We might not be alone in the Universe. Scientists from all over the world have their eyes and ears wide open trying to detect signals of life beyond our planet. But we’re a bit tired of just sitting and waiting. So hop on our spacecraft, because today you have a very important mission. To search for alien life. How would we prepare for this journey? What kind of life would we be looking for? And what would happen if we found it?
So far, we detected over 4,000 exoplanets in our galaxy. And there may be as many as trillions. To make your expedition easier, you’d need to consult with NASA first. NASA has developed the Confidence of Life Detection scale (CoLD) to measure progress in life detection research. The scale has seven levels, ranging from signal detection to follow-up studies once life beyond Earth is confirmed.
First, you’d need to look for biosignatures. This is physical evidence of past or present life on another planet, such as chemical compounds or molecules that indicate biological processes. If an alien astronomer was taking measurements of Earth, they would look for oxygen and methane. Those are biosignatures that indicate life on our planet.
If you’re a celestial technology geek, you might scan for technosignatures. These are signs showing the negative uses of technology that cause artificial air pollution. This means that aliens could figure out we exist because of all that smog we send into the atmosphere. Once a signal is detected, the next step would be to make sure there are no measurement errors or contamination.
If the signal is indeed accurate, the real work begins. In the next level, scientists would try to predict what type of source could generate such a signal. If it was then confirmed it couldn’t have come from a non-biological source, we’d be now on level 4. The next level would be to test the signal against other measurement techniques.
Once everything was verified, we would be able to proudly say we found alien life, and scientists would be able to kickstart follow-up studies at level 7. Now that you know what to look for, where would you look for it? You could start this search in our cosmic backyard. Alien life could be hiding on the subsurface oceans of Europa, one of Jupiter’s moons, or deep beneath the surface of Mars.
Ground telescopes have already detected methane on Mars, sending probes to measure surface levels. That already puts you on the second level of the CoLD scale. Or you could go further and look for alien life on rocky planets outside our Solar System. You’d need to locate planets orbiting a star in its habitable zone.
That’s the area where a planet is not too close to its star and not too far, allowing for temperatures to be just right for liquid water to form. Scientists have already done the hard work for you here. Using the Kepler Object of Interest Exoplanet Archive, researchers identified systems that might have rocky planets that meet the criteria. They found 24 super-habitable planets.
And one of them is very promising. KOI-5715.01 is roughly one billion years older than Earth, which means it’s had enough time for life to develop. Scientists estimate that the best chance of discovering life is on planets between 5 and 8 billion years old. This makes KOI-5715.01 a perfect candidate. While it’s a bit cooler than our planet, it could support life if it contained enough greenhouse gasses.
So let’s say you detected biosignatures on KOI-5715.01. Now you’ve got yourself a potentially habitable exoplanet. NASA would then have to confirm that there were no measurement errors and that the planet really has the potential to host life. The next step would be to predict what type of source could generate such a signal. Scientists would need to confirm this signature couldn’t have come from a non-biological source.
Once that was done, you’d be on level 4 of the CoLD scale. At this level, scientists would test the signal with other advanced measurement methods. NASA’s powerful James Webb Space Telescope would confirm the exoplanet contains a strong signature for life. You would be able to proudly say you found alien life, and scientists would be able to kickstart follow-up studies at level 7.
That means you’d now be ready to fasten your seatbelt and see these aliens for yourself. But how would you get there? That’s when things would get tricky. KOI-5715.01 is located almost three light-years away from us. That’s 700 times further away than Proxima Centauri, the closest star to our Solar System. If we used developing ionic propulsion engines, it would take over 55 million years to get there.
You’d have to make use of some futuristic solutions. Like a laser sail. This technology uses ultra-thin mirrors to capture the momentum of light from stars and then uses this momentum to push a spacecraft to high speeds. If you managed to build laser sails with diameters of 320 km (200 mi), you might be able to reach KOI-5715.01 in about 8,500 years.
Setting aside the fact that you wouldn’t live that long, what would you find once you got there? Alien life could be extremely complex or very basic, and the alien’s appearance would depend on the world they evolved on. Things like gravity, density and the amount of energy given off by its star. They would probably have something that resembles fingers or tentacles to build tools.
And since two legs and two arms are more efficient than four legs, the aliens might have evolved like us to walk upright. Would you like to invite them for a stroll? Well, first you’d need to figure they would have some form of communication. And it might be a little more advanced than speech or writing. They might just exchange pheromones, or even use telepathy. And finally, they would need to reproduce.
We can’t be sure if alien reproduction happens by seeding, fission or egg-laying. So it’s best to leave the romantic stuff here on Earth. While your journey to find alien life might be successful in our hypothetical story, in reality, it’s still very far-fetched. With technology evolving to detect signals from outer space, we might be able to identify them at some point. But there would still be the issue of getting to them. What good does it do knowing something is out there if we can never see it up close?
- “NASA Is Thinking Of New Ways To Find Aliens… If They Exist”. Elizabeth Rayne. 2021. syfy.com.
- “A Call For A Methodical Approach To Identifying Life Beyond Earth”. Bob Yirka. 2021. phys.org.
- “What are chemical signs of life beyond Earth?”. Ariana Remmel. 2020. cen.acs.org.
- “A new frontier is opening in the search for extraterrestrial life”. Adam Frank. 2020. washingtonpost.com.
- “Can We Find Life? | The Search For Life – Exoplanet Exploration: Planets Beyond Our Solar System”. 2022. exoplanets.nasa.gov.