Eliana Willis

CHICAGO — The last key ingredient for life has been discovered on Saturn’s icy moon Enceladus.

Phosphorus is a vital building block of life, used to construct DNA and RNA. Now, an analysis of data from NASA’s Cassini spacecraft reveals that Enceladus’ underground ocean contains the crucial nutrient. Not only that, its concentrations there may be thousands of times greater than in Earth’s ocean, planetary scientist Yasuhito Sekine reported December 14 at the American Geophysical Union’s fall meeting.

Science News headlines, in your inbox

Headlines and summaries of the latest Science News articles, delivered to your email inbox every Friday.

Thank you for signing up!

There was a problem signing you up.

The essential element may abound on many other icy worlds too, holding promise for the search for alien life, said Sekine, of the Tokyo Institute of Technology.

“We knew that Enceladus had most of the elements that are essential for life as we know it — carbon, hydrogen, nitrogen, oxygen and sulfur,” says Morgan Cable, an astrobiologist at the Jet Propulsion Laboratory in Pasadena, Calif., who was not involved in the research. “Now that [phosphorus] has been confirmed … Enceladus now appears to meet all of the criteria for a habitable ocean.”

Many researchers consider Enceladus to be among the most likely places to house extraterrestrial life. It’s a world encased in ice, with an ocean of salty water hidden beneath (SN: 11/6/17). What’s more, in 2005 the Cassini spacecraft observed geysers blasting vapor and ice grains out of Enceladus’ icy shell (SN: 8/23/05). And in that space-faring spray, scientists have detected organic molecules.

But until now, researchers weren’t sure if phosphorus also existed on Enceladus. On Earth’s surface, the element is relatively scarce. Much of the phosphorus is locked away in minerals, and its availability often controls the pace at which life can proliferate.

So Sekine and colleagues analyzed chemical data, collected by the now-defunct Cassini, of particles in Saturn’s E ring, a halo of material ejected from Enceladus’ jets that wraps around Saturn.

Some ice grains in the E ring are enriched in a phosphorus compound called sodium phosphate, the researchers found. They estimate that a kilogram of water from Enceladus’ ocean contains roughly 1 to 20 millimoles of phosphate, a concentration thousands of times greater than in Earth’s big blue ocean.

At the floor of Enceladus’ subsurface ocean, phosphate may arise from reactions between seawater and a phosphate-bearing mineral called apatite, Sekine said, before being ejected through geysers into space. Apatite is often found in carbonaceous chondrites, a primitive, planet-building material (SN: 7/14/17).

From astronomy to zoology

Subscribe to Science News to satisfy your omnivorous appetite for universal knowledge.

But that’s not all. Many other icy ocean worlds may contain apatite as well, Sekine said. Similarly, they too could also carry high levels of phosphate in their oceans. That richness could be a boon for any potential alien organisms.

Though the findings are promising, they give rise to a glaring conundrum, Sekine said. “If life exists [on] Enceladus, why [does] such [an] abundance of chemical energy and nutrients remain?” After all, here on Earth, any available phosphorus is rapidly scavenged by life.

It’s possible that the moon is simply barren of life, Sekine said. But there’s another more hopeful explanation too. Life on frigid Enceladus, he said, may simply consume the nutrient at a sluggish pace. More

Thanks to a bit of good luck, the Mars rover Perseverance has captured the first-ever sound of a Martian dust devil.

The NASA rover has witnessed dusty whirlwinds before. But when this one swept right over Perseverance, the rover’s microphone happened to be turned on. So the first-of-its-kind data include the sounds of dust grains either pinging off the microphone or being transmitted to the mic through the rover’s structure, researchers report December 13 in Nature Communications.

Because the rover’s microphone is turned on only occasionally, the team estimates that such events, when they occur, might be recorded just around 0.5 percent of the time.

[embedded content]
On September 27, 2021, Perseverance’s navigation camera spotted a dust devil (purplish cloud in the images at top, which were processed to reveal the dust) whirling toward it from 50 to 60 meters away. As the whirlwind swept across the rover, Perseverance’s microphone recorded the sound it made, capturing the first-ever audio of a Martian dust devil (middle), and the rover’s instruments detected a slight drop in atmospheric pressure (bottom). These data may someday help researchers better understand dust dynamics on Mars.

Wind speeds in the walls of the dust devil reached nearly 40 kilometers per hour, planetary scientist Naomi Murdoch of the Institut Supérieur de l’Aéronautique et de l’Espace in Toulouse, France, and colleagues report. As with previous whirlwinds detected by other instruments, this late-morning dust devil caused a slight drop in atmospheric pressure and rise in temperature as it swept over the rover on September 27, 2021. It was 25 meters in diameter, at least 118 meters tall and ambled by at about 20 kilometers per hour.

One big surprise, Murdoch says, is that a prodigious amount of dust was airborne in the calm center of the whirlwind as well as in the brisk winds that formed its walls. Data from this event, as well as from other whirlwinds measured by the rover’s instruments, will help researchers better understand how dust gets lifted off the Martian surface (SN: 10/24/06). As of yet, Murdoch says, that remains a mystery to planetary scientists (SN: 7/14/20). More

Late in the evening of February 28, 2021, a coal-dark space rock about the size of a soccer ball fell through the sky over northern England. The rock blazed in a dazzling, eight-second-long streak of light, split into fragments and sped toward the Earth. The largest piece went splat in the driveway of Rob and Cathryn Wilcock in the small, historic town of Winchcombe.

An analysis of those fragments now shows that the meteorite came from the outer solar system, and contains water that is chemically similar to Earth’s, scientists report November 16 in Science Advances. How Earth got its water remains one of science’s enduring mysteries. The new results support the idea that asteroids brought water to the young planet (SN: 5/6/15).

The Wilcocks were not the only ones who found pieces of the rock that fell that night. But they were the first. Bits of the Winchcombe meteorite were collected within 12 hours after they hit the ground, meaning they are relatively uncontaminated with earthly stuff, says planetary scientist Ashley King of London’s Natural History Museum.

The first bits of the Winchcombe meteorite to be recovered were from Rob and Cathryn Wilcock’s driveway in England. The meteorite was so brittle it shattered on impact and made only a small dent in the driveway.R. Wilcock

Other meteorites have been recovered after being tracked from space to the ground, but never so quickly (SN: 12/20/12).

“It’s as pristine as we’re going to get from a meteorite,” King says. “Other than it landing in the museum on my desk, or other than sending a spacecraft up there, we can’t really get them any quicker or more pristine.”

After collecting about 530 grams of meteorite from Winchcombe and other sites, including a sheep field in Scotland, King and colleagues threw a kitchen sink of lab techniques at the samples. The researchers polished the material, heated it and bombarded it with electrons, X-rays and lasers to figure out what elements and minerals it contained.

The team also analyzed video of the fireball from the UK Fireball Alliance, a collaboration of 16 meteor-watching cameras around the world, plus many more videos from doorbell and dashboard cameras. The films helped to determine the meteorite’s trajectory and where it originated.

The meteorite is a type of rare, carbon-rich rock called a carbonaceous chondrite, the team found. It came from an asteroid near the orbit of Jupiter, and got its start toward Earth around 300,000 years ago, a relatively short time for a trip through space, the researchers calculate.

Chemical analyses also revealed that the meteorite is about 11 percent water by weight, with the water locked in hydrated minerals. Some of the hydrogen in that water is actually deuterium, a heavy form of hydrogen, and the ratio of hydrogen to deuterium in the meteorite is similar to that of the Earth’s atmosphere. “It’s a good indication that water [on Earth] was coming from water-rich asteroids,” King says.

Researchers also found amino acids and other organic material in the meteorite pieces. “These are the building blocks for things like DNA,” King says. The pieces “don’t contain life, but they have the starting point for life locked up in them.” Further studies can help determine how those molecules formed in the asteroid that the meteorite came from, and how similar organic material could have been delivered to the early Earth.

“It’s always exciting to have access to material that can provide a new window into an early time and place in our solar system,” says planetary scientist Meenakshi Wadhwa of Arizona State University in Tempe, who was not involved in the study.

She hopes future studies will compare the samples of the Winchcombe meteorite to samples of asteroids Ryugu and Bennu, which were collected by spacecraft and sent back to Earth (SN: 1/15/19). Those asteroids are both closer to Earth than the main asteroid belt, where the Winchcombe meteorite came from. Comparing and contrasting all three samples will build a more complete picture of the early solar system’s makeup, and how it evolved into what we see today. More

Mars might be, geologically speaking, not quite dead.

Researchers have analyzed a slew of recent temblors on the Red Planet and shown that these Marsquakes are probably caused by magma moving deep under the Martian surface. That’s evidence that Mars is still volcanically active, the researchers report October 27 in Nature Astronomy.

Since touching down on Mars four years ago, NASA’s InSight lander has detected more than 1,000 Marsquakes (SN: 11/26/18). Its seismometer records seismic waves, which reveal information about a temblor’s size and location.

Sign Up For the Latest from Science News

Headlines and summaries of the latest Science News articles, delivered to your inbox

Thank you for signing up!

There was a problem signing you up.

Previous studies have determined that several Marsquakes originated from a swath of Martian terrain known as Cerberus Fossae (SN: 5/13/22). This region, which is particularly riddled with faults, is more than 1,000 kilometers from the InSight lander.

But most of the Marsquakes linked to Cerberus Fossae so far have been pretty familiar, scientifically speaking, says Anna Mittelholz, a planetary scientist at Harvard University. Their seismic waves, which are low frequency, “are ones that look much more like what we see for an earthquake,” she says.

Mittelholz and her colleagues have now analyzed a large sample of Marsquakes, including more than 1,000 high-frequency temblors, which look nothing like their earthly brethren. To better understand the origin of the high-frequency quakes, the researchers added together their relatively weak signals. In that stack of seismic waves, the researchers saw a peak in the amount of seismic energy coming from the direction of Cerberus Fossae. That was an impressive undertaking, says Hrvoje Tkalčić, a geophysicist at the Australian National University in Canberra who was not involved with the research. “No study before this one attempted to locate the high-frequency quakes.”

The fact that different types of Marsquakes are all concentrated in one region is a surprise. Previous research has suggested that Marsquakes might be due to Mars’ surface cooling and shrinking over time. That process, which occurs on the moon, would produce temblors evenly spread over the planet, Mittelholz says (SN: 5/13/19). “The expectation was that Marsquakes would originate from all over the place.”

And by comparing the seismic waves that InSight measured with the seismic waves produced in different regions on our own planet, the researchers further showed that the low-frequency Marsquakes are probably produced by magma moving several tens of kilometers below Mars’ surface. “Our results are much more consistent with data from volcanic regions on Earth,” Mittelholz says.

Rather than being a geologically dead planet, as some have suggested, Mars might be a surprisingly dynamic place, the researchers conclude. This finding rewrites our understanding of Mars, Mittelholz says, and there’s still so much more to learn about our celestial neighbor. “We’re only scratching the surface.”   More

It worked! Humanity has, for the first time, purposely moved a celestial object.

As a test of a potential asteroid-deflection scheme, NASA’s DART spacecraft shortened the orbit of asteroid Dimorphos by 32 minutes — a far greater change than astronomers expected.

The Double Asteroid Redirection Test, or DART, rammed into the tiny asteroid at about 22,500 kilometers per hour on September 26 (SN: 9/26/22). The goal was to move Dimorphos slightly closer to the larger asteroid it orbits, Didymos.

Sign Up For the Latest from Science News

Headlines and summaries of the latest Science News articles, delivered to your inbox

Thank you for signing up!

There was a problem signing you up.

Neither Dimorphos nor Didymos pose any threat to Earth. DART’s mission was to help scientists figure out if a similar impact could nudge a potentially hazardous asteroid out of harm’s way before it hits our planet.

The experiment was a smashing success. Before the impact, Dimorphos orbited Didymos every 11 hours and 55 minutes. After, the orbit was 11 hours and 23 minutes, NASA announced October 11 in a news briefing.

A small spacecraft called LICIACube, short for Light Italian CubeSat for Imaging of Asteroids, detached from DART just before impact, then buzzed the two asteroids to get a closeup view of the cosmic smashup. Starting from about 700 kilometers away, this series of images captures a bright plume of debris erupting from Dimorphos (right in the first half of this gif), evidence of the impact that shortened its orbit around Didymos (left). At closest approach, LICIACube was about 59 kilometers from the asteroids.ASI, NASA

“For the first time ever, humanity has changed the orbit of a planetary body,” said NASA planetary science division director Lori Glaze.

Four telescopes in Chile and South Africa observed the asteroids every night after the impact. The telescopes can’t see the asteroids separately, but they can detect periodic changes in brightness as the asteroids eclipse each other. All four telescopes saw eclipses consistent with an 11-hour, 23-minute orbit. The result was confirmed by two planetary radar facilities, which bounced radio waves off the asteroids to measure their orbits directly, said Nancy Chabot, a planetary scientist at Johns Hopkins Applied Physics Laboratory in Laurel, Md.

The minimum change for the DART team to declare success was 73 seconds — a hurdle the mission overshot by more than 30 minutes. The team thinks the spectacular plume of debris that the impactor kicked up gave the mission extra oomph. The impact itself gave some momentum to the asteroid, but the debris flying off in the other direction pushed it even more — like a temporary rocket engine.

“This is a very exciting and promising result for planetary defense,” Chabot said. But the change in orbital period was just 4 percent. “It just gave it a small nudge,” she said. So knowing an asteroid is coming is crucial to future success. For something similar to work on an asteroid headed for Earth, “you’d want to do it years in advance,” Chabot said. An upcoming space telescope called Near Earth Asteroid Surveyor is one of many projects intended to give that early warning. More

“Follow the water” has long been the mantra of scientists searching for life beyond Earth. After all, the only known cradle of life in the cosmos is the watery planet we call home. But now there’s more evidence suggesting that a potential discovery of liquid water on Mars might not be so watertight, researchers report September 26 in Nature Astronomy.

In 2018, scientists announced the discovery of a large subsurface lake near Mars’ south pole (SN: 7/25/18). That claim — and follow-up observations suggesting additional buried pools of liquid water on the Red Planet (SN: 9/28/20) — fueled excitement about finally finding an extraterrestrial world possibly conducive to life.

Sign Up For the Latest from Science News

Headlines and summaries of the latest Science News articles, delivered to your inbox

Thank you for signing up!

There was a problem signing you up.

But researchers have since proposed that those discoveries might not hold up to scrutiny. In 2021, one group suggested that clay minerals and frozen brines, rather than liquid water, might be responsible for the strong radar signals that researchers observed (SN: 7/16/21). Spacecraft orbiting Mars beam radio waves toward the Red Planet and measure the timing and intensity of the reflected waves to infer what’s beneath the Martian surface.   

And now another team has shown that ordinary layers of rock and ice can produce many of the same radar signals previously attributed to water. Planetary scientist Dan Lalich of Cornell University and his colleagues calculated how flat layers of bedrock, water ice and carbon dioxide ice — all known to be plentiful on Mars — reflect radio waves. “It was a pretty simple analysis,” Lalich says.

The researchers found that they could reproduce some of the anomalously strong radar signals thought to be due to liquid water. Individual radar signals from different layers of rock and ice add together when the layers are a certain thickness, Lalich says. That produces a stronger signal, which is then picked up by a spacecraft’s instruments. But those instruments can’t always tell the difference between a radio wave coming from one layer and one that’s the result of multiple layers, he says. “They look like one reflection to the radar.”

These results don’t rule out liquid water on Mars, Lalich and his colleagues acknowledge. “This is just saying that there are other options,” he says.

The new finding is “a plausible scenario,” says Aditya Khuller, a planetary scientist at Arizona State University in Tempe who was not involved in the research. But until scientists get a lot more data from the Red Planet, it’ll be difficult to know whether liquid water truly exists on Mars, Khuller says. “It’s important to be open-minded at this point.” More