Sound waves behave quite differently on Mars than on Earth.
- NASA's Perseverance rover landed on Mars on February 18, and is currently preparing to begin its main mission of searching for signs of ancient life.
- The rover contains two microphone systems, one of which was recently used to capture sounds of the rover traveling at speeds below .01 mph.
- NASA hopes to return Perseverance's rock collection to Earth by 2031.
It's been over a month since Perseverance landed on Mars, where the rover will search for evidence of ancient life. Since the landing on February 18, Perseverance has returned images, conducted tests of its robotic arm and steering system, and recorded the sound of wind on the red planet.
This week, NASA released audio of the six-wheeled rover driving on the surface of Mars, captured by Perseverance's Entry Descent and Landing (EDL) microphones. The 16-minute recording features raw, unedited audio of the rover traveling 90 feet across the Martian surface at speeds approaching about .01 mph.
It's the first time a NASA rover has captured audio of itself driving.
It's also not the most pleasant recording.
"If I heard these sounds driving my car, I'd pull over and call for a tow," Dave Gruel, lead engineer for Mars 2020's EDL Camera and Microphone subsystem, told NASA's Jet Propulsion Laboratory. "But if you take a minute to consider what you're hearing and where it was recorded, it makes perfect sense."
It sounds like that partly because the rover's off-the-shelf EDL microphones weren't intended to capture sounds from the Martian terrain, but rather to record audio as the rover made its descent. And then there's the wheels.
"A lot of people, when they see the images, don't appreciate that the wheels are metal," Vandi Verma, a senior engineer and rover driver at NASA's Jet Propulsion Laboratory in Southern California, told NASA's Jet Propulsion Laboratory. "When you're driving with these wheels on rocks, it's actually very noisy."
Sound waves also behave differently on Mars. Compared to Earth, the red planet's atmosphere is colder, less dense and contains far more carbon dioxide. That means sound waves travel more slowly and quietly, and the atmosphere would absorb more higher-pitched sounds, an effect known as attenuation.
"The variations between Earth and Mars – we have a feeling for that visually," Verma said. "But sound is a whole different dimension: to see the differences between Earth and Mars, and experience that environment more closely."
NASA released an edited version of the audio that filters out some of the screeches and rattles.
Perseverance has a second microphone system included in its SuperCam instrument, which was designed to identify organic compounds on the Martian surface. SuperCam works by firing a laser at rocks and soil, and using a camera and spectrometers to study the composition of the materials.
"SuperCam's laser is uniquely capable of remotely clearing away surface dust, giving all of its instruments a clear view of the targets," Roger Wiens, the project's principal investigator, told NASA.
How do we fly a helicopter on Mars? It takes ingenuity and perseverance. Tune in on Thursday, March 11, 7pm PT (10p… https://t.co/FxHpBCMw8L— NASA JPL (@NASA JPL)1615339147.0
What's next for Perseverance? In April, NASA plans to conduct a test flight of the Ingenuity helicopter, which will fly near the rover to monitor the environment and provide imaging support. Soon after, Perseverance will spend one Mars year (687 Earth days) on its main mission: Collecting arguably the most scientifically significant rock collection in human history. NASA hopes the rocks will contain evidence that life once existed on Mars.
But it might take years to find out, considering that the ultimate goal is to send another spacecraft to Mars to return the rocks to Earth for closer inspection. For that retrieval mission, NASA and the European Space Agency have their sights on launching 2028 and returning in 2031.
The discovery could help astronauts find better ways to grow food in space.
- The bacteria were collected as part of a surveillance program that tasks astronauts with regularly collecting samples from eight sites aboard the International Space Station.
- The bacteria discovered on the space station belong to a family of bacteria that helps plants grow and blocks pathogens.
- Finding sustainable ways to grow food is critical to any long-term space mission.
Three previously unknown strains of bacteria were found growing in the International Space Station, according to a recent genetic analysis. The discovery could help scientists develop better ways to grow food on Mars.
The analysis, published in the journal Frontiers in Microbiology, describes how astronauts collected four strains of bacteria within the space station in 2011, 2015 and 2016. It was part of an ongoing surveillance program that tasks astronauts with monitoring eight sites of the space station for bacterial growth.
Astronauts have already sent hundreds of samples back to Earth for analysis, and thousands more are scheduled to be sent back on return missions.
The newly discovered strains belong to a family of bacteria called Methylobacteriaceae, which is commonly found in soil and freshwater. These bacteria help plants grow, fix nitrogen and stop pathogens.
International Space Station
So, how did these novel microbes get in the space station? They likely came from the plant-growing experiments that astronauts have been conducting for years aboard the ISS, such as the Advanced Plant Habitat, an automated growth chamber that grows plants in space so scientists can study them back on Earth.
The new strains could be beneficial to space farming. After all, it's already clear that the bacteria can survive the conditions of the space station, and the researchers wrote that the strains might possess "biotechnologically useful genetic determinants" that could help astronauts grow food on long-term missions, or on other planets.
"To grow plants in extreme places where resources are minimal, isolation of novel microbes that help to promote plant growth under stressful conditions is essential," study authors Kasthuri Venkateswaran and Nitin K. Singh said in a press release.
"Needless to say, the ISS is a cleanly-maintained extreme environment. Crew safety is the number 1 priority and hence understanding human/plant pathogens are important, but beneficial microbes like this novel Methylobacterium ajmalii are also needed."
To accelerate their understanding of how bacteria behaves in space, Singh and Venkateswaran proposed developing customized equipment that astronauts could use to analyze bacteria on the space station.
"Instead of bringing samples back to Earth for analyses, we need an integrated microbial monitoring system that collect, process, and analyze samples in space using molecular technologies," they said. "This miniaturized 'omics in space' technology — a biosensor development — will help NASA and other space-faring nations achieve safe and sustainable space exploration for long periods of time."
Genome-based phylogenetic tree showing the phylogenetic relationship of Methylobacterium ajmalii sp. nov. with members of the family Methylobacteriaceae.
Credit: Bijlani et al.
NASA is hoping to send humans to Mars by the 2030s, while private companies like SpaceX are aiming to reach the Red Planet this decade. For any Mars mission, developing sustainable ways to grow food is critical. That's mainly because it's impractical for astronauts to pack the food they'll need for the journey, which will take 14 months roundtrip, not including time spent on the planet.
Astronauts also need to stay healthy. The main problem with prepackaged food, besides its weight, is that the nutrients break over time. That's why NASA has been experimenting with growing various types of nutritious plants through projects like Veggie and the more recent Advanced Plant Habitat. These projects help scientists learn about the complexities of growing plants in microgravity, and how plants might grow on Mars.
NASA astronaut and Expedition 64 Flight Engineer Kate Rubins checks out radish plants growing for the Plant Habitat-02 experiment.
But growing plants in space isn't all about nutrition. NASA notes that plants are psychologically beneficial to people, both on Earth and in space. These psychological benefits might become especially important to astronauts on long-term missions millions of miles away from Earth.
Here's how astronaut Peggy Whitson, who worked aboard the International Space Station, described seeing plants in space for the first time:
"It was surprising to me how great 6 soybean plants looked," she told Space Daily. "I guess seeing something green for the first time in a month and a half had a real effect. From a psychological perspective, I think it's interesting that the reaction was as dramatic as it was. [...] I guess if we go to Mars, we need a garden!"
It may be old tech, but it's super-reliable.
It's probably a good idea to stop and take a moment every now and then to marvel at the incredible amount of computing power in your pocket. Today's phones have processors that make the computers of the internet-boom era seem like little more than garage-door openers. Forget about the massive room-sized early computers that couldn't run a game of Pong, much less Panda Pop. Nope, your pocket is packed with power.
It may surprise you then to learn that a processor that was released by IBM and Motorola back in 1997 is the chip that serves as the brain of NASA's cutting-edge Perseverance Mars rover. The craft's developers were more interested in reliability than sheer power, and their solution was a G3 processor, or CPU, used in Apple's Power G3 Macintosh starting in 1998.
The G3 compared to today’s chips
Apple veterans remember the G3 fondly. It was a futuristic, tower-style computer of translucent white and blue. Its side conveniently flipped open to facilitate expansion. It smoked older Macs with a processor operating speed that topped out at a screaming 266 megahertz (MHz).
Not only that, but today's processors are multicore chips, meaning that they're like multiple processors running side by side within the chip. So, see ya later G3, as far as consumer use goes.
Still, the G3 was very reliable, and it was the first of a breed of chips to perform "dynamic branch prediction," an architecture still used today. It involves the CPU predicting upcoming tasks so as to line up its processing resources as efficiently as possible.
Old G3 (left), and the new G3 for Perseverance (right)
Credit: /Henriok/Wikimedia Commons
The chip in Perseverance, the PowerPC 750, isn't even the fastest G3 chip — the single-core chip runs at 200 MHz, which is still 10 times the speed of the chips powering the Spirit and Opportunity rovers, according to NASA.
Perseverance's chip is also not an off-the-shelf PowerPC 750. It's a purpose-built, radiation-hardened version of the chip called the RAD750. Fabricated by BAE Systems, the processor can operate in temperatures between -55 and 125° Celsius (-67 to 257 degrees Fahrenheit), perfect for Mars' frigid atmosphere. Also, because that atmosphere is so thin that its surface is continually bombarded with radiation, the RAD750 can withstand 200,000 to 1,000,000 Rads of radiation.
It's also not the RAD750's first trip to Mars: There was one onboard the Insight craft that landed there in November 2018.
NASA's upcoming Orion craft will also use the RAD750. In 2014, when Orion was announced, NASA's Matt Lemke explained to The Space Review that "it's not about the speed as much as the ruggedness and the reliability. I need to make sure it will always work." Especially attractive was the RAD750's tolerance of radiation: "The one thing we really like about this computer is that it doesn't get destroyed by radiation. It can be upset, but it won't fail. We've done a lot of testing on the different parts in the computer. When it sees radiation, it might have to reset but it will come back up and work again."
The designers of Perseverance were also somewhat parsimonious with onboard memory — every millimeter/gram is precious on a spacecraft. Though storage isn't bad, at 2 GB of Flash memory, there's just 256 megabytes of working RAM and 256 kilobytes of EEPROM (electrically-erasable programmable read-only memory).
Back here on Earth, we're surrounded by RAD750 devices whizzing overhead in about 100 satellites. So far, not one of them has failed. No wonder the chip's been sent on such a critical mission the Red Planet.
"The Expanse" is the best vision I've ever seen of a space-faring future that may be just a few generations away.
- Want three reasons why that headline is justified? Characters and acting, universe building, and science.
- For those who don't know, "The Expanse" is a series that's run on SyFy and Amazon Prime set about 200 years in the future in a mostly settled solar system with three waring factions: Earth, Mars, and Belters.
- No other show I know of manages to use real science so adeptly in the service of its story and its grand universe building.
Yeah, yeah, yeah, I know: Best science fiction show ever. That is a pretty audacious claim and it means I've got some explaining to do. But with 58.5 years of nerdom behind me, including years of watching "Star Trek", "UFO", "Space 1999", "Battlestar Galactica" (the original one that sucked except for the special effects), "Stargate", "The X-Files", "Farscape", "Battlestar Galactica" (the new one that didn't suck) and Firefly I have seen a thing or two concerning science fiction on TV. That's why I'm here ready to stand my ground and proclaim for all nerdom to hear…
"The Expanse" is the greatest science fiction TV show ever. EVER!
For those of you who don't know, "The Expanse" is a series that's run on SyFy and Amazon Prime set about 200 years in the future in a mostly settled solar system (slight spoiler alerts follow). Based on an amazing book series by SA Corey, in this future there are three major political factions in constant conflict with each other. First, there is Earth which remains powerful but is stretched thin by climate change and overpopulation. Then there is Mars, a former colony of Earth, that's now an independent militaristic republic whose technology generally outpaces that of humanity's homeworld. The final faction is "The Belt" which refers to the asteroids and moons of the giant planets. Belters are resource extractors, and they are the oppressed underclass. After generations living on ships and in low-gravity environments, their bodies have changed, making it impossible for many of them to handle the crush of gravity on the inner planets.
The story begins with all three factions at each other's throats. Mars and Earth are in the midst of a long cold war that, occasionally, turns hot. What Earth and Mars have in common, however, is keeping their boot on the neck of the Belters who are, themselves, poised for bloody rebellion. This simmering political, social and military conflict would be enough for a hundred episodes but it's into this pile of dynamite "The Expanse" drops an alien artifact that changes everything and propels the narrative.
Now, the individual elements in what I described above are not really that original. You can find many versions of them in many TV shows across many decades. So, what does "The Expanse" do with these elements that makes it so special? For me the excellence of the show manifests in three distinct ways: characters and acting; universe building; science.
The level of attempted scientific realism in the show is wonderful, extending even to little details like how whiskey spirals out of its bottle due to the Coriolis effect when poured on a rotating space station.
Let's start with characters and acting. No matter how good your science fiction ideas may be, you have to tell your stories through actors pretending to be characters interacting with each other. By its nature, science fiction shows can ask a lot of actors. They have to stare at green screens, pretending to be in awe of an alien mothership that won't get added till post-production CGI; or they dangle from wires emoting through a screen set in the weightlessness of space. It takes serious acting chops to maintain the gravity (or levity) that makes it all believable or better yet relatable. That's why the depth of performances in The Expanse is its best surprise. The recent season, for example, had actor Dominique Tipper killing it across three episodes as Belter engineer Naomi Nagata. Nagata is caught alone on a booby-trapped ship, exhausting herself trying to signal her friends to not attempt a rescue. It's a solo performance reminiscent of Tom Hanks' great work in "Castaway".
Across the seasons, other actors have also filled out their characters with an empathy that's comparable to anything else in any other genre on TV. Thomas Jane's detective Josephus Miller was an epic noir depiction of a man broken by circumstance but still moving towards something better. Shohreh Aghdashloo's foul-mouthed UN leader Chrisjen Avasarala is a skilled politician who will kick your ass and save your world at the same time. And, perhaps best of all, is Wes Chatham's Amos Burton. Born in the worst the streets can offer he became a killer then escaped to become a spaceship mechanic. Chatham plays Burton as simultaneously dangerous, kind, and slightly bewildered, always wanting to do the right thing if he just knew what that was. And don't even get me started on how good Cara Gee is as Belter captain Camina Drummer.
Next, we come to what's called 'universe building' in science fiction. All the great acting needs a fully fleshed out, lived-in world to ground it. How, for example, do the trams work on a hollowed out, spinning asteroid like Ceres that's used as a space settlement? This isn't a physics question. Instead, it means if you arrived on Ceres, where would you find the tram station? What do the maps look like that would help you get around? These are the kind of details that fall both to the writers and the art department. Getting these details wrong means the world your show inhabits will either look cheesy or, worse, sterile, as if all your expensive sets never had anyone live in them.
Happily, everything in "The Expanse" looks lived in. Everything looks like part of an organic whole. The sets and scenes give us a world built by humans for human purposes even if it's a city built into the side of a Martian cliff. From visions of New York City under siege from climate change to the claustrophobic interiors of Belter ships (all webbing, ductwork and grimy computer screens), the universe of "The Expanse" is endlessly rich, interesting, and believable (Adam Savage has a great set of videos on production design in "The Expanse").
Finally, we come to the science, because, after all, this is science fiction. I am not one who demands that my science fiction always get the science right. What matters is that the writers create a self-consistent universe where whatever "science" is invoked remains constant as constraints imposed to provide obstacles and make the story work. But, to my joy, for the most part the "science" used in "The Expanse" is the science I teach in my physics classes. For example, there is no imaginary "artificial gravity" babble. Instead, there is thrust gravity when the engines are on, accelerating spaceships. There is also spin gravity when you're on the inside of something rotating. Other than that, you are "on the float." Just like what will happen in real spaceships and space stations in the future.
The level of attempted scientific realism in the show is wonderful, extending even to little details like how whiskey spirals out of its bottle due to the Coriolis effect when poured on a rotating space station. Most importantly, the writers use the real physics real people will really encounter in real space travel as a kind of extra character in the show. During space battles, as ships roll and pivot, Newton's first law (inertia) means unsecured tools are sent flying across the cabin. That makes them dangerous projectiles our brave heroes must dodge while fighting evil and advancing the storyline. It all makes my physicist's heart weep in gratitude.
Of course, not all the science in "The Expanse" is valid or accurate or correct. But that's OK. No other show I know of manages to use real science so adeptly in the service of its story and its grand universe building. I often rewatch episodes of "The Expanse" just to get a sense of "Oh yeah, that's how it might look." In a way, the show is the best vision I've ever seen of a space-faring future that may be just a few generations away.
Credit: "The Expanse" / Syfy
Now, I get it if you don't agree with me. I love "Star Trek" and I thought "Battlestar Galactica" (the new one) was amazing and I do adore "The Mandalorian". They are all fun and important and worth watching and thinking about. And maybe you love them more than anything else. But when you sum up the acting, the universe building, and the use of real science where it matters, I think nothing can beat "The Expanse". And with a Rotten Tomato average rating of 93%, I'm clearly not the only one who feels this way.
The results could help NASA's Perseverance rover find evidence of ancient life on Mars.
- In a recent study, researchers simulated the environment of ancient Mars and tested whether a type of extremophile found on Earth could grow on fragments of a meteorite from Mars.
- Extremophiles are organisms that have adapted to survive in conditions in which most life forms cannot, such as ice, volcanoes, and space.
- The results showed that the extremophiles were able to convert the rock into energy. What's more, the microbes left behind biosignatures that could help scientists identify evidence of past life on Mars.
Scientists have successfully grown microcrobrial organisms on rocks from Mars, boosting the case that life could have once existed on the Red Planet.
The study, published in Communications Earth & Environment, involved tiny chunks of a Martian meteorite called Northwest Africa 7034, better known by its nickname: Black Beauty. The meteorite was discovered in the Sahara Desert, where it crashed around 1,000 years ago. Today, it's worth 250 times the price of gold.
"Black Beauty is among the rarest substances on Earth, it is a unique Martian breccia formed by various pieces of Martian crust (some of them are dated at 4.42 ± 0.07 billion years) and ejected millions [of] years ago from the Martian surface," study author Tetyana Milojevic, an astrobiologist at the University of Vienna in Austria, told Science Alert.
"We had to choose a pretty bold approach of crushing a few grams of precious Martian rock to recreate the possible look of Mars' earliest and simplest life form."
Ancient Mars probably looked a lot different than the planet does today. NASA data suggest that, billions of years ago, Mars was warmer, wetter, and had a thicker atmosphere, all of which are ingredients for the evolution of life. What kinds of life? It's unclear, but extremophiles are a good bet.
Northwest Africa (NWA) 7034
Extremophiles are organisms that thrive in conditions where most life forms would die. Scientists have observed them in volcanoes, soda lakes, Antarctic ice, and hydrothermal vents. Some have even survived the vacuum of space. The team behind the recent study focused on a particular class of extremophiles called chemolithotrophs, which are microbes that use inorganic compounds as a source of energy.
To test whether chemolithotrophs might have been able to evolve on Mars, the team placed a chemolithtrophic microbe called Metallosphaera sedula onto bits of Black Beauty. The researchers simulated the ancient Martian environment by keeping the microbe-covered rock bits in a bioreactor that controlled temperature and levels of carbon dioxide and air.
The high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) image of the focused ion beam (FIB) section extracted for STEM analysis from the NWA 7034 fragment used in this study
Credit: Milojevic et al.
Using microscopy, the researchers saw that the microbe successfully converted rock pieces into biomass.
"Grown on Martian crustal material, the microbe formed a robust mineral capsule comprised [sic] of complexed iron, manganese and aluminum phosphates," Milojevic told Science Alert.
"Apart from the massive encrustation of the cell surface, we have observed intracellular formation of crystalline deposits of a very complex nature (Fe, Mn oxides, mixed Mn silicates). These are distinguishable unique features of growth on the Noachian Martian breccia, which we did not observe previously when cultivating this microbe on terrestrial mineral sources and a stony chondritic meteorite."
Mars 2020 mission
The study didn't prove that chemolithotrophs or any other type of life ever existed on Mars. But the results did show that the chemolithotrophs left behind unique biosignatures as they converted the rock bits into energy.
With these fingerprints on the books, scientists working with the Mars 2020 mission might be able to find similar biosignatures in rock samples collected or observed by the Perseverance rover, which landed on Mars in February. Rock samples collected by the rover are expected to return to Earth in 2031.