NASA’s OSIRIS-REx spacecraft is a cosmic rock collector. Cheers erupted from mission control at 6:12 p.m. EDT on October 20 as scientists on Earth got word that the spacecraft had gently nudged a near-Earth asteroid called Bennu, and grabbed some of its rocks to return to Earth.
“The spacecraft did everything it was supposed to do,” said mission principal investigator Dante Lauretta of the University of Arizona in Tucson on a NASA TV webcast. “I can’t believe we actually pulled this off.”
OSIRIS-REx arrived at Bennu in December 2018, and spent almost two years making detailed maps of the 500-meter-wide asteroid’s surface features and composition (SN: 10/8/20). Observations from Earth suggested Bennu should be smooth and sandy, but when OSIRIS-REx arrived, it found a treacherous, rocky landscape.
The team selected a relatively smooth patch in a crater named Nightingale. The spot was not without hazards, though — the team was so worried about a particularly large rock nearby that they named it “Mount Doom” (SN: 12/12/19).

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Luckily, the spacecraft did not need to fully land in the crater to complete its mission. As it hovered just above the surface, OSIRIS-REx reached out a robotic arm with an instrument called TAGSAM at the end, for Touch-And-Go Sample Acquisition Mechanism. The instrument tapped the asteroid lightly for several seconds, and released a burst of nitrogen gas to disturb the surface dust and pebbles. Once those small rocks were lofted, some hopefully were blown into the sample collector.
Because signals from Earth took 18½ minutes to reach Bennu, the spacecraft performed the sampling sequence autonomously. When the mission team got the signal that the spacecraft had finished its job and retreated to a safe distance from Bennu, team members pumped their arms in the air, cheered and sent each other socially distant high-fives and hugs.
OSIRIS-REx is not the first spacecraft to grab samples from an asteroid. That distinction goes to Japan’s Hayabusa mission, which brought back grains of asteroid Itokawa in 2010 (SN: 6/14/10). An encore to that mission, Hayabusa2, collected samples of asteroid Ryugu last year, and is on track to land in Australia in December (SN: 2/22/19).
But OSIRIS-REx attempted to collect much more material than Hayabusa2 did. Hayabusa2 hoped to collect 100 milligrams; OSIRIS-REx is aiming for a minimum of 60 grams, or a little more than two ounces.
Hayabusa2’s scientists have no way to know how much material it actually collected until the spacecraft returns to Earth. But OSIRIS-REx’s team plans to find out using the spacecraft itself. On October 24, the spacecraft will extend its arm and spin its whole body. The difference in the way it spins before and after the sample collection will reveal the mass of the sample.
OSIRIS-REx will return to Earth in 2023, where scientists will analyze the rocks in hopes of unlocking details of the history of the solar system and the origins of water and life on Earth (SN: 1/15/19). More

NASA’s Perseverance rover took off at 7:50 a.m. EDT on July 30 from Cape Canaveral, Fla., and is now on its way to Mars with a suite of instruments designed to search for ancient life. The launch is the third this month of spacecraft en route to the Red Planet.
This is the 22nd spacecraft NASA has aimed at Mars (16 of those missions were successful). But Perseverance will be the first mission to cache rock samples from the Red Planet for a future mission to bring back to Earth.
It will also be the first NASA mission in more than 40 years to directly search for life on Mars. The rover will land in a region called Jezero crater (SN: 7/28/20). That crater was once an ancient lake bed, and scientists think its rocks and sediments could preserve signs of life, if life was ever there (SN: 7/29/20). The spacecraft will take video and audio recordings of its own landing as it touches down — another first for a NASA Mars mission.
“This mission has more cameras on it than any we’ve ever sent before,” said Lori Glaze, director of NASA’s Planetary Science Division, on July 30 during a news conference. “It’s going to feel like we’re actually there, riding along with Perseverance on the way down.”
Perseverance, shown here in an artist’s illustration, will seek signs that Mars once hosted alien life.JPL-Caltech/NASA
Mars launches tend to come in clumps thanks to Mars’ and Earth’s orbits. The planets line up on the same side of the sun every two years, so scientists have narrow windows to launch for the most efficient trip. All three of this year’s missions will arrive in February 2021.
The other missions launched in July represent firsts for their respective countries. The United Arab Emirates’ first interplanetary mission, which carries an orbiter called the Hope Probe, launched from Japan on July 19. Hope will measure Mars’ weather, from daily temperature changes to the significance of dust in the planet’s atmosphere (SN: 7/14/20).

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Next up was China’s first Mars mission, Tianwen-1, which means “questions to heaven” and launched on July 23. China has previously sent spacecraft to orbit and land on the moon (SN: 1/3/19). And it is the first nation to send an orbiter, lander and rover all at once on its first attempt to reach Mars. “No planetary missions have ever been implemented in this way,” mission scientists wrote July 13 in Nature Astronomy. “If successful, it would signify a major technical breakthrough.”
Tianwen-1’s lander and rover will touch down in Utopia Planitia in April 2021. Instruments on the rover and lander will test Mars’ soil composition and magnetic and gravitational fields and will probe Mars’ interior.
Utopia Planitia is the same region where the first long-lived Mars lander, NASA’s Viking 1, touched down in 1976 (SN: 7/20/16). Viking was the first spacecraft to search for life on Mars, but its results were inconclusive. Perhaps with the rush of spacecraft this year, and the plans to bring red rocks home, scientists will finally learn whether Mars ever did — or does — host alien life. More

Complex carbon-bearing molecules that could help explain how life got started have been identified in space for the first time.

These molecules, called polycyclic aromatic hydrocarbons, or PAHs, consist of several linked hexagonal rings of carbon with hydrogen atoms at the edges. Astronomers have suspected for decades that these molecules are abundant in space, but none had been directly spotted before.

Simpler molecules with a single ring of carbon have been seen before. But “we’re now excited to see that we’re able to detect these larger PAHs for the first time in space,” says astrochemist Brett McGuire of MIT, whose team reports the discovery in the March 19 Science.

Studying these molecules and others like them could help scientists understand how the chemical precursors to life might get started in space. “Carbon is such a fundamental part of chemical reactions, especially reactions leading to life’s essential molecules,” McGuire says. “This is our window into a huge reservoir of them.”

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Since the 1980s, astronomers have seen a mysterious infrared glow coming from spots within our galaxy and others. Many suspected that the glow comes from PAHs, but could not identify a specific source. The signals from several different PAHs overlap too much to tease any one of them apart, like a choir blending so well, the ear can’t pick out individual voices.

Instead of searching the infrared signals for a single voice, McGuire and colleagues turned to radio waves, where different PAHs sing different songs. The team trained the powerful Green Bank Telescope in West Virginia on TMC-1, a dark cloud about 430 light-years from Earth near the constellation Taurus.

The interstellar cloud TMC-1 (top, black filaments) appears as a dark streak on the sky next to the bright Pleiades star cluster (right)Brett A. McGuire

Previously, McGuire had discovered that the cloud contains benzonitrile, a molecule made of a single carbon ring (SN: 10/2/19). So he thought it was a good place to look for more complicated molecules.

The team detected 1- and 2-cyanonaphthalene, two-ringed molecules with 10 carbons, eight hydrogens and a nitrogen atom. The concentration is fairly diffuse, McGuire says: “If you filled the inside of your average compact car with [gas from] TMC-1, you’d have less than 10 molecules of each PAH we detected.”

But it was a lot more than the team expected. The cloud contains between 100,000 and one million times more PAHs than theoretical models predict it should. “It’s insane, that’s way too much,” McGuire says.

There are two ways that PAHs are thought to form in space: out of the ashes of dead stars or by direct chemical reactions in interstellar space. Since TMC-1 is just beginning to form stars, McGuire expected that any PAHs it contains ought to have been built by direct chemical reactions in space. But that scenario can’t account for all the PAH molecules the team found. There’s too much to be explained easily by stellar ash, too. That means something is probably missing from astrochemists’ theories of how PAHs can form in space.

“We’re working in uncharted territory here,” he says, “which is exciting.”

Identifying PAHs in space is “a big thing,” says astrochemist Alessandra Ricca of the SETI Institute in Mountain View, Calif., who was not involved in the new study. The work “is the first one that has shown that these PAH molecules actually do exist in space,” she says. “Before, it was just a hypothesis.”

Ricca’s group is working on a database of infrared PAH signals that the James Webb Space Telescope, slated to launch in October, can look for. “All this is going to be very helpful for JWST and the research on carbon in the universe,” she says. More

NASA’s Perseverance rover on Mars has seen its future, and it’s full of rocks. Lots and lots of rocks. After spending the summer trundling through Jezero Crater and checking out the sights, it’s now time for Percy to get to work, teasing out the geologic history of its new home and seeking out signs of ancient microbial life.

“We’ve actually been on a road trip,” project manager Jennifer Trosper, who is based at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., said at a July 21 news conference. “And during it, we will take our very first sample from the surface of Mars.”

Percy is about 1 kilometer south of where it landed on February 18 (SN: 2/17/21). After driving itself around a region of sand dunes, accompanied by its tagalong helicopter Ingenuity (SN: 4/30/21), the robotic explorer has pulled up to its first sampling spot: a garden of flat, pale stones dubbed paver stones. “This is the area where we are really going to be digging in, both figuratively and literally, to understand the rocks that we have been on for the last several months,” said Kenneth Farley, Perseverance project scientist at Caltech.

The team has been trying to figure out whether these rocks are volcanic or sedimentary. “We still don’t have the answer,” Farley said. Images taken a few centimeters above the surface show what the team is up against: The rocks are littered with dust and pebbles, probably blown in from elsewhere, and the smoother surfaces have a mysterious purplish coating. “All of these factors conspire to prevent us from peering into the rock and actually seeing what it is made out of,” he said.

In the coming weeks, Percy will bore a smooth cavity in one of those rocks and get below the surface crud. Instruments on its robotic arm will then move in close to produce detailed chemical and mineralogical maps that will reveal the rocks’ true nature. Then, sometime in mid-August, the team will extract its first sample. That sample will go into a tube that will eventually get dropped off — along with samples from other locales — for some future mission to pick up and bring to Earth (SN: 7/28/20).

Cameras scouting farther afield have turned up future sampling sites. A small far-off hill shows hints of finely layered rock that may be mud deposits. “This is exactly the kind of rock that we are most interested in investigating for looking for potential biosignatures,” Farley said.

And the way that rocks are strewn about an ancient river delta in the distance suggests that the lake that once filled Jezero Crater went through multiple episodes of filling in and drying up. If true, Farley said, then the crater may have preserved “multiple time periods when we might be able to look for evidence of ancient life that might have existed on the planet.” More

Jupiter’s icy moon Europa could give the word “moonlight” a whole new meaning. New lab experiments suggest the nightside of this moon glows in the dark.
Europa’s surface, thought to be mostly water ice laced with various salts, is continually bombarded with energetic electrons by Jupiter’s intense magnetic field (SN: 5/19/15). When researchers simulated that interaction in the lab by shooting electrons at salty ice samples, the ice glowed. The brightness of that glow depended on the kind of salt in the ice, researchers report online November 9 in Nature Astronomy.
If the same interaction on Europa creates this never-before-seen kind of moonlight, a future mission there, such as NASA’s planned Europa Clipper spacecraft, may be able to use this ice glow map Europa’s surface composition. That, in turn, could give insight into the salinity of the ocean thought to lurk under Europa’s icy crust (SN: 6/14/19).
“That has implications for the temperature of that liquid water — the freezing point; it has implications for the thickness of the ice shell; it has implications for the habitability of that liquid water,” says Jennifer Hanley, a planetary scientist at Lowell Observatory in Flagstaff, Ariz. not involved in the new work. Europa’s subsurface ocean is considered one of the most promising places to look for extraterrestrial life in the solar system (SN: 4/8/20).

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The discovery of Europa’s potential ice glow “was serendipity,” says Murthy Gudipati, who studies the physics and chemistry of ices at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. Gudipati and colleagues originally set out to investigate how electron bombardment might change the chemistry of Europa’s surface ice. But in video footage of their initial experiments, the team noticed that ice samples pelted with electrons gave off an unexpected glow.
Intrigued, the researchers turned their electron beam on samples of pure water ice, as well as water ice mixed with different salts. Each ice core was cooled to the surface temperature of Europa (about –173° Celsius) and showered with electrons that had the same energies as those that strike Europa. Over 20 seconds of irradiation, a spectrometer measured the wavelengths of light, or spectrum, given off by the ice.
The ice samples all gave off a whitish glow, because they emitted light at many different wavelengths. But the brightness of each ice sample depended on its composition. Ice containing sodium chloride, also known as table salt, or sodium carbonate appeared dimmer than pure water ice. Ice mixed with magnesium sulfate, on the other hand, was brighter.

“I was doing some back of the envelope calculations [of] what would be the brightness of Europa, if we were to be standing on it in the dark,” Gudipati says. “It’s approximately … as bright as me walking on the beach in full moonlight.”
Based on the specs proposed for a camera to fly on the Europa Clipper mission, Gudipati and colleagues estimate that the spacecraft could see Europa’s ice glow during a flyby of the dark side of the moon. Dark patches of Europa could reveal sodium-rich regions, while brighter areas may be rich in magnesium.
But seeing ice glow in the lab does not necessarily mean it happens the same way on Europa, Hanley cautions. Jupiter’s icy moon has been barraged by high-energy electrons for a lot longer than 20 seconds. “Is there ever a point where you might break down the salts, and this glow stops happening?” she wonders.
Other planetary scientists, meanwhile, are not convinced that Europa’s surface is highly salted. These researchers, including Roger Clark of the Planetary Science Institute in Lakewood, Colo., think the apparent hints of salts on Europa are actually created by acids, such as sulfuric acid. Europa’s surface may be coated in both salts and acids, Clark says. “What [the researchers] need to do next is irradiate acids … to see if they can tell the difference between salt with water ice and acids with water ice.” More