It’s a cosmic cover-up! No, don’t put your tinfoil* hats on, this isn’t a conspiracy — it’s just Saturn’s moon Iapetus drifting in front of the bright star Gamma Orionis (aka Bellatrix) captured on Cassini’s narrow-angle camera on August 10, 2013.
Such an event is called an occultation, a term used in astronomy whenever light from one object is blocked by another — specifically when something visually larger moves in front of something apparently smaller. (The word occult means to hide or conceal… nothing mystical implied!)
The animation above was assembled from 19 raw images publicly available on the JPL Cassini mission site, stacked in Photoshop and exported as a gif. They’ve been rotated 90º from the originals but otherwise they’re right from Cassini’s camera.
Iapetus, seen above as just a thin crescent, is best known for its two-toned appearance. One half of the 914-mile-wide moon is bright and icy, the other coated with a layer of dark reddish material, giving it a real “yin-yang” appearance. (Ok, I guess that’s a little mystical. But purely coincidental.)
It’s thought that the dark material originates from a more distant moon, Phoebe, which is being pelted by micrometeorites and shedding its surface out into orbit around Saturn, which eventually gets scooped up by the backwards-orbiting Iapetus.
The difference in albedo affects how Iapetus absorbs solar radiation too, causing the water ice beneath the darker material to evaporate over the course of its 79-Earth-day rotation and migrate around its surface, creating a sort of positive feedback loop.
While neat to look at, occultations are important to science because they provide a way to briefly peer into a world’s atmosphere (or in a small moon’s case, exosphere). Watching how light behaves as it passes behind the limb of a planet or moon lets researchers learn details of the air around it — however tenuous — pretty much for free… no probes or flybys needed!
The occulted star above is Bellatrix, the 1.6-magnitude star that marks Orion’s left shoulder.
Iapetus orbits Saturn at the considerable distance of 2,212,889 miles (3,561,300 km). Learn more about Iapetus here, and as always you can find more fantastic Cassini images from Carolyn Porco’s team at the Space Science Institute in Boulder, Colorado at the CICLOPS site here.
One scientific team has identified 12 “Easily Retrievable Objects” in our solar system that are circling the sun and would not cost too much to retrieve (in relative terms, of course!)
The definition of an ERO is an object that can be captured and brought back to a stable gravitational point near Earth (called a Lagrange point, or more specifically the L1/L2 points between the sun and the Earth.) The change in speed necessary in these objects to make them easily retrievable is “arbitrarily” set at 500 meters per second (1,641 feet/second) or less, the researchers stated.
Catching the objects wouldn’t just be a technology demonstration, but also could shed some light into how the solar system formed. Asteroids are generally considered leftovers of the early days of the neighborhood; under our current understanding of the solar system’s history, a spinning disc of gas and dust gradually clumped into rocks and other small objects, which eventually crashed into each other and formed planets.
Also, steering these objects around has another benefit: teaching humans how to deflect potentially hazardous asteroids from smacking into the Earth and causing damage. As we were reminded about earlier this year, even smaller rocks such as the one that broke up over a portion of Russia can be hazardous.
There are at least a couple of big limitations to the plan. The first is to make sure not to put the asteroid in a path that would hit the Earth. The second is that he L1 and L2 points are somewhat unstable, so over time the asteroid would drift from its spot. It would need a nudge every so often to keep it in that location.
For the curious, this is the complete list of possible asteroids: 2006 RH120, 2010 VQ98, 2007 UN12, 2010 UE51, 2008 EA9, 2011 UD21, 2009 BD, 2008 UA 202, 2011 BL45, 2011 MD, 2000 SG344 and 1991 VG.
SpaceX proved yesterday that their Grasshopper prototype Vertical Takeoff Vertical Landing (VTVL) vehicle can do more than just go straight up and down. The goal of the test, said SpaceX CEO Elon Musk on Twitter was, “hard lateral deviation, stabilize & hover, rapid descent back to pad.”
On August 13th, the Grasshopper did just that, completing a divert test, flying to a 250-meter altitude with a 100-meter lateral maneuver before returning to the center of the pad. SpaceX said the test demonstrated the vehicle’s ability to perform more aggressive steering maneuvers than have been attempted in previous flights.
While most rockets are designed to burn up in the atmosphere during reentry, SpaceX is looking to make their next generation of Falcon 9 rocket be able to return to the launch pad for a vertical landing.
This isn’t easy. The 10-story Grasshopper provides a challenge in controlling the structure. The Falcon 9 with a Dragon spacecraft is 48.1 meters (157 feet) tall, which equates to about 14 stories high. SpaceX said diverts like this are an important part of the trajectory in order to land the rocket precisely back at the launch site after reentering from space at hypersonic velocity.
Also on Twitter this morning, NASA’s Jon Cowert (who is now working with the Commercial Crew program) provided a look back at NASA’s foray into VTVL vehicles with the Delta Clipper Experimental vehicle,(DC-X). The video below is from July 7, 1995, and the Delta Clipper was billed as the world’s first fully reusable rocket vehicle. This eighth test flight proved that the vehicle could turn over into a re-entry profile and re-orient itself for landing. This flight took place at the White Sands Missile Range in southern New Mexico.
But after some problems (fires and the spacecraft actually fell over when a landing strut didn’t extend) NASA decided to try and focus on the X-33 VentureStar, which would land like an airplane…. and that didn’t work out very well either.
Since their discovery, supermassive black holes – the giants lurking in the center of every galaxy – have been mysterious in origin. Astronomers remain baffled as to how these supermassive black holes became so massive.
New research explains how a supermassive black hole might begin as a normal black hole, tens to hundreds of solar masses, and slowly accrete more matter, becoming more massive over time. The trick is in looking at a binary black hole system. When two galaxies collide the two supermassive black holes sink to the center of the merged galaxy and form a binary pair. The accretion disk surrounding the two black holes becomes misaligned with respect to the orbit of the binary pair. It tears and falls onto the black hole pair, allowing it to become more massive.
In a merging galaxy the gas flows are turbulent and chaotic. Because of this “any gas feeding the supermassive black hole binary is likely to have angular momentum that is uncorrelated with the binary orbit,” Dr. Chris Nixon, lead author on the paper, told Universe Today. “This makes any disc form at a random angle to the binary orbit.
Nixon et al. examined the evolution of a misaligned disk around a binary black hole system using computer simulations. For simplicity they analyzed a circular binary system of equal mass, acting under the effects of Newtonian gravity. The only variable in their models was the inclination of the disk, which they varied from 0 degrees (perfectly aligned) to 120 degrees.
After running multiple calculations, the results show that all misaligned disks tear. Watch tearing in action below:
In most cases this leads to direct accretion onto the binary.
“The gravitational torques from the binary are capable of overpowering the internal communication in the gas disc (by pressure and viscosity),” explains Nixon. “This allows gas rings to be torn off, which can then be accreted much faster.”
Such tearing can produce accretion rates that are 10,000 times faster than if the exact same disk were aligned.
In all cases the gas will dynamically interact with the binary. If it is not accreted directly onto the black hole, it will be kicked out to large radii. This will cause observable signatures in the form of shocks or star formation. Future observing campaigns will look for these signatures.
In the meantime, Nixon et al. plan to continue their simulations by studying the effects of different mass ratios and eccentricities. By slowly making their models more complicated, the team will be able to better mimic reality.
Quick interjection: I love the simplicity of this analysis. These results provide an understandable mechanism as to how some supermassive black holes may have formed.
While these results are interesting alone – based on that sheer curiosity that drives the discipline of astronomy forward – they may also play a more prominent role in our local universe.
Before we know it (please read with a hint of sarcasm as this event will happen in 4 billion years) we will collide with the Andromeda galaxy. This rather boring event will lead to zero stellar collisions and a single black hole collision – as the two supermassive black holes will form a binary pair and then eventually merge.
Without waiting for this spectacular event to occur, we can estimate and model the black hole collision. In 4 billion years the video above may be a pretty good representation of our collision with the Andromeda galaxy.
The results have been published in the Astrophysical Journal Letters (preprint available here). (Link was corrected to correct paper on 8/15/2013).
This week, SpaceX founder and billionaire Elon Musk (who also founded electric vehicle manufacturer Tesla Motors) released his vision for a futuristic transportation system. Called hyperloop, it’s supposed to be better than flying supersonic over short distances. To give you a quick overview, we’ve summarized a portion of his paper below.
What is a hyperloop? In Musk’s words, a hyperloop is a system to “build a tube over or under the ground that contains a special environment.” Cars would basically be propelled in this tube. One example could be a huge sort of pneumatic tube where high-speed fans would compress and push the air — although the friction implications make Musk skeptical that it would work. Another option is having a vacuum in the tube and using electromagnetic suspension instead. Musk acknowledges it is hard to maintain a vacuum (one small leak in hundreds of miles of tubing, and the system shuts down), but there are pumping solutions to overcome this. He favors the second solution.
What is the motivation? Musk is seeking an alternative to flying or driving that would be “actually better than flying or driving.” He expressed disappointment that a proposed high-speed rail project in California is actually one of the slowest and most expensive of its type in the world, and speculated that there must be a better way.
What is the biggest technical challenge? Overcoming something called the Kantrowitz limit. Musk describes this as the “top speed law for a given tube to pod area ratio”. More simply, if you have a vehicle moving into an air-filled tube, there needs to be a minimum distance between the walls of the vehicle and the walls of the tube. Otherwise, Musk writes, “the capsule will behave like a syringe and eventually be forced to push the entire column of air in the system. Not good.”
How will Musk overcome that challenge? The principal ways of getting around it is to move slowly or quickly. A hyperfast speed would be a “dodgy prospect”, Musk writes, so his solution is to put an electric compressor fan on the capsule nose that would move high-pressure air from the front to the back of the vehicle. As a bonus, this would reduce friction. Yes, there are batteries available that would have enough power to keep the fan running for the journey’s length, he says.
How is hyperloop powered? Solar panels would be placed on top of the tube, providing enough juice to keep the vehicles moving, according to Musk’s calculations.
What about earthquakes? Musk acknowledges that a long-range system is susceptible to earthquakes. “By building a system on pylons, where the tube is not rigidly fixed at any point, you can dramatically mitigate earthquake risk and avoid the need for expansion joints,” he writes.
Where would hyperloop be used? In a description of the system, Musk says the hyperloop would be best served in “high-traffic city pairs that are less than about 1,500 km or 900 miles apart.” Anything more distant, and supersonic travel would be the best solution. (Short distance supersonic travel isn’t efficient because the plane would spend most of its time ascending and descending.)
Is it cost-effective? Musk estimates the tube would be “several billion dollars”, which he describes as low compared to the “tens of billion [sic] proposed for the track of the California rail project.” The individual capsules would be several hundred million dollars. Moreover, building a tube instead of a railway offers advantages, Musk says: it can be built on pylons (meaning you don’t need to buy the land), it’s less noisy, and there’s no need for fencing.
I want more information. Musk wrote a technical proposal that spans several dozens of pages, which you can check out here. He calls his system an open-source one and seems to be open to ideas to improve it.
Feel free to leave your feedback in the comments. Does this look feasible? Is there anything that could be added to make it a better system?
And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address.
The Sun has provided no shortage of mysteries thus far during solar cycle #24.
And perhaps the biggest news story that the Sun has generated recently is what it isn’t doing. As Universe Today recently reported, this cycle has been an especially weak one in terms of performance. The magnetic polarity flip signifying the peak of the solar maximum is just now upon us, as the current solar cycle #24 got off to a late start after a profound minimum in 2009…
Or is it?
Exciting new research out of the University of Michigan in Ann Arbor’s Department of Atmospheric, Oceanic and Space Sciences published in The Astrophysical Journal this past week suggests that we’re only looking at a portion of the puzzle when it comes to solar cycle activity.
Traditional models rely on the monthly averaged sunspot number. This number correlates a statistical estimation of the number of sunspots seen on the Earthward facing side of the Sun and has been in use since first proposed by Rudolf Wolf in 1848. That’s why you also hear the relative sunspot number sometimes referred to as the Wolf or Zürich Number.
But sunspot numbers may only tell one side of the story. In their recent paper titled Two Novel Parameters to Evaluate the Global Complexity of the Sun’s Magnetic Field and Track the Solar Cycle, researchers Liang Zhao, Enrico Landi and Sarah E. Gibson describe a fresh approach to model solar activity via looking at the 3-D dynamics heliospheric current sheet.
The heliospheric current sheet (or HCS) is the boundary of the Sun’s magnetic field separating the northern and southern polarity regions which extends out into the solar system. During the solar minimum, the sheet is almost flat and skirt-like. But during solar maximum, it’s tilted, wavy and complex.
Two variables, known as SD & SL were used by researchers in the study to produce a measurement that can characterize the 3-D complexity of the HCS. “SD is the standard deviation of the latitudes of the HCS’s position on each of the Carrington maps of the solar surface, which basically tells us how far away the HCS is distributed from the equator. And SL is the integral of the slope of HCS on that map, which can tell us how wavy the HCS is on each of the map,” Liang Zhao told Universe Today.
Ground and space-based observations of the Sun’s magnetic field exploit a phenomenon known as the Zeeman Effect, which was first demonstrated during solar observations conducted by George Ellery Hale using his new fangled invention of the spectrohelioscope in 1908. For the recent study, researchers used data covering a period from 1975 through 2013 to characterize the HCS data available online from the Wilcox Solar Observatory.
Comparing the HCS value against previous sunspot cycles yields some intriguing results. In particular, comparing the SD and SL values with the monthly sunspot number provide a “good fit” for the previous three solar cycles— right up until cycle #24.
“Looking at the HCS, we can see that the Sun began to act strange as early as 2003,” Zhao said. “This current cycle as characterized by the monthly sunspot number started a year late, but in terms of HCS values, the maximum of cycle #24 occurred right on time, with a first peak in late 2011.”
“Scientists believe there will be two peaks in the sunspot number in this solar maximum as in the previous maximum (in ~2000 and ~2002),” Zhao continued, “since the Sun’s magnetic fields in the north and south hemispheres look asymmetric, and the north evolved faster than the south recently. But so far as I can see, the highest value of monthly-averaged sunspot number in this cycle 24 is still the one in the November 2011. So we can say the first peak of cycle 24 could be in November of 2011, since it is the highest monthly sunspot number so far in this cycle. If there is a second peak, we will see it sooner or later.”
The paper also notes that although cycle 24 is especially weak when compared to recent cycles, its range of activity is not unique when compared with solar cycles over the past 260 years.
The HCS value characterizes the Sun over one complete Carrington Rotation of 27 days. This is an averaged value for the rotation of the Sun, as the poles rotate slower than the equatorial regions.
The approximately 22 year span of time that it takes for the poles to reverse back to the same polarity again is equal to two average 11 year sunspot cycles. The Sun’s magnetic field has been exceptionally asymmetric during this cycle, and as of this writing, the Sun has already finished its reversal of the north pole first.
This sort of asymmetry during an imminent pole reversal was first recorded during solar cycle 19, which spanned 1954-1964. Solar cycles are numbered starting from observations which began in 1749, just four decades after the end of the 70-year Maunder Minimum.
“This is an exciting time to study the magnetic field of the Sun, as we may be witnessing a return to a less-active type of cycle, more like those of 100 years ago,” NCAR/HAO senior scientist and co-author Sarah Gibson said.
But this time, an armada of space and ground-based observatories will scrutinize our host star like never before. The SOlar Heliospheric Observatory (SOHO) has already followed the Sun through the equivalent of one complete solar cycle— and it has now been joined in space by STEREO A & B, JAXA’s Hinode, ESA’s Proba-2 and NASA’s Solar Dynamics Observatory. NASA’s Interface Region Imaging Spectrograph (IRIS) was also launched earlier this year and has just recently opened for business.
Will there be a second peak following the magnetic polarity reversal of the Sun’s south pole, or is Cycle #24 about to “leave the building?” And will Cycle #25 be absent all together, as some researchers suggest? What role does the solar cycle play in the complex climate change puzzle? These next few years will prove to be exciting ones for solar science, as the predictive significance of HCS SD & SL values are put to the test… and that’s what good science is all about!
-Read the abstract with a link to the full paper in The Astrophysical Journal by University of Michigan researchers here.
It’s frustrating to make it all the way to Mars, only to land in the wrong spot. So as Masten Space Systems tests its Xombie vertical-launch-vertical-landing rocket prototype on Earth, engineers are also examining a software solution to make Red Planet landings even more precise.
The software is called G-FOLD (for Fuel Optimal Large Divert Guidance algorithm) and is a product of NASA’s Jet Propulsion Laboratory and other NASA departments. The agency is using techniques for spacecraft landings that have origins from the Apollo moon missions of the 1960s, which have some limitations.
“These algorithms do not optimize fuel usage and significantly limit how far the landing craft can be diverted during descent,” JPL stated, adding that the new algorithm can figure out the best fuel-conserving paths in real time, along with a “key new technology required for planetary pinpoint landing.”
Hitting the target exactly is an exciting feat for researchers, JPL explained, because robotic missions can be steered to difficult-to-reach science targets and crewed missions could bring more cargo to their landing site rather than carrying extra fuel.
Xombie first tested out this technique on July 30 and nailed the landing — about half a mile away — when it received the commands while 90 feet in the air. A second flight is planned for August, providing the data analysis goes as planned.
The technology is still new, of course, and there are other concepts out there for pinpoint systems. In May, the European Space Agency released information on a concept it is funding. That system, which is also still being developed, uses a database of landmarks to assist a spacecraft with making landings.
Rocket science university students from Puerto Rico pose for photo op with the Terrier-Improved Malemute sounding rocket that will launch their own developed RockSat-X science experiments to space on Aug. 13 at 6 a.m. from NASA Wallops Flight Facility, VA.
Credit: Ken Kremer/kenkremer.com[/caption]
WALLOPS ISLAND, VA – How many of you have dreamed of flying yourselves or your breakthrough experiments to the High Frontier? Well if you are a talented student, NASA may have a ticket for you.
A diverse group of highly motivated aerospace students from seven universities spread across the United States have descended on NASA’s Wallops Flight Facility along the Eastern Shore of Virginia to fulfill the dream of their lifetimes – launching their very own science experiments aboard a rocket bound for space.
I met the thrilled students and professors today beside their rocket at the Wallops Island launch pad.
On Aug 13, after years of hard work, an impressive array of research experiments developed by more than 40 university students will soar to space on the RockSat-X payload atop a 44-foot tall Terrier-Improved Malemute suborbital sounding rocket at 6 a.m. EDT.
The two stage rocket will rapidly ascend on a southeasterly trajectory to an altitude of some 97 miles and transmit valuable data in-flight during the 12-minute mission.
The launch will be visible to spectators in parts of Virginia, Maryland and Delaware, and perhaps a bit beyond. Check out the visibility map below.
If you’re available, try venturing out to watch it. The available window lasts until 10 a.m. EDT if needed.
The students will put their classroom learning to the test with experiments and instruments built by their own hands and installed on the 20 foot long RockSat-X payload. The integrated payload accounts for nearly half the length of the Terrier Malamute suborbital rocket. It’s an out of this world application of the scientific method.
Included among the dozens of custom built student experiments are HD cameras, investigations into crystal growth and ferro fluids in microgravity, measuring the electron density in the E region (90-120km), aerogel dust collection on an exposed telescoping arm from the rockets side, effects of radiation damage on various electrical components, determining the durability of flexible electronics in the cryogenic environment of space and creating a despun video of the flight.
At the conclusion of the flight, the payload will descend to Earth via a parachute and splash down in the Atlantic Ocean approximately 86 miles offshore from Wallops.
Commercial fishing ships under contract to NASA will then recover the RockSat-X payload and return it to the students a few hours later, NASA spokesman Keith Koehler told Universe Today.
They will tear apart the payload, disengage their experiments and begin analyzing the data to see how well their instruments performed compared to the preflight hypotheses’.
RockSat-X is a joint educational activity between NASA and the Colorado Space Grant Consortium. It is the third of three practical STEM educational programs where the students must master increasingly difficult skill level requirements leading to a series of sounding rocket liftoffs.
In mid-June, some 50 new students participated in the successful ‘RockOn’ introductory level payload launch from Wallops using a smaller Terrier-Improved Orion rocket.
“The goal of the RockSat-X program is to provide students a hands-on experience in developing experiments for space flight,” said Chris Koehler, Director of the Colorado Space Grant Consortium.
“This experience allows these students to apply what they have learned in the classroom to a real world hands-on project.”
The students participating in this year’s RockSat-X launch program hail from the University of Colorado at Boulder; the University of Puerto Rico at San Juan; the University of Maryland, College Park; Johns Hopkins University, Baltimore, Md.; West Virginia University, Morgantown; University of Minnesota, Twin Cities; and Northwest Nazarene University, Nampa, Idaho.
Some of these students today could well become the pioneering aerospace industry leaders of tomorrow!
In the event of a delay forced by weather or technical glitches, August 14 is the backup launch day.
A great place to witness the blastoff is from the NASA Wallops Visitor Center, offering a clear view to the NASA launch range.
It opens at 5 a.m. on launch day and is a wonderful place to learn about NASA missions – especially the pair of exciting and unprecedented upcoming launches of the LADEE lunar science probe to the moon and the Cygnus cargo carrier to the ISS in September.
Both LADEE and Cygnus are historic first of their kind flights from NASA Wallops.
Live coverage of the launch is available via UStream beginning at 5 a.m. on launch day at:
http://www.ustream.tv/channel/nasa-tv-wallops
…………….
Learn more about Suborbital Science, Cygnus, Antares, LADEE, MAVEN and Mars rovers and more at Ken’s upcoming presentations
Aug 12/13: “RockSat-X Suborbital Launch, LADEE Lunar & Antares Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8 PM
Sep 5/6/16/17: LADEE Lunar & Antares/Cygnus ISS Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8 PM
Oct 3: “Curiosity, MAVEN and the Search for Life on Mars – (3-D)”, STAR Astronomy Club, Brookdale Community College & Monmouth Museum, Lincroft, NJ, 8 PM
We have another great app giveaway for you, our valued readers. Star Walk is an app that allows you to point your iPhone at the night sky to provide names and descriptions of all the objects you are seeing. Furthermore, you can click on any individual star, satellite, planet or constellation and an in depth description will conveniently pop up on your screen. Whether you live in the city with lots of light pollution or in the country where there are more stars than black, this app will fill you in on all of the celestial objects you can (or can’t) see.
From the developer:
Star Walk is an award-winning Education app that allows users to easily locate and identify 20,000+ objects in the night sky. The 360-degree, touch control star map displays constellations, stars, planets, satellites, and galaxies currently overhead from anywhere on Earth. Highly praised and the winner of a 2010 Apple Design Award, the latest update allows users to enjoy unprecedented eye candy and interactivity of the star map, achieved with the new camera and high resolution of the new device.
Enter to win one of 10 free copies of this app for your iPhone. How?
In order to be entered into the giveaway drawing, just put your email address into the box at the bottom of this post (where it says “Enter the Giveaway”) before Monday, August 19, 2013. We’ll send you a confirmation email, so you’ll need to click that to be entered into the drawing.