Scientific missions are seeking to answer the question, "What’s out there?" Astrobiologists may find life, but it’s not at all clear they will know it when they see it.

When NASA’s InSight spacecraft touched down on Mars in November, it joined an ongoing assemblage of space research to answer the burning question: Is there life in space?

"Our approach to understanding if other places are habitable is looking at where life as we know it on Earth thrives, like extreme environments," says Mary Voytek, senior scientist for astrobiology in the Science Mission Directorate at NASA headquarters. "Here on Earth, we find microbial ‘extremophiles’ thriving in all kinds of ‘extreme’ environmental conditions, from salt deposits to hot springs, desiccated icy deserts, permafrost, hydrothermal vents on the ocean floor, superheated areas deep within the earth’s crust, and more."

She says NASA’s planetary science missions have enabled researchers to learn more about the environmental conditions on other planets and moons in our solar system and how some resemble those found on Earth in these extreme environments.

"It stands to reason that if life can thrive in those environments here, they might be able to beyond our world, too," Voytek says.

Indeed, it seems inevitable that we will find life outside our solar system when scientists and astrobiologists have more sophisticated equipment to discern it, such as telescopes and spacecraft. Plenty of new technology is being deployed—or will soon be deployed—for these missions.

Mission: Space life

One example is NASA's launch of the Transiting Exoplanet Survey Satellite (TESS) in April 2018. The satellite is expected to find thousands of exoplanets, which are planets that orbit a star outside the solar system. Scientists will study these for signs of life over the course of years and conduct other research as well. In April this year, TESS found its first Earth-sized planet, according to a Carnegie Institution paper.

Kepler, NASA's planet-hunting space telescope (which recently ran out of fuel and was retired), was masterful at finding exoplanets: It found nearly 4,000 of them after its 2009 launch.

"The most recent analysis of Kepler’s discoveries concludes that 20 to 50 percent of the stars visible in the night sky are likely to have small, possibly rocky planets similar in size to Earth and located within the habitable zone of their parent stars. That means they’re located at distances from their parent stars where liquid water—a vital ingredient to life as we know it—might pool on the planet surface," according to NASA.

"In the past 10 years, we have observed thousands of exoplanets, and we know there are several orders of magnitude more," says Voytek. "Early observations suggest that many of these should have habitable environments similar to those that we see in our solar system."

One of the most anticipated space explorers is the James Webb Telescope, which is expected to be sent into the cosmos by 2021. The international project, led by NASA, will feature a number of advanced instruments to explore deep space and characterize exoplanets.

NASA says the Webb telescope will be the premier observatory of the next decade. "It will study every phase in the history of our universe, ranging from the first luminous glows after the Big Bang to the formation of solar systems capable of supporting life on planets like Earth to the evolution of our own solar system."

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Space life close to home?

Of course, we may not need to look beyond our solar system to find space life.

For example, one of Juniper’s moons, Europa, has attracted a lot of scientific attention in recent years because, according to NASA, the moon has the three key ingredients for life: liquid water, to create an environment that facilitates chemical reactions; essential chemical elements that are critical for biological processes; and a source of energy that could be utilized by living things.

"[Europa] is special among the bodies of our solar system in having a potentially enormous volume of liquid water, along with geological activity that could promote the exchange of useful chemicals from the surface with the watery environment beneath the ice," NASA says on its website. "Over the last quarter century, we have learned that Jupiter-like planets are common around other stars and that many could have icy moons like Europa. This realization means that studying Europa will help us understand the habitability of icy worlds throughout the cosmos."

But Europa is not the only planetary moon to attract attention. Saturn’s Enceladus is a small ocean world covered in ice that could harbor life of some sort. Enceladus sends jets of water vapor into its atmosphere; a global ocean flows on Enceladus beneath an ice shell that's about 20 to 25 miles thick. In fact, NASA says that organic compounds—the building blocks of life on Earth—along with volatile gases, water vapor, carbon dioxide, carbon monoxide, salts, and silica have already been detected in Enceladus’ plume.

"Europa gets a lot of attention because [of] tidal heating from Jupiter; we believe there is a subsurface ocean that could support life. We are also looking at the moons of Saturn: Enceladus and Titan," says Voytek. Within our solar system, we may look for life with in situ measurements, she says. However, outside of our solar system, for astrobiologists to study exoplanets that might be habitable, strong telescopes that can detect biosignatures remotely will be necessary.

A future mission, the Europa Clipper, may help answer some questions. Though its launch date hasn’t been set—perhaps 2022—the mission ultimately will place a spacecraft in orbit around Jupiter to perform a detailed investigation of Europa. "The mission will send a highly capable, radiation-tolerant spacecraft into a long, looping orbit around Jupiter to perform repeated close flybys of the icy moon," Voytek says.

No space entities have attracted as much "life in space" attention as the Red Planet. "Mars is a veritable 'Goldilocks' planet," NASA says. It is big enough to have undergone the earliest internal heating and the separation of the crust, mantle, and core processes that shaped terrestrial planets such as Earth, Mercury, and Venus, but it is small enough to have retained the signature of those processes over the next 4 billion years. "Within its own structural signature, Mars may contain the most in-depth and accurate record in the solar system of these processes," NASA says.

And this is what the sophisticated instruments on the recently landed robotic lander InSight are supposed to scrutinize. "Although today it is clear that biology is not abundant on the surface of Mars, it might have been 3.5 billion years ago, when the surface of Mars was warmer and wetter and more similar to Earth," Voytek says.

There have been more than 50 missions to Mars over the years, with a variety of rovers and satellites, and more are planned. For example, the European Space Agency and Russia are jointly planning the mission ExoMars to launch a life-hunting Mars rover in 2020. And if Elon Musk, the leader of Tesla, SpaceX, and other innovative companies, has his way, he will put life on Mars, establishing a populated city by 2050.

Life as we 'don’t know it'

But even if life is "out there," will we indeed even recognize it? Especially if it doesn’t fit into our own description of life?

"Beyond a creature walking or swimming in front of one of our cameras, there are many ways to detect the presence or former presence of biology on another world," Voytek says. "For example, here on Earth, we know photosynthesis produces oxygen that can accumulate in the atmosphere, so we can think about how we could detect atmospheric biosignatures on other worlds, too. This might be one way to look for life on exoplanets, or planets outside of our solar system."

Such biosignature research is gaining traction. NASA’s Astrobiology Program recently awarded $7 million in funding for a new interdisciplinary project, the Laboratory for Agnostic Biosignatures (LAB). Researchers on the LAB project will develop new, non-Earth-like life detection approaches for use on Mars and Jupiter's and Saturn’s icy moons. "Our goal is to go beyond what we currently understand and devise ways to find forms of life we can scarcely imagine," says Sarah Stewart Johnson, principal investigator and Georgetown University professor, in a statement.

"All of these things depend on our understanding of life on Earth," Voytek says. "But another question astrobiologists are considering is life as we 'don’t know it.' Is there life in the universe that doesn’t need water or is made up of a different set of chemical building blocks, and how would we look for that?"

Space life delivered?

Maybe we won’t even have to look for it. Maybe space life will come to us.

A recent paper written by researchers at the Harvard Smithsonian Center for Astrophysics suggests some sort of space life did just that in the form of a mysterious unidentified object that passed by Earth last year. The cigar-shaped entity, known as Oumuamua, was first spotted by the Pan-STARRS1 telescope in Hawaii in October 2017. It had qualities such as an unusual shape—it is 10 times as long as it is wide—and mass. Its ability to apparently accelerate had astrophysicists scratching their heads. Harvard astrophysics researchers, including Avi Loeb, chair of Harvard’s astronomy department, suggest Oumuamua might have had an "artificial origin" and perhaps was some sort of deep space probe from another solar system or defunct alien spacecraft.

Loeb told The Harvard Gazette that while other astronomers, including the researcher who discovered Oumuamua, have dismissed the alien ideas, such debates are an important part of the scientific process. And while alien life may once have been strictly science fiction, Loeb pointed to a growing body of evidence suggesting we’re not alone. "We know a quarter of all the stars in the galaxy have planets in the habitable zone of their host star … so to me, it’s not impossible that there may be life elsewhere," he said.

Loeb’s story isn’t the only recent hint at life elsewhere. Scientists have pondered a series of repeated energy spurts, known as fast radio bursts (FRBs), that were detected for only the second time in modern history. Astronomers working with a new type of radio telescope, the Canadian Hydrogen Intensity Mapping Experiment (CHIME) in British Columbia, recorded the pulses last year and published an article on the discovery in the journal Nature. The researchers speculated that such pulses may indeed end up being a regular part of our universe. However, other speculation is that such high-energy pulses could come from some other-worldly transmitter used by some alien group trying to contact us.

Artificial intelligence's growing influence on spotting space life

AI is playing a larger role in helping researchers sort out the enormous amounts of data generated by some of NASA’s probes. For example, AI and machine learning technology is credited for helping screen data from NASA’s Kepler space telescope to spot Kepler-90, a Sun-like star 2,545 light-years from Earth.

The SETI Institute has been using AI algorithms to analyze more than 20 million signals captured by the Allen Telescope Array radio telescopes, using machine learning to greatly improve how anomalous space signals of interest can be identified and flagged for further examination.

The European Space Agency has research groups looking into the use of AI in automating space mission design, the development of new learning algorithms, and natural language processing.

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