A ladder-like structure in Saturn's F ring seen by Cassini on Feb. 13, 2013 (NASA/JPL-Caltech/SSI)
Saturn’s F ring is certainly a curious structure. Orbiting the giant planet 82,000 kilometers above its equatorial cloud tops, the F ring is a ropy, twisted belt of bright ice particles anywhere from 30-500 km wide. It can appear as a solid band or a series of braided cords surrounded by a misty haze, and often exhibits clumps and streamers created by the gravitational influence of embedded moonlets or passing shepherd moons.
In the picture above, acquired by the Cassini spacecraft on Feb. 13, 2013 and released on May 27, we see a section of the F ring separated into long ropes and spanned by connecting bands of bright material — the “ladder” structure suggested in the title.
Scientists believe that interactions between the F ring and the moons Prometheus and Pandora cause the dynamic structure of the F ring. (Watch an animation of the F ring and shepherd moons here.)
Made of particles of water ice finer than cigarette smoke, the F ring orbits Saturn beyond the outer edge of the A ring across the expanse of the 2,600-km-wide Roche Division. In these images, Saturn and the main ring systems are off frame to the left.
Detail of ladder structure in the F ring
This view looks toward the unilluminated side of the rings from about 32 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft’s narrow-angle camera (NAC).
The view was obtained at a distance of approximately 426,000 miles (686,000 kilometers) from Saturn and at a phase angle of 162 degrees. Image scale is 2 miles (4 kilometers) per pixel.
Shown is the integrated CST-100 crew capsule and Atlas V launcher model at NASA's Ames Research Center. The model is a 7 percent model of the Boeing CST-100 spacecraft, launch vehicle adaptor and launch vehicle. Credit: Boeing
The next time that American astronauts launch to space from American soil it will surely be aboard one of the new commercially built “space taxis” currently under development by a trio of American aerospace firms – Boeing, SpaceX and Sierra Nevada Corp – enabled by seed money from NASA’s Commercial Crew Program (CCP).
Boeing has moved considerably closer towards regaining America’s lost capability to launch humans to space when the firm’s privately built CST-100 crew capsule achieved two key new milestones on the path to blastoff from Florida’s Space Coast.
The CST-100 capsule is designed to carry a crew of up to 7 astronauts on missions to low-Earth orbit (LEO) and the International Space Station (ISS) around the middle of this decade.
Boeing CST-100 crew vehicle docks at the ISS. Credit: Boeing
Boeing’s crew transporter will fly to space atop the venerable Atlas V rocket built by United Launch Alliance (ULA) from Launch Complex 41 on Cape Canaveral Air Force Station in Florida.
The Boeing and ULA teams recently completed the first wind tunnel tests of a 7 percent scale model of the integrated capsule and Atlas V rocket (photo above) as well as thrust tests of the modified Centaur upper stage.
The work is being done under the auspices of NASA’s Commercial Crew Integrated Capability (CCiCap) initiative, intended to make commercial human spaceflight services available for both US government and commercial customers, such as the proposed Bigelow Aerospace mini space station.
Boeing CST-100 capsule mock-up, interior view. Credit: Ken Kremer – kenkremer.com
Since its maiden liftoff in 2002, the ULA Atlas V rocket has flawlessly launched numerous multi-billion dollar NASA planetary science missions like the CuriosityMars rover, Juno Jupiter orbiter and New Horizons mission to Pluto as well as a plethora of top secret Air Force spy satellites.
But the two stage Atlas V has never before been used to launch humans to space – therefore necessitating rigorous testing and upgrades to qualify the entire vehicle and both stages to meet stringent human rating requirements.
“The Centaur has a long and storied past of launching the agency’s most successful spacecraft to other worlds,” said Ed Mango, NASA’s CCP manager at the agency’s Kennedy Space Center in Florida. “Because it has never been used for human spaceflight before, these tests are critical to ensuring a smooth and safe performance for the crew members who will be riding atop the human-rated Atlas V.”
The combined scale model CST-100 capsule and complete Atlas V rocket were evaluated for two months of testing this spring inside an 11- foot diameter transonic wind tunnel at NASA’s Ames Research Center in Moffett Field, Calif.
“The CST-100 and Atlas V, connected with the launch vehicle adaptor, performed exactly as expected and confirmed our expectations of how they will perform together in flight,” said John Mulholland, Boeing vice president and program manager for Commercial Programs.
Testing of the Centaur stage centered on characterizing the flow of liquid oxygen from the oxygen tank through the liquid oxygen-feed duct line into the pair of RL-10 engines where the propellant is mixed with liquid hydrogen and burned to create thrust to propel the CST-100 into orbit.
Boeing is aiming for an initial three day manned orbital test flight of the CST-100 during 2016, says Mulholland.
Artist’s concept shows Boeing’s CST-100 spacecraft separating from the first stage of its launch vehicle, a United Launch Alliance Atlas V rocket, following liftoff from Cape Canaveral Air Force Station in Florida. Credit: Boeing
But that date is dependent on funding from NASA and could easily be delayed by the ongoing sequester which has slashed NASA’s and all Federal budgets.
Chris Ferguson, the commander of the final shuttle flight (STS-135) by Atlantis, is leading Boeing’s flight test effort.
Boeing has leased one of NASA’s Orbiter Processing Facility hangers (OPF-3) at the Kennedy Space Center (KSC) for the manufacturing and assembly of its CST-100 spacecraft.
Mulholland told me previously that Boeing will ‘cut metal’ soon. “Our first piece of flight design hardware will be delivered to KSC and OPF-3 around mid 2013.”
NASA’s CCP program is fostering the development of the CST-100 as well as the SpaceX Dragon and Sierra Nevada Dream Chaser to replace the crew capability of NASA’s space shuttle orbiters.
The Atlas V will also serve as the launcher for the Sierra Nevada Dream Chaser space taxi.
Since the forced retirement of NASA’s shuttle fleet in 2011, US and partner astronauts have been 100% reliant on the Russians to hitch a ride to the ISS aboard the Soyuz capsules – at a price tag exceeding $60 Million per seat.
Simultaneously on a parallel track NASA is developing the Orion crew capsule and SLS heavy lift booster to send humans to the Moon and deep space destinations including Asteroids and Mars.
And don’t forget to “Send Your Name to Mars” aboard NASA’s MAVEN orbiter- details here. Deadline: July 1, 2013
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Learn more about Conjunctions, Mars, Curiosity, Opportunity, MAVEN, LADEE and NASA missions at Ken’s upcoming lecture presentations:
June 4: “Send your Name to Mars” and “CIBER Astro Sat, LADEE Lunar & Antares ISS Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8:30 PM
NASA’s Curiosity Mars Science Laboratory (MSL) rover blasts off for Mars atop a stunningly beautiful Atlas V rocket on Nov. 26, 2011 at 10:02 a.m. EST from Cape Canaveral, Florida. United Launch Alliance (ULA) is now upgrading the Atlas V to launch humans aboard the Boeing CST-100 and Sierra Nevada Dream Chaser space taxis. Credit: Ken Kremer – kenkremer.comThe CST-100 spacecraft awaits liftoff aboard an Atlas V launch vehicle in this artist’s concept. Credit: Boeing
Is time real or is it just an illusion of the human experience? An intriguing new book “Time Reborn” by theoretical physicist Lee Smolin discusses this concept. You can read our full review of this here, but we also have three free copies of this book to give away.
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 Wednesday June 5, 2013. We’ll send you a confirmation email, so you’ll need to click that to be entered into the drawing.
If you’d like to purchase the book, you can find it on Amazon.
Time Reborn: From the Crisis of Physics to the Future of the Universe is one of those books intended to provoke discussion. Right from the first pages, author Lee Smolin — a Canadian theoretical physicist who also teaches philosophy — puts forward a position: time is real, and not an illusion of the human experience (as other physicists try to argue).
Smolin, in fact, uses that concept of time as a basis for human free will. If time is real, he writes, this is the result: “Novelty is real. We can create, with our imagination, outcomes not computable from knowledge of the present.”
Physics as philosophy. A powerful statement to make in the opening parts of the book. The only challenge is understanding the rest of it.
Smolin advertises his book as open to the general reader who has no background in physics or mathematics, promising that there aren’t even equations to worry about. He also breaks up the involved explanations with wry observations of fatherhood, or by bringing up anecdotes from his past.
Artist concept of Gravity Probe B orbiting the Earth to measure space-time, a four-dimensional description of the universe including height, width, length, and time. Image credit: NASA
It works, but you need to be patient. Theoretical physics is so far outside of the everyday that at times it took me (with education focusing on journalism and space policy, admittedly) two or three readings of the same passage to understand what was going on.
But as I took my time, a whole world opened up to me.
I found myself understanding more about Einstein’s special and general relativity than I did in readings during high school and university. The book also made me think differently about cosmology (the nature of the universe), especially in relation to biological laws.
While the book is enjoyable, it is probably best not to read it in isolation as it is a positional one — a book that gathers information scientifically and analytically, to be sure, but one that does not have a neutral point of view to the conclusions.
We’d recommend picking up other books such as the classic A Brief History of Time (by physicist Stephen Hawking) to learn more about the universe, and how other scientists see time work.
Since Asteroid 1998 QE2 has a name which evokes cruise ships, astrophysicist Rhys Taylor has created this wonderful video comparing the two QE2s. He also has more information on his great blog, Physicists of the Caribbean.
GRAIL mission in Lunar Orbit. Artist concept of twin GRAIL spacecraft flying in tandem orbits around the moon to measure its gravity field in unprecedented detail. Credit: NASA/JPL
The moon’s gravity has been a headache ever since the Apollo era. Areas of “mass concentration” or mascons, discovered in 1968, affected spacecraft orbits and made landing on Earth’s neighbor a tricky challenge.
The phenomenon has puzzled scientists, but new data shows that mascons might have come to be after asteroids or comets hit the moon a long time ago.
For nine months last year, until their mission ended with a deliberate crash on a moon mountain, twin washing-machine sized spacecraft Ebb and Flow circled the planet. Their work was known as the GRAIL mission (also known as Gravity Recovery and Interior Laboratory.) As they orbited together, gravity changes in the moon below them slightly changed their distances to each other — sometimes closer, sometimes further.
This allowed scientists to map out the mascons to high precision once they combined that information with computer models of big asteroid impacts as well as how craters on the moon evolved.
Craters on the Moon. Image credit: NASA
Mascons, which are invisible on the surface but appear in gravity maps as a sort of bulls-eye, arise “as a natural consequence of crater excavation, collapse and cooling following an impact,” NASA stated.
The center of the bulls-eye has stronger gravity, with a ring of weaker gravity surrounding the bulls-eye, and then another ring of strong gravity surrounding the bulls-eye and inner ring.
“GRAIL data confirm that lunar mascons were generated when large asteroids or comets impacted the ancient moon, when its interior was much hotter than it is now,” stated Jay Melosh, lead researcher and a GRAIL co-investigator at Purdue University.
“We believe the data from GRAIL show how the moon’s light crust and dense mantle combined with the shock of a large impact to create the distinctive pattern of density anomalies that we recognize as mascons.”
What’s more, researchers expect they’ll be able to apply that understanding to Mercury and Mars, as mascons were also discovered on those terrestrial planets.
The findings appeared in the May 30 edition of Science. You can read the entire article here.
Neil Armstrong in the LM after his historic moonwalk (NASA)
“That’s one small step for man… one giant leap for mankind.” And with those famous words astronaut Neil A. Armstrong awed the entire world on July 21, 1969, becoming the first human to set a booted foot upon a world other than our own. But the historic statement itself has caused no small bit of confusion and controversy over the years, from whether Armstrong came up with it on the spot (he didn’t) to what he actually said… small step for “man?” Where’s the “a?”
Although some have said that the article was left out or cut off (and admittedly it sure sounds that way to me) it turns out it’s probably been there the whole time, hidden behind Neil’s native Ohio accent.
According to a team of speech scientists and psychologists from Michigan State University (MSU) in East Lansing and The Ohio State University (OSU) in Columbus, it is entirely possible that Armstrong said what he had always claimed — though evidence indicates that most people are likely to hear “for man” instead of “for a man” on the Apollo 11 broadcast recordings.
By studying how speakers from Armstrong’s native central Ohio pronounce “for” and “for a,” the team’s results suggest that his “a” was acoustically blended into his “for.”
“Prior acoustic analyses of Neil Armstrong’s recording have established well that if the word ‘a’ was spoken, it was very short and was fully blended acoustically with the preceding word,” says Laura Dilley of Michigan State University. “If Armstrong actually did say ‘a,'” she continues, “it sounded something like ‘frrr(uh).'”
His blending of the two words, compounded with the poor sound quality of the television transmission, has made it difficult to corroborate his claim that the “a” is there.
“If Armstrong actually did say ‘a,’ it sounded something like ‘frrr(uh).'”
– Laura Dilley, Michigan State University
Dilley and her colleagues used a collection of recordings of conversational speech from 40 people raised in Columbus, Ohio, near Armstrong’s native town of Wapakoneta. Within this body of recordings, they found 191 cases of “for a.” They matched each of these to an instance of “for” as said by the same speaker and compared the relative duration. They also examined the duration of Armstrong’s “for (a”) from the lunar transmission.
The researchers found a large overlap between the relative duration of the “r” sound in “for” and “for a” using the Ohio speech data. The duration of the “frrr(uh)” in Armstrong’s recording was 0.127 seconds, which falls into the middle of this overlap. In other words, the researchers conclude, the lunar landing quote is highly compatible with either possible interpretation though it is probably slightly more likely to be perceived as “for” regardless of what Armstrong actually said.
Dilley says there may have been a “perfect storm of conditions” for the word “a” to have been spoken… but not heard.
“We’ve bolstered Neil Armstrong’s side of the story,” she says. “We feel we’ve partially vindicated him. But we’ll most likely never know for sure exactly what he said based on the acoustic information.”
(Personally, I feel that if the first man to walk on the Moon said he said “a,” then he said “a.”)
Artist's conception of Landsat 8 (renamed from Landsat Data Continuity Mission). Credit: NASA/ Goddard/Conceptual Image Lab
Landsat 8 officially opened its eyes to Earth yesterday (May 30). Officials are promising the clearest views yet of the four-decade-old Landsat program, and luckily for people who love amazing Earth views, the images Landsat produces are free.
Before talking a bit about Landsat 8, here’s one way you can find the images: go to this website of raw Landsat data from the United States Geological Survey. In the menu tab “Collection”, go down to “Landsat Archive” and select “Landsat 8 OLI.” Then click a location on the map to see if it’s taken a picture of a spot you’re interested in.
Once you’ve selected it, hit “Add Scene”, then click on the scene list at the bottom right of the screen to download the product. (We’d strongly advise consulting the tutorial on that website for more help. You need to register as a user to download the high-resolution images.)
There isn’t much to see there yet, but over the next few months there should be a wealth of pictures to choose from. More spots where Landsat 8 data will appear are listed on this USGS page.
You may better recall Landsat 8 as the Landsat Data Continuity Mission. Launched on Feb. 11, it was first under the operational control of NASA as the agency put the satellite through its paces — placing it into the proper orbit (it circles in a near-polar orbit) and taking some test images of the planet, for example.
Now that the satellite is ready, the USGS has operational control and will add that to more than 40 years of data collected under the Landsat program. The aim, we assure you, is not just for pretty pictures.
An Atlas-V rocket with the Landsat Data Continuity Mission (LDCM) spacecraft onboard is seen as it launches on Monday, Feb. 11, 2013 at Vandenberg Air Force Base, California. Credit: NASA
Long Earth observation programs show changes in the land over time. We can see cities grow, observe forests shrink or deserts expand in response to human activity or climate change, and also gauge the impact of natural disasters. In the past, Landsat pictures have been used to map the impact of the Mount St. Helen’s eruption of 1980, and to respond to oil gas fires set in Kuwait during the Gulf War of 1991.
These are heavyweight satellites. The truck-sized Landsat 8 weighs 4,566 lbs (2,071 kg) fully loaded with fuel, excluding the weight of the instruments. Its operational land imager can take pictures in nine spectral bands, which is important because certain types of vegetation or land features show up better in different light spectra. (One application is to monitor the health of certain kind of plants in farmer fields, for example.) It also has two thermal infrared sensor bands that will show the heat signature of Earthly features.
For Landsat, officials needed to launch this satellite because its predecessor (Landsat 7)’s operational lifetime is in overtime. Should the satellite have failed before Landsat 8 arrived, 41 years of continuous Earth observations under the same program would have ceased.
Landsat 8 will circle the globe 14 times daily, will repeat its ground track every 16 days, and is expected to do this for at least five years. Check out this USGS feature story for more on how it will contribute to Earth observation.
Timeline showing lifespans of the Landsat satellites. Credit: NASA
An artist's conception of an asteroid collision, in the belt between Mars and Jupiter. Credit: NASA/JPL-Caltech
In perhaps the neatest astronomical application of geneology yet, astronomers found 28 “hidden” families of asteroids that could eventually show them how some rocks get into orbits that skirt the Earth’s path in space.
From scanning millions of snapshots of asteroid heat signatures in the infrared, these groups popped out in an all-sky survey of asteroids undertaken by NASA’s orbiting Wide-Field Infrared Survey Explorer. This survey took place in the belt of asteroids between Mars and Jupiter, where most near-Earth objects (NEOs) come from.
NEOs, to back up for a second, are asteroids and comets that approach Earth’s orbit from within 28 million miles (45 million kilometers). Sometimes, a gravitational push can send a previously unthreatening rock closer to the planet’s direction. The dinosaurs’ extinction roughly 65 million years ago, for example, is widely attributed to a massive rock collision on Earth.
Artist concept of the asteroid belt between Mars and Jupiter. Credit: NASA
There are about 600,000 known asteroids between Mars and Jupiter, and the survey looked at about 120,000 of them. Astronomers then attempted to group some of them into “families”, which are best determined by the mineral composition of an asteroid and how much light it reflects.
While it’s hard to measure reflectivity in visible light — a big, dark asteroid reflects a similar amount of light as a small shiny one — infrared observations are harder to fool. Bigger objects give off more heat.
This allowed astronomers to reclassify some previously studied asteroids (which were previously grouped by their orbits), and come up with 28 new families.
“This will help us trace the NEOs back to their sources and understand how some of them have migrated to orbits hazardous to the Earth,” stated Lindley Johnson, NASA’s program executive for the Near-Earth Object Observation Program.
This diagram illustrates the differences between orbits of a typical near-Earth asteroid (blue) and a potentially hazardous asteroid, or PHA (orange). Image credit: NASA/JPL-Caltech
The astronomers next hope to study these different families to figure out their parent bodies. Astronomers believe that many asteroids we see today broke off from something much larger, most likely through a collision at some point in the past.
While Earthlings will be most interested in how NEOs came from these larger bodies and threaten the planet today, astronomers are also interested in learning how the asteroid belt formed and why the rocks did not coalesce into a planet.
The prevailing theory today says that was due to influences from giant Jupiter’s strong gravity, which to this day pulls many incoming comets and asteroids into different orbits if they swing too close. (Just look at what happened to Shoemaker-Levy 9 in 1994, for example.)
