We’ve seen volcanoes or geysers erupting on the moons of Io and Enceladus. Volcanic remnants remain on Mars and the Moon. But it’s tough for rovers to get inside these challenging environments.
So NASA’s Jet Propulsion Laboratory is trying out a new robot here on Earth to one day, they hope, get inside volcanoes elsewhere in the Solar System.
The series is called VolcanoBot. The first prototype was tested last year inside the the active Kilauea volcano in Hawaii, and a second is set for further work later this year.
As you can see in the picture below, VolcanoBot has a set of small wheels and a host of electronics inside. The goal is to create 3-D maps of the environments in which they roam. And early results are showing some promise, NASA noted in a press release: VolcanoBot discovered the fissure it was exploring did not completely close up, which is something they did not expect.
The Jet Propulsion Laboratory’s VolcanoBot 1 inside a lava tube at the Kilauea volcano in Hawaii. Credit: NASA/JPL-Caltech
“We don’t know exactly how volcanoes erupt. We have models but they are all very, very simplified. This project aims to help make those models more realistic,” stated Carolyn Parcheta, a NASA postdoctoral fellow at the Jet Propulsion Laboratory in California who is leading the research.
“In order to eventually understand how to predict eruptions and conduct hazard assessments, we need to understand how the magma is coming out of the ground,” she added. “This is the first time we have been able to measure it directly, from the inside, to centimeter-scale accuracy.”
The research will continue this year with VolcanoBot 2, which has less mass, less size and has an advanced “vison center” that can turn about.
Artist’s impression of the Cassini spacecraft making a close pass by Saturn’s inner moon Enceladus to study plumes from geysers that erupt from giant fissures in the moon’s southern polar region. Copyright 2008 Karl Kofoed/NASA. Click for full size version.
Parcheta’s research recently attracted the attention of visitors to National Geographic’s website, who voted her #2 in a list of “great explorers” on the Expedition Granted campaign.
Remember that this is early-stage research, with no missions outside of Earth yet assigned. But this is a small step — or roll, in this case — to better understanding how volcanoes work generally, whether on our own planet or other locations.
Jupiter's Europa passes in front of fellow moon Io in this sequence of images taken from the Gemini North observatory Dec. 16, 2014. Credit: Gemini Observatory
On Christmas Eve, as millions upon millions of people focused on wrapping gifts and getting ready for the holidays, an amateur astronomer gave a small gift to the world. The person turned a telescope and camera to Jupiter and caught volcanic Io going across the face of the gas giant. This happened just a few days after professional astronomers caught a rare eclipse involving that very same moon.
“I wish I had been able to go on for longer but Jupiter went behind the house just before the transit ended. The transit is 102 frames (306 captures in total, RGB separate). Seeing was rather poor and a small amount of dew formed resulting in reduced brightness and contrast in some parts of the GIF,” wrote Reddit user IKYLSP.
“Something rather interesting with this one is the brief appearance of Ganymede from behind the planet’s shadow just before it’s eclipsed by the planet. If you zoom in you can actually see it as a half-moon shape which is really awesome.”
Jupiter’s moon Europa passes in front of Io in this picture captured from the Gemini North observatory on Dec. 16, 2014. Credit: Gemini Observatory
Speaking of half-moons, check out another awesome animation of Io taken from the Gemini North observatory on Dec. 16. Here, you can see icy Europa passing in front of the volcanic moon from the telescope’s perspective. Here’s part of what the observatory wrote about the rare event:
Observations of Jupiter’s volcanically active moon Io, obtained that night as part of a program led by Katherine de Kleer of UC Berkeley to watch for volcanic outbursts, revealed an unusual event involving Io and another large jovian moon, Europa. According to de Kleer, the images captured an occultation event in which Europa briefly blocked some of the light from Io, “…giving Io a very un-Io-like appearance!” These sorts of events occur when we observe the moons’ orbits edge-on, and can occasionally view the moons passing in front of one another.
And below you can see individual frames from the eclipse.
Jupiter’s Europa passes in front of fellow moon Io in this sequence of images taken from the Gemini North observatory Dec. 16, 2014. Credit: Gemini Observatory
A montage of images taken of Jupiter and its moon Io (foreground) by the New Horizons mission in 2007. Jupiter is shown in infrared wavelengths while Io is close to true-color. On top of Io is an eruption from the volcano Tvashtar. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
New Horizons, you gotta wake up this weekend. There’s so much work ahead of you when you reach Pluto next year! The spacecraft has been sleeping quietly for weeks in its last great hibernation before the dwarf planet close encounter in July. On Saturday (Dec. 6), the NASA craft will open its eyes and begin preparations for that flyby.
How cool will those closeups of Pluto and its moons look? A hint comes from a swing New Horizons took by Jupiter in 2007 en route. It caught a huge volcanic plume erupting off of the moon Io, picked up new details in Jupiter’s atmosphere and gave scientists a close-up of a mysterious “Little Red Spot.” Get a taste of the fun seven years ago in the gallery below.
An eruption from the Tvashtar volcano on Io, Jupiter’s moon, in several different wavelength images taken by the New Horizons spacecraft in 2007. The left image from the Long Range Reconnaissance Imager (LORRI) shows lava glowing in the night. At top right, the Multispectral Visible Imaging Camera (MVIC) spotted sulfur and sulfor dioxide deposits on the sunny side of Io. The remaining image from the Linear Etalon Imaging Spectral Array (LEISA) shows volcanic hotspots on Io’s surface. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research InstituteJupiter’s “Little Red Spot” seen by the New Horizons spacecraft in 2007. The spot turned red in 2005 for reasons scientists were then unsure of, but speculated it could be due to stuff from inside the atmosphere being stirred up by a storm surge. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research InstituteA “family portrait” of the four Galilean satellites around Jupiter taken by the New Horizons spacecraft and released in 2007. From left, the montage includes Io, Europa, Ganymede and Callisto. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research InstituteA composite of Jupiter’s bands (and atmospheric structures) taken in several images by the New Horizons Multispectral Visual Imaging Camera, showing differences due to sunlight and wind. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research InstituteIn February and March 2007, a huge plume erupted from the Tvashtar volcano on Jupiter’s moon Io. The image sequence taken by New Horizons showed the largest such explosion then viewed by a spacecraft — even accounting for the Galileo spacecraft that examined Io between 1996 and 2001. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research InstituteThe New Horizons flyby of Io in 2007 (right) revealed a changing feature on the surface of the Jupiter moon since Galileo’s image of 1999 (left.) Inside the circle, a new volcanic eruption spewed material; other pictures showed this region was still active. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
A view of Mimas from the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute
Could there be an ocean hidden somewhere in that Death Star-like picture? This is an image of Mimas, a moon of Saturn, and just yesterday (Oct. 15) newly released data from the Cassini spacecraft suggests there are big liquid reservoirs underneath its surface.
“The amount of the to-and-fro motion indicates that Mimas’ interior is not uniform. These wobbles can be produced if the moon contains a weirdly shaped, rocky core or if a sub-surface ocean exists beneath its icy shell,” said Cornell University in a press release. More flybys with the Cassini spacecraft will be required to learn more about what lies beneath.
You can read more about the study (led by Cornell astronomy research associate Radwan Tajeddine) in Science, where it was published. Below, learn more about other worlds in the Solar System that could host oceans under their surface.
Enceladus
Cassini images of Saturn’s moon Enceladus backlit by the sun show the fountain-like sources of the fine spray of material that towers over the south polar region. This image was taken looking more or less broadside at the “tiger stripe” fractures observed in earlier Enceladus images. It shows discrete plumes of a variety of apparent sizes above the limb (edge) of the moon. This image was acquired on Nov. 27, 2005. Image Credit: NASA/JPL/Space Science Institute
After nearly a decade of speculation, this year the Cassini spacecraft returned gravity data suggesting Enceladus (another moon of Saturn) does have a large subsurface ocean near its south pole, if not a global ocean. If confirmed, that could help explain why scientists see water gushing out of fractures in that area. As this recent paper by Cassini scientists shows, Enceladus is a promising location for habitability.
Titan
A halo of light surrounds Saturn’s moon Titan in this backlit picture, showing its atmosphere. Credit: NASA/JPL/Space Science Institute
By the way, anyone noticed that we still haven’t even left Saturn’s system? Titan is usually high on astrobiology wish lists for researchers because its hydrocarbon chemistry could be precursors to how life evolved. What’s not talked about as much, though, is at least two research findings pointing to evidence of a hidden ocean. Evidence comes from Titan’s tidal flexing from interacting with Saturn — which is 10 times more than what would be expected with a solid core — and the way that it moves on its own axis as well as around Saturn.
Europa
Rendering showing the location and size of water vapor plumes coming from Europa’s south pole. Credit: NASA/ESA/L. Roth/SWRI/University of Cologne
That Minecraft-looking object floating beside Europa there is a rendering showing where water vapor erupted from the Jovian moon, spotted by the Hubble Space Telescope in 2013. We were lucky enough to have a close-up view of Europa in the 1990s and early 2000s courtesy of NASA’s Galileo spacecraft. What we know for sure is there’s thick ice on Europa. What’s underneath is not known, but there’s long been speculation that it could be a subsurface ocean that may have more water than our own planet.
Io
Jupiter’s volcanic moon Io , imaged by the Galileo spacecraft in 1997. Credit: NASA/JPL/University of Arizona
Still flying around Jupiter here, we now turn our attention to Io — a place that is often remarked upon because of its blotchy appearance as well as all of the volcanoes on its surface. A newer analysis of Galileo data in 2011 — looking at some of the lesser-understood magnetic field data signatures — led one research team to conclude there could be a magma ocean lurking underneath that violence.
Triton
A glimpse of Triton from the Voyager 2 spacecraft, which flew by the Neptunian moon in August 1989. Credit: NASA/JPL
Little is known about Triton because only one spacecraft whizzed by it — Voyager 2, which took a running pass through the Neptune system in August 1989. An Icarus paper two years ago speculated that the world could host a subsurface ocean, but more data is needed. The energy of Neptune (which captured Triton long ago) could have melted its interior through tidal heating, possibly creating water from the ice in its crust.
Charon
Hubble image of Pluto and some of its moons, Charon, Nix and Hydra. Image Credit: NASA, ESA, H. Weaver (JHU/APL), A. Stern (SwRI), and the HST Pluto Companion Search Team
We don’t have any close-up pictures of this moon of Pluto yet, but just wait a year. The New Horizons spacecraft will zoom past Charon and the rest of the system in July 2015. In the meantime, however, findings based on a model came out this summer in Icarus suggesting Charon — despite being so far from the Sun — might have had a subsurface ocean in the past. Or even now. The key is its once eccentric orbit, which would have produced tidal heating while interacting with Pluto. The science team plans to look for cracks that could be indicative of “the structure of the moon’s interior and how easily it deforms, and how its orbit evolved,” stated Alyssa Rhoden of NASA’s Goddard Space Flight Center in Maryland, who led the research.
Image of Io taken in the near-infrared with adaptive optics at the Gemini North telescope on August 29. In addition to the extremely bright eruption on the upper right limb of the satellite, the lava lake Loki is visible in the middle of Io’s disk, as well as the fading eruption that was detected earlier in the month by de Pater on the southern (bottom) limb. Io is about one arcsecond across. Image credit: Katherine de Kleer/UC Berkeley/Gemini Observatory/AURA
Jupiter’s innermost moon, Io — with over 400 active volcanoes, extensive lava flows and floodplains of liquid rock — is by far the most geologically active body in the Solar System. But last August, Io truly came alive with volcanism.
Three massive volcanic eruptions led astronomers to speculate that these presumed rare outbursts were much more common than previously thought. Now, an image from the Gemini Observatory captures what is one of the brightest volcanoes ever seen in our Solar System.
“We typically expect one huge outburst every one or two years, and they’re usually not this bright,” said lead author Imke de Pater from the University of California, Berkeley, in a press release. In fact, only 13 large eruptions were observed between 1978 and 2006. “Here we had three extremely bright outbursts, which suggest that if we looked more frequently we might see many more of them on Io.”
De Pater discovered the first two eruptions on August 15, 2013, from the W. M. Keck Observatory in Hawaii. The brightest was calculated to have produced a 50 square-mile, 30-feet thick lava flow, while the other produced flows covering 120 square miles. Both were nearly gone when imaged days later.
The third and even brighter eruption was discovered on August 29, 2013, at the Gemini observatory by UC Berkeley graduate student Katherine de Kleer. It was the first of a series of observations monitoring Io.
Images of Io tracking the evolution of the eruption as it decreased in intensity over 12 days. Due to Io’s rapid rotation, a different area of the surface is viewed on each night; the outburst is visible with diminishing brightness on August 29 & 30 and September 1, 3, & 10. Image credit: Katherine de Kleer / UC Berkeley / Gemini Observatory / AURA
This allowed the observations to “represent the best day-by-day coverage of such an eruption,” said de Kleer. The team was able to conclude that the energy emitted from the late-August eruption was about 20 Terawatts, and expelled many cubic kilometers of lava.
“At the time we observed the event, an area of newly-exposed lava on the order of tens of square kilometers was visible,” said de Kleer. “We believe that it erupted in fountains from long fissures on Io’s surface, which were over ten-thousand-times more powerful than the lava fountains during the 2010 eruption of Eyjafjallajokull, Iceland, for example.”
The team hopes that monitoring Io’s surface annually will reveal the style of volcanic eruptions on the moon, the composition of the magma, and the spatial distribution of the heat flows. The eruptions may also shed light on an early Earth, when heat from the decay of radioactive elements — as opposed to the tidal forces influencing Io — created exotic, high-temperature lavas.
“We are using Io as a volcanic laboratory, where we can look back into the past of the terrestrial planets to get a better understanding of how these large eruptions took place, and how fast and how long they lasted,” said coauthor Ashley Davies.
The latest results have been published in the journal Icarus.
Jupiter with polka dot shadows cast by Io, Europa and Callisto as depicted around 1 a.m. EDT Oct. 12. Watch for the Great Red Spot to come into view during the transit. Created with Claude Duplessis' Meridian software
Talk about a great fall lineup. Three of Jupiter’s four brightest moons plan a rare show for telescopic observers on Friday night – Saturday morning Oct. 11-12. For a span of just over an hour, Io, Europa and Callisto will simultaneously cast shadows on the planet’s cloud tops, an event that hasn’t happened since March 28, 2004.
Who doesn’t remember their first time looking at Jupiter and his entourage of dancing moons in a telescope? Because each moves at a different rate depending on its distance from the planet, they’re constantly on the move like kids in a game of musical chairs. Every night offers a different arrangement.
Jupiter and its four brightest moons seen in a small telescope. Credit: Bob King
Some nights all four of the brightest are strung out on one side of the planet, other nights only two or three are visible, the others hidden behind Jupiter’s “plus-sized” globe. Occasionally you’ll be lucky enough to catch the shadow of one of moons as it transits or crosses in front of the planet. We call the event a shadow transit, but to someone watching from Jupiter, the moon glides in front of the sun to create a total solar eclipse.
Since the sun is only 1/5 as large from Jupiter as seen from Earth, all four moons are large enough to completely cover the sun and cast inky shadows. To the eye they look like tiny black dots of varying sizes. Europa, the smallest, mimics a pinprick. The shadows of Io and Callisto are more substantial. Ganymede, the solar system’s largest moon at 3,269 miles (5,262 km), looks positively plump compared to the others. Even a small telescope magnifying around 50x will show it.
Jupiter on Sept. 24 with its moon Europa (at left) casting a pinhead black shadow on Jupiter’s clouds. Credit: John Chumack
The three inner satellites – Io, Europa and Ganymede – have shadow transits every orbit. Distant Callisto only transits when Jupiter’s tilt relative to Earth is very small, i.e. the plane of the planet’s moons is nearly edge-on from our perspective. Callisto transits occur in alternating “seasons” lasting about 3 years apiece. Three years of shadow play are followed by three years of shadowless misses. Single transits are fairly common; you can find tables of them online like this one from Project Pluto or plug in time and date into a free program like Meridian for a picture and list of times.
Because Io, Europa and Ganymede orbit in a 4:2:1 resonance (Io revolves four times around Jupiter in the time it takes Ganymede to orbit once; Europa completes two orbits for Ganymede’s one) it’s impossible for all three to line up – along with Callsto – for a “quadruple transit”. Credit: Matma Rex / Wikipedia
Seeing two shadows inch across Jupiter’s face is very uncommon, and three are as rare as a good hair day for Donald Trump. Averaged out, triple transits occur once or twice a decade. Friday night Oct. 11 each moon enters like actors in a play. Callisto appears first at 11:12 p.m. EDT followed by Europa and then Io. By 12:32 a.m. all three are in place.
Catch them while you can. Groups like these don’t last long. A little more than an hour later Callisto departs, leaving just two shadows. You’ll find the details below. All times are Eastern Daylight or EDT. Subtract one hour for Central time and add four hours for BST (British Summer Time):
* Callisto’s shadow enters the disk – 11:12 p.m. Oct. 11
* Europa – 11:24 p.m.
* Io – 12:32 a.m. ** TRIPLE TRANSIT from 12:32 – 1:37 a.m.
* Callisto departs – 1:37 a.m.
* Europa departs – 2:01 a.m.
* Io departs – 2:44 a.m.
Looking at Jupiter from high above the plane of the solar system in this diagram from more than a century ago, we can better picture how shadow transits and eclipses happen. The tiny disk of Io and the shadow of Ganymede are seen in transit; Callisto is about to be eclipsed by Jupiter’s shadow. Credit: Garrett Serviss from “Pleasures of the Telescope” (annotations: Bob King)
The triple transit will be seen across the eastern half of the U.S., Europe and western Africa. Those living on the East Coast have the best view in the U.S. with Jupiter some 20-25 degrees high in the northeastern sky around 1 a.m. local time. Things get dicier in the Midwest where Jupiter climbs to only 5-10 degrees. From the mountain states the planet won’t rise until Callisto’s shadow has left the disk, leaving a two-shadow consolation prize. If you live in the Pacific time zone and points farther west, you’ll unfortunately miss the event altogether.
From the Eastern Time Zone Jupiter will be well-placed in the eastern sky during the transit. Created with Stellarium
Key to seeing all three shadows clearly, especially if Jupiter is low in the sky, is steady air or what skywatchers call “good seeing”. The sky can be so clear you’d swear there’s a million stars up there, but a look through the telescope will sometimes show dancing, blurry images due to invisible air turbulence. That’s “bad seeing”. Unfortunately, bad seeing is more common near the horizon where we peer through a greater thickness of atmosphere. But don’t let that keep you inside Friday night. With a spell of steady air, all you need is a 4-inch or larger telescope magnifying around 100x to spot all three.
The March 28, 2004 triple transit. Shadows from left: Ganymede, Io and Callisto. You can also see the disks of Io (white dot) and Ganymede (blue dot) in this photo taken in infrared light by the Hubble Space Telescope. Credit: NASA/ESA
If bad weather blocks the view, there are two more triple transits coming up soon – a 95-minute-long event on June 3, 2014 starring Europa, Ganymede and Callisto (not visible in the Americas) and a 25-minute show on Jan. 24, 2015 featuring Io, Europa and Callisto and visible across Western Europe and the Americas. That’s it until dual triple transits in 2032.
An image of Io taken by the automated spacecraft: Galileo. Image Credit: NASA
Io – Jupiter’s innermost Galilean moon – is the most geologically active body in the Solar System. With over 400 active volcanic regions, plumes of sulfur can climb as high as 300 miles above the surface. It is dotted with more than 100 mountains, some of which are taller than Mount Everest. In between the volcanoes and mountains there are extensive lava flows and floodplains of liquid rock.
Intense volcanic activity leads to a thin atmosphere consisting mainly of sulfur dioxide (SO2), with minor species including sulfur monoxide (SO), sodium chloride (NaCl), and atomic sulfur and oxygen. Despite Io’s close proximity to the Earth the composition of its atmosphere remains poorly constrained. Models predict a variety of other molecules that should be present but have not been observed yet.
Recently a team of astronomers from institutions across the United States, France, and Sweden, set out to better constrain Io’s atmosphere. They detected the second-most abundant isotope of sulfur (34-S) and tentatively detected potassium chloride (KCl). The latter is produced in volcanic plumes – suggesting that these plumes continuously contribute to Io’s atmosphere.
Expected yet undetected molecular species include potassium chloride (KCl), silicone monoxide (SiO), disulfur monoxide (S2O), and various isotopes of sulfur. Most of these elements emit in radio wavelengths.
“Depending on their geometry, some molecules emit at well known frequencies when they change rotational state,” Dr. Arielle Moullet, lead author on the study, told Universe Today. “These spectral features are called rotational lines and show up in the (sub)millimeter spectral range.”
These observations were therefore obtained at the Atacama Pathfinder Experiment (APEX) antenna – a radio telescope located 16,700 feet above sea level in northern Chile. The main dish has a diameter of 12 meters, and is a prototype antenna for the Atacama Large Millimeter Array (ALMA).
The Atacama Pathfinder (APEX) antenna. Image Credit: ESO
Following 16.5 hours of total observation time and months of data reduction and analysis, Moullet et al. made a tentative detection of potassium chloride (KCl). Io’s volcanic ejecta produce a large plasma torus around Jupiter, which inlcudes many molecular species including potassium. This detection is therefore considered the “missing link” between Io and this plasma torus.
The team also made the first detection of one of Sulfur’s isotopes known as 34-S. Sulfur has 25 known isotopes – variants of sulfur that still have 16 protons but differ in their number of neutrons. 34-S is the second most abundant isotope with 18 neutrons.
Previously, the first-most abundant isotope of sulfur, 32-S with 16 neutrons, had been detected. Surprisingly the ratio between the two (34/32 S) is twice as high as the solar system reference, suggesting that there is an abundance of 34-S. A fraction this high has only been reported before in a distant quasar – an early galaxy consisting of an intensely luminous core powered by a huge black hole.
“This result tells us that there probably is some fractionation process that we haven’t yet identified, which is happening either in the magma, at the surface, or in the atmosphere itself,” explains Dr. Moullet. Something somewhere is producing an unexplained abundance of this isotope.
Other expected yet undetected molecules including silicone monoxide and disulfur monoxide remain undetected. It is possible that these molecules are simply not present, but more likely that the observations are not sensitive enough to detect them.
“To perform a deeper spectral search with a better sensitivity, our group has been awarded observation time with the Atacama Large Millimeter Array, a cutting edge interferometric facility in Chile, which will eventually include more than fifty 12-meter wide dishes,” explains Dr. Moullet. “We are in the process of analyzing our first dataset obtained with sixteen antennas, which is already much more sensitive than the APEX data.”
While Io is certainly an extreme example, it will likely help us characterize volcanism in general – providing a better understanding of volcanism here on Earth as well as outside the Solar System.
The paper has been accepted for publication in The Astrophysical Journal and is available for download here.
The Voyager spacecraft have been on an extensive mission of discovery that has lasted some 36 years. Image Credit: NASA/JPL
Yesterday, NASA announced that as of August 2012, Voyager 1 is in a new frontier to humanity: interstellar space. Our most distant spacecraft is now in a region where the plasma (really hot gas) environment comes more from between the stars than from the sun itself. (There’s still debate as to whether it’s in or out of the solar system, as this article explains.)
The plucky spacecraft is close to 12 billion miles (19 million kilometers) from home, and in its 36 years of voyaging has taught us a lot about the planets, their moons and other parts of space. Here are 10 of some of its most historic moments. Did we miss any? Let us know in the comments.
10. The launch: Aug. 20, 1977
Voyager 1 launches from the Kennedy Space Center on Sept. 5, 1977. Credit: NASA
Voyager 1 blasted off from Cape Canaveral on Sept. 5, 1977. Its twin, Voyager 2, departed Earth 16 days earlier. Each spacecraft carried various scientific instruments on board as well as a “Golden Record” that had sounds of Earth on it, as well as a diagram showing where Earth is in the universe.
9. Capturing the Earth and Moon together for the first time
On Sept. 18, 1977, Voyager 1 took three images of the Earth and Moon that were combined into this one image. The moon is artificially brightened to make it show up better. Credit: NASA
About two weeks after launching, Voyager 1 turned back towards Earth and took three images, which were combined into this single view of the Earth and Moon together in space. This was the first time both bodies were pictured together, NASA said.
8. The ‘Pale Blue Dot’ image
Voyager 1 pale blue dot. Image credit: NASA/JPL
On February 14, 1990, Voyager 1 was about 3.7 billion miles (6 billion kilometers) away from Earth. Scientists commanded the spacecraft to turn its face towards the solar system and snap some pictures of the planets. Among them was this famous image of Earth, which astronomer Carl Sagan called the Pale Blue Dot. “Look again at that dot. That’s here. That’s home. That’s us,” wrote Sagan in his 1997 book of the same name. In 2013, the spacecraft Cassini also took a picture of Earth, and NASA encouraged everyone to wave back.
7. Finding moons “shepherding” Saturn’s F ring
Prometheus, a small potato-shaped moon of Saturn, shown in this Voyager 1 picture interacting with the planet’s F ring. Credit: NASA/JPL/SSI
Voyager 1 spotted Prometheus and Pandora, two moons of Saturn that keep the F ring separate from the rest of the debris, as well as Atlas, which “shepherds” the A ring. More recently, astronomers have found even more interesting things in Saturn’s rings — such as rain.
6. Spotting what appeared to be a LOT of water ice on Saturn’s moons
Encaladus, a moon of Saturn, as shown in this Voyager 1 image. Credit: NASA
After many years of seeing Saturn’s moons as mere points of light, Voyager 1 buzzed several of them in its quick flyby through the system: Dione, Enceladus, Mimas, Rhea, Tethys and Titan among them. Many of these moons appeared to be icy, which was a surprising find since astronomers previously thought water was pretty rare in the Solar System. We know better now.
5. Imaging Titan’s orange haze
Saturn’s moon Titan lies under a thick blanket of orange haze in this Voyager 1 picture. Credit: NASA
Voyager 1 pictures such as this tortured astronomers for decades — what lies beneath this mysterious haze surrounding Titan, Saturn’s moon? That mystery, in fact, inspired the European Space Agency to send a lander to the moon, called Huygens, which successfully reached the surface in 2005.
4. Finding active volcanoes on Io
Io’s blotchy volcanoes are clearly visible in this image from Voyager 1. Credit: NASA
Voyager 1 helped show us that the Solar System is full of very interesting moons. At Io — a moon of Jupiter — it turns out the moon flexes during its 42-hour orbit of massive Jupiter, which powers a lot of volcanic activity.
3. Voyager 1 becomes the most distant human object
A 2013 computer-generated snapshot riding along with Voyager 1’s looking back at the Sun and inner solar system. The positions of Voyager 2 and Pioneers 10 and 11 show within the viewport as well.
On Feb. 17, 1998, Voyager 1’s distance surpassed that of another long-flying probe, Pioneer 10. This made Voyager 1 the farthest-flung human object in space.
2. Riding the “magnetic highway”
Artist concept of NASA’s Voyager 1 spacecraft exploring a new region in our solar system called the “magnetic highway.” Credit: NASA/JPL-Caltech
In December, NASA said Voyager 1 had reached an area (as of July 28, 2012) where high-energy magnetic particles were starting to bleed through the bubble of lower-energy particles from our sun. “Voyager’s discovered a new region of the heliosphere that we had not realized was there. It’s a magnetic highway where the magnetic field of the Sun is connected to the outside. So it’s like a highway, letting particles in and out,” said project scientist Ed Stone at the time. After that point, as more measurements were analyzed by different teams, there was a lot of debate as to whether Voyager had reached interstellar space.
1. Reaching interstellar space
This graphic shows the main evidence that Voyager 1 has reached interstellar space. The blue line shows particle density, which dropped as Voyager 1 moved away from the sun, and then jumped again after it crossed the “termination shock” that is where the sun’s solar wind (particles streaming from the sun) slows down. Credit: NASA/JPL-Caltech
With Voyager 1 now known to be in interstellar space, we’re lucky enough to have a few years left to communicate with it before it runs out of power. All of the instruments will be turned off by 2025, and then engineering data will be available for about 10 years beyond that. The silent emissary from humanity will then come within 1.7 light years of an obscure star in the constellation Ursa Minor (the Little Bear) called AC+79 3888 in the year 40,272 AD and then orbit the center of the Milky Way for millions of years.
