Posted on by Jenny Winder

Wishing the Zooniverse a Happy 5th Birthday!

Galaxy Zoo was a project set up in July 2007 by astronomers Chris Lintott and Kevin Schawinski asking members of the public to help classify a million galaxy images produced by the Sloan Digital Sky Survey. Five years on and Galaxy Zoo has grown into an entire Zooniverse of projects allowing members to contribute to real science across a range of disciplines. Join us to celebrate the giant of citizen science, mark its achievements and look forward to the future.

Modern science can produce huge amounts of data and making sense of it all can take years and often needs a human eye to pick out the fine details. The Zooniverse unleashes an army of willing volunteers to pore over images and data sets. Galaxy Zoo members have now classified over 250 million galaxies. At the time of writing there are currently 656,773 people taking part in Zooniverse projects across the globe. Galaxy Zoo participants alone have contributed to more than 30 published scientific papers. One of the Zooniverse’s great strengths is the ability to throw up some unexpected discoveries like the now famous Hanny’s Voorwerp, named after Dutch school teacher Hanny van Arkel, the Galaxy Zoo volunteer who spotted it. Such a serendipitous discovery is possible when data is exposed to large numbers of users who are encouraged to flag up anything they think looks out of the ordinary.

To mark Galaxy Zoo’s 5th birthday there will be a relaunch of the project which will compare images using a new dataset from Hubble’s CANDELS survey of distant, early galaxies to what we see today.

The range of projects now available to members is extensive. Users of the Solar Stormwatch project analyse interactive diagrams produced by NASA’s Solar Terrestrial Relations Observatory (STEREO). Planet Hunters use data from Kepler to search for transiting exoplanets. The Milky Way Project users have access to image data from the Spitzer Space Telescope to identify infrared bubbles in the interstellar medium to help us understand how stars form. SETI Live searches for interesting signals coming from the Kepler Field. Moon Zoo participants use data from NASA’s Lunar Reconnaissance Orbiter (LRO) to catalogue features on the Moon down to the size of a wastepaper basket.

Away from space there are also projects involved in climate, nature and humanities. Old Weather is a project that models Earth’s climate using wartime shipping logs and Whale FM members listen to, and catagorize, the songs of Orcas to help understand what the whales are saying, while Ancient Lives gives participants the chance to decipher and study the Oxyrhynchus collection of papyri. The NEEMO project analyzes images of marine life and features taken from the underwater base at the National Marine Sanctuary in Key Largo, Florida. What’s the Score asks people to help describe over four thousand digitised musical scores made available by the Bodleian Libraries. With a global posse of citizen scientists eager to study real data at their disposal, the range of projects will likely grow over the coming years. So happy 5th Birthday Zooniverse and here’s to many more!

To find out more and how you can get involved visit the Zooniverse website

Lead image caption: Galaxies gone wild. Source NASA, ESA, the Hubble Heritage (STScI/AURA) ESA/Hubble Collaboration, and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)

Posted on by Jason Major

WISE Spies a Hunter’s Flame

A vast star-forming cloud of gas and dust in the constellation Orion shines brightly in this image from NASA’s WISE space telescope, where infrared light is represented in visible wavelengths. It’s part of a recent data release from WISE, a trove of infrared images acquired during the telescope’s second sky scan from August to September of 2010 — just as it began to run out of its essential cryogenic coolant.

Shining brightly in infrared radiation, the Flame nebula (NGC 2024) is at the heart of the cloud.  Just below it is the reflection nebula NGC 2023, and the small, bright loop protruding from the edge of the gas and dust cloud just to its lower right is the Horsehead nebula  — whose famous equine profile appears quite different in infrared light than it does in visible.

The two bright blue stars at the upper right portion of the image are both stars in Orion’s belt. Alnitak, the brighter one closer to the Flame nebula, is a multiple star system located 736 light-years away whose stellar wind is responsible for ionizing the Flame nebula and causing it to shine in infrared. Alnilam, the dimmer star at the uppermost corner, is a blue supergiant 24 times the radius of our Sun and 275,000 times as bright, but 1,980 light-years distant.

The red arc at lower right is the bow shock of Sigma Orionis, a multiple-star system that’s hurtling through space at a speed of 5,260,000 mph (2,400 kilometers per second). As its stellar wind impacts the interstellar medium and piles up before it, an arc of infrared-bright radiation is emitted.

Sigma Orionis is also the star responsible for the glow of the Horsehead nebula.

This rich astronomical scene is an expanded view from WISE’s previously-released image of the region (at right) which used data from only three of its four infrared detectors. In contrast, all four detectors were used in the image above, making more of the nebulae’s intricate structures visible as well as providing comparative information for researchers.

“If you’re an astronomer, then you’ll probably be in hog heaven when it comes to infrared data,” said Edward (Ned) Wright of UCLA, the principal investigator of the WISE mission. “Data from the second sky scan are useful for studying stars that vary or move over time, and for improving and checking data from the first scan.”

Read more on the NASA news release here.

Top and right images: NASA/JPL-Caltech/WISE team. Horsehead nebula visible light image was taken with the 0.9-meter telescope at Kitt Peak National Observatory. Photo credit & copyright: Nigel Sharp (NOAO), KPNO, AURA, NSF. Comparison by J. Major/Universe Today.

Posted on by Jason Major

Ping-Pong Particles: What the Higgs Does

Unless you’ve been hiding under a chondrite for the past week you’ve heard the news from CERN regarding the discovery of a new particle that exhibits “Higgs-like” qualities. Particle physics isn’t the easiest discipline to wrap one’s head around, and while we’ve recently shared some simplified explanations of what exactly a Higgs boson is, well…here’s another.

Here, BBC’s Jonathan Amos attempts to demonstrate what the Higgs field does, and what part the boson plays. Some Ping-Pong balls, a little sugar, and a cafeteria tray is all it takes to give an idea of how essential this long-sought after subatomic particle is to the Universe. (If only finding it had been that easy!)

Video: BBC News

Posted on by Nancy Atkinson

Higgs-like Particle Discovered at CERN

This is the signature of one of 100s of trillions of particle collisions detected at the Large Hadron Collider. The combined analysis lead to the discovery of the Higgs Boson. This article describes one team in dissension with the results. (Photo Credit: CERN)

Physicists working at the Large Hadron Collider (LHC) have announced the discovery of what they called a “Higgs-like boson” — a particle that resembles the long sought-after Higgs.

“We have reached a milestone in our understanding of nature,” CERN director general Rolf Heuer told scientists and media at a conference near Geneva on July 4, 2012. “The discovery of a particle consistent with the Higgs boson opens the way to more detailed studies, requiring larger statistics, which will pin down the new particle’s properties, and is likely to shed light on other mysteries of our universe.”


Two experiments, ATLAS and CMS, presented their preliminary results, and observed a new particle in the mass region around 125-126 GeV, the expected mass range for the Higgs Boson. The results are based on data collected in 2011 and 2012, with the 2012 data still under analysis. The official results will be published later this month and CERN said a more complete picture of today’s observations will emerge later this year after the LHC provides the experiments with more data.

“We observe in our data clear signs of a new particle, at the level of 5 sigma, in the mass region around 126 GeV. The outstanding performance of the LHC and ATLAS and the huge efforts of many people have brought us to this exciting stage,” said ATLAS experiment spokesperson Fabiola Gianotti, “but a little more time is needed to prepare these results for publication.”

The discovery of the Higgs is big, in that it is the last undiscovered piece of the Standard Model that describes the fundamental make-up of the universe.

Scientists believe that the Higgs boson, named for Scottish physicist Peter Higgs, who first theorized its existence in 1964, is responsible for particle mass, the amount of matter in a particle. According to the theory, a particle acquires mass through its interaction with the Higgs field, which is believed to pervade all of space and has been compared to molasses that sticks to any particle rolling through it.

And so, in theory, the Higgs would be responsible for how particles come together to form matter, and without it, the universe would have remained a formless miss-mash of particles shooting around at the speed of light.

“It’s hard not to get excited by these results,” said CERN Research Director Sergio Bertolucci. “We stated last year that in 2012 we would either find a new Higgs-like particle or exclude the existence of the Standard Model Higgs. With all the necessary caution, it looks to me that we are at a branching point: the observation of this new particle indicates the path for the future towards a more detailed understanding of what we’re seeing in the data.”

A CERN press release says that the next step will be to determine the precise nature of the particle and its significance for our understanding of the universe.

Are its properties as expected for the long-sought Higgs boson, the final missing ingredient in the Standard Model of particle physics? Or is it something more exotic? The Standard Model describes the fundamental particles from which we, and every visible thing in the universe, are made, and the forces acting between them. All the matter that we can see, however, appears to be no more than about 4% of the total. A more exotic version of the Higgs particle could be a bridge to understanding the 96% of the universe that remains obscure. – CERN press release

“We have reached a milestone in our understanding of nature,” said CERN Director General Rolf Heuer. “The discovery of a particle consistent with the Higgs boson opens the way to more detailed studies, requiring larger statistics, which will pin down the new particle’s properties, and is likely to shed light on other mysteries of our universe.”

Positive identification of the new particle’s characteristics will take more time and more experiments. But the scientists feel that whatever form the Higgs particle takes, our knowledge of the fundamental structure of matter is about to take a major step forward.

Lead image caption: Event recorded with the CMS detector in 2012 at a proton-proton centre of mass energy of 8 TeV. The event shows characteristics expected from the decay of the SM Higgs boson to a pair of photons (dashed yellow lines and green towers). The event could also be due to known standard model background processes. Credit: CERN

Source: CERN

Posted on by Ken Kremer

1st Space-bound Orion Crew Capsule Unveiled at Kennedy

Image caption: Sen. Bill Nelson of Florida welcomes the newly arrived Orion crew capsule at a Kennedy Space Center unveiling ceremony on July 2, 2012 and proclaims Mars is NASA’s long term goal for human exploration. Credit: Ken Kremer

NASA’s first space-bound Orion crew capsule was officially unveiled at a welcoming ceremony at the Kennedy Space Center on Monday (July 2) to initiate a process that the agency hopes will finally put Americans back on a path to exciting destinations of exploration beyond low Earth orbit for the first time in 40 years since Apollo and spawn a new era in deep space exploration by humans – starting with an initial uncrewed test flight in 2014.

Over 450 invited guests and dignitaries attended the Orion arrival ceremony at Kennedy’s Operations and Checkout Building (O & C) to mark this watershed moment meant to reignite human exploration of the cosmos.

“This starts a new, exciting chapter in this nation’s great space exploration story,” said Lori Garver, NASA deputy administrator. “Today we are lifting our spirits to new heights.”

Image caption: Posing in front of NASA’s 1st Orion crew module set for 2014 liftoff are; KSC Director Bob Cabana, Mark Geyer, NASA Orion Program manager, Sen. Bill Nelson (FL), Lori Garver, NASA Deputy Administrator. Credit: Ken Kremer

This Orion capsule is due to lift off on a critical unmanned test flight in 2014 atop a powerful Delta 4 Heavy booster – like the Delta rocket just launched on June 29.

The bare bones, olive green colored aluminum alloy pressure shell arrived at KSC last week from NASA’s Michoud Assembly Facility where the vessel was assembled and the final welds to shape it into a capsule were just completed. Every space shuttle External Tank was built at Michoud in New Orleans.

U.S. Senator Bill Nelson of Florida has spearheaded the effort in Congress to give NASA the goal and the funding to build the Orion Multipurpose Crew Vehicle (MPCV) and the means to launch it atop the most powerful rocket ever built – a Saturn V class booster dubbed the SLS or Space Launch System – to destinations in deep space that have never been explored before.

“Isn’t this beautiful?” said Nelson as he stood in front of the incomplete vessel, motioned to the crowd and aimed his sights high. “I know there are a lot of people here who can’t wait to get their hands and their fingers on this hardware.

“And ladies and gentlemen, we’re going to Mars!” proclaimed Nelson.

“Without question, the long-term goal of our space program, human space program right now is the goal of going to Mars in the decade of the 2030s.”

“We still need to refine how we’re going to go there, we’ve got to develop a lot of technologies, we’ve got to figure out how and where we’re going to stop along the way. The president’s goal is an asteroid in 2025. But we know the Orion capsule is a critical part of the system that is going to take us there.”


Image caption: The green colored aluminum alloy pressure vessel arrived at KSC last week and will be outfitted with all the instrumentation required for spaceflight. Launch is slated for 2014 atop Delta 4 Heavy booster from pad 37 on Cape Canaveral. Crew hatch and tunnel visible at center. Credit: Ken Kremer

Orion is the most advanced spacecraft ever designed.

Over about the next 18 months, engineers and technicians at KSC will install all the systems and gear – such as avionics, instrumentation, flight computers and the heat shield – required to transform this empty shell into a functioning spacecraft.

The 2014 uncrewed flight, called Exploration Flight Test-1 or EFT-1, will be loaded with a wide variety of instruments to evaluate how the spacecraft behaves during launch, in space and then through the searing heat of reentry.

The 2 orbit flight will lift the Orion spacecraft and its attached second stage to an orbital altitude of 3,600 miles, about 15 times higher than the International Space Station. Although the mission will only last a few hours it will be able high enough to send the vehicle plunging back into the atmosphere at over 20.000 MPH to test the craft and its heat shield at deep-space re-entry speeds approaching those of the Apollo moon landing missions.

Image caption: Sen. Bill Nelson of Florida discusses the new arrived Orion capsule with NASA Deputy Administrator Lori Garver while surrounded by a horde of reporters at the Kennedy Space Center unveiling ceremony on July 2, 2012. Credit: Ken Kremer

Orion arrived at Kennedy on nearly the same day that the center opened its door 50 years ago.

“As KSC celebrates its 50th anniversary this month, I can’t think of a more appropriate way to celebrate than by having the very first Orion Multi-Purpose Crew Vehicle here at KSC,” said KSC Center Director Robert Cabana, a former shuttle commander, at the O & C ceremony.

“The future is here, now, and the vehicle we see here today is not a Powerpoint chart. It’s a real spacecraft, moving toward a test flight in 2014.”

In 2017, an Orion capsule will lift off on the first SLS flight. The first crewed Orion will launch around 2021 and orbit the moon, Lori Garver told me in an interview at KSC.

But the entire schedule and construction of the hardware is fully dependent on funding from the federal government.

In these lean times, there is no guarantee of future funding and NASA’s budget has already been significantly chopped – forcing numerous delays and outright mission cancellations on many NASA projects; including the outright termination of NASA next Mars rover and multi-year delays to the commercial crew program and prior plans to launch a crewed Orion to orbit as early as 2013.

Image caption: Veteran NASA Astronaut Rex Walheim discusses Orion with Universe Today. Walheim flew on the last space shuttle mission (STS-135). Credit: Ken Kremer

Astronaut Rex Walheim, who flew on the final space shuttle mission (STS-135) and has had key role in developing Orion, said the Orion capsule can be the principal spacecraft for the next 30 years of human exploration of the solar system.

“It’s the first in a line of vehicles that can take us where we’ve never gone before,” Walheim said. “It’ll be a building block approach, we’ll have to have a lander and a habitation module, but we can get there.”


Image caption: John Karas, Lockheed Martin Vice President for Human Space Flight poses with Orion and discusses the upcoming 2014 EFT-1 test flight with Universe Today. Lockheed is the prime contractor for Orion. Credit: Ken Kremer

“Personally I am thrilled to be working on the next vehicle that will take us beyond low Earth orbit, said John Karas, Lockheed Martin Vice President for Human Space Flight. Lockheed Martin is the prime contractor to build Orion.

“Orion will carry humans to destinations never explored before and change human’s perspectives”

“Folks here are ready to start working on the EFT-1 mission. In about 18 months, EFT-1 will fly on the next Delta 4 Heavy flight.

“I can’t wait to go deeper into the cosmos!” Karas exclaimed.

Ken Kremer

…..
July 13/14: Free Public Lectures about NASA’s Mars and Planetary Exploration, the Space Shuttle, SpaceX , Orion and more by Ken Kremer at the Adirondack Public Observatory in Tupper Lake, NY.

Posted on by Jason Major

What’s a Higgs Boson, Anyway?

With the science world all abuzz in anticipation of tomorrow’s official announcement from CERN in regards to its hunt for the Higgs, some of you may be wondering, “what’s a Higgs?” And for that matter, what’s a boson?

The video above, released a couple of months ago by the talented Jorge Cham at PHDcomics, gives a entertaining run-down of subatomic particles, how they interact and how, if it exists — which, by now, many are sure it does — the Higgs relates to them.

It’s the 7-minutes course in particle physics you’ll wish you had taken in college (unless you’re a particle physicist in which case… well, you’d still probably have enjoyed it.)

Credit: PHDcomics.com

Posted on by Nancy Atkinson

Integrating New Concepts for Entry, Descent and Landing for Future Human Missions to Mars

Editor’s note: This guest post was written by Andy Tomaswick, an electrical engineer who follows space science and technology.

One of the most technically difficult tasks of any future manned missions to Mars is to get the astronauts safely on the ground. The combination of the high speed needed for a short trip in space and the much lighter Martian atmosphere creates an aerodynamics problem that has been solved only for robotic spacecraft so far. If people will one day walk Mars’ dusty surface, we will need to develop better Entry Descent and Landing (EDL) technologies first.

Those technologies are part of a recent meeting of the Lunar Planetary Institute (LPI), The Concepts and Approaches for Mars Exploration conference, held June 12-14 in Houston, which concentrated on the latest advances in technologies that might solve the EDL problem.

Of the multitude of technologies that were presented at the meeting, most seemed to involve a multi-tiered system comprising several different strategies. The different technologies that will fill those tiers are partly mission-dependent and all still need more testing. Three of the most widely discussed were Hypersonic Inflatable Aerodynamic Decelerators (HIADs), Supersonic Retro Propulsion (SRP), and various forms of aerobraking.

HIADs are essentially large heat shields, commonly found many types of manned reentry capsule used in the last 50 years of spaceflight. They work by using a large surface area to create enough drag through the atmosphere of a planet to slow the traveling craft to a reasonable speed. Since this strategy has worked so well on Earth for years, it is natural to translate the technology to Mars. There is a problem with the translation though.

HIADs rely on air resistance for its ability to decelerate the craft. Since Mars has a much thinner atmosphere than Earth, that resistance is not nearly as effective at slowing reentry. Because of this drop in effectiveness, HIADs are only considered for use with other technologies. Since it is also used as a heat shield, it must be attached to the ship at the beginning of reentry, when the air friction causes massive heating on some surfaces. Once the vehicle has slowed to a speed where heating is no longer an issue, the HIAD is released in order to allow other technologies to take over the rest of the braking process.

One of those other technologies is SRP. In many schemes, after the HIAD is released, SRP becomes primarily responsible for slowing the craft down. SRP is the type of landing technology commonly found in science fiction. The general idea is very simple. The same types of engines that accelerate the spacecraft to escape velocity on Earth can be turned around and used to stop that velocity upon reaching a destination. To slow the ship down, either flip the original rocket boosters around upon reentry or design forward-facing rockets that will only be used during landing. The chemical rocket technology needed for this strategy is already well understood, but rocket engines work differently when they are traveling at supersonic speeds. More testing must be done to design engines that can deal with the stresses of such velocities. SRPs also use fuel, which the craft will be required to carry the entire distance to Mars, making its journey more costly. The SRPs of most strategies are also jettisoned at some point during the descent. The weight shed and the difficulty of a controlled descent while following a pillar of flame to a landing site help lead to that decision.

Once the SRP boosters fall away, in most designs an aerobraking technology would take over. A commonly discussed technology at the conference was the ballute, a combination balloon and parachute. The idea behind this technology is to capture the air that is rushing past the landing craft and use it to fill a ballute that is tethered to the craft. The compression of the air rushing into the ballute would cause the gas to heat up, in effect creating a hot air balloon that would have similar lifting properties to those used on Earth. Assuming enough air is rushed into the ballute, it could provide the final deceleration needed to gently drop the landing craft off on the Martian surface, with minimal stress on the payload. However, the total amount this technology would slow the craft down is dependent on the amount of air it could inject into its structure. With more air come larger ballute, and more stresses on the material the ballute is made out of. With those considerations, it is not being considered as a stand-alone EDL technology.

These strategies barely scratch the surface of proposed EDL methods that could be used by a human mission to Mars. Curiosity, the newest rover soon set to land on Mars, is using several, including a unique form of SRP known as the Sky Crane. The results of its systems will help scientists like those at the LPI conference determine what suite of EDL technologies will be the most effective for any future human missions to Mars.

Read our previous article about the difficulties of landing large payloads on Mars, an interview with JPL’s Rob Manning.


Lead image caption: Artist’s concept of Hypersonic Inflatable Aerodynamic Decelerator slowing the atmospheric entry of a spacecraft. Credit: NASA

Second image caption: Supersonic jets are fired forward of a spacecraft in order to decelerate the vehicle during entry into the Martian atmosphere prior to parachute deployment. The image is of the Mars Science Lab at Mach 12 with 4 supersonic retropropulsion jets. Credit: NASA

Source: LPI Concept and Approaches for Mars Exploration

Posted on by Nancy Atkinson

Watch the James Webb Telescope Being Built Via “Webb-cam”

Want to watch the highly anticipated James Webb Space Telescope come together? NASA has set up a webcam – in this case a “Webb-cam” — for anyone to track the progress JWST inside a clean room at Goddard Space Flight Center. Recently, the Mid-Infrared Instrument (MIRI) was delivered and it will be integrated into the science instrument payload. Two cameras show the action, although the cameras will show just screen shots that are updated once every minute.

When is the best time to watch? The clean room is generally occupied Monday through Friday from 5 a.m. to 1:30 p.m. PDT (8 a.m. to 4:30 p.m. EDT).

Click the image above for access to the Webb-cams, or visit the Webb-cam website.

Of the James Webb Space Telescope’s four science instruments, only MIRI can see light in the mid-infrared region of the electromagnetic spectrum. This unique capability will allow the Webb telescope to study physical processes occurring in the cosmos that the other Webb instruments cannot see.

MIRI’s sensitive detectors will allow it to make unique observations of many things, including the light of distant galaxies, newly forming stars within our own Milky Way, and the formation of planets around stars other than our own, as well as planets, comets and the outermost debris disk in our own solar system.

Posted on by Nancy Atkinson

Fireworks Erupt From Newborn Star

Just in time for summer fireworks season, the Hubble science team has released an image of Herbig-Haro 110, a young star with geysers of hot gas skyrocketing away through interstellar space. Twin jets of heated gas are being ejected in opposite directions from this star that is still in the formation process. The Hubble team says these outflows are fueled by gas falling onto the young star, which is surrounded by a disc of dust and gas. If the disc is the fuel tank, the star is the gravitational engine, and the jets are the exhaust. And even though the plumes of gas look like whiffs of smoke, they are actually billions of times less dense than the smoke from a fireworks display.

More information about this image from the HubbleSite:

Herbig-Haro (HH) objects come in a wide array of shapes, but the basic configuration stays the same. Twin jets of heated gas, ejected in opposite directions away from a forming star, stream through interstellar space. Astronomers suspect that these outflows are fueled by gas accreting onto a young star surrounded by a disk of dust and gas. The disk is the “fuel tank,” the star is the gravitational engine, and the jets are the exhaust.

When these energetic jets slam into colder gas, the collision plays out like a traffic jam on the interstate. Gas within the shock front slows to a crawl, but more gas continues to pile up as the jet keeps slamming into the shock from behind. Temperatures climb sharply, and this curving, flared region starts to glow. These “bow shocks” are so named because they resemble the waves that form at the front of a boat.

In the case of the single HH 110 jet, astronomers observe a spectacular and unusual permutation on this basic model. Careful study has repeatedly failed to find the source star driving HH 110, and there may be good reason for this: perhaps the HH 110 outflow is itself generated by another jet.

Astronomers now believe that the nearby HH 270 jet grazes an immovable obstacle — a much denser, colder cloud core — and gets diverted off at about a 60-degree angle. The jet goes dark and then reemerges, having reinvented itself as HH 110.

The jet shows that these energetic flows are like the erratic outbursts from a Roman candle. As fast-moving blobs of gas catch up and collide with slower blobs, new shocks arise along the jet’s interior. The light emitted from excited gas in these hot blue ridges marks the boundaries of these interior collisions. By measuring the current velocity and positions of different blobs and hot ridges along the chain within the jet, astronomers can effectively “rewind” the outflow, extrapolating the blobs back to the moment when they were emitted. This technique can be used to gain insight into the source star’s history of mass accretion.

This image is a composite of data taken with Hubble’s Advanced Camera for Surveys in 2004 and 2005 and the Wide Field Camera 3 in April 2011.

Source: HubbleSite, ESA

Posted on by Jason Major

An Epic Crater Called Odysseus

On June 28 NASA’s Cassini spacecraft passed by Tethys, a 1,062-kilometer (662-mile) -wide moon of Saturn that’s made almost entirely of ice. Tethys is covered in craters of all sizes but by far the most dramatic of all is the enormous Odysseus crater, which spans an impressive 450 kilometers (280 miles) of the moon’s northern hemisphere — nearly two-fifths of its entire diameter!

In fact, whatever struck Tethys in the distant past probably should have shattered it into pieces… but didn’t.

Tethys likely held itself together because when the impact occurred that formed Odysseus, the moon was still partially molten. It was able to absorb some of the energy of the impact and thus avoid disintegration — although it was left with a quite the battle scar as an eternal reminder.

The images below are raw images from Cassini’s latest pass of Tethys, showing the moon’s rugged terrain and portions of Odysseus from a distance of 68,521 kilometers (42,577 miles).

The central peak of Odysseus has collapsed, leaving a depression — another indication that the moon wasn’t entirely solid at the time of impact.

Tethys orbits Saturn at a distance of 294,660 kilometers (183,100 miles), about 62,000 miles closer than the Moon is from Earth. Such a close proximity to Saturn subjects Tethys to tidal forces, the frictional heating of which likely helped keep it from cooling and solidifying longer than more distant moons. As a result Tethys appears somewhat less cratered than sister moons Rhea and Dione, which still bear the marks of their earliest impacts… although looking at the region south of Odysseus it’s hard to image a more extensively-cratered place.

Tethys is just another reminder of the violent place our solar system can be. Find out more about Tethys on the Cassini mission site here.

Image credits: NASA/JPL/Space Science Institute. Edited by J. Major. Images have not been calibrated or validated, and each has been level-adjusted and sharpened to bring out surface detail, and in some areas deinterlacing was used to remove linear raw image artifacts.