A view the Cassini spacecraft took during its flyby of Jupiter's southern pole in 2000. Credit: NASA/JPL/Space Science Institute
Gimme a rocketship – we want to see what those bands are made of! This is a strange view of Jupiter, a familiar gas giant that humanity has sent several spacecraft to. This particular view, taken in 2000 and highlighted on the European Space Agency website recently, shows the southern hemisphere of the mighty planet.
The underneath glimpse came from the Cassini spacecraft while it was en route to Saturn. Lucky for researchers, at the time the Galileo Jupiter spacecraft was still in operation. But now that machine is long gone, leaving us to pine for a mission to Jupiter until another spacecraft gets there in 2016.
That spacecraft is called Juno and is a NASA spacecraft the agency sent aloft in August 2011. And here’s the cool thing; once it gets there, Juno is supposed to give us some insights into how the Solar System formed by looking at this particular planet.
Juno will repeatedly dive between the planet and its intense belts of charged particle radiation, coming only 5,000 kilometers (about 3,000 miles) from the cloud tops at closest approach. (NASA/JPL-Caltech)
“Underneath its dense cloud cover, Jupiter safeguards secrets to the fundamental processes and conditions that governed our Solar System during its formation. As our primary example of a giant planet, Jupiter can also provide critical knowledge for understanding the planetary systems being discovered around other stars,” NASA wrote on the spacecraft’s web page.
The spacecraft is supposed to look at the amount of water in Jupiter’s atmosphere (an ingredient of planet formation), its magnetic and gravitational fields and also its magnetic environment — including auroras.
Much further in the future (if the spacecraft development is approved all the way) will be a European mission called JUICE, for Jupiter Icy Moon Explorer.
Artist’s impression of the Jupiter Icy Moons Explorer (JUICE) near Jupiter and one of its moons, Europa. Credit: ESA/AOES
The mission will check out the planet and three huge moons, Ganymede, Callisto and Europa, to get a better look at those surfaces. It is strongly believed that these moons could have global oceans that may be suitable for life.
Earlier this month, the European Space Agency approved the implementation phase for JUICE, which means that designers now have approval to come up with plans for the spacecraft. But it’s not going to launch until 2022 and get to Jupiter until 2030, if the schedule holds.
This global map of Dione, a moon of Saturn, shows dark red in the trailing hemisphere, which is due to radiation and charged particles from Saturn's intense magnetic environment. Credit: NASA/JPL/Space Science Institute
If you hang out in Saturn’s intense magnetic environment for a while, it’s going to leave a mark. That’s one conclusion from scientists who proudly released new maps yesterday (Dec. 9) of the planet’s icy moons, showing dark blotches on the surfaces of Dione, Rhea, and Tethys.
Cassini has been at Saturn for more than 10 years, and compared to the flyby Voyager mission has given us a greater understanding of what these moons contain. You can see the difference clearly in the maps below; look under the jump and swipe back and forth to see the difference.
So what do these maps yield? Radiation-burned hemispheres in Dione, Tethys, and Rhea. Icy deposits building up on Enceladus from eruptions, which you can see in yellow and magenta, as well as fractures in blue. Dust from Saturn’s E-ring covering several of the moons, except for Iapetus and Tethys.
“Tiger stripes” — sources of ice spewing — in this image of Saturn’s Enceladus taken by the Cassini spacecraft in 2009. Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA
Could these be used by future explorers seeking life in some of these moons? In the meantime, enjoy the difference between Voyager’s view in the 1980s, and Cassini’s view for the past decade, in the comparison maps below.
A caution about the maps: they are a little more enhanced than human vision, showing some features in infrared and ultraviolet wavelengths. “Differences in color across the moons’ surfaces that are subtle in natural-color views become much easier to study in these enhanced colors,” NASA stated.
Artist depiction of Huygens landing on Titan. Credit: ESA
It’s almost exactly 10 years ago that humanity parachuted a spacecraft into Titan, that moon of Saturn that could hold chemistry similar to what sat on Earth before life arose. Called Huygens, the probe survived for just about an hour on the surface on Jan. 14, 2005, transmitting information back about conditions there and on the way down.
Huygens is long dead, but its carrier craft is doing just fine. On Dec. 10, Cassini will make the 107th close pass by Titan to learn more about the moon’s atmosphere. Although Huygens made it to the surface fine, showing at least a basic understanding of how a parachute behaves on Titan, there’s still so much more we need to learn.
Specifically, Cassini’s different instruments have been coming up with different answers for Titan’s atmospheric density, so this flyby is hoping to resolve some of that. In part, they hope to get more accurate measurements by measuring how much drag the spacecraft experiences when it flies past the moon.
Titan’s landscape as seen by the Huygens probe descent through Saturn’s largest moons atmosphere (credit: ESA, NASA, JPL, UA, Rene Pascal)
When Huygens probed the atmosphere on its way down, scientists figured that its measurements agreed in many ways with those taken by the flying-by Voyager 2 spacecraft previously. That said, the probe also discovered “a significant correspondence of wind shear and buoyant stability structures” in the stratosphere and lower tropopause of Titan, according to a 2006 presentation on Huygens results.
A beautiful image of Sasturns tiny moon Daphnis, but where is all the color?
If NASA is so advanced, why are their pictures in black and white?
It’s a question that I’ve heard, in one form or another, for almost as long as I’ve been talking with the public about space. And, to be fair, it’s not a terrible inquiry. After all, the smartphone in my pocket can shoot something like ten high-resolution color images every second. It can automatically stitch them into a panorama, correct their color, and adjust their sharpness. All that for just a few hundred bucks, so why can’t our billion-dollar robots do the same?
The answer, it turns out, brings us to the intersection of science and the laws of nature. Let’s take a peek into what it takes to make a great space image…
Perhaps the one thing that people most underestimate about space exploration is the time it takes to execute a mission. Take Cassini, for example. It arrived at Saturn back in 2004 for a planned four-year mission. The journey to Saturn, however, is about seven years, meaning that the spacecraft launched way back in 1997. And planning for it? Instrument designs were being developed in the mid-1980s! So, when you next see an astonishing image of Titan or the rings here at Universe Today, remember that the camera taking those shots is using technology that’s almost 30 years old. That’s pretty amazing, if you ask me.
But even back in the 1980s, the technology to create color cameras had been developed. Mission designers simply choose not to use it, and they had a couple of great reasons for making that decision.
Perhaps the most practical reason is that color cameras simply don’t collect as much light. Each “pixel” on your smartphone sensor is really made up of four individual detectors: one red, one blue, two green (human eyes are more sensitive to green!). The camera’s software combines the values of those detectors into the final color value for a given pixel. But, what happens when a green photon hits a red detector? Nothing, and therein lies the problem. Color sensors only collect a fraction of the incoming light; the rest is simply lost information. That’s fine here on Earth, where light is more or less spewing everywhere at all times. But, the intensity of light follows one of those pesky inverse-square laws in physics, meaning that doubling your distance from a light source results in it looking only a quarter as bright.
That means that spacecraft orbiting Jupiter, which is about five times farther from the Sun than is the Earth, see only four percent as much light as we do. And Cassini at Saturn sees the Sun as one hundred times fainter than you or I. To make a good, clear image, space cameras need to make use of all the little light available to them, which means making do without those fancy color pixels.
A mosaic of images through different filters on NASA’s Solar Dynamics Observatory. Image credit: NASA/SDO/Goddard Space Flight Center
The darkness of the solar system isn’t the only reason to avoid using a color camera. To the astronomer, light is everything. It’s essentially our only tool for understanding vast tracts of the Universe and so we must treat it carefully and glean from it every possible scrap of information. A red-blue-green color scheme like the one used in most cameras today is a blunt tool, splitting light up into just those three categories. What astronomers want is a scalpel, capable of discerning just how red, green, or blue the light is. But we can’t build a camera that has red, orange, yellow, green, blue, and violet pixels – that would do even worse in low light!
Instead, we use filters to test for light of very particular colors that are of interest scientifically. Some colors are so important that astronomers have given them particular names; H-alpha, for example, is a brilliant hue of red that marks the location of hydrogen throughout the galaxy. By placing an H-alpha filter in front of the camera, we can see exactly where hydrogen is located in the image – useful! With filters, we can really pack in the colors. The Hubble Space Telescope’s Advanced Camera for Surveys, for example, carries with it 38 different filters for a vast array of tasks. But each image taken still looks grayscale, since we only have one bit of color information.
At this point, you’re probably saying to yourself “but, but, I KNOW I have seen color images from Hubble before!” In fact, you’ve probably never seen a grayscale Hubble image, so what’s up? It all comes from what’s called post-processing. Just like a color camera can combine color information from three detectors to make the image look true-to-life, astronomers can take three (or more!) images through different filters and combine them later to make a color picture. There are two main approaches to doing this, known colloquially as “true color” and “false color.”
A “true color” image of the surface of Jupiter’s moon Europa as seen by the Galileo spacecraft. Image credit: NASA/JPL-Caltech/SETI Institute
True color images strive to work just like your smartphone camera. The spacecraft captures images through filters which span the visible spectrum, so that, when combined, the result is similar to what you’d see with your own eyes. The recently released Galileo image of Europa is a gorgeous example of this.
Our eyes would never see the Crab Nebula as this Hubble image shows it. Image credit: NASA, ESA, J. Hester and A. Loll (Arizona State University)
False color images aren’t limited by what our human eyes can see. They assign different colors to different features within an image. Take this famous image of the Crab Nebula, for instance. The red in the image traces oxygen atoms that have had electrons stripped away. Blue traces normal oxygen and green indicates sulfur. The result is a gorgeous image, but not one that we could ever hope to see for ourselves.
So, if we can make color images, why don’t we always? Again, the laws of physics step in to spoil the fun. For one, things in space are constantly moving, usually really, really quickly. Perhaps you saw the first color image of comet 67P/Churyumov-Gerasimenko released recently. It’s kind of blurry, isn’t it? That’s because both the Rosetta spacecraft and the comet moved in the time it took to capture the three separate images. When combined, they don’t line up perfectly and the image blurs. Not great!
The first color image of comet 67P/Churyumov-Gerasimenko. Image credit: ESA/Rosetta
But it’s the inverse-square law that is the ultimate challenge here. Radio waves, as a form of light, also rapidly become weaker with distance. When it takes 90 minutes to send back a single HiRISE image from the Mars Reconnaissance Orbiter, every shot counts and spending three on the same target doesn’t always make sense.
Finally, images, even color ones, are only one piece of the space exploration puzzle. Other observations, from measuring the velocity of dust grains to the composition of gases, are no less important to understanding the mysteries of nature. So, next time you see an eye-opening image, don’t mind that it’s in shades of gray. Just imagine everything else that lack of color is letting us learn.
As of November 2014, these are all of the planetary, lunar and small body surfaces where humanity has either lived, visited, or sent probes to. Composition by Mike Malaska, updated by Michiel Straathof. Image credits: Comet 67P/C-G [Rosetta/Philae]: ESA / Rosetta / Philae / CIVA / Michiel Straathof. Asteroid Itokawa [Hayabusa]: ISAS / JAXA / Gordan Ugarkovic. Moon [Apollo 17]: NASA. Venus [Venera 14]: IKI / Don Mitchell / Ted Stryk / Mike Malaska. Mars [Mars Exploration Rover Spirit]: NASA / JPL / Cornell / Mike Malaska. Titan [Cassini-Huygens]: ESA / NASA / JPL / University of Arizona. Earth: Mike Malaska
Correction, 11:33 a.m. EST: The University of Central Florida’s Phil Metzger points out that the image composition leaves out Eros, which NEAR Shoemaker landed on in 2001. This article has been corrected to reflect that and to clarify that the surfaces pictured were from “soft” landings.
And now there are eight. With Philae’s incredible landing on a comet earlier this week, humans have now done soft landings on eight solar system bodies. And that’s just in the first 57 years of space exploration. How far do you think we’ll reach in the next six decades? Let us know in the comments … if you dare.
More seriously, this amazing composition comes courtesy of two people who generously compiled images from the following missions: Rosetta/Philae (European Space Agency), Hayabusa (Japan Aerospace Exploration Agency), Apollo 17 (NASA), Venera 14 (Soviet Union), the Spirit rover (NASA) and Cassini-Huygens (NASA/ESA). Omitted is NEAR Shoemaker, which landed on Eros in 2001.
Before Philae touched down on Comet 67P/Churyumov–Gerasimenko Wednesday, the NASA Jet Propulsion Laboratory’s Mike Malaska created a cool infographic of nearly every place we’ve lived or visited before then. This week, Michiel Straathof updated the infographic to include 67P (and generously gave us permission to use it.)
And remember that these are just the SURFACES of solar system bodies that we have visited. If you include all of the places that we have flown by or taken pictures from of a distance in space, the count numbers in the dozens — especially when considering prolific imagers such as Voyager 1 and Voyager 2, which flew by multiple planets and moons.
To check out a small sampling of pictures, visit this NASA website that shows some of the best shots we’ve taken in space.
Reprocessed view by Bjorn Jonsson of the Great Red Spot taken by Voyager 1 in 1979 reveals an incredible wealth of detail.
If it weren’t for the Sun, Jupiter’s Great Red Spot would be a much blander feature on the gas giant, a new study reveals. This stands apart from what most scientists think about why for why the spot looks so colorful: that there are features in the clouds that give it its distinctive shade.
The new data comes from observations with the Cassini spacecraft, combined with experiments in the lab. They conclude that the Red Spot’s immense height, combined with sunlight breaking apart the atmosphere there into certain chemicals, make the feature that red that is visible even in small telescopes.
“Our models suggest most of the Great Red Spot is actually pretty bland in color, beneath the upper cloud layer of reddish material,” said Kevin Baines, a Cassini team scientist based at NASA’s Jet Propulsion Laboratory in California, in a statement. “Under the reddish ‘sunburn’ the clouds are probably whitish or grayish.”
The lab experiments combined ammonia and acetylene gases (atmospheric components from Jupiter) with ultraviolet light (simulating what the Sun produces), which created a ruddy substance that matched observations made with the Cassini spacecraft back in 2000. They also tried breaking apart ammonium hydrosulfide, a common element in Jupiter’s high clouds, but the color produced was actually a bright green.
The Great Red Spot is a storm that has been raging on Jupiter since at least when telescopes were first used in the 1600s. Over the past few decades, its size has shrunk considerably –it’s now half of what historical measurements showed — but it is still much larger than Earth. Scientists are hoping the forthcoming Juno mission, which will arrive at Jupiter at 2016, will help learn more about what is going on.
Results were presented at the Division for Planetary Science of the American Astronomical Society’s annual meeting this week in Tucson, Arizona. A press release did not disclose publication plans or if the research is peer-reviewed.
In this near-infrared mosaic, the sun shines off of the seas on Saturn's moon, Titan. Credit: NASA/JPL-Caltech/University of Arizona/University of Idaho
See that yellow smudge in the image above? That’s what the Sun looks like reflecting off the seas of Titan, that moon of Saturn that excites astrobiologists because its chemistry resembles what early Earth could have looked like. This image represents the first time this “sunglint” and Titan’s northern polar seas have been captured in one mosaic, NASA said.
What’s more, if you look closely at the sea surrounding the sunlight, you can see what scientists dub a “bathtub ring.” Besides looking pretty, this image from the Cassini spacecraft shows the huge sea (called Kraken Mare) was actually larger at some point in Titan’s past.
“The southern portion of Kraken Mare … displays a ‘bathtub ring’ — a bright margin of evaporate deposits — which indicates that the sea was larger at some point in the past and has become smaller due to evaporation,” NASA stated. “The deposits are material left behind after the methane and ethane liquid evaporates, somewhat akin to the saline crust on a salt flat.”
In this near-infrared global mosaic of Titan, sunglint and the moon’s polar seas are visible above the shadow. Credit: NASA/JPL-Caltech/University of Arizona/University of Idaho
The sunlight was so bright that it saturated the detector on Cassini that viewed it, called the Visual and Infrared Mapping Spectrometer (VIMS) instrument. The sun was about 40 degrees above the horizon of Kraken Mare then, which is the highest ever observed on Titan.
The T-106 flyby Oct. 23 was the second-to-last closeup view Cassini will have of Titan this year. The spacecraft has been circling Saturn’s system for more than 10 years, and is now watching Titan (and Saturn’s) northern hemisphere enter summer.
Titan is covered in a thick, orangey atmosphere that hid its surface from scientists the first time a spacecraft zoomed by it in the 1980s. Subsequent exploration (most especially by Cassini and a short-lived lander called Huygens) have revealed dunes on and near the equator and at higher altitudes, lakes of methane and ethane.
This cloud in the stratosphere over Titan’s north pole (left) is similar to Earth’s polar stratospheric clouds (right). NASA scientists found that Titan’s cloud contains methane ice, which was not previously thought to form in that part of the atmosphere. Cassini first spotted the cloud in 2006. Credit:
L. NASA/JPL/U. of Ariz./LPGNantes; R. NASA/GSFC/M. Schoeberl
During its 2006 flyby of Titan, the Cassini Space Probe captured some of the most detailed images of Saturn’s largest moon. Amongst them was one showing the lofty cloud formations over Titan’s north pole (shown above). Interestingly enough, these cloud formations bear a strong resemblance to those that are seen in Earth’s own polar stratosphere.
However, unlike Earth’s, these clouds are composed entirely of liquid methane and ethane. Given Titan’s incredibly low temperatures – minus 185 °C (-300 °F) – it’s not surprising that such a dense atmosphere of liquid hydrocarbons exists, or that seas of methane cover the planet.
Cassini's view down into a jetting "tiger stripe" in August 2010. Credit: NASA
Ever since the Cassini space probe conducted its first flyby of Enceladus in 2005, the strange Saturnian moon has provided us with a treasure trove of images and scientific wonders. These include the jets of icy water vapor periodically bursting from its south pole, the possibility of an interior ocean – which may even harbor life – and the strange green-blue stripes located around the south pole.
Ambition is a collaboration between Platige Image and ESA. Shot on location in Iceland, it is directed by Tomek Bagi?ski and stars Aiden Gillen and Aisling Franciosi. Does Ambition accomplish more in 7 minutes than Gravity did in 90? Consider the abstraction of the Rosetta mission in light of NASA’s ambitions. (Credit: ESA, Illustration- TRR)
NASA has taken on space missions that have taken years to reach their destination; they have more than a dozen ongoing missions throughout the Solar System and have been to comets as well. So why pay any attention to the European Space Agency’s comet mission Rosetta and their new short film, “Ambition”?
‘Ambition’ might accomplish more in 7 minutes than ‘Gravity’ did in 90.
‘Ambition’ is a 7 minute movie created for ESA and Rosetta, shot on location in Iceland, directed by Oscar-winning Tomek Baginski, and stars Aidan Gillen—Littlefinger of ‘Game of Thrones.’ It is an abstraction of the near future where humans have become demigods. An apprentice is working to merge her understanding of existence with her powers to create. And her master steps in to assure she is truly ready to take the next step.
In the reality of today, we struggle to find grounding for the quest and discoveries that make up our lives on a daily basis. Yet, as the Ebola outbreak or the Middle East crisis reminds us, we are far from breaking away. Such events are like the opening scene of ‘Ambition’ when the apprentice’s work explodes in her face.
The ancient Greeks also took great leaps beyond all the surrounding cultures. They imagined themselves as capable of being demigods. Achilles and Heracles were born from their contact with the gods but they remained fallible and mortal.
The Comet Rendezvous and Flyby Mission conceived in one of two Mariner Mark II spacecraft was abandoned by the US Congress. The American led mission would have accomplished the objectives now being completed by the European Rosetta mission. (Photo Credit: NASA)
But consider the abstraction of the Rosetta mission in light of NASA’s ambitions. As an American viewing the European short film, it reminds me that we are not unlike the ancient Greeks. We have seen the heights of our powers and ability to repel and conquer our enemies, and enrich our country. But we stand manifold vulnerable.
In ‘Ambition’ and Rosetta, America can see our European cousins stepping ahead of us. The reality of the Rosetta mission is that a generation ago – 25 years — we had a mission as ambitious called Comet Rendezvous Asteroid Flyby (CRAF). From the minds within NASA and JPL, twin missions were born. They were of the Mariner Mark II spacecraft design for deep space. One was to Saturn and the other – CRAF was to a comet. CRAF was rejected by congress and became an accepted sacrifice by NASA in order to save its twin, the Cassini mission.
The short film ‘Ambition’ and the Rosetta mission is a reminder of what American ambition accomplished in the 60’s – Apollo, and the 70s – the Viking Landers, but then it began to falter in the 80s. The ambition of the Europeans did not lose site of the importance of comets. They are perhaps the ultimate Rosetta stones of our star system. They are unmitigated remnants of what created our planet billions of years ago unlike the asteroids that remained close to the Sun and were altered by its heat and many collisions.
Artist Illustration of the Cassini space probe to Saturn and Titan, a joint NASA, ESA mission. Cassini was the only Mariner Mark II spacecraft completed. (Photo Credit: NASA)
Our cousins picked up a scepter that we dropped and we should take notice that the best that Europe spawned in the last century – the abstract art of Picasso and Stravinsky, rocketry, and jet travel — remains alive today. Europe had the vision to continue a quest to something quite abstract, a comet, while we chose something bigger and more self-evident, Saturn and Titan.
‘Ambition’ shows us the forces at work in and around ESA. They blend the arts with the sciences to bend our minds and force us to imagine what next and why. There have been American epoch films that bend our minds, but yet sometimes it seems we hold back our innate drive to discover and venture out.
NASA recently created a 7 minute film of a harsh reality, the challenge of landing safely on Mars. ESA and Rosetta’s short film reminds us that we are not alone in the quest for knowledge and discovery, both of which set the stage for new growth and invention. America needs to take heed so that we do not wait until we reach the moment when an arrow pierces our heel as with Achilles and we succumb to our challengers.
