After decades of gazing longingly at Mars, the world’s space agencies are finally turning back to look at Venus.
Last week NASA announced that it had picked two new missions to go to Venus – one, called VERITAS, to orbit the planet and another, called DAVINCI+, to plunge to its surface. Now the European Space Agency (ESA) is throwing its hat in the ring.
The ESA revealed Thursday that it’s sending its own probe to Venus – an orbiter called EnVision. The mission aims to study how the planet’s atmosphere, surface, and interior interact to create the infernal pressure cooker it is today. Together, the three probes spell a renaissance in Venutian science.
“A new era in the exploration of our closest, yet wildly different, solar system neighbor awaits us,” Günther Hasinger, ESA Director of Science, said in a press release. “Together with the newly announced NASA-led Venus missions, we will have an extremely comprehensive science program at this enigmatic planet well into the next decade.”
The NASA missions are set to launch between 2028 and 2030, and the ESA probe sometime in the early 2030s.
Venus’ climate became hellish long ago, but it may have hosted life
Venus used to be a lot like Earth. The two planets are about the same size, and they’re made of the same material. Scientists think Venus could have even had oceans in the distant past.
But something happened that drastically changed Venus’ climate. Today it’s the hottest planet in our solar system, thick with yellow, heat-trapping clouds of sulfuric acid. Its average surface temperature is a blistering 880 degrees Fahrenheit (471 degrees Celsius) – hot enough to melt lead – and its crushing air pressure is more than 90 times that of Earth’s.
The upcoming missions could help scientists understand how Venus became such an extreme environment, whether it was hospitable to life, and whether or not its volcanoes are still erupting.
The world’s interest in Venus was rekindled in September, when a new study suggested the planet’s clouds could harbor microbial aliens.
That’s because researchers found traces of phosphine – a gas typically produced by microbes on Earth – in the upper reaches of Venus’ clouds. However, a follow-up study suggested those trace elements weren’t phosphine, but rather sulfur dioxide, casting doubt on the idea that Venus could be habitable.
These new missions could help settle that debate.
“It is astounding how little we know about Venus, but the combined results of these missions will tell us about the planet from the clouds in its sky through the volcanoes on its surface, all the way down to its very core,” Tom Wagner, a NASA Discovery Program scientist, said in a statement about the NASA missions. “It will be as if we have rediscovered the planet.”
Grey, heavily cratered, and peering out from the black of space, Ganymede looks a lot like our moon. But the icy rock is more than 400 million miles away – it’s the largest moon in the solar system, and it circles Jupiter.
NASA’s Juno spacecraft has been rocketing around Jupiter since 2016, but on Monday, it zipped past Ganymede, coming within 645 miles of the moon. No spacecraft had gotten that close in more than two decades – the last approach was NASA’s Galileo spacecraft in 2000.
In just 25 minutes, Ganymede went from being a distant point of light from Juno’s vantage point to a looming, round disk, then back to a point of light. It was just enough time for the probe to snap five photos.
NASA released the first two images on Tuesday; they’re the most detailed snapshots ever captured of the gargantuan moon.
“This is the closest any spacecraft has come to this mammoth moon in a generation,” Scott Bolton, who leads the Juno spacecraft team, said in NASA’s press release. “We are going to take our time before we draw any scientific conclusions, but until then we can simply marvel at this celestial wonder – the only moon in our solar system bigger than the planet Mercury.”
Scientists believe that Ganymede may host an ocean of salty water 500 miles beneath its icy shell – which would hold more water than Earth does. It’s also the only moon in the solar system with its own magnetic field, which creates an aurora at its poles. Scientists hope the Juno flyby will help them learn more about both Ganymede’s ice shell and its magnetic field.
The first Juno image, below, captures almost an entire side of the ice-encrusted moon. Each pixel covers about 0.6 miles (1 kilometer).
This image is just from the Juno camera’s green-light filter. In the coming days, NASA expects to receive more images from the spacecraft, including those captured with its red- and blue-light filters. That will allow the agency to create a colorful portrait of Ganymede.
Juno’s black-and-white navigation camera also snapped a photo, below, of Ganymede’s dark side.
It’s visible thanks to light scattered from Jupiter.
If star-hopping aliens ever visited our solar system, Saturn is probably the planet they’d remember.
The seven giant rings circling its equator make Saturn the most distinct planet orbiting the sun. It may not be obvious in images of the hula-hoop planet, but the ice and rock chunks that make up those rings are circling Saturn at rates nearly 70 times the speed of sound. What’s more, each ring is moving at its own pace.
“In a way, the ring system is like a mini solar system,” James O’Donoghue, a planetary scientist at Japan’s space agency, JAXA, told Insider. “Objects close to Saturn orbit faster otherwise they would fall in, while objects far away can afford to go slower. This is the same for planets.”
When he put his skills to work to depict Saturn’s rings, O’Donoghue created an animation (below) that shows how the each ring moves through its own motions in a beautiful, circular dance.
In the animation, the line labeled “synchronous orbit” is synced up with the spin of Saturn itself, so it shows which parts of the rings you would see over time if you stood at that spot on the planet.
Saturn’s slowest, outermost ring spins at about 37,000 mph (16.4 kilometers per second) – slower than the rotation of Saturn itself. The innermost chunks of ice and rock shoot through space at about 52,000 mph (23.2 kilometers per second).
Up close, Saturn’s rings aren’t as chaotic as their speeds might make them seem. According to O’Donoghue, grains of ice on neighboring tracks are only moving at a few centimeters per minute relative to each other.
“That speed is like walking one step every 30 minutes, or similar to rush hour traffic,” he said on Twitter. “So collisions aren’t very dramatic.”
Saturn is slowly swallowing its rings
In addition to being incredibly fast-moving, Saturn’s rings are very long and thin. If you unfurled them – as O’Donoghue did in the image below – all the planets would fit comfortably within their length.
But in total, the rings have just 1/5,000th the mass of our moon.
“In other words, our moon could be used to make 5,000 Saturn ring systems,” O’Donoghue told Insider. “This highlights how extremely thin and fragile the rings of Saturn are.”
This fragility is a subject of O’Donoghue’s scientific research. In studying Saturn’s upper atmosphere, he and his colleagues found that the rings are slowly disappearing. Thousands of kilograms of ring material rain onto the planet every second. At that rate, the rings shouldn’t last more than 300 million years in their current “full” form, he said.
“Saturn’s ring system is not exactly stable, appearing to be more like a temporary debris field of some ancient moon or comet which got too close and broke apart, rather than a permanent feature,” O’Donoghue added. “We can count ourselves lucky we live in a time when Saturn’s rings have such an enormous presence in the solar system.”
The moon orbits Earth – right? The answer is actually a little more complicated than that.
The moon is circling a point about 3,000 miles from our planet’s center, just below its surface. Earth is wobbling around that point, too, making its own circles.
That spot is the Earth-moon system’s center of mass, known as the barycenter. It’s the point of an object (or system of them) at which it can be balanced perfectly, with the mass distributed evenly on all sides.
The Earth-moon barycenter doesn’t line up exactly with our planet’s center. Instead, it’s “always just below Earth’s surface,” as James O’Donoghue, a planetary scientist at the Japanese space agency (JAXA), explained on Twitter.
It’s hard to imagine what that looks like without seeing it for yourself. So O’Donoghue made an animation to demonstrate what’s going on. It shows how Earth and the moon will move over the next three years.
The distance between Earth and the moon is not to scale in the animation, but O’Donoghue used NASA data, so the positions over time are accurate.
“You can pause the animation on the present date to figure out where the Earth and moon physically are right now,” O’Donoghue said.
Every planetary system – including the star or planet that appears to be at the center – orbits an invisible point like this one. Our solar system’s barycenter is sometimes inside the sun, sometimes outside of it. Barycenters can help astronomers find hidden planets circling other stars: A star’s wobbling motion allows scientists to calculate mass they can’t see in a given system.
O’Donoghue made a similar animation of Pluto and its moon, Charon. In this system, the barycenter is always outside of Pluto.
That’s because Charon’s mass is not that much smaller than Pluto’s, so the system’s mass is more evenly distributed than Earth and our moon.
Because the barycenter is outside of Pluto, O’Donoghue said, you could actually consider this to be a “double (dwarf-)planet system” rather than a dwarf planet and its moon.
Narrator: The best way to explore a new world is to land on it. That’s why humans have sent spacecraft to the Moon, Venus, Mars, Saturn’s moon, Titan, and more.
But there are a few places in the solar system we will never understand as well as we’d like. One of them is Jupiter.
Jupiter is made of mostly hydrogen and helium gas. So, trying to land on it would be like trying to land on a cloud here on Earth. There’s no outer crust to break your fall on Jupiter. Just an endless stretch of atmosphere.
The big question, then, is: Could you fall through one end of Jupiter and out the other? It turns out, you wouldn’t even make it halfway. Here’s what would happen if you tried to land on Jupiter.
*It’s important to note that we feature the Lunar Lander for the first half of the descent. In reality, the Lunar Lander is relatively delicate compared to, say, NASA’s Orion spacecraft. Therefore, the Lunar Lander would not be used for a mission to land on any world that contains an atmosphere, including Jupiter. However, any spacecraft, no matter how robust, would not survive for long in Jupiter, so the Lunar Lander is as good of a choice as any for this hypothetical scenario.
First things first, Jupiter’s atmosphere has no oxygen. So make sure you bring plenty with you to breathe. The next problem is the scorching temperatures. So pack an air conditioner. Now, you’re ready for a journey of epic proportions.
For scale, here’s how many Earths you could stack from Jupiter’s center. As you enter the top of the atmosphere, you’re be traveling at 110,000 mph under the pull of Jupiter’s gravity.
But brace yourself. You’ll quickly hit the denser atmosphere below, which will hit you like a wall. It won’t be enough to stop you, though.
After about 3 minutes you’ll reach the cloud tops 155 miles down. Here, you’ll experience the full brunt of Jupiter’s rotation. Jupiter is the fastest rotating planet in our solar system. One day lasts about 9.5 Earth hours. This creates powerful winds that can whip around the planet at more than 300 mph.
About 75 miles below the clouds, you reach the limit of human exploration. The Galileo probe made it this far when it dove into Jupiter’s atmosphere in 1995. It only lasted 58 minutes before losing contact and was eventually destroyed by the crushing pressures.
Down here, the pressure is nearly 100 times what it is at Earth’s surface. And you won’t be able to see anything, so you’ll have to rely on instruments to explore your surroundings.
By 430 miles down, the pressure is 1,150 times higher. You might survive down here if you were in a spacecraft built like the Trieste submarine – the deepest diving submarine on Earth. Any deeper and the pressure and temperature will be too great for a spacecraft to endure.
However, let’s say you could find a way to descend even farther. You will uncover some of Jupiter’s grandest mysteries. But, sadly, you’ll have no way to tell anyone. Jupiter’s deep atmosphere absorbs radio waves, so you’ll be shut off from the outside world- unable to communicate.
Once you’ve reached 2,500 miles down, the temperature is 6,100 ºF. That’s hot enough to melt tungsten, the metal with the highest melting point in the Universe. At this point, you will have been falling for at least 12 hours. And you won’t even be halfway through.
At 13,000 miles down, you reach Jupiter’s innermost layer. Here the pressure is 2 million times stronger than at Earth’s surface. And the temperature is hotter than the surface of the sun. These conditions are so extreme they change the chemistry of the hydrogen around you. Hydrogen molecules are forced so close together that their electrons break lose, forming an unusual substance called metallic hydrogen. Metallic hydrogen is highly reflective. So, if you tried using lights to see down here it would be impossible.
And it’s as dense as a rock. So, as you travel deeper, the buoyancy force from the metallic hydrogen counteracts gravity’s downward pull. Eventually, that buoyancy will shoot you back up until gravity pulls you back down, sort of like a yo-yo. And when those two forces equal, you’ll be left free-floating in mid-Jupiter, unable to move up or down, and no way to escape!
Suffice it say, trying to land on Jupiter is a bad idea. We may never see what’s beneath those majestic clouds. But we can still study and admire this mysterious planet from afar.
A special thanks to Kunio Sayanagi at Hampton University, for his help with this video.
EDITOR’S NOTE: This video was originally published in February 2018.
China’s first interplanetary probe is now so close to Mars that its camera can make out craters across the red planet’s surface.
The Tianwen-1 spacecraft, a suite of robots launched by the China National Space Administration (CNSA) in July, has spent the last six months speeding through space. At just 2.2 million kilometers (1.4 million miles) from its destination, the probe beamed back its very first photo: a black-and-white snapshot of Mars.
The CNSA released the picture on Friday. In a press release, the agency said that the probe had fired an engine as part of its fourth “orbital correction,” or adjustment of its path through space. Now Martian gravity should pull the mission into just the right orbit around the planet.
The five-ton probe is set to carry out a braking operation to slow its high-speed spaceflight and slip into orbit around Mars on February 10. Following that, the spacecraft will spend a couple months surveying a landing site at Utopia Planitia, a vast field of ancient volcanic rock.
The orbiter is supposed to drop a lander-rover combo to the planet’s surface in May, the CNSA said. If the rocket-powered descent goes smoothly, the lander will deploy a two-track ramp for the rover to roll onto Martian soil. The rover’s radar system will help Chinese researchers seek out underground pockets of liquid water. (The orbiter, meanwhile, will continue circling the red planet and relaying data to Earth.)
Such ancient water reservoirs could be remnants of a time billions of years ago when Mars flowed with rivers, courtesy of a much thicker and protective atmosphere than exists today. During this era, Mars somewhat resembled Earth, and scientists think it may have hosted alien microbial life. Any underground pockets of water, shielded from the sun’s unfiltered radiation and the vacuum of space, might still harbor such species, if they exist.
If successful, Tianwen-1 will be the first Mars mission to send a spacecraft into orbit, drop a landing platform, and deploy a rover all in one expedition. It will also mark China’s first landing on another planet and help the nation prepare a future mission that might return a Martian rock or dirt sample to Earth in the late 2020s.
As of Friday, the CNSA said Tianwen-1 is just about 1.1 million kilometers (680,000 miles) from its destination.
Two other missions which launched around the same time as Tianwen-1 – NASA’s Perseverance rover and the United Arab Emirates’ Hope probe – are also arriving at Mars in the next two weeks. All three missions are taking advantage of a window when Mars passes close to Earth, decreasing travel time and cost.
China attempted to send an orbiter to Mars in 2011, but the Russian spacecraft that was meant to carry it there stalled in Earth’s orbit and never left.
Tianwen-1 is the closest China has ever gotten to another planet. With luck – and the right engineering to weather a harrowing “seven minutes of terror” as it plunges toward Mars – it will reach the surface.
NASA sent its InSight lander to Mars with an ambitious mission: to study the planet’s deep internal structure. A crucial piece of that effort – the “mole” – has failed despite two years of attempts to salvage it.
The mole is a revolutionary heat probe designed to burrow 16 feet into the Martian soil and take the planet’s temperature. Its measurements would have revealed clues about how the planet formed and has changed over the last 4.6 billion years – a history that would help scientists track down Martian water, and possibly life.
But the mole has made little progress in the unexpectedly thick soil. Now the InSight team must ration the lander’s solar power. NASA announced Thursday that the mole won’t be able to dig its hole.
“It’s a bit of a personal tragedy,” Sue Smrekar, a lead scientist on the InSight team who has spent 10 years working on the mole, told Insider. “Everyone tried as hard as they could make it work. So I can’t ask for anything more than that.”
No other Mars mission in NASA’s foreseeable can take the internal temperature measurements for which the mole was designed.
“This has been our best attempt to get that data,” Smrekar added. “From my personal standpoint, it’s super disappointing, and scientifically it’s also a very significant loss. So it feels really like a huge letdown.”
An unexpected energy crisis
The InSight team spent two years maneuvering the lander’s robotic arm to see if it could help the mole burrow further. The probe, a 16-inch-long pile driver, is designed to leverage the loose dirt that other Mars missions have encountered. The soil would flow around the mole’s outer hull and provide friction to keep hammering deeper.
But in February 2019, the mole found itself bouncing in place on a foundation of firm soil called “duracrust.” The next two years were spent troubleshooting, beaming new software to InSight to teach its robotic arm new maneuvers to assist the mole, and anxiously waiting for photos that might show progress.
“It’s just been a huge effort across the board, and one that we never anticipated,” Smrekar said. “We thought that we were going to punch the hole down.”
The InSight team first instructed the robotic arm to push on the mole, but that just caused it to pop out of the hole. Once they got the probe back in the ground, a year later, they instructed the arm to pile dirt on top of it, hoping that would provide enough friction for the probe to dig deeper.
But the mole made no progress with 500 hammer strokes last Saturday. The top of it was just 2 or 3 centimeters below the surface.
By then, InSight’s problems were compounding. Unlike other sites where NASA has sent rovers and landers, the open plain where InSight sits wasn’t having powerful gusts of wind. Smrekar calls such gusts “cleaning events,” since they blow the planet’s pervasive red dust off any robots in the area. Without them, InSight’s solar panels have accumulated a significant layer of dust.
At the same time, the seasons were changing and InSight’s home on a flat plain near Mars’ equator was getting colder. In the chill, InSight will require more energy just to stay functional, even while its solar panels are absorbing less sunlight than they should.
“Power is decreasing and so we’re coming up on a time period where, for probably two or three months, we’re probably going to have to stand down from doing instrument operations for awhile and just kind of go into survival mode until it gets warmer on Mars,” Smrekar said.
With this new time constraint, Saturday’s hammering attempt was the mole’s last chance to burrow.
A planet’s internal temperature reveals its history
If the mole had hammered down to 16 feet below, it would have measured temperatures all the way down its hole. That would allow scientists to calculate how much heat is leaving Mars – a metric called “heat flow.”
“It’s a single number, the heat flow, but it has ramifications for all kinds of aspects of understanding Mars,” Smrekar said.
Heat leaving a planet is, in part, warmth left over from its formation, but it also comes from decaying radioactive elements. Measuring the heat flow would tell scientists how much radioactive material is inside the Martian crust – the outer layer of the planet – versus the mantle beneath.
That would reveal not only how material was distributed when the planet formed (and whether it’s made of the same stuff as Earth), but also how the planet’s internal structure has changed over time.
“That goes back to understanding the early evolution of Mars, that time period when there was a lot of liquid water on the surface,” Smrekar said.
A higher concentration of radioactive material in the mantle would make that layer more active. More radioactive material in the crust could keep the planet’s upper layers warm.
Heat flow could also indicate how deep you’d have to drill into Mars to reach liquid water today. Underground water on the planet could still host microbial life. Future humans traveling to Mars will likely need to harvest water there.
Now there is no possibility of measuring the planet’s heat flow in the foreseeable future.
“I was hoping to get the data and be able to understand what that means for Mars,” Smrekar said.