Posted on by Nancy Atkinson

Mystery Moonlets Cause Constant Changes in Saturn’s F Ring

Scientists from the Cassini mission are finding Saturn’s rings to be very dynamic; constantly changing and evolving. This is especially true for one of Saturn’s outermost rings, the F ring. This ring can change rapidly, sometimes on a timescale of hours, and astronomers believe it’s probably the only location in the solar system where large scale collisions happen on a daily basis. New images from the Cassini spacecraft have revealed unprecedented detail of this ring, including evidence that several small, unseen moons collide with other ring particles and cause perturbations called jets, streamers and fans.

Saturn’s F ring is very thin, just a few hundred kilometers wide, and is held together by two shepherd moons, Prometheus and Pandora, which orbit inside and outside the ring. For some time, scientists have suspected the presence of tiny moonlets that orbit Saturn in association with the clumpy F ring. As the small satellites move close to the F ring core they leave a gravitational signature. In some cases they can draw out material in the form of a “streamer.” Another perturbation called “jets” are the result of collisions between small nearby moonlets and the core of the F ring.

Scientists speculate that there could be several small moons with a variety of sizes that create these structures.

The leader of this analysis, Carl Murray of Queen Mary, University of London said, “Previous research has noted the features in the F ring and concluded that either another moon of radius about 100km must be present and scattering the particles in the ring, or a much smaller moonlet was colliding with its constituent particles. We can now say that the moonlet is the most likely explanation and even confirm the identity of one culprit.”

A ~5km object discovered by Cassini in 2004 (called S/2004 S 6) is the best candidate to explain some of the largest jets seen in the images.

The Cassini images also show new features called “fans” which result from the gravitational effect of small (~1km) satellites orbiting close to the F ring core.

Understanding these processes helps scientists understand the early stages of planet formation.

Professor Keith Mason, CEO of the Science and Technology Facilities Council which funds UK involvement in Cassini-Huygens said “This incredibly successful mission has taught us a great deal about the solar system and the processes at work in it. Understanding how small objects move within the dust rings around Saturn gives an insight into the processes that drive planetary formation, where the proto-planet collects material in its orbit through a dust plane and carves out similar grooves and tracks.”

Original News Source: Physorg

Posted on by Nancy Atkinson

Images From The STS-124 Mission

The crew of the STS-124 mission has been busy installing equipment on the International Space Station, fixing a toilet, and trying out the latest robotic arm that’s part of the shiny new Kibo module. The image above shows some of the new additions to the station, which just keeps growing in size with every mission. The mass of modules shown are: the Japanese Pressurized Module (left), the Japanese Logistics Module (top center), the Harmony node (center), the Destiny laboratory (right) of the ISS, and the forward section of Space Shuttle Discovery that is docked to the station.


Astronauts Mike Fossum (left) and Ron Garan, during the second EVA for the mission. The two astronauts installed television cameras on the Kibo Japanese Pressurized Module (JPM) that will aid in the Kibo robotic arm operations, they also removed thermal covers from the Kibo robotic arm, prepared an upper JPM docking port for flight day seven’s attachment of the Kibo logistics module, readied a spare nitrogen tank assembly for its installation during the third spacewalk, retrieved a failed television camera from the Port 1 truss, and inspected the port Solar Alpha Rotary Joint (SARJ). In looking at the SARJ, Fossum found grease streaks and a small amount of a dust-like material. In the third spacewalk, coming up on Sunday, the astronauts will take samples of the materials for further testing. They’ll also continue outfitting and activating the Kibo module.


Inside Kibo: STS 124 Commander Mark Kelly (right) and pilot Ken Ham add a rack inside the recently installed Kibo Pressurized Module.


This is a great image of Space Shuttle Discovery with Earth’s limb in the background. Also visible are parts of the shuttle: the Remote Manipulator System (RMS), the docking mechanism, vertical stabilizer and orbital maneuvering system (OMS) pods. This was taken on flight day two, before the shuttle docked with the space station.

Image Source: NASA Human Spaceflight Gallery

Posted on by Nancy Atkinson

A Look at Mars Soil Before It Bakes in TEGA

NASA’s Phoenix Lander scooped up this Martian soil on sol 11 of the mission, (June 5, 2008 here on Earth.) This will be the first soil sample to be sent to the oven of the Thermal and Evolved-Gas Analyzer, or TEGA, laboratory on the lander deck. The soil will be “baked” sometime today, and the gases that are emitted will be analyzed to determine the chemical make-up of the Martian arctic soil. The material includes a light-toned clod possibly from crusted surface of the ground, similar in appearance to clods observed near a foot of the lander. This is an approximate true-color view of the contents of the scoop on the Robotic Arm, created by combining separate images taken by the Robotic Arm Camera, using illumination by red, green and blue light-emitting diodes on the camera.
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This image shows the Robotic Arm scoop containing a soil sample poised over the partially open door of TEGA’s oven. The material inside the scoop has been slightly brightened in this image.

This image shows the trenches dug by Phoenix’s Robotic Arm. The trench on the left was nicknamed “Dodo” and was dug first as a test. The trench on the right is “Baby Bear,” and the sample dug from this trench will be delivered to TEGA. The Baby Bear trench is 9 centimeters (3.1 inches) wide and 4 centimeters (1.6 inches) deep.

News Source: Phoenix News

Posted on by Nancy Atkinson

Planetary Potential from Protoplanetary Disks

How planets form is one of the major questions in astronomy. Only recently have we been able to study the disks of dust and gas surrounding other stars in an effort to understand the process of how planets coalesce and form from these “protoplanetary” materials. But this is a difficult task at best, given the observational distances. “This is a vast topic with many challenges,” said David Wilner from the Harvard-Smithsonian Center for Astronomy at his talk at the American Astronomical Society meeting this week. “But over the course of the past few decades with observations of nearby star systems, we’ve come to a basic outline of the process of solar system formation.”

There are a couple of hurdles to overcome in studying protoplanetary disks. First, the bulk of the disk mass is cold and dark, as the molecular hydrogen doesn’t radiate. These areas are probed only through a couple of minor constituents: thermal emission from dust and scattered light from the star.

Second, the amount of “stuff” astronomers are looking at is actually fairly small. Usually, the amount of protoplanetary material is about 1/100th the mass of the star, and about 1/4000th of a degree in the sky.

Through observations of many systems with several telescopes, we can see these disk systems in a variety of wavelengths in an effort to see both the star and the disk components. Wilner said there are two properties that are particularly important to know: Disk masses in general, as the luminosity is directly proportional to the mass, and second is the disk lifetime. From current knowledge, the dust disk disperses by 50% in 3 million years, and 90% by 5 million years.

As an example, Milner discussed the Rho Ophiuchi nebula, (image above), located near the constellations Scorpius and Ophiuchus, about 407 light years away from Earth.

“The Rho Oph cloud is spectacular, with beautiful dark regions that are columns of gas and dust extinguishing the background star field. This is the material that is forming stars and planets.”

Wilner said the steps in solar system formation are as follows: first the formation of a primordial proto-star disk, then the protoplanetary disk, and then debris disk within a planetary system.

But the main problems in our understanding lies in that astronomers haven’t yet actually seen all the steps in this process, and can’t prove directly that these early disks go on to form the planets. There are several clues, such as that gaps form in the dust around clumps of materials, similar to the gaps in the rings of Saturn around moons.


For the past 15 years protoplanetary disks have been studied with various interferometers at the Keck Observatory on Mauna Kea at various wavelengths from .87 microns to 7 mm. And the past five years the Spitzer Space Telescope has lent its infrared capabilities to further our knowledge to our current understanding. But soon, a new telescope in the high Chilean desert might provide the resolution needed to offer a glimpse at not only the gaps in the disks, but a new window on how materials around emerging planets may form moons. The Atacama Large Millimeter/submillimeter Array (ALMA), will operate at wavelengths of 0.3 to 9.6 millimeters.

Wilner obviously looks forward to putting observational capabilities of this array to work. Scheduled to be completed in 2012, ALMA will help fill in the “gaps” of our knowledge about planetary formation.

Source: AAS Meeting presentation, with clarification from Chris Lintott

Posted on by Nancy Atkinson

Closest Images Ever of Mars Dust Grains

“To see a world in a grain of sand…” – English Poet William Blake

The Phoenix science team tested out the lander’s Optical Microscope by imaging grains of sand and dust particles, some as small as one-tenth the diameter of a human hair. These are the highest resolution image ever of small soil particles from another planet. “We have images showing the diversity of mineralogy on Mars at a scale that is unprecedented in planetary exploration,” said Michael Hecht of NASA’s Jet Propulsion Laboratory.

The microscope observed particles that had fallen onto an exposed surface of the lander. “It’s a first quick look,” Hecht said. “This experiment was partly an insurance policy for something to observe with the microscope before getting a soil sample delivered by the arm, and partly a characterization of the Optical Microscope. All the tools are working well.”

However, some of the particles may be “alien” – that is, they might have come from inside the spacecraft when Phoenix dropped to Mars surface at landing. But at first glance, many of these grains match expectations for Martian particles. “We will be using future observations of soil samples delivered by the Robotic Arm to confirm whether the types of particles in this dustfall sample are also seen in samples we can be certain are Martian in origin,” Hecht said.

The particles show a range of shapes and colors.

“You can see the amount of variety there is in what appears otherwise to be just reddish brown soil,” said Tom Pike, Phoenix science team member from Imperial College London. He noted that one translucent particle resembles a grain of salt, but that it is too early to say for sure.

Meanwhile, Phoenix received commands Thursday to collect its first soil sample to be delivered to its science lab instrument on the lander deck. Those commands were originally sent on Wednesday, but the lander didn’t receive them as the relay for the commands, the Mars Odyssey, had gone into safe mode. The orbiter may have been hit by a cosmic ray, and engineers from JPL say nominal operations of the spacecraft should return by the end of the week. This type of event has occurred a couple of times in the Odyssey mission, and engineers don’t appear overly concerned about the situation.

So, the commands were successfully re-sent via the Mars Reconnaissance Orbiter. Look for the first science results from Phoenix within the next day or so.

Original News Source: Phoenix news release

Posted on by Nancy Atkinson

Recipe for Giant Lunar Telescopes

Moon dust. Credit: NASA

Someone has finally figured out something useful for all the dust on the moon’s surface: mix it with some epoxy and a pinch of carbon to create giant telescope mirrors. “We could make huge telescopes on the moon relatively easily, and avoid the large expense of transporting a large mirror from Earth,” said Peter Chen at a press conference today at the American Astronomical Society meeting. “Since most of the materials are already there in the form of dust, you don’t have to bring very much stuff with you, and that saves a ton of money.”

Chen and is team had been working with carbon-fiber composite materials to produce high-quality telescope mirrors. But then they decided to try an experiment. They substituted tiny carbon nanotubes for the carbon-fiber composites, and mixed in epoxies with crushed rock that has the same
composition and grain size as lunar dust, they discovered to their surprise that they had created a very strong material with the consistency of concrete. This material can be used instead of glass to
make mirrors.

Then they spun their concoction at room temperature to create a 12-inch-wide telescope mirror form, which they then coated with aluminum to create a highly reflective surface.

“Our method could be scaled-up on the moon, using the ubiquitous lunar dust, to create giant telescope mirrors up to 50 meters in diameter,” said collaborator Douglas Rabin. Currently the world’s largest optical telescope is the 10.4-meter Gran Telescopio Canarias in the Canary Islands, so this would be quite a step up.

Like liquid mirror telescopes, these large telescopes on the moon have definite advantages. With a stable platform, and no atmosphere to absorb or blur starlight, the monster scope could record the spectra of extra solar terrestrial planets and detect atmospheric biomarkers such as ozone and methane. Two or more such telescopes spanning the surface of the Moon can work together to take direct images of Earth-like planets around nearby stars and look for brightness variations that come from oceans and continents.

“Constructing giant telescopes provides a strong rationale for doing astronomy from the moon,” says Chen. “We could also use this on-site composite material to build habitats for the astronauts, and mirrors to collect sunlight for solar-power farms.”

Posted on by Nancy Atkinson

Beer and Burgers With a Side of Science

Astronomers and cosmologists endeavor to solve some of the great mysteries of the universe. One mystery scientists here at the AAS meeting in St. Louis are seriously trying to address is how to make science more interesting and accessible to the general public. While this issue has little cosmic implications, having a science literate population in our ever-growing technology-based civilization is not just an advantage, but becoming an absolute necessity. In attempt to tackle this concern, a group of astronomers are encouraging others to follow the lead of a concept that seems to be working: Invite the public out for a beer.

Science Cafes, or “Cafe Scientifique,” are billed as places where, for the price of glass of beer or a cup of coffee, anyone can come to explore the latest ideas in science and technology. The people leading these groups are committed to promoting public engagement with science, as well as helping scientists improve their communication skills.

“Beer and science are two things a lot of us love,” said Randy Landsberg, Director of the Kavli Institute of Cosmological Science in Chicago. “We started a Science Cafe just because we thought it would be fun. We wanted to get people engaged to understand the research we’re doing, and researchers to be better at conveying the science. The drinks help.”

Meetings take place in cafes, bars, restaurants but always outside a traditional scientific or academic context.

“We want to provide a fun place to hear about science,” said Landsberg.

The group in Chicago meets at a local establishment that supports the effort by offering free appetizers. Their format is a brief introduction to the topic, (15-20 minutes) with limited visual aids (detailed PowerPoint’s are frowned upon). Then they take a break, get some beer and follow with a question and answer session for about 90 minutes. People can leave anytime they want, and the scientists are monitored. “If the speaker starts talking about derivatives, we try to rein him in,” Landsberg said.

They try to vary the topics. “It’s not all cosmology all the time. We’ve done global warming, flying snakes, biology of gender, and one entitled ‘The Dark Side: from dark energy and dark matter to Washington and science policy.'”

Ben Wiehe, the Outreach Coordinator at WGBH Educational Foundation in Boston, has been instrumental promoting Science Cafes with PBS’s NOVAscienceNOW. “Science Cafes are taking place in a lot of bars, coffeehouses, bookstores, churches, and even hardware stores. You want to go where your audience is naturally gathering anyway,” he said. “If you want teens to show up, you may have to consider whether you want to meet at a bar. But you can choose a library or some other place. Where and when you have your meetings will help determine the demographics.”

Wiehe said “field research” (i.e., checking out the local bars) is necessary to help choose a location. But the main goal of Science Cafes is to reach out to new audiences of people who don’t normally talk about science.

Surveys of Science Cafe attendees are overwhelmingly positive about the experience, with comments like, “I love coming to these. Please do this more!” and “Beer + Intellectual Stimulation = Fun.”

To keep the size intimate, the Chicago group has resorted to requiring tickets (free) to attend. They have 385 people registered on their email list, but want to limit attendance at any one event to 50-70 people.

R. J. Wyatt from the Southern California Academy of Sciences says for their Science Cafes, he likes to get people to consider alternate possibilities. “Sometimes we want to cover topics that are edgy and confrontational,” he said. “If we can assuage anyone’s fears, and get them fascinated about science you can shift people’s thinking in how they think about themselves and their world.”

Venerable cosmologist Michael Turner offered a speaker’s perspective on how to best choose a speaker.

“It’s a theorem that someone who gives a good public lecture is not necessarily a good Cafe Scientifique choice,” he said. “You’re not doing a lecture. It has to be spontaneous and extraordinarily flexible. Shorter is better, and if you’re talking about astronomy you can just show astronomical pictures, and do a four star presentation.”

Turner added, “Loose ends are really important. If you’ve explained everything and its absolutely perfect, then there will be no questions and no follow up. There has to be some ‘hanging chads’ to get people engaged.”

For more information about finding or starting a Science Cafe, see the links above, or NOVAscienceNOW’s Science Cafe page.

Posted on by Nancy Atkinson

Press Conference via Astronomy Cast Live

2nd UPDATE:

We wanted to bring you a symposium on the International Year of Astronomy via UStream. Unfortunately, there is no internet connection available in the room the symposium is being held. We apologize, and thank you for your interest!

UPDATE: IYA SYMPOSIUM
We’ll also be UStreaming a Symposium on Preparing for the International Year of Astronomy, which will deal with the practical aspects of making the International Year of Astronomy a success. The symposium starts at 2:00 pm Central time. If you want to participate in the chat room, go here. (UPDATE – not available)

Some fun topics today for a press conference from the American Astronomical Society: lunar telescopes and SETI. We’ll try to write about those topics soon, but you can watch the press conference live at Astronomy Cast’s UStream channel.

It all starts at 9:30 a.m. Central time (15:30 UT). Video is embedded below. If you want to participate in the chat room, go here.

Online Video provided by Ustream

Posted on by Nancy Atkinson

So, What Do Astronomers Do With A 55 Meter-Long Image?

The new 55-meter image that was unveiled today is impressive, but does it hold any scientific value? A resounding yes to that question came from astronomers who helped work on this project, and given the standing room only for the oral presentation of the scientific research going into this image, plenty of other astronomers are interested in the discoveries from Spitzer’s five-year effort of gathering infrared data of our home galaxy. “This is a legacy science project,” said Barbara Whitney of the Space Science Institute, “that shows star formation as never seen before on both the large and small scale. Most of these star forming regions are being seen for the first time.”

“This is the highest-resolution, largest, most sensitive infrared picture ever taken of our Milky Way,” said Sean Carey of NASA’s Spitzer Science Center. “Where previous surveys saw a single source of light, we now see a cluster of stars. With this data, we can learn how massive stars form, map galactic spiral arms and make a better estimate of our galaxy’s star-formation rate,” Carey explained.

From our vantage point on Earth, we see the Milky Way as a blurry, narrow band of light that stretches across the sky. In the visible, we only see about 5% of what’s actually out there. But with Spitzer’s dust-piercing infrared eyes, astronomers have peered 60,000 light-years away into this fuzzy band, called the galactic plane, and saw all the way to the other side of the galaxy.

The result is a cosmic tapestry depicting an epic coming-of-age tale for stars.

While evolved stars are seen as blue, the star forming regions are seen as green. The regions where young stars reside are revealed as “bubbles,” or curved ridges in the green clouds. These bubbles are carved by the winds from the outflow of dust from the young stellar objects. The starlets appear as yellow and red dots, and wisps of red are dust particles.

“With these Spitzer data, we’ve been able to catalogue more than 100 million stars,” said Edward Churchwell of the University of Wisconsin, at Madison.

“This picture shows us that our Milky Way galaxy is a crowded and dynamic place. We have a lot to learn. I’ve definitely found a lot of things in this map that I didn’t expect to see,” said Carey.