This Galielo image shows Jupiter's moon Ganymede in enhanced colour. The JWST aimed its instruments at our Solar System's largest moon to study its surface. Credit: NASA
In 1610, Galileo Galilei looked up at the night sky through a telescope of his own design. Spotting Jupiter, he noted the presence of several “luminous objects” surrounding it, which he initially took for stars. In time, he would notice that these “stars” were orbiting the planet, and realized that they were in fact Jupiter’s moons – which would come to be named Io, Europa, Ganymede and Callisto.
Of these, Ganymede is the largest, and boasts many fascinating characteristics. In addition to being the largest moon in the Solar System, it is also larger than even the planet Mercury. It is the only satellite in the Solar System known to possess a magnetosphere, has a thin oxygen atmosphere, and (much like its fellow-moons, Europa and Callisto) is believed to have an interior ocean.
The gravity of the Earth is a tough thing to escape, but breaking free from the gravity of the Sun is on a whole other level. But humans have achieved this amazing accomplishment, and right now there are several spacecraft leaving the Solar System and never coming back.
There are many hazards out there, eager to disrupt and dismantle the mighty machines we send out into space. How long can they survive to perform their important missions?
Every few months, an eager new spacecraft arrives on the launch pad, ready for its date with destiny. If we don’t blow it all to bits with a launch vehicle failure, it’ll be gently placed into orbit with surgical precision. Then it’ll carry out a noble mission of exploring the Solar System, analyzing the Earth, or ensuring we have an infinite number of radio stations in our cars, allowing us to never be satisfied with any of them.
Space is hostile. Not just to fragile hu-mans, but also to our anthropomorphized Number Five is alive robotic spacecraft which we uncaringly send to do our bidding. There are many hazards out there, eager to disrupt and dismantle our stalwart electronic companions. Oblivion feeds voraciously on our ever trusting space scouts and their tiny delicate robotic hearts, so many well before their time.
How long have they got? How long will our spacecraft survive as we cast them on their suicide missions to “go look at stuff on behalf of the mighty human empire”? When spacecraft are hurled into the void, all mission planners know they’re living on borrowed time.
The intrepid Mars Exploration Rovers, Spirit and Opportunity, were only expected to operate for 3 months. NASA’s Spitzer Space Telescope carried a tank of expendable helium coolant to let it see the dimmest objects in the infrared spectrum.
Sometimes the spacecraft wear down for unexpected reasons, like electronic glitches, or parts wearing out. Hubble was equipped with rotating gyroscopes that eventually wore out over time, making it more difficult to steer at its targets, and only an intervention by rescue and repair allowed the mission to keep going.
In general, a spacecraft is expected to last a few months to a few years. Spirit and Opportunity only had a planned mission of 3 months. It took Spirit more than 6 dauntless years to finally succumb to the hostile Martian environment. Opportunity is still kicking more than a decade later, thanks to some very careful driving and gusts of Martian wind clearing off its solar panels which didn’t surprise anybody.
Artist impression of Rosetta and Asteroid 2867 Steins. Credit: ESA
ESA’s Rosetta spacecraft needed to survive for 10 years in a dormant state before its encounter with Comet 67/P. It’s expected to last until the end of 2015. Then its orbit will carry it too far from the Sun to operate its solar panels, then it’ll go to sleep one last time.
As a testament to luck and remarkable feats of engineering, some survive much longer than anyone ever expected. NASA’s Voyager Spacecraft, launched in 1977, are still going and communicating with Earth. It’s believed they’ll survive until 2025, when their radioisotope thermoelectric generators stop producing power.
At which point they’ll return to the Earth at the heart of a massive alien spacecraft and scare the bejeebus out of us.
… And I know what you’re thinking. Once our spacecraft stop functioning, they’ll still exist. Perhaps getting close enough to another source of solar energy to start transmitting again.
So, how long will our spacecraft hold together in something roughly robot-probe shaped? Any spacecraft orbiting a planet or Moon won’t last long geologically before they’re given a rocky kiss of death with help from a big group hug from gravity.
This might take a decade, a hundred years or a million. Eventually, that spacecraft is racing towards a well distributed grave on its new home.
Solar Dynamics Observatory. Credit: NASA
A spacecraft that’s orbiting the Sun should last much longer. However, a gravitational threesome with a planet or large asteroid could drag it into a solar death spiral or hurl it into a planet. There are asteroids whipping around from the formation of the Solar System, and they haven’t crashed into anything… yet.
A lucky spacecraft might last hundreds of millions, or even billions of years. Our little robot friends that leave the gravitational pull of the Solar System have a chance of making it for the long haul.
Once they’re out in interstellar space, there will be very few micrometeorites to punch little holes in them. Unless they happen to run into another star – and that’s very unlikely – they’ll travel through space until they’re worn away over billions of years, and who knows what that means for future alien archaeology students. The golden records on the Voyager spacecraft were designed to still be playable for a billion years in space.
Artist’s concept of NASA’s Voyager spacecraft. Image credit: NASA/JPL-Caltech
It’s tough to keep a spacecraft operating in space. It’s a really hostile place, ready to fry their little silicon brains, scuttle them with a micrometeorite, or just erode them away over an incomprehensible length of time.
Are horrible space agency fiends tossing our trusting big eyed robot pals to their doom on one-way missions into the abyss? Don’t worry viewers, I have it on good authority this is what the robots want.
Beloved astronaut Chris Hadfield said if Voyager had stayed at home where it’s safe, it would’ve been sad forever, because it never would have discovered things. I think he’s right, Voyager is as happy as it could be exploring the parts of our Universe the rest of us aren’t able to go and see for ourselves.
What’s your favorite spacecraft survivor story? Tell us in the comments below.
These six narrow-angle color images were made from the first ever "portrait" of the solar system taken by Voyager 1 on Valentine’s Day on Feb. 14, 1990, which was more than 4 billion miles from Earth and about 32 degrees above the ecliptic. Venus, Earth, Jupiter, and Saturn, Uranus, Neptune are seen in these blown-up images, from left to right and top to bottom. Credit: NASA/JPL-Caltech
A quarter of a century has passed since NASA’s Voyager 1 spacecraft snapped the iconic image of Earth known as the “Pale Blue Dot” that shows all of humanity as merely a tiny point of light.
The outward bound Voyager 1 space probe took the ‘pale blue dot’ image of Earth 25 years ago on Valentine’s Day, on Feb. 14, 1990 when it looked back from its unique perch beyond the orbit of Neptune to capture the first ever “portrait” of the solar system from its outer realms.
Voyager 1 was 4 billion miles from Earth, 40 astronomical units (AU) from the sun and about 32 degrees above the ecliptic at that moment.
The idea for the images came from the world famous astronomer Carl Sagan, who was a member of the Voyager imaging team at the time.
He head the idea of pointing the spacecraft back toward its home for a last look as a way to inspire humanity. And to do so before the imaging system was shut down permanently thereafter to repurpose the computer controlling it, save on energy consumption and extend the probes lifetime, because it was so far away from any celestial objects.
Sagan later published a well known and regarded book in 1994 titled “Pale Blue Dot,” that refers to the image of Earth in Voyagers series.
This narrow-angle color image of the Earth, dubbed “Pale Blue Dot,” is a part of the first ever “portrait” of the solar system taken by Voyager 1 on Valentine’s Day on Feb. 14, 1990. Credit: NASA/JPL-Caltech
“Twenty-five years ago, Voyager 1 looked back toward Earth and saw a ‘pale blue dot,’ ” an image that continues to inspire wonderment about the spot we call home,” said Ed Stone, project scientist for the Voyager mission, based at the California Institute of Technology, Pasadena, in a statement.
Six of the Solar System’s nine known planets at the time were imaged, including Venus, Earth, Jupiter, and Saturn, Uranus, Neptune. The other three didn’t make it in. Mercury was too close to the sun, Mars had too little sunlight and little Pluto was too dim.
Voyager snapped a series of images with its wide angle and narrow angle cameras. Altogether 60 images from the wide angle camera were compiled into the first “solar system mosaic.”
Voyager 1 was launched in 1977 from Cape Canaveral Air Force Station in Florida as part of a twin probe series with Voyager 2. They successfully conducted up close flyby observations of the gas giant outer planets including Jupiter, Saturn, Uranus and Neptune in the 1970s and 1980s.
Both probes still operate today as part of the Voyager Interstellar Mission.
“After taking these images in 1990, we began our interstellar mission. We had no idea how long the spacecraft would last,” Stone said.
Hurtling along at a distance of 130 astronomical units from the sun, Voyager 1 is the farthest human-made object from Earth.
Solar System Portrait – 60 Frame Mosaic. The cameras of Voyager 1 on Feb. 14, 1990, pointed back toward the sun and took a series of pictures of the sun and the planets, making the first ever “portrait” of our solar system as seen from the outside. Missing are Mercury, Mars and Pluto. Credit: NASA/JPL-Caltech
Voyager 1 still operates today as the first human made instrument to reach interstellar space and continues to forge new frontiers outwards to the unexplored cosmos where no human or robotic emissary as gone before.
Here’s what Sagan wrote in his “Pale Blue Dot” book:
“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. … There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world.”
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
It hard to think of a more influential modern planetary scientist than Carolyn Porco, the leader of the imaging team for NASA’s Cassini mission exploring Saturn. But before Cassini, Porco was involved in Voyager missions, and she’ll be leading up the imaging team for New Horizons.?
We record Astronomy Cast as a live Google+ Hangout on Air every Monday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch here on Universe Today or from the Astronomy Cast Google+ page.
It hard to think of a more influential modern planetary scientist than Carolyn Porco, the leader of the imaging team for NASA’s Cassini mission exploring Saturn. But before Cassini, Porco was involved in Voyager missions, and she’ll be leading up the imaging team for New Horizons.
We record Astronomy Cast as a live Google+ Hangout on Air every Monday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch here on Universe Today or from the Astronomy Cast Google+ page.
A map of Saturn's F ring from 2006 shows one of the few bright, extended clumps (indicated by a green box) seen during six years of observation by Cassini. Image credit: NASA/JPL-Caltech/SSI
Nothing stands still. Everything evolves. So why shouldn’t Saturn’s kookie, clumpy F ring put on a new face from time to time?
A recent NASA-funded study compared the F ring’s appearance in six years of observations by the Cassini mission to its appearance during the Saturn flybys of NASA’s Voyager mission, 30 years earlier.
A kink in part of Saturn’s F ring. While the ring is held together by the shepherd moons Prometheus and Pandora, which orbit just inside and outside the ring, embedded moonlets are believed responsible for the kinks and clumps. The rings is several hundred kilometers wide. Credit: NASA
While the F ring has always displayed clumps of icy matter, the study team found that the number of bright clumps has nose-dived since the Voyager space probes saw them routinely during their brief flybys 30 years ago. Cassini spied only two of the features during a six-year period.
Scientists have long suspected that moonlets up to 3 miles (5 km) wide hiding in the F ring are responsible for its uneven texture. Kinks and knots appear and disappear within months compared to the years of observation needed changes in many of the other rings.
Saturn’s F ring is extremely narrow compared to the historic A, B and C rings. It measures just a few hundred kilometers across. Credit: NASA/Cassini
“Saturn’s F ring looks fundamentally different from the time of Voyager to the Cassini era,” said Robert French of the SETI Institute in Mountain View, California, who led the study along with SETI Principal Investigator Mark Showalter. “It makes for an irresistible mystery for us to investigate.”
A 2007 artist impression of small boulder-like chunks of ice that comprise Saturn’s rings. The largest are about 10-12 feet across.They clump together to form elongated, curved aggregates, continually forming and dispersing. Credit: NASA/JPL/Univ. of Colorado
Because the moonlets lie close to the ring and cross through it every orbit, the research team hypothesizes that the clumps are created when they crash into and pulverize smaller ring particles during each pass. They suspect that the decline in the number of exceptionally bright kinks and the clumps echoes a decline in the number of moonlets available to do the job.
So what happened between Voyager and Cassini? Blame it on Prometheus. The F ring circles Saturn at a delicate point called the Roche Limit. Any moons orbiting closer than the limit would be torn apart by Saturn’s gravitational force.
The culprit? Prometheus measures 74 miles (119 km) across and orbits the inner edge of Saturn’s F ring. Credit: NASA
“Material at this distance from Saturn can’t decide whether it wants to remain as a ring or coalesce to form a moon,” said French. “Prometheus orbits just inside the F ring, and adds to the pandemonium by stirring up the ring particles, sometimes leading to the creation of moonlets, and sometimes leading to their destruction.”
Every 17 years the orbit of Prometheus aligns with the orbit of the F ring in a way that enhances its gravitational influence. The researchers think the alignment spurs the creation of lots of extra moonlets which then go crashing into the ring, creating bright clumps of material as they smash themselves to bits against other ring material.
Sounds like a terrifying version of carnival bumper cars. In this scenario, the number of moonlets would gradually drop off until another favorable Prometheus alignment.
The Voyagers encounters with Saturn occurred a few years after the 1975 alignment between Prometheus and the F ring, and Cassini was present for the 2009 alignment. Assuming Prometheus has been “working” to build new moons since 2009, we should see the F ring light up once again with bright clumps in the next couple years.
This animated gif shows Voyager 1's approach to Jupiter during a period of over 60 Jupiter days in 1979. Credit: NASA.
Back in the 1970’s when NASA launched the two Voyager spacecraft to Jupiter, Saturn, Uranus, and Neptune, I remember being mesmerized by a movie created from Voyager 1 images of the movement of the clouds in Jupiter’s atmosphere. Voyager 1 began taking pictures of Jupiter as it approached the planet in January 1979 and completed its Jupiter encounter in early April. During that time it took almost 19,000 pictures and many other scientific measurements to create the short movie, which you can see below, showing the intricate movement of the bright band of clouds for the first time.
Now, 35 years later a group of seven Swedish amateur astronomers achieved their goal of replicating the Voyager 1 footage, not with another flyby but with images taken with their own ground-based telescopes.
“We started this joint project back in December of 2013 to redo the NASA Voyager 1 flyby of Jupiter,” amatuer astronomer Göran Strand told Universe Today. “During 90 days we captured 560 still images of Jupiter and turned them into 90 complete maps that covered the whole of Jupiter’s surface.”
Their newly released film, above details the work they did and the hurdles they overcame (including incredibly bad weather in Sweden this winter) to make their dream a reality. They called their project “Voyager 3.”
Animated gif of the ‘Voyager 3’ team re-enactment of the Voyager 1 flyby. Credit: Voyager 3 team, via Kristoffer Åberg.It is really an astonishing project and those of you who do image processing will appreciate the info in the video about the tools they used and how they did their processing to create this video.
The seven Swedish astronomers who participated in the Voyager 3 project are (from left to right in the photo below) Daniel Sundström, Torbjörn Holmqvist, Peter Rosén (the project initiator), Göran Strand, Johan Warell and his daughter Noomi, Martin Högberg and Roger Utas.
The Swedish team of amateur astronomers who compiled the ‘Voyager 3’ project. Image courtesy Peter Rosén.
Space historian Andrew Chaikin sat down with planetary scientist Carolyn Porco, and she discusses how her career has ended up focusing on the Saturn system. I love how Porco relates how even she has been “blown away” by some of the imagery sent back by the missions — just like the rest of us! — saying she’s had to call members of her team several times to verify she wasn’t looking at computer simulations vs. real images.
Enjoy this candid interview of one of the leading planetary scientists of our day.
