The technical terms for the seven minutes of terror is “entry, descent, and landing,” or EDL. It starts when the spacecraft enters the Martian upper atmosphere at around 20,000 kilometers per hour (12,500 miles per hour) and faces rapidly increasing temperatures. Perseverance is protected by a heat shield and shell, as well as a suite of 28 sensors that monitor hot gases and winds. Temperatures peak at a punishing 13,00 °C (2,400 °F).
About four minutes into EDL—roughly 11 kilometers (seven miles) above the surface and still hurtling to the ground at about 1,500 km/h (940 mph)—the rover deploys a 21-meter parachute The spacecraft will get rid of its heat shield soon. Underneath are a slew of other radar instruments and cameras that will be used to set the spacecraft down in a safe spot. Software called Terrain-Relative Navigation processes images taken by the cameras and compares them with an onboard topographical map to figure out where the spacecraft is and which potential safe spots it should head for.
At a little less than six minutes into EDL and around two kilometers in the air, the outer shell and parachute separate from the rover, and Perseverance heads directly for the ground. The descent stage (attached on top of the rover) uses its thrusters to find a safe spot within 10 to 100 meters of its current drop location, and slows down to around 2.7 km/h (1.7 mph). Nylon cords on the descent stage lower the rover to the ground from 20 meters (66 feet) in the air. Once the rover touches the ground, the cords are severed and the descent stage flies away to crash into the ground from a safe distance. Perseverance is now at its new home.
Spirit and Opportunity helped us better understand the history of water on Mars, and Curiosity found evidence of complex organics—carbon-rich molecules that are the raw ingredients for life. Combined, this evidence told us Mars may have been habitable in the past. Perseverance is going to take the next big step:looking for signs of ancient extraterrestrial life.
Why Jezero crater? It’s a former lake bed that’s 3.8 billion years old. A river used to carry water into it, and it is at the river delta where sediments could have deposited preserved organic compounds and minerals associated with biological life.
Twenty-three cameras on Perseverance will study Mars for evidence of life. The most important of these are the Mastcam-Z camera, which can take stereoscopic and panoramic images and has an extraordinarily high zoom capability to highlight targets (such as soil patterns and old sediment formations) that deserve closer study; SuperCam, which can investigate chemical and mineral composition in the rock and has a microphone that will be used to listen to the Martian weather; and the PIXL and SHERLOC spectrometers, which will look for complex molecules that indicate biology. SHERLOC’s Watson camera will also do some microscopic imaging down to a resolution of 100 microns (hardly bigger than the width of a human hair).
Briony Horgan, a planetary scientist at Purdue University who’s part of the Mastcam-Z team, says scientists are most interested in finding organic matter that’s either heavily concentrated or could only be the result of biological activity, such as stromatolites (fossilized remains created by layers of bacteria). “If we find particular patterns, it could qualify as a biosignature that’s evidence of life,” she says. “Even if it’s not concentrated, if we see it in the right context, it could be a really powerful sign of a real biosignature.”
After Perseverance lands, engineers will spend several weeks testing and calibrating all instruments and functions before the science investigation begins in earnest. Once that’s over, Perseverance will spend a couple more months driving out to the first exploration sites at Jezero crater. We could find evidence of life on Mars as soon as this summer—if it was ever there.
New world, new tech
Like any new NASA mission, Perseverance is also a platform for demonstrating some of the most state-of-the-art technology in the solar system.
One is MOXIE, a small device that seeks to turn the carbon-dioxide-heavy Martian atmosphere into usable oxygen through electrolysis (using an electric current to separate elements). This has been done before on Earth, but it’s important to prove that it works on Mars if we hope humans can live there one day. Oxygen production could not only provide a Martian colony with breathable air; it could also be used to generate liquid oxygen for rocket fuel. MOXIE should have about 10 opportunities to make oxygen during Perseverance’s first two years, during different seasons and times of the day. It will run for about an hour each time, producing 6 to 10 grams of oxygen per session.
There’s also Ingenuity, a 1.8-kilogram helicopter that could take the first powered controlled flight ever made on another planet. Deploying Ingenuity (which is stowed underneath the rover) will take about 10 days. Its first flight will be about three meters into the air, where it will hover for about 20 seconds. If it successfully flies in Mars’s ultra-thin atmosphere (1% as dense as Earth’s), Ingenuity will have many more chances to fly elsewhere. Two cameras on the helicopter will help us see exactly what it sees. On its own, Ingenuity won’t be critical for exploring Mars, but its success could pave the way for engineers to think about new ways to explore other planets when a rover or lander will not suffice.
Neither of those demonstrations will be the marquee moment for Perseverance. The highlight of the mission, which may take 10 years to realize, will be the return of Martian soil samples to Earth. Perseverance will drill into the ground and collect more than 40 samples, most of which will be returned to Earth as part of a joint NASA-ESA mission. NASA officials suggest that this mission could come in either 2026 or 2028, which means the earliest they may be returned to Earth is 2031.
Collecting such samples is no small feat. Robotics company Maxar built the sample handling arm (SHA) that controls the drilling mechanism to collect cores of Martian soil from the ground. The company had to build something that worked autonomously, with hardware and electronics that could withstand temperature swings from -73 °C (100 °F) at night to more than 20 °C (70 °F) during the day. And most important, it had to build something that could contend with the Martian dust.
“When you’re talking about a moving mechanism that has to apply force and go exactly where you need it to go, you can’t have a tiny little dust particle stopping the whole show,” says Lucy Condakchian, the general manager of robotics at Maxar. SHA, located underneath the rover itself, is exposed to a ton of dust kicked up by the rover’s wheels or by drilling. Various innovations should help it withstand this problem, including new lubricants and a metallic accordion design for its lateral (front-to-back) movement.
Before any of those things are proved to work, however, the rover needs to make it to Mars in one piece.
“It never gets old,” says Condakchian. “I’m just as nervous as I’ve been on the previous missions. But it’s a good nervous—an excitement to be doing this again.”
How do I know if egg freezing is for me?
The tool is currently being trialed in a group of research volunteers and is not yet widely available. But I’m hoping it represents a move toward more transparency and openness about the real costs and benefits of egg freezing. Yes, it is a remarkable technology that can help people become parents. But it might not be the best option for everyone.
Read more from Tech Review’s archive
Anna Louie Sussman had her eggs frozen in Italy and Spain because services in New York were too expensive. Luckily, there are specialized couriers ready to take frozen sex cells on international journeys, she wrote.
Michele Harrison was 41 when she froze 21 of her eggs. By the time she wanted to use them, two years later, only one was viable. Although she did have a baby, her case demonstrates that egg freezing is no guarantee of parenthood, wrote Bonnie Rochman.
What happens if someone dies with eggs in storage? Frozen eggs and sperm can still be used to create new life, but it’s tricky to work out who can make the decision, as I wrote in a previous edition of The Checkup.
Meanwhile, the race is on to create lab-made eggs and sperm. These cells, which might be made from a person’s blood or skin cells, could potentially solve a lot of fertility problems—should they ever prove safe, as I wrote in a feature for last year’s magazine issue on gender.
Researchers are also working on ways to mature eggs from transgender men in the lab, which could allow them to store and use their eggs without having to pause gender-affirming medical care or go through other potentially distressing procedures, as I wrote last year.
From around the web
The World Health Organization is set to decide whether covid still represents a “public health emergency of international concern.” It will probably decide to keep this status, because of the current outbreak in China. (STAT)
Researchers want to study the brains, genes, and other biological features of incarcerated people to find ways to stop them from reoffending. Others warn that this approach is based on shoddy science and racist ideas. (Undark)
A watermark for chatbots can expose text written by an AI
For example, since OpenAI’s chatbot ChatGPT was launched in November, students have already started cheating by using it to write essays for them. News website CNET has used ChatGPT to write articles, only to have to issue corrections amid accusations of plagiarism. Building the watermarking approach into such systems before they’re released could help address such problems.
In studies, these watermarks have already been used to identify AI-generated text with near certainty. Researchers at the University of Maryland, for example, were able to spot text created by Meta’s open-source language model, OPT-6.7B, using a detection algorithm they built. The work is described in a paper that’s yet to be peer-reviewed, and the code will be available for free around February 15.
AI language models work by predicting and generating one word at a time. After each word, the watermarking algorithm randomly divides the language model’s vocabulary into words on a “greenlist” and a “redlist” and then prompts the model to choose words on the greenlist.
The more greenlisted words in a passage, the more likely it is that the text was generated by a machine. Text written by a person tends to contain a more random mix of words. For example, for the word “beautiful,” the watermarking algorithm could classify the word “flower” as green and “orchid” as red. The AI model with the watermarking algorithm would be more likely to use the word “flower” than “orchid,” explains Tom Goldstein, an assistant professor at the University of Maryland, who was involved in the research.
The Download: watermarking AI text, and freezing eggs
That’s why the team behind a new decision-making tool hope it will help to clear up some of the misconceptions around the procedure—and give would-be parents a much-needed insight into its real costs, benefits, and potential pitfalls. Read the full story.
This story is from The Checkup, MIT Technology Review’s weekly newsletter giving you the inside track on all things health and biotech. Sign up to receive it in your inbox every Thursday.
I’ve combed the internet to find you today’s most fun/important/scary/fascinating stories about technology.
1 Elon Musk held a surprise meeting with US political leaders
Allegedly in the interest of ensuring Twitter is “fair to both parties.” (Insider $)
+ Kanye West’s presidential campaign advisors have been booted off Twitter. (Rolling Stone $)
+ Twitter’s trust and safety head is Musk’s biggest champion. (Bloomberg $)
2 We’re treating covid like flu now
Annual covid shots are the next logical step. (The Atlantic $)
3 The worst thing about Sam Bankman-Fried’s spell in jail?
Being cut off from the internet. (Forbes $)
+ Most crypto criminals use just five exchanges. (Wired $)
+ Collapsed crypto firmFTX has objected to a new investigation request. (Reuters)
4 Israel’s tech sector is rising up against its government
Tech workers fear its hardline policies will harm startups. (FT $)
5 It’s possible to power the world solely using renewable energy
At least, according to Stanford academic Mark Jacobson. (The Guardian)
+ Tech bros love the environment these days. (Slate $)
+ How new versions of solar, wind, and batteries could help the grid. (MIT Technology Review)
6 Generative AI is wildly expensive to run
And that’s why promising startups like OpenAI need to hitch their wagons to the likes of Microsoft. (Bloomberg $)
+ How Microsoft benefits from the ChatGPT hype. (Vox)
+ BuzzFeed is planning to make quizzes supercharged by OpenAI. (WSJ $)
+ Generative AI is changing everything. But what’s left when the hype is gone? (MIT Technology Review)
7 It’s hard not to blame self-driving cars for accidents
Even when it’s not technically their fault. (WSJ $)
8 What it’s like to swap Google for TikTok
It’s great for food suggestions and hacks, but hopeless for anything work-related. (Wired $)
+ The platform really wants to stay operational in the US. (Vox)
+ TikTok is mired in an eyelash controversy. (Rolling Stone $)
9 CRISPR gene editing kits are available to buy online
But there’s no guarantee these experiments will actually work. (Motherboard)
+ Next up for CRISPR: Gene editing for the masses? (MIT Technology Review)
10 Tech workers are livestreaming their layoffs
It’s a candid window into how these notoriously secretive companies treat their staff. (The Information $)