Tech
The best places to find extraterrestrial life in our solar system, ranked
Unlike the myriad of new exoplanets we’re identifying every year, when it comes to worlds in the solar system, we have the ability to send probes to these places and study them directly. “We can measure things that would be impossible to measure with telescopes,” says David Catling, an astrobiologist at the University of Washington. They could study things up close, maybe fly into the atmosphere or land on the surface, and perhaps one day even bring back samples that could reveal whether these planets and moons are home to materials or fossils that are evidence of life—or perhaps life itself.
Here are the 10 best places in the solar system to look for extraterrestrial life, subjectively ranked by yours truly for how likely we are to find life—and how easy it would be to find it if it’s there.
NASA
10. Triton
Triton is the largest moon of Neptune, and one of the most exotic worlds in the solar system. It’s one of only five moons in the solar system known to be geologically active, as evidenced by its active geysers that spew sublimated nitrogen gas. Its surface is mostly frozen nitrogen, and its crust is made of water ice, and it has an icy mantle. Yes, this is a cold, cold world. But in spite of that, it seems to get some heat generated by tidal forces (gravitational friction between Triton and Neptune), and that could help warm up the waters and give rise to life through any organics that might exist on the moon.
But actually finding life on Triton seems like a very distant possibility. The only mission to ever visit the world was Voyager 2 in 1989. The window for such a mission opens up only every 13 years. The best opportunity to visit Triton would be the proposed Trident mission (which seems unlikely to get launched after NASA just greenlighted two new missions to Venus later this decade). And lastly, the horrendous cold tempers hopes that life could stay unfrozen for long enough to make a home for itself.
NASA / JPL-CALTECH / UCLA / MPS / DLR / IDA / JUSTIN COWART
9. Ceres
The largest asteroid and smallest dwarf planet in the solar system could be home to liquid water, sitting deep underground. Ceres, a dwarf planet that sits between Mars and Jupiter, was studied by NASA’s Dawn probe from orbit from 2015 to 2018. Scientists are still unpacking and analyzing that data, but tantalizing studies in the past few years suggest there’s an ocean sitting 25 miles below the surface, and could stretch for hundreds of miles. It would almost certainly be extremely salty—which would keep the water from freezing even well below 0°C. Dawn even found evidence of organic compounds on Ceres that could act as raw materials for life.
But Ceres ranks second-to-last on our list because its habitability has too many questions attached. The evidence of subsurface water and the organic materials is still very new. Even if those things are there, it would need some source of heat and energy that could actually help encourage that water and organic material to react in such a way that it leads to life. And even if that occurred, finding that life means we have to drill at least two-dozen miles into the ground to access that water and study it. Lastly, Ceres is tiny—more than 13 times smaller than Earth. It’s not yet clear how that fraction of gravity could affect life on the dwarf planet, but if Earth is our compass for what’s habitable, Ceres’s small size is probably not an asset. There’s no shortage of new proposals for future missions to study the dwarf planet, including ones that would even attempt a sample return mission. But nothing is going up soon.
NASA/JPL/UNIVERSITY OF ARIZONA
8. Io
Boasting over 400 active volcanoes, Io is the most geologically active world in the solar system. All of that activity is thought to be caused by tidal heating created as Io’s interior is gravitationally pulled between Jupiter and the other Jovian moons. The volcanism results in a huge coating of sulfur and sulfur dioxide frost (yes, that’s a thing!) across the globe, along with a super thin sulfur dioxide atmosphere. There might even be a subsurface ocean on Io, but it would be made of magma, not water.
Life on Io is very unlikely. But all that heat is a bit of an encouraging sign. There may be locations on the surface or underground that aren’t overwhelmed by the volcanic activity—more temperate places where hardy forms of life have found a way to survive. We wouldn’t be able to study those spots directly, but a probe might be able to find evidence of life if it gets lucky.
That’s easier said than done. The best chance of studying Io is through a proposed NASA mission called Io Volcano Observer (IVO), which if approved would launch in 2029 and do ten flybys of Io. But like Trident, IVO was vying for the same mission spots that were snatched by two upcoming Venus missions.
NASA/JPL/ DLR (GERMAN AEROSPACE CENTER)
7. Calisto
Calisto’s claim to fame is that it has the oldest surface in the solar system. That doesn’t really mean much in terms of habitability though. Where Calisto shines for our purposes is that it’s another moon that’s thought to have a vast subsurface ocean, 155 miles underground. It also retains a thin atmosphere of hydrogen, carbon dioxide, and oxygen, which is more diverse and Earth-like than most of the other solar system moons that could be habitable.
Still, Callisto’s chances of hosting life are not as favorable as other worlds, namely because it’s still pretty damn cold. Our next best chance of really exploring it will be the European Space Agency’s Jupiter Icy Moon Explorer (JUICE), launching next year and set to explore three of Jupiter’s moons. JUICE will make several close flybys of Callisto during its mission.
NASA/JPL
6. Ganymede
The largest moon to orbit Jupiter, and simply the largest moon in the solar system, is covered up in an icy shell. But underneath that surface is home to a global underground saltwater ocean that might contain more water than all of Earth’s own oceans combined. Naturally, all that water has scientists hopeful that some kind of life could exist on the moon. The moon even has a very thin oxygen atmosphere—nothing to write home about, but it’s something neat. And Ganymede has something else no other moon in the solar system has: a magnetic field. A magnetic field is critical for protecting worlds from harmful radiation spewed by the sun.
But Ganymede isn’t perfect. A subsurface ocean is difficult to study, so if there’s life on the planet, we’re going to have a difficult time finding it. And so far, there has not yet been a dedicated mission to study Ganymede, although the JUICE will be the most in-depth investigation of Ganymede when it enters the moon’s orbit in 2032. It may have an opportunity to peer down at the surface and study the interior using radar, and clue scientists into Ganymede’s potential habitability.
ESA – C. CARREAU
5. Venus
Here at the halfway point is where we start to get into the good stuff. Venus has surface temperatures that are hot enough to melt lead, and surface pressures that are more than 80 times as harsh as what we experience on Earth. And yet, maybe Venus is home to life! Those prospects ignited last year when researchers detected phosphine gas in very thick Venusian atmosphere. On Earth, phosphine is primarily produced naturally by life in oxygen-poor ecosystems, which raises the possibility that there might be life on Venus responsible for producing it as well. And the most likely scenario would be microbial life that’s hanging within the clouds—airborne life, basically.
Now, the phosphine detections have come under scrutiny, and the idea of airborne life is certainly not something all scientists can get behind. But this and other work that’s explored Venus’s history of water have renewed a lot of great interest into the idea that Venus may have once been habitable, and might still be. The new DAVINCI+ and VERITAS missions that NASA will launch late this decade won’t find life, but they will get us closer to answering that question more concretely.
NASA/JPL/SPACE SCIENCE INSTITUTE
4. Enceladus
Saturn’s sixth largest moon is completely covered in clean ice, making it one of the most reflective bodies in the solar system. Its surface is ice cold, but there’s quite a bit of activity going on underneath. The moon ejects plumes that contain a myriad of different compounds, including salt water, ammonia, and organic molecules like methane and propane. Enceladus is thought to have a global salty ocean. And NASA’s found evidence of hydrothermal activity deep underground, which could very well provide a source of heat that’s necessary to give life a chance to evolve and thrive.
In some ways, Enceladus ought to be higher up my list than Titan, were it not for the fact that there just simply isn’t any mission on the books right now to study it. Plenty of proposals have been debated for the last several years, including several under NASA. All are geared toward an astrobiological investigation that would look more closely for signs that Enceladus is habitable to life. While digging underground into the ocean would be the most surefire way to determine whether the moon is home to life, we might also catch a lucky break and be able to detect biosignatures that have been spewed up by the moon’s cryovolcanoes (volcanos that erupt vaporized materials like water or ammonia rather than molten rock). But not for a long time.
NASA/JPL/UNIVERSITY OF ARIZONA/UNIVERSITY OF IDAHO
3. Titan
Titan, Saturn’s largest moon, is another world that sets itself apart from the rest of the solar system. It has one of the most robust atmospheres for a rocky world in the solar system outside of Earth and Venus. It’s teeming with different bodies of liquid: lakes, rivers, and seas. But they’re not made of water—they’re made of methane and other hydrocarbons. Titan is extremely rich in organic materials, so it’s already rich in the raw materials needed for life. And it may also have a subsurface ocean of water as well, though this will need to be verified.
Scientists have just the mission lined up: the NASA Dragonfly mission, which will send a drone helicopter to explore Titan’s atmosphere directly and give us a much needed sense of exactly how developed its prebiotic chemistry runs. That mission launches in 2027 and will arrive at Titan in 2034.
NASA/JPL/UNIVERSITY OF ARIZONA
2. Europa
Jupiter’s moon has an icy shell that’s 10 to 15 miles thick covering up a huge subsurface ocean that’s heated up by tidal forces. That heating is thought to help create an internal circulation system that keeps waters moving and replenishes the icy surface on a regular basis. This means the ocean floor is interacting with the surface—which means if we want to determine whether life exists in those subsurface oceans, we may not necessarily need to go all the way down there. Scientists have found deposits of clay-like minerals associated with organic materials on Europa. And it’s suspected that radiation hitting the icy surface could result in oxygen that might find its way into the subsurface oceans and be used by emerging life. All the ingredients for life are potentially here.
Luckily, we’re set to study Europa in great detail. JUICE will make two flybys of Europa during its time in the Jovian system. But the marquee mission on the books is Europa Clipper, a spacecraft that would conduct low-altitude flights that would attempt to study and characterize the surface, and investigate the subsurface environment as best it can. Clipper launches in 2024, and will reach Europa in 2030.
NASA/JPL-CALTECH
1. Mars
Mars takes the top spot for several reasons. We know it was once habitable billions of years ago, when it had lakes and rivers of liquid water on its surface. We know it had a robust atmosphere back then to keep things warm and comfy. And we currently have a rover on the surface, Perseverance, whose express goal is to look for signs of ancient life. It will even secure samples that we’ll one day bring back to Earth to study in the lab.
So what does that have to do with finding current life? Well, if there are signs of ancient life, it’s possible life on Mars still exists. Probably not on the surface, but maybe underground. There have already been a few big studies that have used radar observations to show that reservoirs of liquid water probably exist a couple kilometers below the surface. We’ve found bacteria on Earth surviving in similar conditions, so it’s entirely possible something is living in those parts of Mars as well. Getting down there will be insanely difficult, but if we have reason to believe something is lurking in these reservoirs, it’ll be all hands on deck to figure out how we can get there and see for ourselves.
My senior spring in high school, I decided to defer my MIT enrollment by a year. I had always planned to take a gap year, but after receiving the silver tube in the mail and seeing all my college-bound friends plan out their classes and dorm decor, I got cold feet. Every time I mentioned my plans, I was met with questions like “But what about school?” and “MIT is cool with this?”
Yeah. MIT totally is. Postponing your MIT start date is as simple as clicking a checkbox.
COURTESY PHOTO
Now, having finished my first year of classes, I’m really grateful that I stuck with my decision to delay MIT, as I realized that having a full year of unstructured time is a gift. I could let my creative juices run. Pick up hobbies for fun. Do cool things like work at an AI startup and teach myself how to create latte art. My favorite part of the year, however, was backpacking across Europe. I traveled through Austria, Slovakia, Russia, Spain, France, the UK, Greece, Italy, Germany, Poland, Romania, and Hungary.
Moreover, despite my fear that I’d be losing a valuable year, traveling turned out to be the most productive thing I could have done with my time. I got to explore different cultures, meet new people from all over the world, and gain unique perspectives that I couldn’t have gotten otherwise. My travels throughout Europe allowed me to leave my comfort zone and expand my understanding of the greater human experience.
“In Iceland there’s less focus on hustle culture, and this relaxed approach to work-life balance ends up fostering creativity. This was a wild revelation to a bunch of MIT students.”
When I became a full-time student last fall, I realized that StartLabs, the premier undergraduate entrepreneurship club on campus, gives MIT undergrads a similar opportunity to expand their horizons and experience new things. I immediately signed up. At StartLabs, we host fireside chats and ideathons throughout the year. But our flagship event is our annual TechTrek over spring break. In previous years, StartLabs has gone on TechTrek trips to Germany, Switzerland, and Israel. On these fully funded trips, StartLabs members have visited and collaborated with industry leaders, incubators, startups, and academic institutions. They take these treks both to connect with the global startup sphere and to build closer relationships within the club itself.
Most important, however, the process of organizing the TechTrek is itself an expedited introduction to entrepreneurship. The trip is entirely planned by StartLabs members; we figure out travel logistics, find sponsors, and then discover ways to optimize our funding.
COURTESY PHOTO
In organizing this year’s trip to Iceland, we had to learn how to delegate roles to all the planners and how to maintain morale when making this trip a reality seemed to be an impossible task. We woke up extra early to take 6 a.m. calls with Icelandic founders and sponsors. We came up with options for different levels of sponsorship, used pattern recognition to deduce the email addresses of hundreds of potential contacts at organizations we wanted to visit, and all got scrappy with utilizing our LinkedIn connections.
And as any good entrepreneur must, we had to learn how to be lean and maximize our resources. To stretch our food budget, we planned all our incubator and company visits around lunchtime in hopes of getting fed, played human Tetris as we fit 16 people into a six-person Airbnb, and emailed grocery stores to get their nearly expired foods for a discount. We even made a deal with the local bus company to give us free tickets in exchange for a story post on our Instagram account.
This is today’s edition of The Download, our weekday newsletter that provides a daily dose of what’s going on in the world of technology.
How ubiquitous keyboard software puts hundreds of millions of Chinese users at risk
For millions of Chinese people, the first software they download onto devices is always the same: a keyboard app. Yet few of them are aware that it may make everything they type vulnerable to spying eyes.
QWERTY keyboards are inefficient as many Chinese characters share the same latinized spelling. As a result, many switch to smart, localized keyboard apps to save time and frustration. Today, over 800 million Chinese people use third-party keyboard apps on their PCs, laptops, and mobile phones.
But a recent report by the Citizen Lab, a University of Toronto–affiliated research group, revealed that Sogou, one of the most popular Chinese keyboard apps, had a massive security loophole. Read the full story.
—Zeyi Yang
Why we should all be rooting for boring AI
Earlier this month, the US Department of Defense announced it is setting up a Generative AI Task Force, aimed at “analyzing and integrating” AI tools such as large language models across the department. It hopes they could improve intelligence and operational planning.
But those might not be the right use cases, writes our senior AI reporter Melissa Heikkila. Generative AI tools, such as language models, are glitchy and unpredictable, and they make things up. They also have massive security vulnerabilities, privacy problems, and deeply ingrained biases.
Applying these technologies in high-stakes settings could lead to deadly accidents where it’s unclear who or what should be held responsible, or even why the problem occurred. The DoD’s best bet is to apply generative AI to more mundane things like Excel, email, or word processing. Read the full story.
This story is from The Algorithm, Melissa’s weekly newsletter giving you the inside track on all things AI. Sign up to receive it in your inbox every Monday.
The ice cores that will let us look 1.5 million years into the past
To better understand the role atmospheric carbon dioxide plays in Earth’s climate cycles, scientists have long turned to ice cores drilled in Antarctica, where snow layers accumulate and compact over hundreds of thousands of years, trapping samples of ancient air in a lattice of bubbles that serve as tiny time capsules.
By analyzing those cores, scientists can connect greenhouse-gas concentrations with temperatures going back 800,000 years. Now, a new European-led initiative hopes to eventually retrieve the oldest core yet, dating back 1.5 million years. But that impressive feat is still only the first step. Once they’ve done that, they’ll have to figure out how they’re going to extract the air from the ice. Read the full story.
—Christian Elliott
This story is from the latest edition of our print magazine, set to go live tomorrow. Subscribe today for as low as $8/month to ensure you receive full access to the new Ethics issue and in-depth stories on experimental drugs, AI assisted warfare, microfinance, and more.
The must-reads
I’ve combed the internet to find you today’s most fun/important/scary/fascinating stories about technology.
1 How AI got dragged into the culture wars
Fears about ‘woke’ AI fundamentally misunderstand how it works. Yet they’re gaining traction. (The Guardian)
+ Why it’s impossible to build an unbiased AI language model. (MIT Technology Review)
2 Researchers are racing to understand a new coronavirus variant
It’s unlikely to be cause for concern, but it shows this virus still has plenty of tricks up its sleeve. (Nature)
+ Covid hasn’t entirely gone away—here’s where we stand. (MIT Technology Review)
+ Why we can’t afford to stop monitoring it. (Ars Technica)
3 How Hilary became such a monster storm
Much of it is down to unusually hot sea surface temperatures. (Wired $)
+ The era of simultaneous climate disasters is here to stay. (Axios)
+ People are donning cooling vests so they can work through the heat. (Wired $)
4 Brain privacy is set to become important
Scientists are getting better at decoding our brain data. It’s surely only a matter of time before others want a peek. (The Atlantic $)
+ How your brain data could be used against you. (MIT Technology Review)
5 How Nvidia built such a big competitive advantage in AI chips
Today it accounts for 70% of all AI chip sales—and an even greater share for training generative models. (NYT $)
+ The chips it’s selling to China are less effective due to US export controls. (Ars Technica)
+ These simple design rules could turn the chip industry on its head. (MIT Technology Review)
6 Inside the complex world of dissociative identity disorder on TikTok
Reducing stigma is great, but doctors fear people are self-diagnosing or even imitating the disorder. (The Verge)
7 What TikTok might have to give up to keep operating in the US
This shows just how hollow the authorities’ purported data-collection concerns really are. (Forbes)
8 Soldiers in Ukraine are playing World of Tanks on their phones
It’s eerily similar to the war they are themselves fighting, but they say it helps them to dissociate from the horror. (NYT $)
9 Conspiracy theorists are sharing mad ideas on what causes wildfires
But it’s all just a convoluted way to try to avoid having to tackle climate change. (Slate $)
10 Christie’s accidentally leaked the location of tons of valuable art 
Seemingly thanks to the metadata that often automatically attaches to smartphone photos. (WP $)
Quote of the day
“Is it going to take people dying for something to move forward?”
—An anonymous air traffic controller warns that staffing shortages in their industry, plus other factors, are starting to threaten passenger safety, the New York Times reports.
The big story
Inside effective altruism, where the far future counts a lot more than the present
October 2022
Since its birth in the late 2000s, effective altruism has aimed to answer the question “How can those with means have the most impact on the world in a quantifiable way?”—and supplied methods for calculating the answer.
It’s no surprise that effective altruisms’ ideas have long faced criticism for reflecting white Western saviorism, alongside an avoidance of structural problems in favor of abstract math. And as believers pour even greater amounts of money into the movement’s increasingly sci-fi ideals, such charges are only intensifying. Read the full story.
—Rebecca Ackermann
We can still have nice things
A place for comfort, fun and distraction in these weird times. (Got any ideas? Drop me a line or tweet ’em at me.)
+ Watch Andrew Scott’s electrifying reading of the 1965 commencement address ‘Choose One of Five’ by Edith Sampson.
+ Here’s how Metallica makes sure its live performances ROCK. ($)
+ Cannot deal with this utterly ludicrous wooden vehicle.
+ Learn about a weird and wonderful new instrument called a harpejji.
