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.
Shadows cast on Saturn’s A ring. – Credit: NASA/JPL/Space Science Institute
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.
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.
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).
Mimas, with prominent Herschel crater. – Source: NASA/JPL-Caltech
Then again, maybe…
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.
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.
Cassini mission overview infographic – Click for larger version – Source: NASA/JPL
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.
Still from the short film Cassini’s Grand Finale, the spacecraft is shown diving between Saturn and the planet’s innermost ring. – Credit: NASA/JPL-Caltech
It happened exactly 20 years after cosmonaut Yuri Gagarin became the first human in space. It was the first American manned spaceflight in six years, following the 1975 Apollo-Soyuz Test Project. It was the beginning of an era that ushered in a new generation of spaceflight technology.
It was STS-1, the first of more than 130 flights of the Space Shuttle program.
Shuttle Columbia was selected for the maiden voyage of the program. Not only was this the first crewed flight for the shuttle, it was the first flight period. Shuttle Enterprise had been utilized for flight (and landing) tests within the atmosphere, but wasn’t designed to be space-ready (including not having a heat shield for re-entry).
So Columbia was not only a mission, but a flight test in its own right. Her crew consisted of Commander John W. Young and pilot Robert L. Crippen. Young was already a veteran of the space program, having flown as pilot of the Gemini Program’s first manned flight (Gemini 3 – known around these parts as that time John Young smuggled a corned beef sandwich into space), served as commander of Gemini 10, was the command module pilot of Apollo 10 (the “dress rehearsal” for Apollo 11), and also walked on the Moon as commander of Apollo 16. This, however, would be Crippen’s first spaceflight. Both of these men were qualified test pilots, and STS-1 was one heck of a test flight.
At 7:00am on April 12, 1981, after a two-day delay, STS-1 lifted off from Launch Pad 39A at Kennedy Space Center–the same launch pad that took Neil Armstrong, Buzz Aldrin, and Michael Collins to the Moon, and is currently leased to SpaceX where it will serve to create a new type of spaceflight history. The launch was just as flawless as Launch Controller Chuck Hannon wished, when one minute and forty-five seconds prior to lift-off, he told the crew: “Smooth sailing, baby.”
STS-1 Columbia at launch on April 12, 1981 – Credit: NASA
SHUTTLE LAUNCH CONTROL: T minus ten, nine, eight, seven, six, five, four, we’ve gone for main engine start, we have main engine start. And we have lift off of America’s first space shuttle, and the shuttle has cleared the tower.
Minutes later, Columbia and her crew were beginning the first of 37 total orbits to take place over the course of just more than two days. A new era was born, as we became a world with reusable space planes.
The primary mission of STS-1 was to conduct a general check-out of the Space Shuttle system, reach orbit successfully, and land safely back on Earth. Despite a few anomalies, which were recorded and solved for future flights, STS-1 was a smashing success. Orbiter Columbia performed amazingly and would be used for the next four shuttle missions until STS-6, when Challenger became the second orbiter in the fleet.
STS-1 was the solid first step in the three decades-long adventure that was the Space Shuttle program.
If you had a really, really, really good telescope and took a peep at the International Space Station (which would be quite a feat for as quickly as it moves across the sky), you might notice what looks like a make-up kit or a watercolor palette dangling from the side of the station.
MISSE-3 just prior to retrieval during an STS-118 spacewalk. – Credit: NASA
While some astronauts have taken their makeup into space, and some have found time to create art in orbit, they don’t tend to leave their supplies attached to the outside of the ISS. Ruling those out, instead what you’d probably be looking at is a Materials International Space Station Experiment (MISSE).
MISSE project specimens are placed onto trays and inserted into Passive Experiment Containers (PECs). – Credit: NASA
MISSE projects serve as a laboratory to test and study various material samples as they’re exposed to a space environment. Attached on the outside of the ISS, the specimens are simultaneously exposed to a variety of conditions that would be very difficult, if even possible, to mimic on Earth, including exposure to: atomic oxygen, various levels of radiation, vacuum, extreme temperatures, and zero gravity. While MISSE wasn’t the first project of this type–similar experiments had been carried out on Skylab, Mir, and NASA’s Long Duration Exposure Facility (LDEF)–it was the most formal and programmatic.
The first two MISSE projects were deployed in 2001, carried to the ISS via the Discovery crew of STS-105. They were originally planned to only be deployed for one year, but as a result of the grounding of the Shuttle program following the STS-107 Columbia disaster, they ended up staying in orbit for 3 years. There were a total of 8 MISSE experiments conducted by NASA, sometimes deployed in multiples and sometimes singly.
NASA astronaut Andrew Feustel swaps the MISSE PEC7A & 7B with PEC8 – Credit: NASA
The samples are loaded into trays and installed inside suitcase-like Passive Experiment Containers (PECs). When ready to be deployed, the PECs are carried outside the station during an EVA (extra vehicular activity), and fastened to the station’s exterior. The mounting location has changed throughout the program’s history.
Samples from MISSE 3 and 4 carried 8 million basil seeds that were then provided “to children for science experiments to stimulate interest in space science”. Other samples included paints, lubricants, fabrics, and solar cell technologies. In total, more than 4,000 samples have been tested through MISSE.
As part of NASA’s efforts to privatize routine space projects, MISSE was recently transferred to the private corporation Alpha Space:
MISSE is now a privatized, commercial facility owned and operated by Alpha Space with a permanent placement on the ISS. The facility and its first set of experiments have been manifested to fly to the International Space Station in September of 2017 on the SpaceX Dragon resupply vehicle’s flight SpaceX-13.
Now dubbed MISSE-FF (Material International Space Station Experiment Flight Facility), Alpha Space’s contract is good through at least June 30, 2024 (currently the authorized remaining lifetime of the station). Alpha Space’s plans call for a permanently-mounted tower that will hold multiple PECs at once. If the customers are there (some have already signed contracts), Alpha Space is ready to provide routine testing in the unparalleled environment of space. They expect to begin operations this year (2017).
Animation of Alpha Space’s PEC deployment – Source: Alpha Space
SpaceX is no stranger to making commercial spaceflight history. They were the first private corporation to launch a liquid-fueled rocket into orbit, send a re-supply spacecraft to the International Space Station, and to land their first-stage rockets back on Earth (for potential re-use), among other milestones. They’re also on the cusp of providing transportation services for International Space Station crew members.
SpaceX Falcon 9 moments before landing on February 19, 2017 – Source: SpaceX
On February 19, 2017, SpaceX accomplished another major feat: They became the first private company to launch from the historic Launch Pad 39A at Kennedy Space Center.
Launch Pad 39A
SpaceX became the first commercial corporation to lease space and operate out of Kennedy Space Center when, in 2014, they signed a 20-year lease for the historic Launch Pad 39A. It was from this launch pad that Apollo 11 blasted off for the Moon, when Neil Armstrong and Buzz Aldrin became the first humans to step foot on our lunar neighbor. It also hosted the first Space Shuttle mission, as well as some 90 others. Now, and for at least the next two decades, it’s in the hands of SpaceX, further cementing the foothold that the private sector has made in the space program.
SpaceX and NASA CRS-10 mission patches – Source: Public Domain and SpaceX
Launch and Landing
At 9:39am EST, on February 19, SpaceX’s Falcon 9 rocket ignited and thundered into the clouds. The rocket was topped with the Dragon capsule, carrying more than 5,000 pounds (2,267 kg) worth of cargo destined for the International Space Station. Dragon arrived and successfully docked with the ISS a couple of days following launch.
Dr. Michelle Thaller, NASA astrophysicist and contributor to myriad space documentary programs, was at Sunday’s launch and graciously shared her experience with me. “Launches are always wonderfully, viscerally exciting,” she said. “The Falcon 9 has a wonderful, big, booming sound, similar to an Atlas, and it puts on a great fireworks show.”
But that wasn’t the only show in store for the lucky spectators in Florida that day. After shoving Dragon into orbit, the Falcon first stage began its 100-kilometer return trip back to Earth. In fewer than 10 minutes following lift-off, the first stage rocket re-emerged through the clouds and landed at Landing Zone 1, just a few miles away from the launch pad. Thaller described the period of suspense in between the launch and the Falcon landing, and said that in some ways there was more anticipation for the landing than there was for the launch.
[N]othing quite prepares you for what happens 7 minutes later, just as the adrenaline is wearing off. Silently, at first, this 230-foot first stage turns around and comes down out of the sky. Smoothly, surreally, a tower the size of a 15 story building just comes and sets itself down. Only once it’s down do you hear the double pop of a sonic boom. It sort of turns your stomach. Things that big are not supposed to just come out of the sky and land. It’s awesome.
Awesome, indeed. See for yourself:
As a kid, I remember watching cartoons that showed rockets landing on various planets. The rockets would turn themselves around and gently land engine-side down. I would always exclaim, “That’s not how rockets work! They burn up, or have parachutes attached and they land in the ocean! How silly.”
Yet, here we are.
I’ve often been jealous about being born too late to experience the race to the Moon. I’ve been somewhat depressed since watching the last Shuttle mission touch down in 2011. But when I take a step back and look at what is occurring today and what we have to look forward to, I can’t help but recognize what a wonderful time it is to be alive.
You can watch the full webcast of the launch on SpaceX’s YouTube channel.
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