Posted on by Jason Major

Face-to-Face With Some Shattered Lunar Boulders

The remains of crumbled boulders in Schiller crater (NASA/GSFC/Arizona State University)

[/caption]

Breaking up may be hard to do, but these two lunar boulders seem to have succeeded extremely well! Imaged by the Lunar Reconnaissance Orbiter Camera (LROC) in October of 2009, this crumbled couple was recently identified by Moon Zoo team member Dr. Anthony Cook and brought to the attention of the project’s forum moderator.

The tracks left in the regolith — lunar soil — behind the boulders tell of their past rolling journeys down the slope of the elongated Schiller crater, in which they reside. Rolling boulders have been spotted before on the Moon, but what made these two split apart? And…why does that one on the lower right look so much like half a face?

Several things can cause lunar boulders to come loose and take the nearest downhill course. Meteorite impacts can shake the ground locally, giving the rocks enough of a nudge to set them on a roll. And moonquakes — the lunar version of earthquakes, as the name implies (although not due to tectonic plate shifts but rather to more mysterious internal lunar forces) — can also dislodge large boulders.

The low gravity on the Moon can make large rocks take a bounding path, evidenced by the dotted-line appearance of some of the trails.

Could all that bounding and bouncing have made the two boulders above shatter apart? Or was something else the cause of their crumbling?

Dr. Cook suggested that the boulders could have fractured before they began rolling, and then the added stress of their trip down the crater’s slope (uphill is to the right) made them break apart at the end of their trip… possibly due to further weathering and the extreme temperature variations of lunar days and nights.

Although a sound idea, Dr. Cook added, “I’m a bit puzzled though why the one on the top left has rock debris so far away from the centre. The boulder that looks like a skull rock on the bottom right has debris a lot closer to it, that could simply be explained by bits falling off as one would expect from the explanation above.”

This is one rock that's not happy about its breakup!

Another idea is that the boulders were struck by meteorites, but it seems extremely improbable that two would have been hit right next to each other. Still, not impossible, especially given the geologic time spans in play.

And as far as the “skull rock” boulder is concerned… that’s a little something called pareidolia, the tendency for our brains to interpret random shapes as something particularly significant. In this case it’s a human face, one of the most popular forms of pareidolia (perhaps best known by the famous “Face on Mars”, which, as we all now know, has been since shown to be just another Martian mesa.)

It does look like a face though, and not a particularly happy one!

Find out more about rolling boulders and Schiller crater on the LROC site hosted by Arizona State University here, and take a look at the full image scan of the region yourself… you may find more of these broken-up rolling rocks!

LROC WAC global 100-meter mosaic image of the 180-km long, 70-km wide Schiller crater. Overlaid onto a laser altimetry elevation model. (NASA/GSFC/Arizona State University)
Posted on by Nancy Atkinson

Dream Job: Go to Hawaii and Eat Astronaut Food

Expedition 20 crew on the ISS share a meal in the galley in the Unity Node. Credit: NASA

[/caption]

If you’ve always dreamed of being an astronaut here’s the next best thing, and the location couldn’t be more idyllic. Scientists from Cornell and the University of Hawaii are conducting a 120-day Mars exploration analog study in a simulated Mars habitat on the lava fields of the Big Island of Hawai’i. The study will focus on the diets of six volunteers, who will be required to live and work like astronauts, including suiting up in space gear whenever they head outside of their habitat. But the emphasis will be for participants compare two types of foods: crew-cooked vs. pre-prepared, in order to avoid what has been termed “menu fatigue” over a long-duration mission. Applications are currently being taken for the job.

Jean Hunter, associate professor of biological and environmental engineering at Cornell and several colleagues have received a $947,000 NASA grant for the study, the Hawaii Space Exploration Analogue & Simulation, or HI-SEAS. Hunter said current astronauts on the International Space Station not only tire of eating foods they normally enjoy but also tend to eat less, which can put them at risk for nutritional deficiency, loss of bone and muscle mass, and reduced physical capabilities. Plus, all foods decline in nutritional quality over time, and only a few of the many available astronaut foods have the three-to-five-year shelf life required for a Mars mission.

Bags of Space Station food and utensils on tray. Credit: NASA

So, the participants will also help determine how being on a landed mission on Mars would make different ways of cooking — and perhaps gardening — possible, which would give the astronauts more food variety and relieve menu fatigue.

So, the study will help determine the palatability of ‘instant’ foods and food prepared by the crew from shelf stable ingredients, and determine whether food acceptability changes over time. It will also help estimate use of crew time, power, and water for meal preparation and cleanup, for both instant and crew-cooked foods and determine if crewmembers’ taste and smelling acuity change over time.

Participants chosen will need to attend a workshop and two-week training mission. Round trip travel, food and lodging expenses are provided. The crew will receive $5,000 as compensation. The researchers said the qualifications for people applying for the study are similar to those required by NASA for their astronaut applicants.

Hurry, as the deadline is 11:59pm Hawaii time on February 29th, 2012. You can find more information and the application form at the HI-SEAS website. You can also check out their Facebook page.

Good luck (Pomaika`i)!

Posted on by Ken Kremer

A Penny for your Curiosity on Mars

NASA's Mars rover Curiosity carries a Lincoln Penny on the calibration target to be used by a camera at the end of the robotic arm. The calibration target for the Mars Hand Lens Imager (MAHLI) camera is attached to a shoulder joint of the arm. Inset shows the location of the calibration target. Credit: NASA/JPL-Caltech

[/caption]

NASA’s huge Curiosity Mars Science Lab (MSL) rover is carrying a vintage Lincoln penny along for the long interplanetary journey to Mars – and it’s not to open the first Martian savings account.

Scientists will use the century old Lincoln penny – minted back in 1909 – as a modern age calibration target for one of Curiosity’s five powerful science cameras attached to the end of the hefty, 7 foot (2.1 meter) long robotic arm.

The car sized rover is on course to touchdown at the foothills of a towering and layered mountain inside Gale Crater in just 161 days on Aug. 6, 2012.

So far Curiosity has traveled 244 million kilometers since blasting off on Nov. 26, 2011 from Florida and has another 322 million kilometers to go to the Red Planet.

The copper penny is bundled to a shoulder joint on the rovers arm along with the other elements of the calibration target, including color chips, a metric standardized bar graphic, and a stair-step pattern for depth calibration.

The whole target is about the size of a smart phone and looks a lot like an eye vision chart in an ophthalmologist’s office. And it serves a similar purpose, which will be to check the performance of Curiosity eyes – specifically the Mars Hand Lens Imager (MAHLI) camera located at the terminus of the robotic arm.

Curiosity’s Calibration Target
Two instruments at the end of the robotic arm on NASA's Mars rover Curiosity will use calibration targets attached to a shoulder joint of the arm. Credit: NASA/JPL-Caltech

MAHLI will conduct close-up inspections of Martian rocks and soil. It can show tiny details, finer than a human hair.

The term “hand lens” in MAHLI’s name refers to the standard practice by field geologists’ of carrying a hand lens during expeditions for close up, magnified inspection of rocks they find along the way. So it’s also critical to pack various means of calibration so that researchers can interpret their results and put them into proper perspective.

MAHLI can also focus on targets over a wide range of distances near and far, from about a finger’s-width away out to the Red Planets horizon, which in this case means the mountains and rim of the breathtaking Gale Crater landing site.

“When a geologist takes pictures of rock outcrops she is studying, she wants an object of known scale in the photographs,” said MAHLI Principal Investigator Ken Edgett, of Malin Space Science Systems, San Diego, which supplied the camera to NASA.

Curiosity Mars Science Laboratory Rover - inside the Cleanroom at KSC
Curiosity with robotic arm extended. Calibration target is located at a shoulder joint on the arm. Photo taken just before encapsulation for 8 month long interplanetary Martian Journey and touchdown inside Gale Crater. Credit: Ken Kremer

The target features a collection of marked black bars in a wide range of labeled sizes to correlate calibration images to each image taken by Curiosity.

“If it is a whole cliff face, she’ll ask a person to stand in the shot. If it is a view from a meter or so away, she might use a rock hammer. If it is a close-up, as the MAHLI can take, she might pull something small out of her pocket. Like a penny.”

Edgett donated the special Lincoln penny with funds from his own pocket. The 1909 “VDB” cent stems from the very first year that Lincoln pennies were minted and also marks the centennial of President Abraham Lincoln’s birth. The VDB initials of the coin’s designer – Victor David Brenner — are on the reverse side. In mint condition the 1909 Lincoln VDB copper penny has a value of about $20.

The Lincoln penny in this photograph is part of a camera calibration target attached to NASA's Mars rover Curiosity. Credit: NASA/JPL-Caltech

“The penny is on the MAHLI calibration target as a tip of the hat to geologists’ informal practice of placing a coin or other object of known scale in their photographs. A more formal practice is to use an object with scale marked in millimeters, centimeters or meters,” Edgett said. “Of course, this penny can’t be moved around and placed in MAHLI images; it stays affixed to the rover.”

“Everyone in the United States can recognize the penny and immediately know how big it is, and can compare that with the rover hardware and Mars materials in the same image,” Edgett said.

“The public can watch for changes in the penny over the long term on Mars. Will it change color? Will it corrode? Will it get pitted by windblown sand?”

MAHLI’s calibration target also features a display of six patches of pigmented silicone to assist in interpreting color and brightness in the images. Five of them are leftovers from Spirit and Opportunity. The sixth has a fluorescent pigment that glows red when exposed to ultraviolet light, allows checking of an ultraviolet light source on MAHLI. The fluorescent material was donated to the MAHLI team by Spectra Systems, Inc., Providence, R.I.

Three-dimensional calibration of the MSL images will be done using the penny and a stair-stepped area at the bottom of the target.

“The importance of calibration is to allow data acquired on Mars to be compared reliably to data acquired on Earth,” said Mars Science Laboratory Project Scientist John Grotzinger, of the California Institute of Technology, Pasadena.

Curiosity is a 1 ton (900 kg) behemoth. She measures 3 meters (10 ft) in length and is nearly twice the size and five times as heavy as Spirit and Opportunity, NASA’s prior set of twin Martian robots. The science payload is 15 times heavier than the twin robots.

Curiosity is packed to the gills with 10 state of the art science instruments that are seeking the signs of life in the form of organic molecules – the carbon based building blocks of life as we know it.

NASA could only afford to build one rover this time.

Curiosity MSL location on 27 Feb 2012. Credit: NASA

Curiosity will be NASA’s last Mars rover since the 4th generation ExoMars rover due to liftoff in 2018 was just cancelled by the Obama Administration as part of a deep slash to NASA’s Planetary Science budget.

Posted on by Jason Major

A Weekend Sky Show: Moon, Venus and Jupiter

Moon and Venus on Feb. 25, 2012. © Jason Major

[/caption]

As promised by Nancy in a previous article on Universe Today, Venus was visible during the daylight hours this Saturday, very close to the crescent Moon. If you had clear weather you may have been able to catch a glimpse of the scene above, photographed from my location in north Texas at 6:35 p.m. local time.

Dim but visible, Venus is the “star” at lower left.

Later that same evening the show really went into full force as the Moon was illuminated by Earthshine in the western sky, with Venus ablaze and Jupiter making a bright appearance as well!

Nancy wrote on Feb. 24: If you don’t see Venus during the day, try to see Venus immediately at sunset; and right now, the Moon, Venus and Jupiter are lining up for triple conjunction at dusk, and with clear skies, it will be a great view that is almost impossible to miss!

A great view indeed! I grabbed a quick shot with my iPhone camera of the conjunction, and took the opportunity to point out the view to some neighbors as well.

Conjunction of the Moon, Venus and Jupiter on Feb. 25, 2012. (Jason Major)

One of the more dramatic planetary conjunctions I’ve seen, especially with the light from a fading sunset illuminating the stage.

Sometimes the best astronomy is the type you can see with your own eyes… and be able to easily share with others!

ADDED 2/26: Sunday evening brought some great views as well! Here’s a photo from around 6:45 pm on Feb. 26th:

Jupiter, the Moon and Venus on Feb. 26, 2012. © Jason Major

 

Posted on by Tammy Plotner

Weekly SkyWatcher’s Forecast – February 27-March 4, 2012

AE Aurigae - Credit: T.A.Rector and B.A.Wolpa/NOAO/AURA/NSF

[/caption]

Greetings, fellow SkyWatchers! It’s going to be a great week for lunar studies and an even better time to study some interesting single stars. Need more? Then keep an eye on the skies as the Delta Leonid meteor shower heats up towards its later week peak. Get out those binoculars and telescopes and I’ll see you in the backyard…

Monday, February 27 – With tonight’s Moon in a much higher position to observe, let’s begin with an investigation of Mare Fecunditatis – the Sea of Fertility. Stretching 1463 kilometers in diameter, the combined area of this mare is equal in size to the Great Sandy Desert in Australia – and almost as vacant in interior features. It is home to glasses, pyroxenes, feldspars, oxides, olivines, troilite and metals in its lunar soil, which is called regolith. Studies show the basaltic flow inside of the Fecunditatis basin perhaps occurred all at once, making its chemical composition different from other maria. The lower titanium content means it is between 3.1 and 3.6 billion years old!

The western edge of Fecunditatis is home to features we share terrestrially – grabens. These down-dropped areas of landscape between parallel fault lines occur where the crust is stretched to the breaking point. On Earth, these happen along tectonic plates, but on the Moon they are found around basins. The forces created by lava flow increase the weight inside the basin, causing a tension along the border which eventually fault and cause these areas. Look closely along the western shore of Fecunditatis where you will see many such features.

Today is the birthday of Bernard Lyot. Born in 1897, Lyot went on to become the inventor of the coronagraph in 1930. By all accounts, Lyot was a wonderful and generous man who sadly died of a heart attack when returning from a trip to view a total eclipse. Although we cannot hand you a corona, we can show you a star that wears its own gaseous envelope.

Let’s go to our maps west of M36 and M38 to identify AE Aurigae. As an unusual variable, AE is normally around 6th magnitude and resides approximately 1600 light years distant. The beauty in this region is not particularly the star itself but the faint nebula in which it resides known as IC 405, an area of mostly dust and very little gas. What makes this view so entertaining is that we are looking at a “runaway” star. It is believed that AE once originated from the M42 region in Orion. Cruising along at a very respectable speed of 80 miles per second, AE flew the “stellar nest” some 2.7 million years ago! Although IC 405 is not directly related to AE, there is evidence within the nebula that areas have been cleared of their dust by the rapid northward motion of the star. AE’s hot, blue illumination and high energy photons fuel what little gas is contained within the region. Its light also reflects off the surrounding dust. Although we cannot “see” with our eyes like a photograph, together the pair forms an outstanding view for the small backyard telescope and it is known as “The Flaming Star.”

Tuesday, February 28 – Since the stars of our study constellation of Monoceros are quite dim when the Moon begins to interfere, why not spend a few days really taking a look at the Moon’s surface and familiarizing yourself with its many features? Tonight would be a great time for us to explore “The Sea of Nectar.” At around 1000 meters deep, Mare Nectaris covers an area of the Moon equal to that of the Great Sandhills in Saskatchewan, Canada. Like all maria, it is part of a gigantic basin that is filled with lava, and evidence of grabens exists along its western basin edge. While Nectaris’ basaltic flows appear darker than those in most maria, it is one of the older formations on the Moon and as the terminator progress, you’ll be able to see where ejecta belonging to Tycho crosses its surface. For now? Let’s have a closer look at the mare itself and its surrounding craters… Enjoy these many features which are also lunar challenges – and we’ll be back to study each later in the year!

Now, let’s have a look about a fistwidth north-northwest of Sirius – for Beta Monocerotis. Discovered by Sir William Herschel in 1781, Beta is perhaps one of the most outstanding triple systems in the sky, with each of its three bright, white components near equal magnitude. Residing about 100-200 light-years away, these identical spectral type stars are separated by no more than 400 AU and don’t appear to have changed positions since measured by Struve in 1831. Although you won’t be able to split this system with binoculars, even a small telescope will pick apart their brilliancy and make Beta a star to remember!

Wednesday, February 29 – Tonight let your imagination sweep you away as we go mountain climbing – on the Moon! Tonight all of Mare Serenitatis will be revealed and along its northwestern shore lie some of the most beautiful mountain ranges you’ll ever view – The Caucasus to the north and the Apennines to the south. Like its earthly counterpart, the Caucasus Mountain range stretches almost 550 kilometers and some of its peaks reach upwards to 6 kilometers – a summit as high as Mount Elbrus!

Slightly smaller than its terrestrial namesake, the lunar Apennine mountain range extends some 600 kilometers with peaks rising as high as 5 kilometers. Be sure to look for Mons Hadley, one of the tallest peaks that you will see at the northern end of this chain. It rises above the surface to a height of 4.6 kilometers, making that single mountain about the size of asteroid Toutatis.

Thursday, March 1 – In 1966 Venera 3 became the first craft to touch another world as it impacted Venus. Although its communications failed before it could transmit data, it was a milestone achievement.

George Abell was born on this day in 1927. Abell was the man responsible for cataloging 2712 clusters of galaxies from the Palomar sky survey, which was completed in 1958. Using these plates, Abell put forth the idea that the grouping of such clusters distinguished the arrangement of matter in the universe. He developed the “luminosity function,” which shows relationship between brightness and number of members in each cluster, allowing you to infer their distances. Abell also discovered a number of planetary nebulae and developed the theory (along with Peter Goldreich) of their evolution from red giants. Abell was a fascinating lecturer and a developer of many television series dedicated to explaining science and astronomy in a fun and easy to understand format. He was also a president and member of the Board of Directors for the Astronomical Society of the Pacific, as well as serving in the American Astronomical Society, the Cosmology Commission of the International Astronomical Union, and he accepted editorship of the Astronomical Journal just before he died.

Tonight your lunar assignments are relatively easy. We will begin by identifying “The Sea of Vapors.” Look for Mare Vaporum on the southwest shore of Mare Serenitatis. Formed from newer lava flow inside an old crater, this lunar sea is edged to its north by the mighty Apennine Mountains. On its northeastern edge, look for the now washed-out Haemus Mountains. Can you see where lava flow has reached them? This lava has come from different time periods and the slightly different colorations are easy to spot even with binoculars.

Further south and edged by the terminator is Sinus Medii – “The Bay in the Middle.” With an area about the size of both Massachusetts and Connecticut, this lunar feature is the mid-point of the visible lunar surface. In 1930, experiments were underway to test this region for surface temperature – a project begun by Lord Rosse in 1868. Surprisingly enough, results of the two studies were very close, and during full daylight temperatures in Sinus Medii can reach the boiling point as evidenced by Surveyors 4 and 6 – which landed near its center.

Now take a hop north of Mare Vaporum for a look at “The Rotten Swamp” – Palus Putredinus. More pleasingly known as the “Marsh of Decay,” this nearly level surface of lava flow is also home to a mission – the hard-landing of Lunik 2. On September 13, 1959 astronomers in Europe reported seeing the black dot of the crashing probe. The event lasted for nearly 300 seconds and spread over an area of 40 kilometers

Friday, March 2 – Tonight it’s time to relax and enjoy the Delta Leonid meteor shower. Burning through our atmosphere at speeds of up to 24 kilometers per second, these slow travelers will seem to radiate from a point around the middle of Leo’s “back.” The fall rate is rather slow at around 5 per hour, but they are still worth keeping a watch for!

Tonight let’s return again to the lunar surface to study how the terminator has moved and take a close look at the way features change as the Sun brightens the moonscape. Can you still see Langrenus? How about Theophilus, Cyrillus and Catharina? Does Posidonius still look the same? Each night features further east become brighter and harder to distinguish – yet they also change in subtle and unexpected ways. We’ll look at that in the days ahead, but tonight let’s walk the terminator as one of the most beautiful features has now come into view – “The Bay of Rainbows.” Sinus Iridum’s C-shape is easily recognizable in even small binoculars – yet there are a wonderland of small details in and around the area for the small telescope that we’ll study as the year goes by.

Saturday, March 3 – Tonight’s bright skies are brought to you by the Moon! Have you noticed how difficult it is to see any stars belonging to Monoceros with these conditions? Don’t worry. We’ll be back. For now, let’s continue onwards with our lunar studies as we locate the emerging “Sea Of Islands.” Mare Insularum will be partially revealed tonight as one of the most prominent of lunar craters – Copernicus – now comes into view. While only a small section of this reasonably young mare is now visible southeast of Copernicus, the lighting will be just right to spot its many different colored lava flows. To the northeast is a lunar club challenge: Sinus Aestuum. Latin for the Bay of Billows, this mare-like region has an approximate diameter of 290 kilometers, and its total area is about the size of the state of New Hampshire. Containing almost no features, this area is low albedo – providing very little surface reflectivity.

Tonight let’s try a lovely triple star system – Beta Monocerotis. Located about a fist width northwest of Sirius, Beta is a distinctive white star with blue companions. Separated by about 7 arc seconds, almost any magnification will distinguish Beta’s 4.7 magnitude primary from its 5.2 magnitude secondary to the southeast. Now, add a little power and you’ll see the fainter secondary has its own 6.2 magnitude companion less than 3 arc seconds away to the east.

Before you call it a night, be sure to have a quick look at Mars. Right now the red planet is at opposition and can be seen from sunset until sunrise in the constellation of Leo. You may have also noticed that it is dimming slightly, too. It has now reached an estimated -1.23 magnitude. Be sure to look for wonderful features like Sytris Major and the polar caps!

Sunday, March 4 – In 1835, Giovanni Schiaparelli opened his eyes for the very first time and opened ours with his accomplishments! As the director of the Milan Observatory, Schiaparelli (and not Percival Lowell) was the fellow who popularized the term “Martian canals” somewhere around the year 1877. Far more importantly, Schiaparelli was the man who made the connection between the orbits of meteoroid streams and the orbits of comets almost eleven years earlier!

Tonight let’s turn binoculars or telescopes toward the southern lunar surface as we set out to view one of the most unusually formed craters – Schiller. Located near the lunar limb, Schiller appears as a strange gash bordered on the southwest in white and black on the northeast. This oblong depression might be the fusion of two or three craters, yet shows no evidence of crater walls on its smooth floor. Schiller’s formation still remains a mystery. Be sure to look for a slight ridge running along the spine of the crater to the north through the telescope. Larger scopes should resolve this feature into a series of tiny dots.

Let’s try our hand at Beta Orionis … the bright, blue/white star in the southwestern corner of Orion. As you may have noticed for the most part – the brighter the stars are, the closer they are. Not so Rigel! As the seventh brightest star in the sky, it breaks all the “rules” by being an amazing 900 light years away! Can you imagine what an awesome supergiant this white hot star really is? Rigel is actually one of the most luminous stars in our galaxy and if it were as close as Sirius it would be 20% as bright as tonight’s Moon! As an added bonus, most average backyard telescopes can also reveal Rigel’s 6.7 magnitude blue companion star. And if these “two” aren’t enough – note the companion is also a spectroscopic double!

Until next week? Ask for the Moon… but keep on reaching for the stars!

If you enjoy the weekly observing column, why not consider buying the fully illustrated book, The Night Sky Companion 2012. It’s available in both a softcover and Kindle format!

Posted on by Steve Nerlich

Journal Club – Shaping The Invisible

Today's Journal Club is about a new addition to the Standard Model of fundamental particles.

[/caption]

According to Wikipedia, a journal club is a group of individuals who meet regularly to critically evaluate recent articles in the scientific literature. And of course, the first rule of Journal Club is… don’t talk about Journal Club.

So, without further ado – today’s journal article is about dark matter and how to determine where it is and how dense it is – although still without actually seeing it.

Today’s article:
Chae et al Dark matter density profiles of the halos embedding early-type galaxies: characterizing halo contraction and dark matter annihilation strength.

We can see how the gravitational influence of invisible dark matter is affecting the general morphology of a galaxy and the motion of the stars within that galaxy. These factors can then hint at where the dark matter is and how dense it is.

Traditional thinking positions dark matter in a halo shape around a galaxy – meaning more of it is outward than inward – which helps explain why visible objects in the outer rim of a galaxy seem to orbit the galactic center at about the same periodicity as inner visible objects. This is contrary to our local Keplerian understanding of orbital mechanics where close-in Mercury orbits the Sun (containing over 99% of the solar system’s mass) in 88 days while distant Neptune takes a leisurely 165 years.

We assume galaxies’ relatively even periodicities are a result of each galaxy’s total mass (visible and dark) being distributed throughout its structure and not concentrated in its center.

The authors use the term ‘early-type’ galaxy to describe their target population for this research. ‘Early-type’ seems unnecessary jargon – being a reference to the Hubble sequence, for which Hubble explained at some length that he was just putting galaxies in a sequence for ease of classification and he did not mean to imply any temporal sequence from the arrangement.

As it happens, our modern understanding is that these ‘early’ types, the elliptical and lenticular galaxies, are actually some of the oldest galaxy forms around. Young galaxies tend to be bright spirals. Over time, these spirals either fade, so you no longer see their spiral arms (lenticulars), or they collide with other galaxies and their ageing stars get jumbled up into random orbits to form big, blobby shapes (ellipticals).

So everywhere you see ‘early-type’ in this article – you should substitute elliptical and lenticular. Jargon prevents the general reader from being able to follow the meaning of a specialist writer – you don’t have to do this to be a scientist.

Anyhow, the researchers conducted a statistical analysis of the estimated stellar mass values and velocity dispersions of star populations within different elliptical and lenticular galaxies. Their objective was to try and get a fix on the distribution of the invisible dark matter that we think all galaxies contain.

Their analysis found that dark matter was more concentrated towards the centers of elliptical and lenticular galaxies – and the authors conclude that nearby elliptical and lenticular galaxies might hence be ideal candidates for the identification of gamma ray output from dark matter annihilation.

The last suggestion seems a bit of an intellectual leap. There have been a few reported observations of radiation output of uncertain origin from the centers of galaxies. Dark matter annihilation has been one suggested cause – but you’d think there’s a lot of stuff going on in the center of a galaxy that could offer an alternate explanation.

I could not find in the paper any suggestions as to why ‘halo contraction’ (presumably jargon for ‘dark matter concentration’) occurs in these galaxy types more often than others – which seemed the more obvious point to offer speculation on.

So… comments? Why, when knowing diddly-squat about the particle nature of dark matter, should we assume it possesses the ability to self-annihilate? Is ‘early-type’ unnecessary jargon or entrenched terminology? Is the question ‘does anyone want to suggest an article for the next edition of Journal Club’ just rhetorical?

Posted on by Nancy Atkinson

Accident Damages Mirror on Telescope Slated for Dark Energy Camera

Cracks in the secondary mirror on the Blanco telescope in Chile after an accident on February 20, 2012. Credit: Cerro Tololo Inter-American Observatory

[/caption]

An accident at the Blanco 4m telescope at Chile’s Cerro Tololo Inter-American Observatory has severely damaged a secondary mirror. The telescope is currently shut down for installation of the highly anticipated Dark Energy Survey Camera, and on February 20, 2012, the telescope’s f/8 secondary mirror was dropped during testing, resulting in fractures in the glass in the center of the mirror. Officials at the telescope said they are analyzing the extent of the damage to the mirror, and whether it extends beyond the visible cracks on the surface. They are also reviewing how the accident might affect the installation of the “DECam.”

Two staff members were injured during the incident, but are expected to fully recover. According to a post on the CTIO website, the f/8 had been removed for the installation of the DECam, and the f/8 was on the dome floor to test the focus mechanism. “The mirror and its back end assembly were being transferred to a handling cart to enable the tests. Unfortunately, the mirror was improperly installed on the cart and when the mirror was being rotated on the cart, the entire cart/mirror assembly toppled over injuring two of our technical staff,” said the report.

The mirror itself impacted the dome floor, causing the fractures, pictured above.

At this time, officials say it is not clear if the mirror is repairable or not and are reviewing what needs to be done to stabilize the cracks in the mirror. The accident is being investigated and initially, officials said they didn’t expect the incident delay the installation and commissioning of Dark Energy Camera as the f/8 is not required for the installation or operation of the Dark Energy Camera system. However, a later update said the DECam installation schedule was being modified to allow for the absence of the f/8 mirror.

The Dark Energy Camera will map 300 million galaxies with an extremely red sensitive 500 Megapixel camera, with a 1 meter diameter, 2.2 degree field of view prime focus corrector, and a data acquisition system fast enough to take images in 17 seconds.

The CTIO website said they would be providing future updates on the status of the mirror and the DECam installation.

Our previous article about the DECam.

Posted on by Jason Major

Yes, As a Matter of Fact It IS Rocket Science

Feb. 24, 2012 launch of Atlas V with MUOS-1. Credit: Jen Scheer (@flyingjenny)

[/caption]

On the afternoon of February 24, 2012, at 5:15 p.m. EST local time, a United Launch Alliance Atlas V rocket lifted off from the pad at Cape Canaveral Air Force Base carrying in its payload the US Navy’s next-generation narrowband communications satellite MUOS-1. After two scrubbed launches the previous week due to weather, the third time was definitely a charm for ULA, and the launch went nominally (that’s science talk for “awesome”.)

But what made that day, that time the right time to launch? Do they just like ending a work week with a rocket launch? (Not that I could blame them!) And what about the weather… why go through the trouble to prepare for a launch at all if the weather doesn’t look promising? Where’s the logic in that?

As it turns out, when it comes to launches, it really is rocket science.

There are a lot of factors involved with launches. Obviously all the incredible engineering it takes to even plan and build a launch vehicle, and of course its payload — whatever it happens to be launching in the first place. But it sure doesn’t end there.

Launch managers need to take into consideration the needs of the mission, where the payload has to ultimately end up in orbit… or possibly even beyond. Timing is critical when you’re aiming at moving targets — in this case the targets being specific points in space (literally.) Then there’s the type of rocket being used, and where it is launching from. Only then can weather come into the equation, and usually only at the last minute to determine if the countdown will proceed before the launch window closes.

How big that launch window may be — from a few hours to a few minutes — depends on many things.

Kennedy Space Center’s Anna Helney recently assembled an article “Aiming for an Open Window” that explains how this process works:

_________________

The most significant deciding factors in when to launch are where the spacecraft is headed, and what its solar needs are. Earth-observing spacecraft, for example, may be sent into low-Earth orbit. Some payloads must arrive at a specific point at a precise time, perhaps to rendezvous with another object or join a constellation of satellites already in place. Missions to the moon or a planet involve aiming for a moving object a long distance away.

For example, NASA’s Mars Science Laboratory spacecraft began its eight-month journey to the Red Planet on Nov. 26, 2011 with a launch aboard a United Launch Alliance (ULA) Atlas V rocket from Cape Canaveral Air Force Station in Florida. After the initial push from the powerful Atlas V booster, the Centaur upper stage then sent the spacecraft away from Earth on a specific track to place the laboratory, with its car-sized Curiosity rover, inside Mars’ Gale Crater on Aug. 6, 2012. Due to the location of Mars relative to Earth, the prime planetary launch opportunity for the Red Planet occurs only once every 26 months.

Additionally, spacecraft often have solar requirements: they may need sunlight to perform the science necessary to meet the mission’s objectives, or they may need to avoid the sun’s light in order to look deeper into the dark, distant reaches of space.

A Delta II arcs across the sky carrying NASA's Suomi NPP spacecraft. Image credit: NASA/Bill Ingalls

Such precision was needed for NASA’s Suomi National Polar-orbiting Partnership (NPP) spacecraft, which launched Oct. 28, 2011 aboard a ULA Delta II rocket from Vandenberg Air Force Base in California. The Earth-observing satellite circles at an altitude of 512 miles, sweeping from pole to pole 14 times each day as the planet turns on its axis. A very limited launch window was required so that the spacecraft would cross the ascending node at exactly 1:30 p.m. local time and scan Earth’s surface twice each day, always at the same local time.

All of these variables influence a flight’s trajectory and launch time. A low-Earth mission with specific timing needs must lift off at the right time to slip into the same orbit as its target; a planetary mission typically has to launch when the trajectory will take it away from Earth and out on the correct course.

According to [Eric Haddox, the lead flight design engineer in NASA’s Launch Services Program], aiming for a specific target — another planet, a rendezvous point, or even a specific location in Earth orbit where the solar conditions will be just right — is a bit like skeet shooting.

“You’ve got this object that’s going to go flying out into the air and you’ve got to shoot it,” said Haddox. “You have to be able to judge how far away your target is and how fast it’s moving, and make sure you reach the same point at the same time.”

But Haddox also emphasized that Earth is rotating on its axis while it orbits the sun, making the launch pad a moving platform. With so many moving players, launch windows and trajectories must be carefully choreographed.

__________________

It’s a fascinating and complex set of issues that mission managers need to get just right in order to ensure the success of a launch — and thus the success of a mission, whether it be putting a communication satellite into orbit or a rover onto Mars… or somewhere much, much farther than that.

Read the rest of the article here.

Posted on by Paul Scott Anderson

35 Years Later, the ‘Wow!’ Signal Still Tantalizes

The "Wow!" signal. Credit: Wikimedia Commons

Since the SETI program first began searching for possible alien radio signals a few decades ago, there have been many false alarms but also instances of fleeting signals of interest which disappeared again as quickly as they had appeared. If a potential signal doesn’t repeat itself so it can be more carefully observed, then it is virtually impossible to determine whether it is of truly cosmic origin. One such signal in particular caught astronomers’ interest on August 15, 1977. The famous “Wow!” signal was detected by the Big Ear Radio Observatory at Ohio State University; it was thirty times stronger than the background noise but lasted only 72 seconds and was never heard again despite repeated subsequent searches.

In a new book titled The Elusive Wow, amateur astronomer Robert Gray chronicles the quest for the answer to this enduring puzzle.

When the signal was first seen in the data, it was so pronounced that SETI scientist Jerry Ehman circled it on the computer printouts in red ink and wrote “Wow!” next to it. It appeared to fit the criteria for an extraterrestrial radio signal, but because it wasn’t heard again, the follow-up studies required to either confirm or deny this were not possible. So what was it about the signal that made it so interesting?

First, it did appear to be an artificial radio signal, rather than a natural radio emission such as a pulsar or quasar. The Big Ear telescope used a receiver with 50 radio channels; the signal was only heard on one frequency, with no other noise on any of the other channels. A natural emission would cause static to appear on all of the frequencies, and this was not the case. The signal was narrow and focused, as would be expected from an artificial source.

The Big Ear Radio Observatory. Credit: Big Ear Radio Observatory / North American AstroPhysical Observatory / Ohio State University

The signal also “rose and fell” during the 72 seconds, as would be expected from something originating in space. When the radio telescope is pointed at the sky, any such signal will appear to increase in intensity as it first moves across the observational beam of the telescope, then peak when the telescope is pointed straight at it and then decrease as it moves away from the telescope. This also makes a mere computer glitch a less likely explanation, although not impossible.

What about satellites? This would seem to be an obvious possible explanation, but as Gray notes, a satellite would have to be moving at just the right distance and at just the right speed, to mimic an alien signal. But then why wasn’t it observed again? An orbiting satellite will broadcast its signal repeatedly. The signal was observed near the 1420 MHz frequency, a “protected spectrum” in which terrestrial transmitters are forbidden to transmit as it is reserved for astronomical purposes.

There may be a bias in thinking that any alien signals will be like ours which leak out to space continuously, ie. all of our radio and TV broadcasts. That is, “normal” radio emissions from every-day type technologies which could easily be seen on an ongoing basis. But what if they were something more like beacons, sent out intentionally but only on a periodic basis? As Gray explains, radio searches to date have tended to look at many different spots in the sky, but they will only examine any particular spot for a few minutes or so before moving on to the next. A periodic signal could easily be missed completely, or if seen, it may be a long time before it is seen again.

Of course, it is also possible that any other civilizations out there might not even use radio at all, especially if they are more advanced than us (while other intelligent life might be behind us, as well). A newer branch of SETI is now searching for artificial sources of light, like laser beams, used as beacons.

So where does this leave us? The “Wow!” signal still hasn’t been adequately explained, although various theories have been proposed over the years. Perhaps one day it will be observed again, or another one like it, and we will be able to solve the mystery. Until then, it remains a curiosity, a tantalizing hint of what a definite signal from an extraterrestrial civilization might look like.

More information is available at the Big Ear Radio Observatory website.

Posted on by Jason Major

Mercury Down Under

MESSENGER wide-angle camera image of Mercury's southern hemisphere.

[/caption]

NASA’s MESSENGER spacecraft, about to wrap up its first full year in orbit around Mercury, captured this view of the planet’s heavily-cratered southern hemisphere on August 28, 2011. Because of its orbit, MESSENGER gets particularly good panoramic views of Mercury’s underside.

Here’s why…

MESSENGER’s orbit, established on March 18, 2011 at 00:45 UTC, is not a simple circling path around the first rock from the Sun. Instead it is highly elliptical, bringing it 124 miles (200 km) above Mercury’s north pole at its closest and more than 9,420 miles (15,193 km) from its south pole at its farthest! (See diagram below.)

The close approaches over the northern hemisphere allow MESSENGER to study the Caloris basin, Mercury’s largest surface feature and, at over 960 miles (1,550 km) across, one of the largest impact craters in the entire Solar System.

The view of Mercury’s southern hemisphere above features some notable craters as well: the relatively youthful 444-mile (715-km) -wide Rembrandt basin is seen at top right, while the smaller pit-floor crater Kipling can be discerned to its left, just below the planet’s limb.

When craters are larger than 300 km in diameter, they are referred to as basins.

During its 12 months in orbit MESSENGER will have experienced only two days on Mercury! This is because Mercury rotates very slowly on its axis, completing a full solar day (sunrise to sunrise) every 176 Earth days. (And you thought your work day seemed to last forever!)

Three perspectives of MESSENGER's orbit.

Find out more about the MESSENGER mission here.

Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.