What do you do when your 7 and 11 year-old children ask you if you have pets in space? ….you make them of course! pic.twitter.com/Ct0tdKPxQf
— Randy Bresnik (@AstroKomrade) September 18, 2017
In September of 2011, China launched its first prototype space station. Tiangong-1 (translated into English: “Heavenly Palace 1”), was in operation until March 2016. During its operational history, it received three of visits by the China National Space Administration (CNSA). The unmanned Shenzou 8 docked with Tiangong-1 in November 2011, followed by two crewed missions: Shenzou 9 docked in June 2012, and Shenzou 10 in June 2013. China’s first two female astronauts participated in the crewed Shenzou missions to the space station: Liu Yang, China’s first woman in space, went up with Shnenzou 9, and Wang Yaping hitched a ride on Shenzou 10.
In March of 2016, CNSA announced that they had retired the station and included a vague comment about losing communications with Tiangong-1. Amateur astronomers observing the station began to suspect that CNSA had lost any ability to control the station; it had gone rogue. In September of 2016, CNSA admitted that they had no control over the space station and that they expected it to burn up in the Earth’s atmosphere by the end of 2017.
The Aerospace Corporation, a California nonprofit corporation that provides technical guidance and advice on space missions, predicts that Tiangong-1 will re-enter the Earth’s atmosphere between December 2017 and March 2018. In an interview with Newsweek, senior member of the technical staff for The Aerospace Corporation, Andrew Abraham stated that they track the “data closely and perform re-entry calculations on a regular basis to monitor any changes in the space station’s orbit or decay rate.”
The Aerospace Corporation has a webpage devoted to the Tiangong-1 re-entry, with a wealth of information, including a very informative FAQ.
An approximately true color/contrast image processed from the image 61 raw framelets. This image should give a fairly good idea of what the Great Red Spot and surrounding areas would look like to human eyes from Juno’s position.
The data used to create the above image come from the Juno spacecraft’s JunoCam. After the recent end to Cassini’s mission, Juno is currently the only orbiter exploring a planet in our outer solar system.
On September 15, 2017, Cassini’s extraordinary, decades-long mission ended. The discovery machine sent back its final transmissions before vaporizing within Saturn’s atmosphere. Its atoms now a part of the planet that it put into such sharp focus for us. It marked the end of an era.
The past week has been bittersweet. I’ve spent many hours remembering and sharing some of my favorite Cassini images. I’ve only posted a small fraction of my favorites, and every time I hit the publish button I’d remember another image that I wish I had included. I could devote this entire blog to sharing images and discoveries that we owe to Cassini and never run out of content. The robot was truly remarkable.
I’ve saved my favorite image for today’s post, as I wrap up Cassini Week.
This image blew me away the first time I saw it. It’s an image seared into my mind and one I’ll never forget. But there’s more to it than just what you see at first glance. There’s a deeper meaning to be uncovered upon closer inspection.
Look closer at the image above. Click on it; look at it in full screen. On the left side, between Saturn’s brighter main rings and the G ring is a pale blue dot. It’s the same pale blue dot that Carl Sagan waxed poetically about nearly 30 years ago, when we first saw our home planet from a similar perspective.
“That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives.
The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there…
There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world.”
Sagan’s words have never rang more true.
Cassini, along with all of the other instruments of science, do more than just teach us about the subjects of their attention. They teach us about ourselves. They put our infinitesimally small corner of the Universe in perspective. Cassini showed us worlds we could have hardly imagined. Each discovery making the Universe a little larger, a little more dynamic.
For some, that might make you feel small. Personally, I don’t think that’s a bad thing. It puts our more minor inconveniences and frustrations in perspective. It’s a reminder of how far we’ve come as a species, how fortunate we are to live our lives at such an exciting time.
And, it gives us the tiniest glimpse of the potential of our future.
We’ve all marveled over Cassini’s images of the Saturn system for more than a decade. Saturn is a truly dynamic place, surrounded by equally dynamic worlds. But Cassini’s images did more than just capture images of these distant places; it created art. Breathtaking ‘landscapes’, magnificent portraits, and photographs perfectly timed and framed. Cassini has all of the skill and talent of a master photographer, with special thanks to its imaging team back on Earth. Below are just a few of my favorite Cassini photos.
Janus (179 kilometers, or 111 miles across) is on the far left. Pandora (81 kilometers, or 50 miles across) orbits between the A ring and the thin F ring near the middle of the image. Brightly reflective Enceladus (504 kilometers, or 313 miles across) appears above the center of the image. Saturn’s second largest moon, Rhea (1,528 kilometers, or 949 miles across), is bisected by the right edge of the image. The smaller moon Mimas (396 kilometers, or 246 miles across) can be seen beyond Rhea also on the right side of the image.
In the famous words of the 21st Century philosopher, Beyoncé, “if you like it then you shoulda put a ring on it”.
In that case, the Universe must have really liked Saturn.
While all of the gas giants in our solar system have rings, Saturn’s are by far the most prominent and celebrated. And while humans have been admiring Saturn’s rings for centuries (when Galileo first discovered them, he described them as Saturn’s ears), it was Cassini that brought them into razor-sharp focus.
Several sets of shadows are cast onto the A ring in this image taken about a week after Saturn’s August 2009 equinox.
Near the middle of the image, shadows are cast by vertically extended clumps in the kinky, discontinuous ringlets of the Encke Gap in the A ring. These clumps are casting shadows approximately 275 kilometers (170 miles) long, implying a clump height about 600 meters (2,000 feet) above the ring plane.
In the middle left of the image, the waves created by Daphnis (8 kilometers, 5 miles across) on the edge of the Keeler Gap cast shadows on the A ring that are about 450 kilometers (280 miles) long, indicating waves that rise about one kilometer above the ring plane. The moon itself is not visible at this resolution, but it, too, orbits in the Keeler Gap of the A ring. Daphnis has an inclined orbit, and its gravitational pull perturbs the orbits of the particles of the A ring forming the Keeler Gap’s edge and sculpts the edge into waves having both horizontal (radial) and out-of-plane components. Material on the inner edge of the gap orbits faster than the moon so that the waves there lead the moon in its orbit. Material on the outer edge moves slower than the moon, so waves there trail the moon.
This view from NASA’s Cassini spacecraft shows a wave structure in Saturn’s rings known as the Janus 2:1 spiral density wave. Resulting from the same process that creates spiral galaxies, spiral density waves in Saturn’s rings are much more tightly wound. In this case, every second wave crest is actually the same spiral arm which has encircled the entire planet multiple times.
NASA’s Cassini spacecraft captured these remarkable views of a propeller feature in Saturn’s A ring on Feb. 21, 2017. These are the sharpest images taken of a propeller so far, and show an unprecedented level of detail. The propeller is nicknamed “Santos-Dumont,” after the pioneering Brazilian-French aviator.
Have you heard of Saturn’s propellers before? They’re the result of a very small moon, unseen in the photo above, disturbing ring material. They offer a unique opportunity for researchers to track the orbits of unseen objects that are embedded within a disk of material.
Cassini delivers this stunning vista showing small, battered Epimetheus and smog-enshrouded Titan, with Saturn’s A and F rings stretching across the scene.
Stay tuned for more, as we continue our Cassini Week celebration.
When Cassini launched in 1997, it carried with it a special payload: a probe named Huygens that would penetrate the permanent haze of Saturn’s largest moon Titan, and reveal to us the shrouded world below.
And what a world Titan is!
It’s larger than Mercury, approaching the diameter of Mars (Titan: 5,150 km / Mars: 6,780 km). It has an atmosphere with superrotating winds, composed of 95 nitrogen and 5% methane. And it has an abundance of massive liquid methane lakes and rivers, as well as water ice and rocks of all sizes. A truly dynamic place that can only be referred to as a world.
And we owe most of what we know about Titan thanks to Huygens and Cassini.
The probe was named after the man who discovered Titan in 1655, the Dutch astronomer Christiaan Huygens.
After a seven year journey, Cassini entered Saturn’s orbit on July 1, 2004. On Christmas Day of that year (Spacecraft Event Time), the shelled Huygens probe separated from Cassini and began its three-week coast to Titan’s surface. Finally, on January 14, 2005, Huygens fell through Titan’s atmosphere, slowed by parachutes, for 2 hours and 27 minutes, before landing on the surface. On the way down, its suite of instruments and cameras captured priceless data about the mysterious world on which it would spend the rest of its life.
Huygens sent data back from the surface of Titan for 72 minutes, before Cassini–our relay station to the probe–dipped below the moon’s horizon. The amount of data collected and transmitted during that short time, however, was phenomenal. In addition to the breathtaking photos, Huygens provided us with unprecedented data about the alien moon, data that is still being analyzed for new discoveries to this day.
This week we’re celebrating the accomplishments of the Cassini spacecraft which, in just a few days, will plunge into Saturn’s atmosphere in its Grand Finale. Today, we take a look at just two of Saturn’s more than 60 moons: Mimas and Pan.
When it comes to Saturn’s moon Mimas, Cassini kept delivering surprise after surprise. First, there was a fantastic image showing us, in great detail, Mimas’s remarkable Herschel crater (Voyager 1 was the first to give us images of Herschel crater, but they paled in comparison to what Cassini revealed).
But Cassini revealed another surprise on Mimas. When it took a look at its infrared profile and created a temperature map, we found Pac-Man.
While Mimas is quite a unique satellite of our beloved ringed planet, Pan certainly deserves some recognition as well.
The above image was captured in March of 2017, as Cassini zoomed within 15,300 miles (24,600 kilometers) of Pan.
I don’t know about you, but this moon makes me hungry for a pan of ravioli.
Stay tuned, more Cassini action to come as we prepare for the Grand Finale.
The final chapter in a remarkable mission of exploration and discovery, Cassini’s Grand Finale is in many ways like a brand new mission. Twenty-two times, NASA’s Cassini spacecraft will dive through the unexplored space between Saturn and its rings. What we learn from these ultra-close passes over the planet could be some of the most exciting revelations ever returned by the long-lived spacecraft. This animated video tells the story of Cassini’s final, daring assignment and looks back at what the mission has accomplished.
On September 15, one of the most fruitful space missions ever imagined will come to an end. After two decades in space, Cassini’s fuel supplies are close to being depleted. To avoid contaminating one of Saturn’s moons, including a pair that could harbor life–Enceladus and Titan–the decision was made to retire Cassini into Saturn’s atmosphere. Up until contact between the orbiter and Earth is lost, Cassini will continue to study our beloved ringed planet. New insight will be gleaned from this mission that’s only made possible by Cassini’s fatal approach to the gas giant. Among the data to be collected:
- The spacecraft will make detailed maps of Saturn’s gravity and magnetic fields, revealing how the planet is arranged internally, and possibly helping to solve the irksome mystery of just how fast Saturn is rotating.
- The final dives will vastly improve our knowledge of how much material is in the rings, bringing us closer to understanding their origins.
- Cassini’s particle detectors will sample icy ring particles being funneled into the atmosphere by Saturn’s magnetic field.
- Its cameras will take amazing, ultra-close images of Saturn’s rings and clouds.
Cassini launched on Oct. 15, 1997. After a seven-year journey the orbiter arrived at Saturn, carrying the European Space Agency’s Huygens probe. In 2005, the probe successfully landed on Saturn’s largest moon, Titan.
Quick facts about Titan:
- Titan is the solar system’s second largest moon.
- It’s the only moon in our solar system that has cloud systems and a dense, planet-like atmosphere.
- Titan has liquid hydrocarbon lakes, mountains, and seasonal weather patterns.
For 13 years, Cassini has orbited Saturn and provided us with fascinating information about, not just the planet, but its intricate ring system and many moons.
In addition to the important scientific data that was collected by Cassini, are the breathtaking images that have been collected: storms and aurorae on Saturn, detailed views of the worlds that are Saturn moons, and remarkable visions of Saturn’s sensational rings.
For the next week, we celebrate Cassini’s achievements.