Cassini Bids Its Final Farewell to Saturn’s Moon Enceladus
Just after noon Eastern today, Cassini will fly by the icy moon Enceladus for the final time—and a tearful farewell it’ll be. Over the last few months, the little space probe has gotten up close and personal with Enceladus, and they’ve developed quite a rapport. The last time they saw each other, Cassini was making one of its closest approaches ever, flying directly through the moon’s mysterious geyser plumes to sample their chemistry.
This final flyby won’t be quite as eventful—but it’s not just a ceremonial tip of the hat. Even in its last moments with Enceladus, Cassini will be doing important science to try and understand the moon’s underground ocean. From 3,106 miles above the surface, the probe will measure the heat emanating from the moon’s liquid interior, information that’s crucial to understanding the moon’s geological processes—and its potential habitability. That measurement is possible because Enceladus, along with Saturn’s other moons, is in the middle of the planet’s years-long winter. In the absence of the sun’s heat, Cassini can get better measurements of the moon’s ambient energy.
After waving goodbye to Enceladus, Cassini will continue on its exploration of Saturn’s system, climbing to a final set of orbits in the outer rings before diving once more toward the planet’s surface. It’ll gather some final measurements of the innermost rings before it disintegrates, becoming just more dust to feed Saturn’s atmosphere.
The thing that dropped through Earth’s atmosphere on November 13 was not a UFO. Nor was it a meteor, a spy satellite, or a very surprised whale. It was—probably…almost certainly—a segment of rocket casing from an old space probe.
Nor did it completely fall to Earth. Instead, the object designated WT1190F (yeah, we read it as “WTF” too) burned up hundreds of miles above the Indian Ocean. It was one of tens of thousands of pieces of so-called space junk orbiting the Earth. In fact, WT1190F’s big, elliptical orbit actually encompassed the moon, too. Despite having no close observations of the object, scientists know all this, and more.
“The first clue that it was something manmade come from old observations of it going back to 2009,” says Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics. Made by astronomer Bill Gray at NASA’s Jet Propulsion Laboratory, these observations showed WT1190F getting pushed around by the sun’s radiation. The only way those orbital wobbles would be consistent with physics would be if the object were either an incredibly light rock, or hollow.
What’s more, in the hour before WT1190F struck the atmosphere, astronomers noticed WT1190F switching from bright to dim, flashing on and off. “That means the thing is spinning, maybe at 70 or 80 rotations per minute,” says McDowell. That is almost exactly the spin rate that NASA’s engineers apply to ejected rocket sections to make sure their orbits stay stable.
“The facts that it is light, that it is a meter or two in size, and that it is spinning so fast lead us to the idea that it is a discarded rocket stage,” says McDowell. In fact, they even have a pretty good idea which rocket the debris belonged to. “If you look back on things launched out to lunar distance before 2009 that haven’t been seen recently, there are only a couple of candidates.”
One was a Japanese probe, called Nazumi, meant to study the Martian atmosphere and solar wind interaction—similar to NASA’s MAVEN probe currently in Mars orbit. The other was NASA’s Lunar Prospector, which mapped the Moon’s surface and looked for polar ice deposits. Both were launched in 1998.
Of course, the debris could have come from even older rockets, dating back to the Apollo missions. But McDowell says that’s dubious. Objects ellipsing both the Earth and Moon are subject to the sun’s gravitational pull, which tends to flick them out of orbit after too many years.
That leaves just a few more options. Chief among them (if you are a paranoid science writer) is the possibility that WT1190F was actually a military spy satellite—either American or not. But that idea doesn’t quite jibe with the realities of military spying. For one, nobody to McDowell’s knowledge is using satellites to surveil the Moon. “There’s really no military reason to launch further out than geostationary orbit,” he says. Which, at 26,000 miles out is pretty far, but not like moon far.
Second, a spy satellite would probably have solar panels. These would catch the light as the probe neared Earth’s atmosphere. Yeah, the piece of junk flickered, but not like it would have with solar panels attached.
OK, so why all the detective work? Seriously, everything in space has a price tag featuring numerous commas. Why not just add a tracking device to everything the US sends up there? Turns out, that would be really, really expensive, because the telemetry devices would need to stay on for decades.
It turns out, looking for space debris isn’t too much different from tracking nukes, which is how the US Air Force got into the business—and became the world’s experts. “They originally set up to warn of Soviet missile attacks, and they got into space tracking because they needed to know when a thing that popped up on their radars was or was not a missile,” says McDowell.
The Air Force gets help from other agencies, and amateur spotters like McDowell. (He considers himself an amateur because looking for space junk is not part of his official astrophysicist job.) “We track 16,000 pieces of space junk in low or medium earth orbit, and there are about 100 pieces of junk out at lunar distance,” he says.
His not-job is getting a lot easier, due to advances in what’s known as ‘moving time domain astronomy.’ “It’s a buzzword that means looking for things that vary with time in the sky,” says McDowell. Telescopes like the LSST—currently under construction in Chile—image some fraction of the sky each night. Then, it will compare that image to those from previous nights. The difference between the images will reveal exploding stars, asteroids, and space junk.
Right, sure. But what about UFOs? It was aliens, right? “If WT1190F was aliens, they were really tiny aliens,” says McDowell. Tiny, and really, really awful at landing.
NASA takes some awesome pictures. In the last few weeks, the agency has treated Earthlings to images from the icy moon Enceladus, captured by the Saturn-orbiting Cassini probe, and increasingly detailed views of Charon as seen by intrepid New Horizons. But in terms of sheer beauty, these most recent images put those icy rocks all to shame—and NASA didn’t even have to leave Earth’s orbit to get them.
The Solar Dynamics Observatory is a semi-autonomous spacecraft suspended about 22,000 miles above Earth in an inclined geosynchronous orbit. The observatory keeps its eyes on the sun nearly constantly—it captures an image more than once every second. In this case, the images are a solar storm—the star acts up, erupting into coronal mass ejections and solar flares. Once in a while, those emissions will make it all the way to Earth, leading to the northern lights (neat!) or disrupted GPS satellites, or even delayed airplane travel. Part of the observatory’s mission is to monitor and understand that potentially dangerous solar activity.
On October 27, a pair of active regions rotated into the observatory’s view. By viewing the sun in extreme ultraviolet light, the satellite’s instruments were able to capture magnetic field lines blooming and connecting the two explosive areas. Those emissions didn’t pose any threat, but the SDO is on notice. One day, the observatory just might record the solar storm that leads to its own demise.
Starting around 8 am Eastern time, two American astronauts stepped outside the comfort of their sometimes-home on the International Space Station and into the menacing emptiness of space. For about six and a half hours, Expedition 45 commander (and Year in Space guinea pig) Scott Kelly and flight engineer Kjell Lindgren will be doing routine maintenance and upgrades on the station—the very first spacewalk for both astronauts. You can watch the sometimes-flickery stream live as they work to get everything done. Hopefully they’ll have a chance to relax for a second and take in the view:
— Intl. Space Station (@Space_Station) October 28, 2015
Today, if all goes well, a Progress cargo spacecraft will launch from Baikonur Cosmodrome in Kazakhstan and start heading toward the International Space Station. Filled with three tons of food, fuel and supplies, this will be the third mission to resupply the the International Space Station since SpaceX’s Falcon broke up on the way to the ISS in June—and hopefully the third to succeed.
It’s been a rough year for space launches, at least ones filled with non-human cargo. Since last October, three ISS resupply launches have failed—the most recent, fiery failure from home-team favorite SpaceX, which still hasn’t revealed when it will be ready to resume missions. Luckily, that streak hasn’t extended into other ISS missions; in the last three months, two Soyuz spacecraft propelled six astronauts into space without a hiccup, one in July, and one in September.
You can watch the launch from NASA’s live feed above, which will begin covering the events at 12:30 pm Eastern time. The launch itself is scheduled for 12:49 pm.
Today, scientists revealed evidence—the best yet—that liquid water exists on Mars. While planetary researchers have known for a while that Mars locks away some water in solid ice form, a new Nature Geoscience paper shows that long streaks on Mars’ steep slopes were formed by flowing water.
In this video, the brown splotchy areas in a shot of Mars’ Hale Crater are the traces of those liquid flows. You’re not seeing the water itself; instead, the lines are the salt deposits left behind when the water evaporates. The Mars Reconnaisance Orbiter, which captured the images, only observes the surface at 3 pm every day, when conditions are too hot for liquid water.
You can see the tear-like streaks in the black and white images, too, flowing down Mars’ Horowitz crater, Garni crater, and Coprates Chasma. NASA scientists analyzed spectral data of the briny formations and found water molecules embedded within the salt crystals, a telltale sign that flowing water formed the deposits. Now scientists just need to figure out where the water is coming from—and how humans might be able to use it to colonize the red planet.
A few minutes after midnight east coast time, three more humans will leave the safe confines of Earth to live in a metal and glass cage in the sky. We speak, of course, of the International Space Station.
A Soyuz spacecraft will take off from the Baikonur Cosmodrome in Kazakhstan at 10:37 local time, or 12:37 am EDT on Wednesday. If you’re curious to follow along, you can watch NASA TV’s live broadcast of the launch above, starting at 11:45 pm EDT tonight.
It’s been a rough year for space travel—at least non-human space travel. Three ISS resupply missions have met a fiery end since October, including two from the US and one from Russia. Human crew launches to the ISS haven’t hit any major glitches yet (the last was in July), and hopefully that streak will continue.
The three space-bound crew members are Sergei Volkov of the Russian Federal Space Agency, Andreas Mogensen of the European Space Agency, and and Aidyn Aimbetov of the Kazakh Space Agency. For eight days, a total of nine crew members will be crowded on the ISS. Then on September 4, the current expedition commander, Gennady Padalka of the Russian Federal Space Agency—along with Mogensen and Aimbetov—will return on the same Soyuz spacecraft back to Earth.
Stuck the landing! Orion’s riskiest test a success! pic.twitter.com/nmqddTtdep
— Orion Spacecraft (@NASA_Orion) August 26, 2015
NASA’s test flight of Orion, the space capsule that could one day take astronauts to Mars, was a big success back in December. But that test was too easy. When the capsule fell from low Earth orbit, it had all of its parachutes working to slow it down. So today, NASA gave itself a handicap. In space, stuff goes wrong all the time—what happens if two of the parachutes fail?
No big deal, according to today’s parachute test. This morning, a plane dropped a mockup of the Orion capsule 35,000 feet above the US Army’s Yuma Proving Ground in Arizona. (The real billion-dollar Orion capsule is, of course, too precious to bang up in parachute tests.) Orion has a total of eleven parachutes, five of which are relevant to this test: two small drogue parachutes for stabilization and three main parachutes to slow it down to 20 mph.
This time, though, only one drogue parachute and two main parachutes deployed, and they did just fine. NASA deemed the landing a success—though one of the mockup’s panels did come off. Not the smoothest landing, perhaps, but not a catastrophic one.
The Orion mockup came to a stop upside down. One panel has fallen off. pic.twitter.com/O6gI4z0Wef
— Jason Davis (@jasonrdavis) August 26, 2015
NASA has been testing the parachutes since 2012, including many types of parachute failures. For example, they’ve previously dropped capsules when one drogue parachute fails or one main parachute does not inflate properly. Today’s test, with two missing parachutes, is the riskiest so far.
Now that NASA knows Orion can safely get back to Earth, it just needs to figure out exactly how to get the spacecraft out into space.
If you dabble in NASA news, you’ve probably heard of the agency’s main space centers: Johnson (the “Houston, we have a problem” one) and Kennedy (the Cape Canaveral launch site one). Today, though, all eyes were on the lesser-known Stennis Space Center in Hancock County, Mississippi, where NASA completed one of the last tests of an engine that will help to propel its Orion crew capsule on future deep-space missions—maybe even a manned mission to Mars.
When the Space Launch System sends the Orion spacecraft into orbit, its first stage will be powered by four RS-25 engines, an old design used as the main engine for NASA’s shuttle program. But the engine has undergone a number of changes to work with the SLS, including designs to deal with higher propellant inlet pressure, lower temperatures, and a new engine controller unit. This was the sixth of seven planned static fire tests of the updated engine.
Today’s test at NASA’s largest rocket engine testing facility mimicked a full launch, firing the engine’s 512,000 pounds of thrust for a straight 535 seconds, the time it would take to climb 200 miles. It burned a combination of liquid oxygen and liquid hydrogen, releasing its exhaust in a massive plume of steam out of one side of the test stand—along with all the energy that typically would got into, you know, actually launching the thing. Onlookers watching from a safe distance got nearly nine minutes of bone-rattling power. Keep an eye out for the last planned engine test for the RS-25.
Meteorological Agency/National Meteorological Satellite Center/CIMSS
It was just before midnight on Wednesday when a pair of explosions lit up the Chinese port city of Tianjin. No one yet knows what caused the blasts. What is known is they occurred in a shipping container facility, exploded with a force equivalent to two dozen tons of TNT, and claimed at least 50 lives. More evidence is rolling in—some of it from a trio of Asian1 satellites, which picked up thermal signatures from the twin explosions.
The image here shows the three satellite captures stacked on top of each other. The explosion is shown by the black and grey pixels that appear in the middle of each image. The top is from the Himawari-8, a Japanese orbiter that just came on line in early July and has the best weather sensors in orbit. The other two are older models from Japan (middle panel) and South Korea (lower panel).
Although a tragic case study, it’s impossible not to notice how much more sophisticated Himawari-8 is than its aging peers. Not only is its imagery is far less pixelated, but its capture rate is one image every ten minutes, compared to thirty and fifteen minute respective rates of the satellite imagery shown below it. Even ten minutes is the lower limit of new satellite’s capability. If it had been programmed to focus on Tianjin in advance, it could have returned imagery at thirty second intervals. The frame rate and pixel resolution are such that you can clearly see the smoke clouds from the blast in Himawari-8’s frame2.
All three captures were taken using filters that capture narrow slices of the infrared band, perfect for capturing things like low cloud cover (like the vertical blue pixels on the right hand side of the images), fog, and fire. While captured by Japanese and Korean satellites, the data was turned into imagery by the The Cooperative Institute for Mesoscale Meteorological Studies at the University of Madison, Wisconsin.
The Asian satellites aren’t the only pieces of technology that captured the blast. A local seismograph registered the blasts as 2.3 and 2.9 moment magnitude.
Cell phone video from multiple sources captured the explosion as it happened. In those shots, the fireballs appear to reach hundreds of feet into the sky. Chinese media are reporting over 1,000 fire fighters in the area, though efforts have been momentarily suspended because the authorities don’t know what other dangerous materials might be in the container facility. At least 12 of the dead are fire fighters.
1 UPDATE 3:54 PM EST 08/13/15 Originally, this story listed all three satellites as Japanese. The data in the lower panel comes from a satellite operated by South Korea.
2 UPDATE 8:00PM EST 08/13/15 Earlier this sentence said these are shock waves. This sensor is pretty cool, but it can’t sense sound waves. And if it could, it wouldn’t be able to see them with a 10 minute frame rate. These are smoke clouds, moving at the speed of wind.
Pluto isn’t the only dwarf planet NASA is interested in these days. The space agency sent up a probe named Dawn in 2007 to two big rocks in the asteroid belt: Ceres and Vesta. Now, Dawn is circling in on Ceres, which is about 40 percent the size of Pluto, and returning new topographic images of its pockmarked surface.
With those better close-ups, the astronomers back at home are starting the process of giving Ceres’ features official names. The International Astronomical Union is in charge of naming things, and man, those guys must have fun going through their mythology textbooks. All of Ceres’ newly-christened craters and other features have names inspired by harvest deities from a wide range of cultures (Ceres itself is named after the Roman goddess of agriculture).
See that crater with the two bright neon spots? That’s Occator, the most mysterious crater on the whole asteroid (and Ceres’ helpful assistant-god in Roman mythology). Nobody knows that those bright spots are. Same goes for the bright spot all the way to the left, which used to be called Spot 1. Now it’s named Haulani, for the Hawaiian goddess of plants. Those are the ones most likely to show up in your astronomy pop quiz, but here are some of the rest, for the record:
Zadeni: Georgian god of fruitfulness
Coniraya: Incan god of fertility
Kerwan: Hopi spirit of corn
Ezinu: Sumerian goddess of grain
Kirnis: Lithuanian god of cherries
Urvara: Hindu goddess of fertility
Rongo: Maori god of agriculture
Everybody loves pictures from space. People love pictures *of* space. And even though most folks tend to watch them on wee little screens with mmmmaybe retina-class resolution, the world is still full of IMAX screens and, someday soon, Oculus Rifts. So a bigger, better camera in space sounds like a pretty good idea to us. “Oh, really,” you say. “Well, how about a RED Epic Dragon that can shoot 6K and 3D? How about 300 frames per second?” Well, yes. That will be fine. Thank you.
The International Space Station got just such a camera back in January, delivered in one of SpaceX’s Dragon capsules. Here’s a taste of the video that it shot in 4K of astronaut Terry Virts dissolving effervescent tabs (i.e. Alka-Seltzer) in a ball of floating water. Important stuff up there, NASA. WIRED is still a regular old terrestrial HD outlet, but we’ve zoomed in so you can see that bubbling up close.
The last time we saw the so-called EM Drive, it was causing a kerfuffle over at NASAspaceflight.com, where a member of a tiny team called Eagleworks at NASA’s Johnson Space Center had posted some information about a propellantless propulsion device. People got really excited, like you do when you think super smart physicists might have figured out a way to travel to the farthest reaches of space by bouncing microwaves around in a cavity—no propellant, no extra weight, no end in sight. But as we explained, the NASA team’s results appeared just on the threshold of detection, weren’t peer-reviewed, and, you know, violated this pesky thing called conservation of momentum.
All of those problems are still true. A new publication purports to test the drive’s magical thrust-making abilities. This time, the news is coming from a team at the Dresden University of Technology. They presented their results (thrust signatures of +/-20 microNewtons, if you must know) at a conference today, the Propulsion and Energy Forum and Exposition held by the American Institute for Aeronautics and Astronautics.
To be fair, these researchers constructed their version of the device so they could try to eliminate potential sources of error or interference, and they don’t say that they’ve validated the drive—just that they can’t explain where their teeny tiny thrust signatures are coming from. Despite what the Internet is saying, nobody has confirmed anything, and those silly physical laws still say propellantless space drives are impossible. If you want a physics primer and a refresher on the history of this crazy hype-machine of a device, here you go. Sorry to crush your dreams, space cadets.
NASA announced today the discovery of Kepler 452b, which it’s touting as the most Earth-like exoplanet found so far. It even released a pretty artist impression of the planet’s lakes and mountains. But hold up: There’s also a nearly even chance that Kepler 452b is a gassy planet, NASA’s scientists say. Earth’s cousin? Maybe that superweird cousin who doesn’t come to family reunions.
While NASA is understandably eager to show off the successes of the Kepler mission, astronomers actually know very little about Kepler 452b. That’s because finding exoplanets is really, really hard. Kepler looks for tiny changes in light as a planet passes in front of its star. And that method only tells scientists the size of the planet and its distance from the sun.
Here’s what NASA does know about Kepler 452b. It has a radius 60 percent larger than Earth’s. It takes 385 days to orbit around its star, which is also similar to our sun. But there’s one crucial fact astronomers do not know: Kepler 452b’s mass. Models suggest it may be five times as massive as Earth, which would make it rocky planet. But the chances of it being rocky are only slightly better than 50-50.
And that makes the artist impression even more impressionistic than you might have thought. Basically, NASA had a planetary geologist come up with a possible description of a rocky planet based on the few known facts about Kepler 452b, and the SETI Institute, whose scientists were part of the study, hired an artist to draw up it. It’s certainly pretty, but don’t take it as fact.
Today, a three-crew team of international astronauts safely rocketed toward the International Space Station. After a brief delay due to weather, their Soyuz rocket launched from the Baikonur Cosmodrome in Kazakhstan at 5:02pm Eastern time, successfully discarding the three stages of its engine on its way into orbit. Russian cosmonaut Oleg Kononenko, American astronaut Kjell Lindgren, and Japanese astronaut Kimiya Yui join astronauts American Scott Kelly, Russian Gennada Padalka, and Russian Mikhail Kornienko aboard the space station.
Launching into space is never exactly relaxing, but tensions must have been particularly high for this set of new crew members. Their mission should have launched in May, but it was delayed while Russia investigated the failure of one of its Progress cargo missions, also powered by a Soyuz rocket. And three weeks ago, SpaceX’s unmanned Dragon 9 rocket exploded less than three minutes into its flight, making it the third failed launch to the ISS in less than a year.
Once the rocket made it safely into orbit about 10 minutes into flight—marked by the release of an R2D2 figurine, floating gently around the now low-gravity cockpit—first-time flyers Yui and Lindgren shared a triumphant (and probably relieved) fist-bump. After a 5 hour, 43 minute flight, they’ll dock with the ISS and begin their normal duties. Welcome to space!
This morning, the three astronauts aboard the International Space Station pulled a Sandra Bullock. Well, not quite—they weren’t captured outside their craft, pummeled by debris, and sent adrift into space with only their wits and a dwindling oxygen supply to save them. But this is (hopefully) as close as real astronauts will ever get to that situation.
Around 6:30 AM Eastern, mission control notified the crew that a piece of debris from an old Russian weather satellite was heading their way, scheduled to whiz by the station at 8:01 AM. Normally, the ISS would get a bigger heads-up about incoming space debris. But this time it wasn’t prepared to move out of the way. So instead, the crew—including Commander Gennady Padalka, Scott Kelly, and Mikhail Kornienko—hid out in the Soyuz spacecraft docked to the station, ready to abandon ship if the space shrapnel came too close.
This is the fourth time in history the ISS crew has had to jump in the Soyuz for protection (it’s less likely that debris will hit the relatively small, hidden capsule) and potential evacuation. The amount of trash floating around in low Earth orbit is a constant threat to the station. “We follow space debris all the time, but most of it falls outside the imaginary protective box that we put around the station,” says NASA spokesperson Kyle Herring.
Since its launch in 1998, the station has had to maneuver out of the way of debris 22 times. It even has a new predetermined avoidance maneuver in place for just these situations, which will kick off a thruster to slightly change the station’s orbit at the push of a button.
Today, though, there wasn’t enough time for that maneuver to make a difference, so the crew just hunkered down, closing themselves inside the Soyuz and counting down the minutes until the debris’ closest approach. That was after an hour and a half of quickly taking steps to protect the station as best they could, sealing off the separate modules to contain the damage if the debris hit only part of the station.
Luckily, the satellite debris didn’t come into contact with the ISS. Mission control sent the all-clear minutes after the debris had passed, and the astronauts are now back in the station, in the process of reconfiguring it for normal operations. Ryan Stone would be proud.
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