Universe Today

November 12, 2008December 24, 2015 by Astronomy Cast

Podcast: The Moon, Part 2 – Exploration of the Moon

Astronauts on the Moon. Image credit: NASA

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Let’s continue on our journey to the Moon. Last week we talked about the physical characteristics of the Moon, its appearance in the sky and how it interacts with the Earth. This week we’re going to take a look at how scientists have expanded our understanding of the Moon. From ancient astronomers using nothing more than their eyes and the first telescope observations of Galileo to the exploration by robotic spacecraft. And of course, the first tentative steps by the human explorers of the Apollo program.

Click here to download the episode.

Or subscribe to: astronomycast.com/podcast.xml with your podcatching software.

The Moon, Part 2 – Transcript and show notes.

November 12, 2008December 24, 2015 by Nancy Atkinson

Cassini Finds New Mysterious Infrared Aurora

An infrared camera aboard NASA’s Cassini spacecraft has discovered a unique aurora lighting up Saturn’s polar cap. The mysterious new aurora is unlike any other known in our solar system. “We’ve never seen an aurora like this elsewhere,” said Tom Stallard, an RCUK Academic Fellow working with Cassini data at the University of Leicester. Stallard is lead author of a paper released today (13th
November) in the journal Nature. “It’s not just a ring of aurorae like those we’ve seen at Jupiter or Earth. This one covers an enormous area across the pole. Our current ideas on what forms Saturn’s aurorae predict that this region should be empty, so finding such a bright one here is a fantastic surprise.”

Aurorae are caused when charged particles stream along the magnetic field of a planet and into its atmosphere. On Earth these charged particles come from the solar wind – a stream of particles that
emanates from the Sun.

Jupiter’s main auroral ring, caused by interactions internal to Jupiter’s magnetic environment, is constant in size. Saturn’s main aurora, which is caused by the solar wind, changes size dramatically as the wind varies. The newly observed aurora at Saturn, however, doesn’t fit into either category.

“Saturn’s unique auroral features are telling us there is something special and unforeseen about this planet’s magnetosphere and the way it interacts with the solar wind and the planet’s atmosphere,” said
Nick Achilleos, Cassini scientist on the Cassini magnetometer team at the University College London. “Trying to explain its origin will no doubt lead us to physics which uniquely operates in the environment of Saturn.”

The new infrared aurora appears in a region hidden from NASA’s Hubble Space Telescope, which has provided views of Saturn’s ultraviolet aurora. Cassini observed it when the spacecraft flew near Saturn’s polar region. In infrared light, the aurora sometimes fills the region from around 82 degrees north all the way over the pole. This new aurora is also constantly changing, even disappearing within a 45 minute-period.

Source: NASA

November 12, 2008December 24, 2015 by Nancy Atkinson

Less Than 20 Years Until First Contact?

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The Allen Telescope Array (ATA) has come online with its initial configuration of 42 antennas. The project, led by the SETI Institute, is a non-governmental project funded by Microsoft co-founder Paul Allen in which eventually 350 small radio antennas will scan the sky for signs of extraterrestrial intelligence. To test the system, the ATA sucessfully picked up the New Horizons probe on its way to Pluto. Senior SETI scientist Seth Shostak said at an event in San Francisco Tuesday night that the array could become strong enough by 2025 to look deep enough into space to find extraterrestrial signals. “We’ll find E.T. within two dozen years,” he said.

That’s, of course, assuming the distance we can look into space will be increased with new instruments yet to be built, and that the projected computing power under Moore’s Law actually happens.

Shostak estimated that if the assumptions about computing power and the strength of forthcoming research instruments are correct, we should be able to search as far out as 500 light years into space by 2025, a distance he predicted would be enough–based on scientist Frank Drake’s estimate of there being 10,000 civilizations in our galaxy alone capable of creating radio transmitters–to find evidence of intelligent life that is broadcasting its existence.

Only time will tell.

For the New Horizons observation, made Sept. 10, operators of the ATA used a synthesized beam formed with 11 of the array’s 6.1-meter (20 foot) antennas – a method called “beamforming” that electronically combines the antennas into a single virtual telescope. The 8.4-GHz spacecraft carrier signal was then fed into the SETI Prelude detection system.

“We’re happy to be the ATA’s new friend in the sky, helping SETI to verify the operations of their electronics,” says New Horizons Principal Investigator Alan Stern. “It’s also nice to know that someone else is checking in on us during our long voyage to Pluto and beyond.”

And what does New Horizons look like to the Allen Telescope Array? This plot shows 678 hertz (Hz) of spectrum collected over 98 seconds. The New Horizons signal can be easily seen as a bright diagonal line, drifting at rate of -0.6 > Hz/second.

What New Horizons looks like to The ATA. Credit: SETI Institute

Sources: CNET, New Horizons

November 12, 2008December 24, 2015 by Nancy Atkinson

This Week’s “Where In The Universe” Challenge

Here’s this week’s “Where In The Universe” challenge. Take a look and see if you can name where in the Universe this image is from. Give yourself extra points if you can name the spacecraft responsible for the image. The new way we’re doing this challenge is that we’ll provide the image today, but won’t reveal the answer until tomorrow. This gives you a chance to mull over the image and provide your answer/guess in the comment section — if you dare! Check back tomorrow on this same post to see how you did. Good luck!

UPDATE (11/3): The answer has now been posted below. If you haven’t made your guess yet, no peeking before you do!!

Nice job on this one, everyone. Yes, its the sun. This image was taken back in July of 2002 of an active region of the sun. The image was produced by the Swedish 1-meter Solar Telescope on the island of La Palma, Spain. (I apologize, obviously that’s not a “spacecraft” and I should not have used the word “spacecraft” in the above paragraph — habits are hard to break.) These aren’t just little bumps on the sun. The structures in the dark sunspots in the upper central area of the image show distinct elevation above the dark “floor” of the sunspot. The height of the structures has been estimated by astronomers to be between 200 and 450 km, and the smallest resolvable features in the image are about 70 km in size! Wow!

I actually saw this image first on the Boston Globe’s The Big Picture, but here’s the original press release and info on this great image of the sun.

November 12, 2008April 26, 2016 by Nancy Atkinson

Europa Submarine Prototype Gets Another Test

ENDURANCE submarine. Credit: John Rummel, NASA

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A submersible probe that could possibly be used on Jupiter’s icy moon, Europa is taking the next step to test its capabilities. The Environmentally Non-Disturbing Under-ice Robotic Antarctic Explorer, also known as ENDURANCE, will swim untethered under ice, and collect data to create three-dimensional maps of underwater environments. The probe also will take samples of microbial life. Earlier this year, it operated successfully in a 25 meter frozen lake in Wisconsin, USA. Now it will plunge under a permanently ice covered lake in Antarctica that is 40 meters deep. ENDURANCE isn’t like the Mars Rovers or other remote-operated probes. Once deployed, it’s on its own to systematically explore, take water samples, and find its way back. “It will have to think on its own,” said Peter Doran, an Earth scientist at the University of Illinois in Chicago.

In the February 2008 test, ENDURANCE successfully found its way around the bottom of the lake and back to the hole that drilled in the ice to get the probe in and out of the lake. It also demonstrated that its electronics functioned perfectly well in cold water.

At Lake Bonney in Antarctica, ENDURANCE will not only map the lake and explore its biology, but also take a close look at the base of a feature called Blood Falls, where reddish, iron-containing salts spill out of the face of a glacier at the lake’s upper end.

If all goes well the next test would have the probe or an improved version descend through 3.5 km of ice to one of the world’s largest, deepest and most mysterious lakes, Lake Vostok, also in Antarctica.
But even that pales in comparison to what a probe might encounter at Europa. Scientists believe that Europa’s ocean could be up to 100 kilometers deep, under 6 kilometers of ice.

Hot water drills will bore a hole for ENDURANCE to enter the water in Antarctica. If all goes well, the probe will be tested again in 2009.

But many hurdles remain before an underwater vehicle could possibly head to Europa. Presently, Endurance is too massive to send on interplanetary travel. Engineers will also have to come up with a way to drill through Europa’s icy crust and lower the sub safely through the ice.

But many scientists feel that an orbiting spacecraft would be the best way to study Europa, before sending an underwater probe. The Jet Propulsion Laboratory is currently working on a concept called the Europa Explorer which would deliver a low orbit spacecraft to determine the presence (or absence) of a liquid water ocean under Europa’s ice surface. It would also map the surface and subsurface for future exploration.

Source: COSMOS

November 12, 2008December 24, 2015 by Tammy Plotner

Ready… Willing… And Abell! The Perseus Galaxy Cluster by Kent Wood

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What you’re looking at isn’t a Hubble Deep Field image peering into the furthest reaches of space. What you’re seeing is a galaxy field photographed with a 12.5″ telescope located right here on planet Earth aimed 2 degrees east of Algol. It’s a challenging galaxy cluster in Perseus known as Abell 426…

So, what exactly is it? The Perseus galaxy cluster consists of about 500 members located some 250 million light-years away. They are diffuse, they are faint, and they are dominated by radio source Perseus A – Seyfert galaxy NGC 1275. Just contained in this area alone is more than 200 trillion solar masses! In the X-ray band, no galaxy cluster out there shines brighter.

Although George Abell died several years ago, one of the most enduring legacies he left astronomy is a catalog of galaxy groups that he compiled in the 1950’s. Since that time, it has been the goal of almost all backyard astronomers with larger telescopes to conquer as many of the Abell list as we possibly can, following in his footsteps hoping to catch just a glimpse of what he once saw using the plates of Palomar Observatory Sky Survey (POSS). Although our human eyes can never match what a camera can see, so much progress has been made since Abell’s time that revealing true science is within the grasp of the amateur.

Things that we can’t see visually, like gravitationally lensed quasars are revealed – interactions of dark matter and gas. In 2003, the Chandra X-ray telescope took a very close look at radio source 3C 84 and found it was blowing bubbles of plasma into the core of the cluster. To Chandra’s “eyes”, they appeared as holes in the image – pushing away the X-ray emitting gas. What exactly are they? Try relativistic particles – a particle moving at the speed of light. In astrophysics, jets of relativistic plasma are produced by the centers of active galaxies and quasars… and my friends? That can be captured in photographs, just like Kent’s.

According to the Chandra research team; “A similar front may exist round both inner bubbles but is masked elsewhere by rim emission from bright cooler gas. The continuous blowing of bubbles by the central radio source, leading to the propagation of weak shocks and viscously-dissipating sound waves seen as the observed fronts and ripples.” This resulted in the deepest tone ever detected from the Cosmos – a tone no human will ever hear. Or will it? Abell 426 calls loudly… And it calls very loudly to some of us.

A few years ago I decided to tackle the Perseus Galaxy Cluster with a 12.5″ telescope, too. But, I am a visual astronomer. There will never be a day when I can see with my eyes what Kent has captured with a 12.5 Planewave CDK, but perhaps those of you who hear the call of Abell 426 would like to know what it’s like to step into the heart of a galaxy cluster? This is from my personal observing reports:

“So, do I always do what you tell me to? Well, yeah! You are my Master… And if you tell me to go walk outside and look to the northwest? I will obey. And if you tell me the skies will clear? I will listen. If you hand me a dark skies night, one with 6.5 visibility and 7/10 stability… Put a 12.5 scope beneath my hands. If you give me a map… I will walk with you to the stars. If you give me a notebook and a mechanical pencil… I will study. And if you give me a galaxy field? I will do my best to make you proud. When I pulled the dob out, I could only see Perseus. Why is it that things happen this way? The cold wind would take a bite out of me quickly if I used the west side yard… But Algol is at maximum and it was simply all I could see! Why would I want to chase after an old study when the east sky is filled with new ones? Why? I don’t understand why! All I understand is that tonight I want Abell 426. Starting at Algol, I shift into my “weird” study mode and stop to ride the diffraction waves. I know I’m rather strange, but I’d really like to know if I can catch a spectroscopic difference between Algol at maximum and Algol at minimum. Yeah, I’m sure I’m probably being kinda’ dumb because my equipment is so primitive… But I’m curious. OK? Making my notes, I put the diffraction grating away once again. I learn. Therefore I am. Now, let’s rock and roll…

Abell 426 has been a longstanding favourite of mine. It is a curious galaxy cluster in the respect that the finer the night, the more galaxies will reveal themselves. While tonight is not the most exceptional night I’ve ever encountered, it is a fine one for galaxy studies. Brushing Algol away in the eyepiece, I close my eyes and sing along with the music for several minutes, mentally and visually preparing myself for faint studies. I am becoming accustomed to the cold, and when my eyes are ready? It’s time to go to the finder, for the first study lays right in the field with a star.

The NGC1224 requires wide aversion. It is faint, round, and shows some concentration toward the nucleus with patience. Held indirect, this small galaxy has a UGC-like signature. Next stop on the hop is the NGC1250. Very diffuse and small…. Also requiring wide aversion. While allowing the eye to bounce around the field, it is possible to make out a slight north/south tilt to this galaxy that may indicate it to be a spiral. Curiously enough, it is during this motion that a pinprick of a nucleus can be detected. Pushing on toward the heart of the Perseus Galaxy cluster, my next destination is a chain of three. First study mark is the NGC1259. Whoa! Extreme aversion here, boss… Very, very diffuse and faint. It can only be caught by focusing attention on the tiny star in the westward drift. The NGC1260 only requires slight aversion, however. It is small and somewhat diffuse. Definitely ovoid in structure… And definitely the easiest to see of these three! The NGC1264 also requires very wide aversion. Very faint and diffuse. Very round…. Very challenging! Now, triangulating with this series, it’s time to go for the NGC1257. Very faint, diffuse and small with a concentration toward the core, it holds a little surprise. There’s a tiny star at the northeast end that allows one to see upon wide aversion that the galaxy itself seems to migrate to the northeast/southwest. Excellent!

From here I have the option of continuing on the same trajectory or doing a lateral “thing”. I find myself grinning, because I know from past experience that my maps don’t always reveal everything there is to be seen in such a cluster. I’ll have to be awfully careful when going toward the heart of Abell 426, or I’ll lose my sense of direction and darn well get lost! Oh well, eh? It wouldn’t be the first time I’ve been told to do so.

The NGC1271 skirts the most populated part of this Abell cluster. If I’ve got the right one, we’re talking about a super wide aversion, very faint, very small patch that is barely capturable. Even patience and my own set of tricks can draw nothing more than a slightly regular contrast change in this area. Next up is an extremely challenging triple. The NGC1267, NGC1268 and NGC1269 are three incredibly tiny, very diffuse round gems that would be indistinguishable at lower power. Phew! This little trio is really bad… I couldn’t even qualify these as “hairy stars” because they’re so diffuse!

Breathing quietly so I don’t fog anything up, right now I’d just about sell my soul for a cup of chai and a few minutes by the fire. But, I realize that if I stand down now, I’ll lose whatever sense of orientation that I’ve gained. (and that, coming from a blond, is no joke.) I can see the “heart” of Abell 426, and I know how easy it would be to just let go… Enjoy! Not care? Not hardly. (don’t stop, ~T…. just don’t stop.)

NGC1273 is faint. It requires aversion, but the brighter core region holds up to indirect vision. The NGC1272, is also round… Almost planetary in appearance. This is a galaxy that is definitely a player in this field!! The NGC1270 is very diffuse and a wide aversion. It contains a very small, almost stellar nucleus. Now the cluster is getting thick and tight. Can I do this and do it correctly? Hey, hey… Let’s give it a go. I can’t do anything worse than be wrong, eh? NGC1279 is faint, diffuse, but holds. It stretches just every so slightly, like a thin smear held at slight aversion to the north/south. It is even with no nucleus present. The NGC1274 is very faint and very diffuse and even. It is best seen while concentrating on the NGC1279. Just an incredibly misty oval. The NGC1275… (holy sh*t! one i can see!!) is very bright compared to all the previous studies. Most definitely has a bright and easily held direct nucleus.

And now I’m laughing out loud, because these little puppies are everywhere. Much like studying Virgo clusters, once you see a bright galaxy, what seems like swarms come out to play all around! I guess it’s time for me to bow gracefully out of the middle of this dance before I make a great fool of myself. Let’s just head back toward the outskirts and although these might not be considered to be part of the Abell 426, at least I stand a better chance at identification!

Going for a pair, I find the NGC1282 to be diffuse, slight in size and quite ovoid. Very even in structure, no hint of a nucleus even a full avert. The companion, NGC1283, is very diffuse and I probably wouldn’t have even caught it except for that I was looking at some small field stars that triangulate in this area when it made its’ foggy appearance. Now for the NGC1294 and NGC1293… Wide aversion shows two round fuzzies with prickly nucleus structure. The pair reminds me of two impossibly small “gone to seed” dandelions waiting to be scattered on the cosmic winds… Huh? Listen. When I start writing junk like that in my notes, I’m either high on photons or nearing hypothermia. Or maybe both, eh?”

If the Perseus Galaxy cluster calls to you in a low tone… listen. It called to George Abell in 1958 and it called to Kent Wood just a few days ago. We’re glad it did…

Many, many thanks to AORAIA member Kent Wood for his superb image and allowing us to share what our eyes cannot see!

Full Rez Image

November 12, 2008December 24, 2015 by Tammy Plotner

Hydrus

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The constellation of Hydrus was originally created by Petrus Plancius from the observations of Dutch sea navigators Pieter Dirkszoon Keyser and Frederick de Houtman when exploring the southern hemisphere and should not be confused with its more northerly counterpart – Hydra. Hydruss’ stellar patterns became known when it appeared on a celestial globe in 1597 and was considered a constellation when it was added to Johann Bayer’s Uranometria catalog in 1603. It survived the years to become one of the 88 modern constellations recognized by the International Astronomical Union. Hydrus is a southern circumpolar constellation and covers approximately 243 square degrees of sky. It contains 3 major stars which make up its asterism and 19 stars which have Bayer/Flamsteed designations. Hydrus is bordered by the constellations of Dorado, Eridanus, Horologium, Mensa, Octans, Phoenix, Reticulum and Tucana. It can be seen by observers located at at latitudes between +8° and ?90° and is best visible at culmination during the month of November.

Because Hydrus wasn’t visible to the ancient Greeks or Romans, no mythology surrounds this constellation. It is, however, just another example of how constellation names and figures can sometimes repeat themselves, like Ursa Major and Minor, Canis Major and Minor, Pegasus and Equuleus, Leo and Lynx… Perhaps the ancient Maori had legends about this handful of stars! To them, the Hydrus was the water snake who killed crocodiles by entering into their mouths and killing them from the inside…

Let’s begin our binocular tour with the second brightest of the stars – Alpha Hydri – the “a” symbol on our map. Once upon a time in the year 2900 BC, this happy little F class dwarf star had the honor of being the southern pole star. Thanks to the precession of the equinoxes, it has long since moved away, but continues to be of interest as it gears up to become a red giant star. Rotating completely on its axis about every 26 hours, all of Alpha’s exterior activity happens acoustically rather than magnetically. Why? Because 71 light year distant Alpha has a high metal content!

Now, drop south for Beta Hydri – the “B” symbol on our map. In binoculars you’ll see a nice visual double star. Beta is located 24.4 light years from our solar system and right now serves the distinction of being the brightest star closest to the south celestial pole. What’s special about it? What you’re looking at is nearly a duplicate of our own Sun. While it is just slightly larger and brighter, Beta is most definitely a subgiant near or at the end of its hydrogen fusing life – on its way to becoming a red giant no larger than the orbit of Earth. Its maximum rotation period is 29 days, very near to that of the 24 day cycle of Sol and its evolutionary fate appears to be similar – a “one day” white dwarf star.

Hop north and east for Gamma Hydri – the “Y” shape on our map. If you think you’re seeing red compared the the soft yellow-white of the other stars – you’re right. Gamma is a luminous class M red giant star that has signed off core hydrogen fusion and is approaching the end of its life span. While it is not terribly large – not even the size of the orbit of Mercury compared to our Sun, Gamma puts out some real stellar luminosity – shining 650 times brighter than Sol. This may be because it is firing up its helium to fuse carbon and oxygen… or it may have depleted its helium and is about to toss off its outer envelope and become a dead, white dwarf!

Before we move on, let’s head back north… Stopping first to pay our respects to visual double star Pi 1 Hydri – a non-interacting pair of 6th magnitude giants. Look closely because Pi 1 is red and Pi 2 is orange! Now, hop east to Eta 2 – the “n 2” symbol on our map. What’s so special about Eta 2? First off, Eta Hydri is a double star – a true binary star consisting of a blue-white dwarf called Eta 1 and a yellow giant star, Eta 2. But hey, that’s not what really fun. What’s really run is there is a giant planet orbiting around Eta 2! It’s about 217 light years from Earth and it goes by the very unromantic name of HD 11977 b. Sure, it’s about six and a half times the size of Jupiter, which puts it right up there at dead star size… But hey! It’s a planet! This means at least a few intermediate-mass stars could host substellar companions – either planets or brown dwarfs. When later measured by Doppler, science proved HD 11977 b was clearly within the planetary mass and became the first to be accurately determined.

Are you ready for a true telescope challenge? Hydra isn’t precisely known for bright objects, so our first is IC 1717 (RA 01h 32m 30.0s Dec -67 32′ 12.0″). What is it? Well… nothing. The only thing we really know for sure it that something was there when Dreyer cataloged this position because Dreyer was exceedingly good at his job. Maybe it was a comet… Maybe it was something variable. It never hurts to look!

Just in case you have an small telescope, you might want to try NGC 1466 (RA 03:44.5 Dec -71:41). This 11.5 magnitude globular cluster doesn’t belong to the Milky Way Galaxy… it belongs to the Large Magellanic Cloud. Even that far away, science has been able to spot that it has 44 RR Lyra type variable stars and is every bit as old as the galaxy halo to which it belongs!

For large telescopes, try NGC 1511 (RA 3:59.5 Dec -67:38), too. This ‘object’ is actually a triple set of galaxies whose co-ordinates are so close to one another that they almost appear as one unit. Interacting galaxies? You bet. This galaxy collision is a process that’s been going on for a billion years and will eventually become a giant elliptical galaxy at then end. Chances are NGC 1511 has already absorbed at least one galaxy in its past. According to scientists, “the peculiar optical ridge to the east of NGC 1511 is probably the stellar remnant of a galaxy completely disrupted by interactions with NGC 1511”.

Sources: Wikipedia, Chandra Observatory
Charts Courtesy of Your Sky.

November 11, 2008December 24, 2015 by Ian O'Neill

Studying the Life Cycle of Butterflies and Spiders in Space

Will butterflies in space grow different to butterflies on Earth? (NASA, editing by Ian O'Neill)

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Space biology experiments have just arrived in the classroom. With a focus on hundreds of K-12 students, a University of Colorado, Boulder payload will be launched on board Space Shuttle Endeavour on November 14th carrying spiders and butterfly larvae. The purpose? To provide an educational research tool for youngsters, helping to develop their interest in biology and space science. The butterfly larvae will be studied over their complete life cycle in space; from larvae to pupae to butterfly to egg. Web-building spiders will be studied to see how their behaviour alters when lacking gravity. Both sets of experiments will then be compared with control subjects on the ground… I wish I had the chance to do this kind of research when in school. I wish I had the chance to do this kind of research now!

“This program is an excellent example of using a national asset like the International Space Station to inspire K-12 students in science, technology, engineering and math,” said BioServe Director Louis Stodieck, principal investigator on the project. BioServe has flown two previous K-12 payloads as part of their CSI program on other shuttle flights to the International Space Station (ISS).

This particular experiment will study the activities and feeding habits of web-building spiders when in space, compared to spiders in the classroom. The hundreds of students from several locations in the US are involved in the project and will learn valuable research techniques along with boosting their interest in the sciences. After all, it isn’t every day you get a chance to carry out cutting-edge research on the world’s most extreme science laboratory!

The second set of experiments will be another space/Earth comparison, but this time a study of the full lifespan of painted lady butterflies. Four-day old pupae will be launched into space and watched via downlink video, still images and data from the ISS. Partners in the project include the Denver Museum of Nature and Science, the Butterfly Pavilion in Westminster, CO and the Baylor College of Medicine’s Center for Education Outeach.

BioServe is a non-profit, NASA funded organization hoping to include payloads on each of the remaining shuttle flights until retirement. “Between now and then, we are seeking sponsors for our educational payloads to enhance the learning opportunities for the K-12 community in Colorado and around the world,” added BioServe Payload Mission Manager Stefanie Countryman.

The full details on the project can be found on the University of Colorado pages.

This is where the strength of the International Space Station really comes into play. Real science being carried out by schools in the US to boost interest not only in space travel, but biology too. It’s a relief, I was getting a little tired hearing about busted toilets, interesting yet pointless boomerang “experiments”, more tests on sprouting seeds and the general discontent about the ISS being an anticlimax.

Let’s hope BioServe’s projects turn out well and all the students involved are inspired by the opportunities of space travel. Although I can’t help but feel sorry for the confused spiders and butterfly larvae when they realise there’s no “up” any more (I hope they don’t get space sick).

Source: UC Boulder

November 11, 2008December 24, 2015 by Nancy Atkinson

Chandrayaan-1 Almost There, UPDATE 11/12

Chandrayaan-1's first picture of the Moon. Credit: ISRO

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UPDATE: The Indian Space Research Organization (ISRO) announced on 11/12 that the 100 km science orbit has been successfully achieved. Congrats to the Chandrayaan-1 team!

India’s space agency released the first picture of the Moon taken by the Chandrayaan-1 spacecraft. While it’s not a superlative image, as Emily Lakdawalla from the Planetary Society blog says, it is a milestone. Emily also explained that this photo has a resolution more than 3,000 times poorer than the eventual science images will have because the camera on Chandrayaan-1 was designed to take images from an a 100-kilometer science orbit (this image was taken on Nov. 4 at 311,200 kilometers away from the Moon). And today, the spacecraft got closer to that final science orbit by firing its engines for 31 seconds, reducing its perigee (nearest distance to the moon) from 187 km to 101 km.

Chandrayaan-1’s orbit is still elliptical, and its apogee (farthest distance from the moon) is now 255 km. In this orbit, Chandrayaan-1, takes two hours and nine minutes to go around the Moon. On Wednesday evening, the Spacecraft Control Centre at Bangalore will issue commands for the spacecraft to fire its engines again to reduce the apogee to 100 km, putting the spacecraft into its final science orbit.

Then, on either Nov. 14 or 15, the Moon Impact Probe will be released. It weighs 35 kg, and once released will take about 25 minutes to impact. It will hit a pre-selected location (Chandrayaan-1 Twitter says to keep an eye on Shackleton Crater), and the primary objective is to demonstrate the technologies required for landing the probe at a desired location on the Moon and to qualify some of the technologies related to future soft landing missions.

Sources: ISRO, The Hindu

November 11, 2008December 24, 2015 by Nancy Atkinson

When Moons and Rings Collide

Saturn's moon Prometheus collides with the F Ring. Credit: NASA/JPL/Space Science Institute

This is absolutely astounding! The Cassini spacecraft captured a collision between Saturn’s moon Prometheus and the F ring, which creates a “streamer;” material being pulled from the ring by the moon’s gravity, leaving behind a dark channel. There’s even a movie of the event! The creation of these streamers and channels occurs in a cycle that repeats during each of Prometheus’ orbits. During its 14.7 hour orbit of Saturn, when Prometheus reaches apoapse, or where it is farthest away from Saturn and closest to the F ring, the oblong moon draws a streamer of material from the ring. But since Prometheus orbits faster than the material in the ring, this new streamer is pulled from a different location in the ring about 3.2 degrees (in longitude) ahead of the previous one. In this way, a whole series of streamer-channels is created along the F ring, and Cassini has captured more images showing what are called streamer-channels.

New images, as the one below, again look at the streamer-channels. This image looks toward the unilluminated side of the rings from about 36 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on September 30, 2008. The view was acquired at a distance of approximately 970,000 kilometers (602,000 miles) from Saturn and at a Sun-ring-spacecraft, or phase, angle of 45 degrees. Image scale is 5 kilometers (3 miles) per pixel.

Streamers and channels. Credit: NASA/JPL/Space Science Institute"

In some observations, 10 to 15 streamer-channels can easily be seen in the F ring at one time (at left). Eventually, a streamer-channel disappears as shearing forces (i.e., Keplerian shear) act to disperse the constituent dust particles.

The movie shows just under half of a complete streamer-channel cycle. The dark frames in the movie represent the period during which Prometheus and the F ring pass through Saturn’s shadow. The images in the movie were acquired by the Cassini spacecraft narrow-angle camera on November 23 and 24, 2006. The movie sequence consists of 72 clear spectral filter images taken every 10.5 minutes over a period of about 12.5 hours.

Source: Cassini,