Raw image of Saturn with two moons acquired by Cassini on March 11, 2014 (NASA/JPL-Caltech/SSI)
On March 11, NASA’s Cassini spacecraft was acquiring some images of Saturn’s back-lit limb when two of its moons decided to make an entrance. Like stage hands in a darkened theatre the moons quickly passed across the scene, moving between Saturn and the spacecraft and, because of exposure time and spacecraft motion, getting a bit blurred in the process.
In the image above the silhouette of one moon can be seen at bottom right — Mimas, perhaps — while another’s crescent can be made out at upper left… possibly Enceladus. Very cool!
Watch an animation of the moons below:
Two of Saturn’s moons drift into the scene on March 11, 2014 (NASA/JPL-Caltech/SSI. Animation by Jason Major.)
While I admit I’m not 100% sure which moons these are, based on their apparent shapes, positions, and relative sizes I’d make my guess that these are 318-mile (511-km) -wide Enceladus and the 246-mile (395-km) -wide Mimas.
Possible location of icy spray, if Enceladus is in fact this moon’s real name
Cassini was 843,762 miles (1,357,903 km) from Saturn when the images were acquired. And, if the larger moon at left is Enceladus, I’m thinking south in these images is up based on the barely-perceptible presence of a lighter area along its top edge that could be icy spray from its southern geysers. (See enlarged detail at right.)
Saturn, of course, is on the right. A small segment of the bright arc of its backlit limb is what’s running diagonally down across the image.
These images have not yet been calibrated or cataloged by NASA or the Cassini team.
See the latest raw images from Cassini on JPL’s mission page here.
*I say “dark moons” but actually Enceladus and Mimas are pretty bright, both being composed of a lot of ice. Enceladus is actually the most reflective world in the Solar System!
The Cassini spacecraft uses a Pi Transfer to navigate its path around Saturn. Credit: NASA.
Got circles on the brain today? It’s Pi Day — (3/14 for those of us on the west side of the pond) and a celebration of math and science – as well as the infinite and irrational! It is also Albert Einstein’s birthday. What’s Pi? Π is the 16th letter in the Greek alphabet and is used to represent a mathematical constant, the ratio of a circle’s circumference to its diameter, approximately equal to 3.1415…
In basic mathematics, Pi is used to find area and circumference of a circle. You might not use it yourself every day, but Pi is used in most calculations for building and construction, quantum physics, communications, music theory, medical procedures, air travel, and space flight, to name a few.
You might imagine that NASA regularly uses Π to calculate trajectories of spacecraft. Above is a visible documentation of a technique called a “pi transfer” used by the Cassini spacecraft to complete a maneuver to fly by Saturn’s moon Titan flyby.
NASA explains:
A pi transfer uses the gravity of Saturn’s largest moon, Titan, to alter the orbit of the Cassini spacecraft so it can gain different perspectives on Saturn and achieve a wide variety of science objectives. During a pi transfer, Cassini flies by Titan at opposite sides of its orbit about Saturn (i.e., Titan’s orbital position differs by pi radians between the two flybys) and uses Titan’s gravity to change its orbital perspective on the ringed planet.
This image was taken on January 19, 2007, showing the perspective the spacecraft had of Saturn and its rings during the pi transfer.
Other ways NASA uses Pi is to determine the size of craters and extrasolar planets, figuring out how much propellent a spacecraft has, and learning what an asteroid is made of. Mike Seibert from the Mars Exploration Rover team explained on Twitter today how they use Pi every day to talk to the Opportunity rover:
Fact: We use pi is used every single sol when operating Opportunity. Robots like radians, humans like degrees. Pi is our translator.
The Leaning Tower of Pisa is photographed with two Iridium Flares, airplanes and stars among the dark sky background. Credit and copyright: Giuseppe Petricca.
There is so much going on in this picture – taken by astrophotographer Giuseppe Petricca — it’s hard to know where to start. Of course, there’s the famous Leaning Tower in Pisa, Italy. But one evening earlier this week, a “beautiful encounter” happened, said Petricca via email.
“A wonderful -7.5 magnitude Iridium Flare, clearly visible even in the light polluted sky of the city center, photographed from the famous Miracle Square, with the Leaning Tower as a special guest,” he said. “But I was lucky, because two airplanes crossed the portion I was photographing, and a second Iridium satellite was really near the bright one, but this second one did not create a flare.”
Also visible in the background is the dim but beautiful Ursa Minor, culminating with the North Star, Polaris, high corner in the top left corner.
Wow.
The picture is an 8 second exoposure, f4.0, ISO 100 taken with a Nikon Coolpix P90 Bridge on a tripod.
“I was planning to do this shot for two or three days, and luckily the clouds gave way to clear sky just in time,” said Petricca.
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
Damage to the iconic Arecibo Observatory from an earthquake earlier this year has been repaired and the telescope is now back to full service. On January 13, 2014, the William E. Gordon radio telescope sustained damage following a 6.4 magnitude earthquake that was centered 37 miles northwest of Arecibo. A large cable that supports the telescope’s receiver platform had “serious damage,” according to Bob Kerr, the Director of the Arecibo Observatory.
“In an abundance of caution, telescope motion had been very limited since the earthquake,” said Kerr in a press release issued today. “Nevertheless, the telescope continued its science mission, including participation in a 10-day global ionospheric study in late January and continuing a productive search for pulsars in the sky above Arecibo.”
The platform hangs above the Arecibo dish, supported by cables. Via Cornell University.
The cable that was damaged was one of 18 cables that supports the 900-ton focal platform of the telescope. This particular cable was actually a known potential problem, Kerr told Universe Today in a previous interview. He said that during original construction of the telescope in 1962, one of the original platform suspension cables that was delivered to the observatory was too short, and another short cable section was “spliced” to provide sufficient reach to the platform.
“That cable segment and splice near the top of one of the telescope towers was consequently more rigid than the balance of the suspension system,” Kerr said. “When the earthquake shook the site, just after midnight on January 13, it is that short cable and splice that suffered damage.”
“You might say that our structural Achilles heel was exposed,” Kerr added.
Inspectors from New York’s Ammann & Whitney Bridge Construction, who have been inspecting the Arecibo observatory site since 1972, were brought in to access the situation and Kerr said a relatively low-cost (less than $100,000) repair option was designed and carried out, bringing the telescope back into full service as of March 13, exactly two months from when the earthquake occurred.
The Arecibo Observatory is operated by SRI International, teaming with Universidad Metropolitana and the Universities Space Research Association, in a cooperative agreement with the National Science Foundation.
The Challenger space shuttle a few moments after the rupture took place in the booster. Credit: NASA
What you see above is 32 minutes of something going wrong during each launch. While humanity has been launching things into space since the 1950s, you can see just how hard it is — over and over again. And when humans are riding aboard the rockets, the toll becomes more tragic.
According to the YouTube author of the video above, the vehicles shown include “V2, Vanguard TV3, Explorer S-1, Redstone 1, Titan I, Titan II, Titan IV, Atlas, Atlas-Centaur, N1, Delta, Delta III, Foton, Soyuz, Long March, Zenith, Space Shuttle Challenger, and more.”
Naturally, with each failure the engineers examine the systems and work to fix things for next time. A famous example is the Challenger shuttle explosion, which you can see about halfway through the video. There were multiple causes for the failure (human and technical), but one of them was an O-ring that failed in cold weather before the launch. NASA revised the launch rules and with contractors, made some changes to the booster rocket design, as a 2010 Air and Space Smithsonian article points out:
Freezing temperatures weakened an O-ring seal in a joint between two segments of the right booster. The weakness allowed hot gases to burn through the casing, causing the shuttle to break apart on ascent, which killed the seven-member crew. Two joints were redesigned with interlocking walls that had new bolts, pins, sensors, seals, and a third O-ring.
Still, launching is a risky business. That’s why it’s so important that engineers try to catch problems before they happen, and that as soon as a problem is seen, it’s fixed.
NASA's Robonaut 2 (left) flashes a Star Trek Vulcan salutation along with George Takei, a star of the original series, in 2012. "It was a keen demonstration of Robonaut 2’s manual dexterity. The gesture is difficult for many humans to make," Takei wrote on Facebook. Credit: NASA/James Blair
Legs — yes, legs — are on the manifest for the next SpaceX Dragon flight. The commercial spacecraft is expected to blast off March 16 with appendenges for Robonaut 2 on board, allowing the humanoid to move freely around station. After some initial tests in June will come R2’s first step, marking a new era in human spaceflight.
What’s exciting about R2 is not only its ability to take over simple tasks for the astronauts in station, but in the long run, to head “outside” to do spacewalks. This would greatly reduce risk to the astronauts, as extravehicular activity is one of the most dangerous things you can do outside (as a spacesuit leak recently reminded us.)
When installed, Robonaut will have a “fully extended leg span” of nine feet (wouldn’t we love to see the splits with that). Instead of a foot, each seven-jointed leg will have an “end effector” that is a sort of clamp that can grab on to things for a grip. It’s similar to the technology used on the Canadarm robotic arm, and also like Canadarm, there will be a vision system so that controllers know where to grasp.
NASA Expedition 35 astronaut Tom Marshburn (background) performs teleoperation activitites with Robonaut 2 aboard the International Space Station in 2013. Credit: NASA
The robot first arrived on station in February 2011 and (mostly while tied down) has done a roster of activities, such as shake hands with astronaut Dan Burbank in 2012 (a humanoid-human first in space), say hello to the world with sign language, and do functions such as turn knobs and flip switches. During Expedition 34/35 in 2012-13, astronaut Tom Marshburn even made Robonaut 2 catch a free-floating object through teleoperation.
Eventually NASA expects to use the robot outside the station, but more upgrades to Robonaut 2’s upper body will be needed first. The robot could then be used as a supplement to spacewalks, which are one of the most dangerous activities that humans do in space.
Closer to Earth, NASA says the technology has applications for items such as exoskeletons being developed to help people with physical disabilities.
NASA’s Robonaut 2 with “climbing legs” intended to let the robot rove around in the microgravity environment aboard the International Space Station. This version is being tested on the ground for eventual use in space. Credit: NASAR2A waving goodbye. Robonaut R2A waving goodbye as Robonaut R2B launches into space aboard STS-133 from the Kernnedy Space Center. R2 is the first humanoid robot in space. Credit: Joe Bibby
It’s a tough old universe out there. A young star has lots to worry about, as massive stars just beginning to shine can fill a stellar nursery with a gale of solar wind.
No, it’s not a B-movie flick: the “Death Stars of Orion” are real. Such monsters come in the form of young, O-type stars.
And now, for the first time, a team of astronomers from Canada and the United States have caught such stars in the act. The study, published in this month’s edition of The Astrophysical Journal, focused on known protoplanetary disks discovered by the Hubble Space Telescope in the Orion Nebula.
These protoplanetary disks, also known as “tadpoles” or proplyds, are cocoons of dust and gas hosting stars just beginning to shine. Much of this leftover material will go on to aggregate into planets, but nearby massive O-Type stars can cause chaos in a stellar nursery, often disrupting the process.
“O-Type stars, which are really monsters compared to our Sun, emit tremendous amounts of ultraviolet radiation and this can play havoc during the development of young planetary systems,” said astronomer Rita Mann in a recentpress release. Mann works for the National Research Council of Canada in Victoria and is lead researcher on the project
Scientists used the Atacama Large Millimeter Array (ALMA) to probe the proplyds of Orion in unprecedented detail. Supporting observations were also made using the Submillimeter Array in Hawaii.
ALMA saw “first light” in 2011, and has already achieved some first rate results.
“ALMA is the world’s most sensitive telescope at high-frequency radio waves (e.g., 100-1000 GHz). Even with only a fraction of its final number of antennas, (with 22 operational out of a total planned 50) we were able to detect with ALMA the disks relatively close to the O-star while previous observatories were unable to spot them,” James Di Francesco of the National Research Council of Canada told Universe Today. “Since the brightness of a disk at these frequencies is proportional to its mass, these detections meant we could measure the masses of the disks and see for sure that they were abnormally low close to the O-type star.”
The ALMA antennae on the barren plateau of Chajnantor. Credit: ALMA (ESO/NAOJ/NRAO).
ALMA also doubled the number of proplyds seen in the region, and was also able to peer within these cocoons and take direct mass measurements. This revealed mass being stripped away by the ultraviolet wind from the suspect O-type stars. Hubble had been witness to such stripping action previous, but ALMA was able to measure the mass within the disks directly for the first time.
And what was discovered doesn’t bode well for planetary formation. Such protostars within about 0.1 light-years of an O-type star are consigned to have their cocoon of gas and dust stripped clean in just a few million years, just a blink of a eye in the game of planetary formation.
With a O-type star’s “burn brightly and die young” credo, this type of event may be fairly typical in nebulae during early star formation.
“O-type stars have relatively short lifespan, say around 1 million years for the brightest O-star in Orion – which is 40 times the mass of our Sun – compared to the 10 billion year lifespan of less massive stars like our Sun,” Di Francesco told Universe Today. “Since these clusters are typically the only places where O-stars form, I’d say that this type of event is indeed typical in nebulae hosting early star formation.”
It’s common for new-born stars to be within close proximity of each other in such stellar nurseries as M42. Researchers in the study found that any proplyds within the extreme-UV envelope of a massive star would have its disk shredded in short order, retaining on average less than 50% the mass of Jupiter total. Beyond the 0.1 light year “kill radius,” however, the chances for these proplyds to retain mass goes up, with researchers observing anywhere from 1 to 80 Jupiter masses of material remaining.
The findings in this study are also crucial in understanding what the early lives of stars are like, and perhaps the pedigree of our own solar system, as well as how common – or rare – our own history might be in the story of the universe.
There’s evidence that our solar system may have been witness to one or more nearby supernovae early in its life, as evidenced by isotopic measurements. We were somewhat lucky to have had such nearby events to “salt” our environment with heavy elements, but not sweep us clean altogether.
“Our own Sun likely formed in a clustered environment similar to that of Orion, so it’s a good thing we didn’t form too close to the O-stars in its parent nebula,” Di Francesco told Universe Today. “When the Sun was very young, it was close enough to a high-mass star so that when it blew up (went supernova) the proto-solar system was seeded with certain isotopes like Al-26 that are only produced in supernova events.”
This is the eventual fate of massive O-type stars in the Orion Nebula, though none of them are old enough yet to explode in this fashion. Indeed, it’s amazing to think that peering into the Orion Nebula, we’re witnessing a drama similar to what gave birth to our Sun and solar system, billions of years ago.
The Orion Nebula is the closest active star forming region to us at about 1,500 light years distant and is just visible to the naked eye as a fuzzy patch in the pommel of the “sword” of Orion the Hunter. Looking at the Orion Nebula at low power through a small telescope, you can just make out a group of four stars known collectively as the Trapezium. These are just such massive hot and luminous O-Type stars, clearing out their local neighborhoods and lighting up the interior of the nebula like a Chinese lantern.
And thus science fact imitates fiction in an ironic twist, as it turns out that “Death Stars” do indeed blast planets – or at least protoplanetary disks – on occasion!
Be sure to check out a great piece on ALMA on a recent episode of CBS 60 Minutes:
Read the abstract and the full (paywalled) paper on ALMA Observations of the Orion Proplyds in The Astrophysical Journal.
It’s a staple of science fiction, restarting our dying star with some kind of atomic superbomb. Why is our Sun running out of fuel, and what can we actually do to get it restarted?
Stars die. Occasionally threatening the Earth and its civilization in a variety plot devices in science fiction. Fortunately there’s often a Bruce Willis coming in to save the day, delivering a contraption, possibly riding a giant bomb shaped like a spaceship, to the outer proximity of our dying Sun that magically fixes the broken star and all humanity is saved.
Is there any truth in this idea? If our Sun dies, can we just crack out a giant solar defibrillator and shock it back into life? Not exactly.
First, let’s review at how stars die. Our Sun is halfway through its life. It’s been going for about 4.5 billion years, and in 5 billion years it’ll use up all the hydrogen in its core, bloat up as a red giant, puff off its outer layers and collapse down into a white dwarf.
Is there a point in there, anywhere, that we could get it back to acting like a sun? Technically? Yes. Did you know it will only use up a fraction of its fuel during its lifetime? Only in the core of the Sun are the temperatures and pressures high enough for fusion reactions to take place. This region extends out to roughly 25% of the radius, which only makes up about 2% of the volume.
Outside the core is the radiative zone, where fusion doesn’t take place. Here, the only way gamma radiation can escape is to be absorbed and radiated countless times, until it reaches the next layer of the Sun: the convective zone. Here temperatures have dropped to the point that the whole region acts like a giant lava lamp. Huge blobs of superheated stellar plasma rise up within the star and release their energy into space. This radiative zone acts like a wall, keeping the potential fuel in the convective zone away from the fusion furnace.
Cutaway to the Interior of the Sun. Credit: NASA
So, if you could connect the convective zone to the solar core, you’d be able to keep mixing up the material in the Sun. The core of the Sun would be able to efficiently fuse all the hydrogen in the star.
Sound crazy? Interestingly, this already happens in our Universe. For red dwarf stars with less than 35% the mass of the Sun, their convective zones connect directly to the core of the star. This is why these stars can last for hundreds of billions and even trillions of years. They will efficiently use up all the hydrogen in the entire star thanks to the mixing of the convective zone. If we could create a method to break through the radiative zone and get that fresh hydrogen into the core of the Sun, we could keep basking in its golden tanning rays for well past its current expiration date.
I never said it would be easy. It would take stellar engineering at a colossal scale to overcome the equilibrium of the star. A future civilization with an incomprehensible amount of energy and stellar engineering ability might be able to convert our one star into a collection of fully convective red dwarf stars. And these could sip away their hydrogen for trillions of years.
Tell us in the comments on how you think we should go about it. My money is on giant ‘magic bullet’ blender” or a perhaps a Dyson solar juicer.
Hydrothermal vents deep in Earth's oceans. Could similar types of vents power the transport of silica and other materials out from Enceladus? Credit: NOAA
When it comes to life on Earth, we’re not sure if it came from the outside (transported by comets) or on the inside. A new theory focuses on the “interior ” theory, saying that microbes could have evolved from non-living matter such as chemical compounds in minerals and gases.
“Before biological life, one could say the early Earth had ‘geological life’. It may seem unusual to consider geology, involving inanimate rocks and minerals, as being alive. But what is life?” stated Terry Kee, a biochemist at the University of Leeds in the United Kingdom who participated in the research.
“Many people have failed to come up with a satisfactory answer to this question. So what we have done instead is to look at what life does, and all life forms use the same chemical processes that occur in a fuel cell to generate their energy.”
When thinking of a car, the research team says, they point out that fuel cells create electrical energy through the reaction of fuels and oxidants. This is called a “redox reaction”, which takes place when a molecule loses electrons and another molecule gains them.
In plants, photosynthesis creates electrical energy when carbon dioxide breaks down into sugars, and water is oxidized into molecular oxygen. (By contrast, humans oxidize sugars into carbon dioxide and break down the oxygen into water — another electrical energy process.)
Now, let’s go a step further. Hydrothermal vents are hot geysers on the sea floor that are often considered an interesting spot for life studies. They host “extremophiles”, or forms of life that exist (“thrive” is the better word) despite a harsh environment. The researchers say these vents are a sort of “environmental fuel cell” because electrical energy is generated from redox reactions between seawater oxidants and hydrothermal vents.
And this is where the new research comes in. At the University of Leeds and NASA’s Jet Propulsion Laboratory, the researchers put iron and nickel in the place of the usual “platinum catalysts” found in fuel cells and electrical experiments.
Rendering showing the location and size of water vapor plumes coming from Europa’s south pole.
While the power was reduced, electricity did indeed flow. And while researchers still don’t know how non-life could have transformed into life, they say this is another step to understanding what happened. What’s more, it could be useful for future trips to other planets.
“These experiments simulate the electrical energy produced in geological systems, so we can also use this to simulate other planetary environments with liquid water, like Jupiter’s moon Europa or early Mars,” stated Laura Barge, a researcher from the NASA Astrobiology Institute* who led the research.
“With these techniques we could actually test whether any given hydrothermal system could produce enough energy to start life, or even, provide energetic habitats where life might still exist and could be detected by future missions.”
Artist's conception of the Milky Way galaxy. Credit: Nick Risinger
Is it stretching it too far to think of a Lord of the Rings-esque “Entmoot” when reading the phrase “Council of Giants”? In this case, however, it’s not trees gathering in a circle, but galaxies.
A new map of the galactic neighborhood shows how the Milky Way may be restricted by a bunch of galaxies surrounding and constricting us with gravity.
“All bright galaxies within 20 million light years, including us, are organized in a ‘Local Sheet’ 34-million light years across and only 1.5 million light years thick,” stated Marshall McCall of York University in Canada, who is the sole author of a paper on the subject.
“The Milky Way and Andromeda are encircled by twelve large galaxies arranged in a ring about 24-million light years across. This ‘Council of Giants’ stands in gravitational judgment of the Local Group by restricting its range of influence.”
The “Council of Giants” is shown in this diagram based on 2014 research from York University. It shows the brightest galaxies within 20 million light-years of the Milky Way. The galaxies in yellow are the “Council.” (You can see a larger image if you click on this.) Credit: Marshall McCall / York University.
Here’s why McCall thinks this is the case. Most of the Local Sheet galaxies (the Milky Way, Andromeda, and 10 more of the 14 galaxies) are flattened spiral galaxies with stars still forming. The other other two galaxies are elliptical galaxies where star-forming ceased long ago, and of note, this pair lie on opposite sides of the “Council.”
“Winds expelled in the earliest phases of their development might have shepherded gas towards the Local Group, thereby helping to build the disks of the Milky Way and Andromeda,” the Royal Astronomical Society stated. The spin in this group of galaxies, it added, is unusually aligned, which could have occurred due to the influence of the Milky Way and Andromeda “when the universe was smaller.”
The larger implication is the Local Sheet and Council likely came to be in “a pre-existing sheet-like foundation composed primarily of dark matter”, or a mysterious substance that is not measurable by conventional instruments but detectable on how it influences other objects. McCall stated that on a small scale, this could help us understand more about how the universe is constructed.
