biosignatures and technosignatures as a continuum. So far, scientists have designed their life-detection tools to target either smart or dumb life, but in the wake of discovering exoplanets, the same kinds of telescopes and the same kinds of detectors attached to those telescopes can now be deployed for finding both kinds of life.  These searches could even happen at the same time as astronomers look for signatures of biospheres and technology in the same parts of the electromagnetic spectrum while observing the same planet.  

The decades-old biases against technospheres, including the giggle-factor tying them to little green men and UFO conspiracies, are no longer tenable. Astronomers will still have to make hard decisions based on limited resources, but those decisions should be made just on the strength of the specific search proposal rather than parsing the search for life into an artificial biosignature-versus-technosignature split. We are in truly a remarkable moment. After thousands of years of just arguing over the question of life in the universe, we are finally capable of searching for answers. Finding any kind of life—dumb or smart—would constitute a fundamental reframing of our place in the cosmos. Let’s look for all of it.