While Saturn is far away from us, scientists have just found a way to make the journey there easier. A new technique pinpointed the position of the ringed gas giant to within just two miles (four kilometers).
It’s an impressive technological feat that will improve spacecraft navigation and also help us better understand the orbits of the outer planets, the Jet Propulsion Laboratory (JPL) said.
It’s remarkable how much there is to learn about Saturn’s position given that the ancients discovered it, and it’s easily visible with the naked eye. That said, the new measurements with the Cassini spacecraft and the Very Long Baseline Array radio telescope array are 50 times more precise than previous measurements with telescopes on the ground.
“This work is a great step toward tying together our understanding of the orbits of the outer planets of our solar system and those of the inner planets,” stated study leader Dayton Jones of JPL.
What’s even more interesting is scientists have been using the better information as it comes in. Cassini began using the improved method in 2013 to improve its precision when it fires its engines.
This, in the long term, leads to fuel savings — allowing the spacecraft a better chance of surviving through the end of its latest mission extension, which currently is 2017. (It’s been orbiting Saturn since 2004.)
The technique is so successful that NASA plans to use the same method for the Juno spacecraft, which is en route to Jupiter for a 2016 arrival.
Scientists are excited about Cassini’s mission right now because it is allowing them to observe the planet and its moons as it reaches the summer solstice of its 29-year orbit.
This could, for example, provide information on how the climate of the moon Titan changes — particularly with regard to its atmosphere and ethane/methane-riddled seas, both believed to be huge influencers for the moon’s temperature.
Beyond the practical applications, the improved measurements of Saturn and Cassini’s position are also giving scientists more insight into Albert Einstein’s theory of general relatively, JPL stated. They are taking the same techniques and applying them to observing quasars — black-hole powered galaxies — when Saturn passes in front of them from the viewpoint of Earth.
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.
“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.
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.
Feel like visiting a dwarf planet today? How about a comet or the planet Mars? Luckily for us, there are sentinels across the Solar System bringing us incredible images, allowing us to browse the photos and follow in the footsteps of these machines. And yes, there are even a few lucky humans taking pictures above Earth as well.
Below — not necessarily in any order — are some of the best space photos of 2014. You’ll catch glimpses of Pluto and Ceres (big destinations of 2015) and of course Comet 67P/Churyumov–Gerasimenko (for a mission that began close-up operations in 2014 and will continue next year.) Enjoy!
From a distance, Saturn’s rings look like a sheer sheet, but peer up close and you can see that impression is a mistake. Shadows from rubble believed to be two miles (3.2 kilometers) high are throwing shadows upon the planet’s B ring in this image from the Cassini spacecraft.
While the picture is from 2009, it caught the eye of the lead of the Cassini imaging team, who wrote eloquently about it in a blog post recently celebrating the link between wonder and the holidays.
“I have often thought: What a surreal sight this would be if you were flying low across the rings in a shuttle craft. To your eyes, the rings would seem like a gleaming white, scored, gravelly sheet below you, extending nearly to infinity,” wrote Carolyn Porco, the lead imager for the mission at the Cassini Imaging Central Laboratory for Operations (CICLOPS).
“And as you flew, you would see in the distance a wall of rubble that, eventually, as it neared, you would come to realize towered two miles above your head. There isn’t another sight like it in the Solar System!”
Besides the inherent beauty and delicacy of this picture, another notable feature is how hard it is to capture. According to CICLOPS, one can only take this photo during Saturn’s equinox — once every 15 years in Earth time! That’s because the angle of the Sun’s light reaches the plane of the rings, allowing shadows to fall. The area itself is likely filled with moonlets of a kilometer (0.62 miles) in size.
“It is possible that these bodies significantly affect the ring material streaming past them and force the particles upward, in a ‘splashing’ manner,” the CICLOPS website notes.
We’ve included more pictures of Saturn’s rings below, all taken from the Cassini spacecraft. The machine is healthy and working hard after about 10.5 years working at the planet. One of its major tasks now is to observe changes in the planet and particularly its large moon, Titan, as the system nears the solstice.
Now in its seventh year of compilation and the second year running on Universe Today, we’re proud to feature our list of astronomical happenings for the coming year. Print it, bookmark it, hang it on your fridge or observatory wall. Not only is this the yearly article that we jokingly refer to as the “blog post it takes us six months to write,” but we like to think of it as unique, a mix of the mandatory, the predictable and the bizarre. It’s not a 10 ten listicle, and not a full-fledged almanac, but something in between.
A rundown of astronomy for 2015: There’s lots of astronomical action to look forward to in the coming year. 2015 features the minimum number of eclipses that can occur, two lunars and two solars. The Moon also reaches its minimum standstill this coming year, as its orbit runs shallow relative to the celestial equator. The Moon will also occult all naked eye planets except Saturn in 2015, and will occult the bright star Aldebaran 13 times — once during every lunation in 2015. And speaking of Saturn, the rings of the distant planet are tilted an average of 24 degrees and opening to our line of sight in 2015 as they head towards their widest in 2018.
Finally, solar activity is trending downwards in 2015 after passing the sputtering 2014 maximum for solar cycle #24 as we now head towards a solar minimum around 2020.
Our best bets: Don’t miss these fine celestial spectacles coming to a sky near YOU next year:
– The two final total lunar eclipses in the ongoing tetrad, one on April 4th and September 28th.
– The only total solar eclipse of 2015 on March 20th, crossing the high Arctic.
– A fine dusk pairing of the bright planets Jupiter and Venus on July 1st.
– Possible wildcard outbursts from the Alpha Monocerotid and Taurid meteors, and a favorable New Moon near the peak of the August Perseids.
– Possible naked eye appearances by comet Q2 Lovejoy opening 2015 and comet US10 Catalina later in the year.
– The occultation of a naked eye star for Miami by an asteroid on September 3rd.
– A series of fine occultations by the Moon of bright star Aldebaran worldwide.
The rules: The comprehensive list that follows has been lovingly distilled down to the top 101 astronomical events for 2015 worldwide. Some, such as lunar eclipses, are visible to a wide swath of humanity, while others, such as many of the asteroid occultations or the sole total solar eclipse of 2015 happen over remote locales. We whittled the list down to a “Top 101” using the following criterion:
Meteor showers: Must have a predicted ZHR greater than 10.
Conjunctions: Must be closer than one degree.
Asteroid occultations: Must have a probability ranking better than 90 and occult a star brighter than magnitude +8.
Comets: Must reach a predicted brightness greater than magnitude +10. But remember: comets don’t always read prognostications such as this, and may over or under perform at whim… and the next big one could come by at any time!
Times quoted are geocentric unless otherwise noted, and are quoted in Universal Time in a 24- hour clock format.
These events are meant to merely whet the appetite. Expect ‘em to be expounded on fully by Universe Today as they approach. We linked to the events listed where possible, and provided a handy list of resources that we routinely consult at the end of the article.
Got it? Good… then without further fanfare, here’s the top 101 astronomical events for 2015 in chronological order:
21- Io and Ganymede both cast shadows on Jupiter from 00:04 to 00:33 UT.
21- Callisto and Europa both cast shadows on Jupiter from 13:26 to 13:59 UT.
23- Saturn reaches opposition at ~1:00 UT.
24- Asteroid 1669 Dagmar occults the +1st magnitude star Regulus at ~16:47 UT for the Arabian peninsula,
the brightest star occulted by an asteroid for 2015.
28- Ganymede and Io both cast shadows on Jupiter from 02:01 to 04:18 UT.
30- Comet 19P/Borrelly may reach binocular visibility.
June
01- The International Space Station reaches full illumination as the June solstice nears, resulting in multiple nightly passes favoring northern hemisphere observers.
04- Io and Ganymede both cast shadows on Jupiter from 4:54 to 6:13 UT.
05- Venus reaches greatest eastern (dusk) elongation for 2015, 45 degrees from the Sun at 16:00 UT.
10- Asteroid 424 Gratia occults a +6.1 magnitude star at ~15:10 UT for northwestern Australia.
13- The Perseid meteors peak from 06:30 to 09:00 UT, with a maximum predicted ZHR of 100 favoring North America.
19- Mars crosses the Beehive Cluster M44.
28- Asteroid 16 Psyche occults a +6.4 magnitude star at ~9:49 UT for Bolivia and Peru.
29- Supermoon 1 of 3 for 2015: The Moon reaches Full at 18:38 UT, 20 hours from perigee.
September
01- Neptune reaches opposition at ~3:00 UT.
03- Asteroid 112 Iphigenia occults a +3rd magnitude star for Mexico and Miami at ~9:20 UT. This is the brightest star occulted by an asteroid in 2015 for North America.
02- Geostationary satellite and SDO eclipse season begins as we approach the September equinox.
04- Mercury reaches its greatest elongation for 2015, at 27 degrees east of the Sun at 8:00 UT in the dusk skies.
05- The Moon occults Aldebaran for northeastern North America at ~5:38 UT.
13- “Shallow point” (also known as the minor lunar standstill) occurs over the next lunation, as the Moon’s orbit reaches a shallow minimum of 18.1 degrees inclination with respect to the celestial equator… the path of the Moon now begins to widen towards 2025.
13- A partial solar eclipse occurs, centered on 6:55 UT crossing Africa and the Indian Ocean.
01- The International Space Station reaches full illumination as the December solstice nears, resulting in multiple nightly passes favoring the southern hemisphere.
04- Mercury occults the +3.3 magnitude star Theta Ophiuchi for South Africa at 16:16 UT prior to dusk.
06- The Moon occults Mars for central Africa at ~2:42 UT.
07- The Moon occults Venus in the daytime for North America at ~16:55 UT.
14- The Geminid meteor shower peaks at 18:00 UT, with a ZHR=120 favoring NE Asia.
Peekaboo! Tethys makes a (mostly in vain) attempt to hide behind Rhea in this picture taken by the Cassini spacecraft a couple of years ago, but highlighted by NASA in a recent picture essay. Besides the neat view of the orbital dance, one thing that is clearly visible between the two moons is the different colors — a product of their different surfaces. It turns out that Tethys’ bright surface is due to geysers from another moon.
“Scientists believe that Tethys’ surprisingly high albedo is due to the water ice jets emerging from its neighbor, Enceladus,” NASA stated. “The fresh water ice becomes the E ring [of Saturn] and can eventually arrive at Tethys, giving it a fresh surface layer of clean ice.”
Saturn has an astounding number of moons — 62 moons discovered so far, and 53 of them named, if you don’t count the spectacular ring that surrounds the planet. The collection of celestial bodies includes Titan, the second-biggest moon in the Solar System. It’s so big that it includes a thick atmosphere. (Ganymede, around Jupiter, is the biggest.)
Below are some other pictures of moons dancing around Saturn — some harder to spot than others. All images were taken by the Cassini spacecraft since it arrived at the planet in 2004.
Titan is Saturn’s largest moon and is constantly surprising scientists as the Cassini spacecraft probes under its thick atmosphere. Take its dunes, for example, which are huge and pointed the wrong way.
Why are they pointing opposite to the prevailing east-west winds? It happens during two rare wind reversals during a single Saturn year (30 Earth years), investigators suggest.
Investigators repurposed an old NASA wind tunnel to simulate how Titan is at the surface, watching how the wind affects sand grains. (They aren’t sure what kind of sand is on Titan, so they tried 23 different kinds to best simulate what they think it is, which is small hydrocarbon particles that are about 1/3 the density of what you find on Earth.)
After two years of work with the model — not to mention six years of refurbishing the tunnel — the team determined that the wind must blow 50% faster than believed to get the sand moving.
“It was surprising that Titan had particles the size of grains of sand—we still don’t understand their source—and that it had winds strong enough to move them,” stated Devon Burr, an associate professor at the University of Tennessee Knoxville’s earth and planetary science department, who led the research. “Before seeing the images, we thought that the winds were likely too light to accomplish this movement.”
The winds reverse when the Sun moves over the equator, affecting Titan’s dense atmosphere. And the effects are powerful indeed, creating dunes that are hundreds of yards (or meters) high and stretch across hundreds of miles (or kilometers).
To accomplish this, the winds would need to blow no slower than 3.2 miles per hour (1.4 meters per second), which sounds slow until you consider how dense Titan’s atmosphere is — about 12 times thicker surface pressure than what you would find on Earth. More information on the research is available in the journal Nature.
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.
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.
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.
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.
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.