Terran Fleet at Mars Takes a Break for Conjunction – Enjoy the Video and Parting View

Curiosity and Mount Sharp - Parting Shot ahead of Solar Conjunction. Enjoy this parting view of Curiosity's elevated robotic arm and drill are staring at you - back dropped with her ultimate destination - Mount Sharp - in this panoramic vista of Yellowknife Bay basin snapped on March 23, Sol 223, by the rover's navigation camera system. The raw images were stitched by Marco Di Lorenzo and Ken Kremer and colorized. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/KenKremer (kenkremer.com). See video below explaining Mars Solar Conjunction

Curiosity and Mount Sharp – Parting Shot ahead of Mars Solar Conjunction
Enjoy this parting view of Curiosity’s elevated robotic arm and drill staring at you; back dropped with her ultimate destination – Mount Sharp – in this panoramic vista of Yellowknife Bay basin snapped on March 23, Sol 223, by the rover’s navigation camera system. The raw images were stitched by Marco Di Lorenzo and Ken Kremer and colorized. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/KenKremer (kenkremer.com)
See video below explaining Mars Solar Conjunction[/caption]

Earth’s science invasion fleet at Mars is taking a break from speaking with their handlers back on Earth.

Why ? Because as happens every 26 months, the sun has gotten directly in the way of Mars and Earth.

Earth, Mars and the Sun are lined up in nearly a straight line. The geometry is normal and it’s called ‘Mars Solar Conjunction’.

Conjunction officially started on April 4 and lasts until around May 1.

From our perspective here on Earth, Mars will be passing behind the Sun.

Watch this brief NASA JPL video for an explanation of Mars Solar Conjunction.

Therefore the Terran fleet will be on its own for the next month since the sun will be blocking nearly all communications.

In fact since the sun can disrupt and garble communications, mission controllers will be pretty much suspending transmissions and commands so as not to inadvertently create serious problems that could damage the fleet in a worst case scenario.

Right now there are a trio of orbiters and a duo of rovers from NASA and ESA exploring Mars.

The spacecraft include the Curiosity (MSL) and Opportunity (MER) rovers from NASA. Also the Mars Express orbiter from ESA and the Mars Odyssey (MO) and Mars Reconnaissance Orbiter (MRO) from NASA.

Geometry of Mars Solar Conjunction
Geometry of Mars Solar Conjunction

Because several of these robotic assets have been at Mars for nearly 10 years and longer, the engineering teams have a lot of experience with handling them during the month long conjunction period.

“This is our sixth conjunction for Odyssey,” said Chris Potts of JPL, mission manager for NASA’s Mars Odyssey, which has been orbiting Mars since 2001. “We have plenty of useful experience dealing with them, though each conjunction is a little different.”

But there is something new this go round.

“The biggest difference for this 2013 conjunction is having Curiosity on Mars,” Potts said. Odyssey and the Mars Reconnaissance Orbiter relay almost all data coming from Curiosity and the Mars Exploration Rover Opportunity, as well as conducting the orbiters’ own science observations.

The rovers and orbiters can continue working and collecting science images and spectral data.

But that data will all be stored in the on board memory for a post-conjunction playback starting sometime in May.

Ken Kremer

…………….

Learn more about Curiosity’s groundbreaking discoveries and NASA missions at Ken’s upcoming lecture presentations:

April 20/21 : “Curiosity and the Search for Life on Mars – (in 3-D)”. Plus Orion, SpaceX, Antares, the Space Shuttle and more! NEAF Astronomy Forum, Suffern, NY

April 28: “Curiosity and the Search for Life on Mars – (in 3-D)”. Plus the Space Shuttle, SpaceX, Antares, Orion and more. Washington Crossing State Park, Titusville, NJ, 130 PM

‘Green Peas’ Offer Tiny Clues to Early Universe

A montage of the six Green Pea galaxies that University of Michigan astronomy researchers studied. Image credit: Anne Jaskot

Today, we see an unobstructed view of the cosmos in all directions. But, a time existed near the Big Bang when the space between galaxies was an opaque fog where nothing could be seen. And according to two University of Michigan researchers, rare Green Pea galaxies, discovered in 2007, could offer clues into a pivotal step, called reionization, in the Universe’s evolution when space became transparent.

Reionization occurred just a few million years after the Big Bang. During this time, the first stars were beginning to blaze forth and galaxies. Astronomers believe these massive stars blasted the early universe with high-energy ultraviolet light. The UV light interacted with the neutral hydrogen gas it met, scraping off electrons and leaving behind a plasma of negatively charged electrons and positively charged hydrogen ions.

“We think this is what happened but when we looked at galaxies nearby, the high-energy radiation doesn’t appear to make it out. There’s been a push to find some galaxies that show signs of radiation escaping,” Anne Jaskot, a doctoral student in astronomy, says in a press release.

In findings released in the current edition of the Astrophysical Journal, Jaskot and Sally Oey, an associate professor of astronomy, the astronomers focused on six of the most intensely star-forming Green Pea galaxies between one billion and five billion light-years from Earth. The galaxies are compact and closely resemble early galaxies. The objects are thought to be a type of Luminous Blue Compact Galaxy, a type of starburst galaxy where stars are forming at prodigious rates. They were discovered in 2007 by volunteers with the citizen science project Galaxy Zoo. Named “peas” because of their fuzzy green appearance, the galaxies are very small. Scientists estimate that they are no larger than about 16,000 light-years across making them about the size of the Large Magellanic Cloud, a irregular galaxy near our Milky Way Galaxy.

Using data from the Sloan Digital Sky Survey, Jaskot and Oey studied the emission lines from the galaxies to determine how much light was absorbed. Emission lines tell astronomers not only what elements are present in the stars but also much about the intervening space. By studying this interaction, the researchers determined that the galaxies produced more radiation than observed, meaning some must have escaped.

“An analogy might be if you have a tablecloth and you spill something on it. If you see the cloth has been stained all the way to the edges, there’s a good chance it also spilled onto the floor,” Jaskot said. “We’re looking at the gas like the tablecloth and seeing how much light it has absorbed. It has absorbed a lot of light. We’re seeing that the galaxy is saturated with it and there’s probably some extra that spilled off the edges.”

This Week in Space Pics – April 5, 2013

The temperature anomaly map above, based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite, shows how this affected temperatures in the Northern Hemisphere.

So much space awesomeness this week.

Satellites collect more than just pretty pictures. NASA’s Earth Observatory website released this temperature anomaly map above, based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite, shows how this affected temperatures in the Northern Hemisphere.

See more of this week’s best images, below:

Comet PANSTARRS and M31 on April 4, 2013, as seen from Sweden. Credit and copyright: Göran Strand.
Credit and copyright: Göran Strand.

Our viewers have been sending in gorgeous pictures of Comet PANSTARRS paired with the Andromeda Galaxy, or M31. Göran Strand shared this view taken from Sweden on April 4, 2013 on Universe Today’s Flickr photo stream.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

With more than 400 active volcanoes, Io is the most volcanically active world in the Solar System. However, according to a new study released this week, the locations of Io’s volcanoes don’t quite line up where scientists think they should be. This five-frame sequence of images from NASA’s New Horizons mission captures the giant plume from Io’s Tvashtar volcano in March, 2007.

These three frames show the supernova dubbed SN UDS10Wil, or SN Wilson, the most distant Type Ia supernova ever detected. The leftmost frame in this image shows just the supernova’s host galaxy, before the violent explosion. The middle frame shows the galaxy after the supernova had gone off, and the third frame indicates the brightness of the supernova alone. Credit: NASA, ESA, A. Riess (STScI and JHU), and D. Jones and S. Rodney (JHU)
Credit: NASA, ESA, A. Riess (STScI and JHU), and D. Jones and S. Rodney (JHU)

These three frames from NASA’s Hubble Space Telescope show the supernova dubbed SN UDS10Wil, or SN Wilson, the most distant Type Ia supernova ever detected. The leftmost frame in this image shows just the supernova’s host galaxy, before the violent explosion. The middle frame shows the galaxy after the supernova had gone off, and the third frame indicates the brightness of the supernova alone.

This sequence of seven images from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter shows wind-caused changes in the parachute of NASA's Mars Science Laboratory spacecraft as the chute lay on the Martian ground during months after its use in safe landing of the Curiosity rover. Image credit: NASA/JPL-Caltech/Univ. of Arizona.
Image credit: NASA/JPL-Caltech/Univ. of Arizona.

This sequence of seven images from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter shows wind-caused changes in the parachute of NASA’s Mars Science Laboratory spacecraft as the chute lay on the Martian ground during months after its use in safe landing of the Curiosity rover.

A part of the Small Magellanic Cloud galaxy is dazzling in this new view from NASA's Great Observatories. The Small Magellanic Cloud, or SMC, is a small galaxy about 200,000 light-years way that orbits our own Milky Way spiral galaxy. Credit: NASA.
Credit: NASA.

The combined light of NASA’s Great Observatories creates amazingly beautiful images. A part of the Small Magellanic Cloud galaxy is dazzling in this new view from NASA’s Great Observatories. The Small Magellanic Cloud, or SMC, is a small galaxy about 200,000 light-years way that orbits our own Milky Way spiral galaxy.

A large prominence from the Sun, on April 1, 2013. Credit and copyright: Paul Andrew.
Credit and copyright: Paul Andrew.

Sheets of luminous plasma arc into space in this image of a large prominence from the Sun, taken on April 1, 2013.

An overlay of radio emission (contours) and a Hubble space telescope image of Supernova 1987A. Credit: ICRAR (radio contours) and Hubble (image.)
Credit: ICRAR (radio contours) and Hubble (image.)

Using the Australia Telescope Compact Array radio telescope in New South Wales, Australia, Supernova 1987A has been now observed in unprecedented detail and created this overlay of radio emission (contours) and a Hubble space telescope image of Supernova 1987A.

Prometheus keeps lonely watch over Saturn's F-ring in this image from NASA's Cassini mission. This view looks toward the unilluminated side of the rings from about 52 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 15, 2013.
Credit: NASA/JPL-Caltech/Space Science Institute

Prometheus keeps lonely watch over Saturn’s F-ring in this image from NASA’s Cassini mission. This view looks toward the unilluminated side of the rings from about 52 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 15, 2013.

Some of the Best Images of Earth from Space

A 'Blue Marble' image of the Earth taken from the VIIRS instrument aboard NASA's most recently launched Earth-observing satellite - Suomi NPP. This composite image uses a number of swaths of the Earth's surface taken on January 4, 2012. Credit: NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring.

This video compilation from the Goddard Space Flight Center takes a look back at the best views of our planet from space in the last year, including true color satellite images, Earth science data visualizations, time lapses from the International Space Station, and computer models.

Hydrogen Peroxide Could Feed Life on Europa

Reprocessed Galileo image of Europa's frozen surface by Ted Stryk (NASA/JPL/Ted Stryk)
Reprocessed Galileo image of Europa's frozen surface by Ted Stryk (NASA/JPL/Ted Stryk)

According to research by NASA astronomers using the next-generation optics of the 10-meter Keck II telescope, Jupiter’s ice-encrusted moon Europa has hydrogen peroxide across much of the surface of its leading hemisphere, a compound that could potentially provide energy for life if it has found its way into the moon’s subsurface ocean.

“Europa has the liquid water and elements, and we think that compounds like peroxide might be an important part of the energy requirement,” said JPL scientist Kevin Hand, the paper’s lead author. “The availability of oxidants like peroxide on Earth was a critical part of the rise of complex, multicellular life.”

The paper, co-authored by Mike Brown of the California Institute of Technology in Pasadena, analyzed data in the near-infrared range of light from Europa using the Keck II Telescope on Mauna Kea, Hawaii, over four nights in September 2011. The highest concentration of peroxide found was on the side of Europa that always leads in its orbit around Jupiter, with a peroxide abundance of 0.12 percent relative to water. (For perspective, this is roughly 20 times more diluted than the hydrogen peroxide mixture available at drug stores.) The concentration of peroxide in Europa’s ice then drops off to nearly zero on the hemisphere of Europa that faces backward in its orbit.

Hydrogen peroxide was first detected on Europa by NASA’s Galileo mission, which explored the Jupiter system from 1995 to 2003, but Galileo observations were of a limited region. The new Keck data show that peroxide is widespread across much of the surface of Europa, and the highest concentrations are reached in regions where Europa’s ice is nearly pure water with very little sulfur contamination.

This color composite view combines violet, green, and infrared images of Europa acquired by Galileo in 1997 for a view of the moon in natural color (left) and in enhanced color (right). Credit: NASA/JPL/University of Arizona
This color composite view combines violet, green, and infrared images of Europa acquired by Galileo in 1997 for a view of the moon in natural color (left) and in enhanced color (right). Credit: NASA/JPL/University of Arizona

The peroxide is created by the intense radiation processing of Europa’s surface ice that comes from the moon’s location within Jupiter’s strong magnetic field.

“The Galileo measurements gave us tantalizing hints of what might be happening all over the surface of Europa, and we’ve now been able to quantify that with our Keck telescope observations,” Brown said. “What we still don’t know is how the surface and the ocean mix, which would provide a mechanism for any life to use the peroxide.”

Read more: Evidence for a Deep Ocean on Europa Might Be Found on its Surface

The scientists think hydrogen peroxide is an important factor for the habitability of the global liquid water ocean under Europa’s icy crust because hydrogen peroxide decays to oxygen when mixed into liquid water. “At Europa, abundant compounds like peroxide could help to satisfy the chemical energy requirement needed for life within the ocean, if the peroxide is mixed into the ocean,” said Hand.

(Source: NASA)

What’s notable to add, on March 26, 2013, the U.S. President signed a bill that would increase the budget for NASA’s planetary science program as well as provide $75 million for the exploration of Europa. Exactly how the funds will be used isn’t clear — perhaps for components on the proposed Europa Clipper mission? —  but it’s a step in the right direction for learning more about this increasingly intriguing world. Read more on SETI’s Destination: Europa blog.

Join International Dark Sky Week (April 5-11, 2013)

International Dark Sky Week banner, courtesy Sean Parker Photography.

Take the next few nights to celebrate the stars! The International Dark Sky Week is a worldwide event, and part of Global Astronomy Month – going on now! The goals of IDSW are to appreciate the beauty of the night sky and to raise awareness of how poor-quality lighting creates light pollution.

The International Dark-Sky Association says that light pollution is a growing problem: “Not only does it have detrimental effects on our views of the night sky, but it also disrupts the natural environment, wastes energy, and has the potential to cause health problems.”

Here are some ways that the IDA suggests how you can spread the word about IDSW during April 5-11 — as well and all year long:

Join IDA online! Post about dark skies awareness on the social media sites, and you can follow the IDA on Facebook, Twitter, G+ and any other social media you like. And if you would like to become a partner email [email protected] to learn more. See a list of existing partners here.

Check around your home. Make sure your outdoor-lighting fixtures are well shielded — or at least angled down — to minimize “light trespass” beyond your property. Do you have security lights that stay on all night? Consider adding a motion-detector, which can pay for itself in energy savings in just a few months. You’ll find lots of great suggestions in “Good Neighbor Outdoor Lighting” and you can perform your own outdoor lighting audit.

Talk to your neighbors. Explain that bright, glaring lights are actually counterproductive to good nighttime vision. Glare diminishes your ability to see well at night, because the pupils of your eyes constrict in response to the glare — even though everything else around you is dark. Show them this handout.

International Dark Sky Week poster. Image courtesy Sean Parker Photography.
International Dark Sky Week poster. Image courtesy Sean Parker Photography.

Ask your local library if you can put up an IDA poster showing good and bad lights. Include a photo of the Earth at night, and take some pictures around town that show examples of good and bad lighting.

Become a Citizen Scientist with GLOBE at Night and similar programs, observe light pollution wherever you are and contribute to reports coming in from across the globe about light pollution. Or join GLOBE at Night’s Adopt-A-Street program and ‘map’ light pollution in your community.

Become a Dark Sky Ranger. Teachers and families can do these activities that include an outdoor lighting audit, a game, and hands-on crafts to help visualize the night sky better. In English. In Portuguese.

Attend or throw a star party! International Dark Sky Week is a great opportunity to dust off the old telescope in your attic and use it share in the wonder of the universe with your family, friends, and neighbors. Visit the Night Sky Network to find a calendar of star parties or to find an astronomy club in your area. Click here to find out what’s up in the sky. This activity book is full of great activities for budding stargazers of all ages!

Photograph the sky and enter it in the 2013 International Earth and Sky Photo Contest, run by The World at Night, or photograph some constellations and submit the pictures to the Dark Skies Photo Project to measure light pollution.

Here’s a great video: “Losing the Dark,” IDA’s public service announcement:

Comet PANSTARRS Meets the Andromeda Galaxy — More Amazing Images

Comet PANSTARRS and M31 on April 4, 2013, as seen from Sweden. Credit and copyright: Göran Strand.

More of our readers had success in capturing the awesomeness of seeing Comet PANSTARRS encounter the Andromeda Galaxy (M31) in the night sky. Göran Strand sent us this absolutely gorgeous image, taken from 70 km north of Östersund, Sweden — a really dark site with no light pollution. “This photo is a 30 minute exposure through my 300mm/f2.8 lens using my full format Nikon D3s camera,” Göran said. “Besides seeing the comet and the galaxy, I also got to see 4 elks, 2 meteors, 1 bolide and 1 aurora. So all in all, it was a good night!”

That’s for sure!

See more images below of this great meet-up in the skies, and see our earlier post of our readers’ images here.

Comet C/2011 L4 Panstarrs and the Andromeda Galaxy: Two Frame Mosaic from New Mexico Skies, April 4, 2013. Taken from New Mexico Skies at 23:22  UT using an FSQ 10.6-cm and STL11K camera.  Credit and copyright: Joseph Brimacombe.
Comet C/2011 L4 Panstarrs and the Andromeda Galaxy: Two Frame Mosaic from New Mexico Skies, April 4, 2013.
Taken from New Mexico Skies at 23:22 UT using an FSQ 10.6-cm and STL11K camera. Credit and copyright: Joseph Brimacombe.
The encounter between Comet PANSTARRS and the Andromeda Galaxy, as seen from Ireland. 'A difficult image to capture due to low cloud, the low altitude of the target and tracking Issue.'  Image details: Date: 03 Apr 2013, 22:30-23:30 Exposure: 9 x 5min, ISO 1600, F5, 6 x dark frames, 6 x flats frames. Equipment: Canon 1000D, CG5 Mount, Sigma 70-300mm set at 200mm. Credit and copyright: Brendan Alexander.
The encounter between Comet PANSTARRS and the Andromeda Galaxy, as seen from Ireland. ‘A difficult image to capture due to low cloud, the low altitude of the target and tracking Issue.’ Image details: Date: 03 Apr 2013, 22:30-23:30
Exposure: 9 x 5min, ISO 1600, F5, 6 x dark frames, 6 x flats frames.
Equipment: Canon 1000D, CG5 Mount, Sigma 70-300mm set at 200mm. Credit and copyright: Brendan Alexander.
Comet PANSTARRS and M31 taken from the Scottish Dark Sky Observatory on April 3, 2013. Credit and copyright: Dave Hancox via Google+.
Comet PANSTARRS and M31 taken from the Scottish Dark Sky Observatory on April 3, 2013. Credit and copyright: Dave Hancox via Google+.
Comet C/2011 L4 (PANSTARRS) and M31 (Andromeda Galaxy) taken from just outside St Clears, Carmarthenshire, Wales on 29th March 2013 around 9pm. Credit and copyright: Pete Newman.
Comet C/2011 L4 (PANSTARRS) and M31 (Andromeda Galaxy) taken from just outside St Clears, Carmarthenshire, Wales on 29th March 2013 around 9pm. Credit and copyright: Pete Newman.

Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.

How Do Astronauts on the Space Station Stay in Touch with Earth?

The International Space Station. Credit: NASA

Gemini 8 was in trouble. The spacecraft was spinning rapidly, the astronauts were fighting to stay conscious, and worst of all — they were out of the reach of NASA’s Mission Control.

The astronauts eventually did make contact during that 1966 mission, and splashed down safely. Still, the incident illustrated a weakness of having scattered ground stations staying in touch with orbiting spacecraft. NASA had a large network of stations, including ships and remote satellite dishes, but there were large gaps in coverage.

Today, NASA and Roscosmos (the Russian space agency) have virtually 100% communications contact with orbiting astronauts and cosmonauts in the International Space Station, including video. That’s due to a network of satellites called the Tracking and Data Relay Satellite system. The first of these satellites launched 30 years ago today (April 5) in 1983.

A United Launch Alliance Atlas V 401 rocket streaks away from Space Launch Complex 41 into the night sky over Cape Canaveral Air Force Station in Florida, carrying NASA's Tracking and Data Relay Satellite-K, TDRS-K, to orbit. Credit: NASA/Glenn Benson
A United Launch Alliance Atlas V 401 rocket streaks away from Space Launch Complex 41 into the night sky over Cape Canaveral Air Force Station in Florida, carrying NASA’s Tracking and Data Relay Satellite-K, TDRS-K, to orbit. Credit: NASA/Glenn Benson

TDRS includes seven operational satellites that are in geosynchronous orbit (essentially, in an orbit that keeps them above a fixed location on Earth.) The satellites are designed to serve spacecraft that are orbiting in low Earth orbit, above 45 miles (73 kilometers) in altitude. They’re spaced out to make sure that customers receive coverage throughout the orbit. Operations on the ground consist of two ground terminals located near Las Cruces, New Mexico.

Launching these satellites took years. Although the first satellite was deployed successfully, the second one was destroyed in the Challenger shuttle explosion of 1986. The rest of the first generation of TDRS satellites went into space between 1988 and 1995. Three more advanced satellites then launched between 2000 and 2002.

This means the TDRS fleet is getting pretty old, but luckily, there are fresh replacements on the way. TDRS-K launched in January and is still being tested before assuming operational status. TDRS-L will launch in 2014, and TDRS-M in 2015.

Io’s Volcanoes are in the Wrong Place

This five-frame sequence of images from NASA's New Horizons mission captures the giant plume from Io's Tvashtar volcano in March, 2007. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

Jupiter’s moon Io features at least 400 active volcanoes, making it the most volcanically active world in our Solar System. However, the location of the volcanoes on Io just doesn’t match up with scientific models that predict how the moon’s interior is heated.

“Rigorous statistical analysis of the distribution of volcanoes in the new global geologic map of Io,” said Christopher Hamilton of the University of Maryland, College Park and the Goddard Spaceflight Center. “We found a systematic eastward offset between observed and predicted volcano locations that can’t be reconciled with any existing solid body tidal heating models.”

Io’s internal heat is created by the tidal forces inflicted from the giant planet Jupiter on one side and from two neighboring moons that orbit further from Jupiter – Europa and Ganymede on the other.

Researchers say there are questions about how this tidal heating affects the moon’s interior. Some propose it heats up the deep interior, but the prevailing view is that most of the heating occurs within a relatively shallow layer under the crust, called the asthenosphere. The asthenosphere is where rock behaves like putty, slowly deforming under heat and pressure.

“Our analysis supports the prevailing view that most of the heat is generated in the asthenosphere, but we found that volcanic activity is located 30 to 60 degrees East from where we expect it to be,” said Hamilton.

On Earth, a simple explanation how volcanoes are created is that when tectonic plates shift in such a way, the subsurface magma is able to flow onto the surface. On Io, the tidal forces from Jupiter actually force Io’s surface to bulge up and down by as much as 100 m, causing magma to flow continuously.

The scientists explained the tug-of-war between Jupiter’s massive gravity and the smaller but precisely timed pulls from two neighboring moons like this:

Io orbits faster than these other moons, completing two orbits every time Europa finishes one, and four orbits for each one Ganymede makes. This regular timing means that Io feels the strongest gravitational pull from its neighboring moons in the same orbital location, which distorts Io’s orbit into an oval shape. This in turn causes Io to flex as it moves around Jupiter.

For example, as Io gets closer to Jupiter, the giant planet’s powerful gravity deforms the moon toward it and then, as Io moves farther away, the gravitational pull decreases and the moon relaxes. The flexing from gravity causes tidal heating — in the same way that you can heat up a spot on a wire coat hanger by repeatedly bending it, the flexing creates friction in Io’s interior, which generates the tremendous heat that powers the moon’s extreme volcanism.

This is a map of the predicted heat flow at the surface of Io from different tidal heating models. Red areas are where more heat is expected at the surface while blue areas are where less heat is expected. Figure A shows the expected distribution of heat on Io's surface if tidal heating occurred primarily within the deep mantle, and figure B is the surface heat flow pattern expected if heating occurs primarily within the asthenosphere. In the deep mantle scenario, surface heat flow concentrates primarily at the poles, whereas in the asthenospheric heating scenario, surface heat flow concentrates near the equator. Credit: NASA/Christopher Hamilton.
This is a map of the predicted heat flow at the surface of Io from different tidal heating models. Red areas are where more heat is expected at the surface while blue areas are where less heat is expected. Figure A shows the expected distribution of heat on Io’s surface if tidal heating occurred primarily within the deep mantle, and figure B is the surface heat flow pattern expected if heating occurs primarily within the asthenosphere. In the deep mantle scenario, surface heat flow concentrates primarily at the poles, whereas in the asthenospheric heating scenario, surface heat flow concentrates near the equator. Credit: NASA/Christopher Hamilton.

But a new geologic map of Io showed the offset of the volcanoes from where the model predicted them to be.

Possibilities to explain the offset include a faster than expected rotation for Io, an interior structure that permits magma to travel significant distances from where the most heating occurs to the points where it is able erupt on the surface, or a missing component in existing tidal heating models, like fluid tides from an underground magma ocean, according to the team.

The magnetometer instrument on NASA’s Galileo mission detected a magnetic field around Io, suggesting the presence of a global subsurface magma ocean. As Io orbits Jupiter, it moves inside the planet’s vast magnetic field. Researchers think this could induce a magnetic field in Io if it had a global ocean of electrically conducting magma.

“Our analysis supports a global subsurface magma ocean scenario as one possible explanation for the offset between predicted and observed volcano locations on Io,” says Hamilton. “However, Io’s magma ocean would not be like the oceans on Earth. Instead of being a completely fluid layer, Io’s magma ocean would probably be more like a sponge with at least 20 percent silicate melt within a matrix of slowly deformable rock.”

Tidal heating is also thought to be responsible for oceans of liquid water likely to exist beneath the icy crusts of Europa and Saturn’s moon Enceladus. Since liquid water is a necessary ingredient for life, some researchers propose that life might exist in these subsurface seas if a useable energy source and a supply of raw materials are present as well. These worlds are far too cold to support liquid water on their surfaces, so a better understanding of how tidal heating works may reveal how it could sustain life in otherwise inhospitable places throughout the Universe.

“The unexpected eastward offset of the volcano locations is a clue that something is missing in our understanding of Io,” says Hamilton. “In a way, that’s our most important result. Our understanding of tidal heat production and its relationship to surface volcanism is incomplete. The interpretation for why we have the offset and other statistical patterns we observed is open, but I think we’ve enabled a lot of new questions, which is good.”

Io’s volcanism is so extensive that it gets completely resurfaced about once every million years or so, actually quite fast compared to the 4.5-billion-year age of the solar system. So in order to know more about Io’s past, we have to understand its interior structure better, because its surface is too young to record its full history, according to Hamilton.

Source: JPL

A Look at the Hazards of Green Laser Pointers

An appropriate use of a laser during last year's Jupiter-Venus conjunction. (Photo by Author).

Those handheld green lasers pointers may not be as harmless as you thought.

A recent study released by researchers at the National Institute of Standards and Technology (NIST) has revealed an alarming trend. Of 122 hand-held laser pointers tested, 44% of red lasers and 90% of green lasers tested failed federal safety regulations.

The primary culprit was overpowered units. The Code of Federal Regulations in the United States limits commercial class IIIa lasers to 5 milliwatts (mW). And yes, lasers above 5 mW are commercially available in the United States, but it is illegal to market them as Class IIIa devices.  Some units in the NIST study  tested as high as 13 times over the legal limit at 66.5 mW. For context, many military grade rifle mounted lasers are rated at 50 mW.

A diagram of a typical diode-pumped solid-state laser. (Credit: NASA/Langley).
A diagram of a typical diode-pumped solid-state laser. (Credit: NASA/Langley).

“Our results raise numerous safety questions regarding laser pointers and their use,” stated NIST laser safety officer in the recent paper presented at the Laser Safety Conference in Orlando, Florida.

Why should backyard astronomers care? Well, since hand-held lasers first became commercially available they’ve become a familiar staple at many public star parties. Reflecting back off of the dust and suspended particles in the atmosphere, a green laser provides a pointer beam allowing the user to trace out constellations and faint objects. Lasers can also be mounted on the optical tube assemblies of a telescope for pointing in lieu of a finder scope.

A typical 5mW green laser pointer. (Photo by Author).
A typical 5mW green laser pointer. (Photo by Author).

An amateur astronomy club based near San Antonio, Texas even coordinated signaling the International Space Station with a pair of powerful searchlights and a 1 watt blue laser in 2012, just to prove that it was possible.

But such devices are not toys. Even a 5 mW laser can temporarily blind someone at short range. Further eye damage can often linger for days or even permanently and can go unnoticed. This is why researchers working around lasers in research facilities such as LIGO (the Laser Interferometer Gravitational Wave Observatory) must submit to routine eye exams.

Its not the Death Star... LIGO engineers practicing proper safety around the gravity wave observatory's  200 watt laser. Credit: NSF/LIGO).
Its not the Death Star… LIGO engineers practicing proper safety around the gravity wave observatory’s 35 watt Nd YAG laser. Credit: NSF/LIGO).

The trouble with green lasers is that, well, they look too much like light sabers.

It’s for this reason I keep mine on a very “short leash” at star parties and NEVER hand it off to anyone, no matter how well meaning, child or adult. I also NEVER point it below the local horizon, (there’s wildlife in them trees). A laser reflected inadvertently off of an optical surface such as a car window or primary mirror can also do just as much damage as a direct aiming.

And also, NEVER aim one at an aircraft. In fact, it’s a federal violation to do so. The Federal Aviation Administration has reported a 13-fold trend in reported aircraft/laser incidents from 2005 to 2011. There has also been an upward trend in individuals being tracked down and prosecuted for such offenses. If it blinks, assume it’s an aircraft and steer clear!

Reported incidents of laser/aircraft violations from 2005-2011. (Credit: Federal Aviation Administration).
Reported incidents of laser/aircraft violations from 2005-2011. (Credit: Federal Aviation Administration).

In a post-9/11 era, the Department of Homeland Security has been concerned with the potential threat posed by laser pointers as well. It’s not yet illegal to fly in the US with a 5mW laser pointer in your carry-on luggage, but and several countries now outlaw them all together, a note for traveling astronomers. Note that the de facto policy often comes down to the particular TSA officer you’re dealing with.

With this sort of news, we wonder if laser pointers might become outlawed entirely in the coming years. 5mW range lasers are generally classed IIIa or 3R systems. By the American National Standards Institute (ANSI) guidelines, such devices under the recent NIST study would fall into the much more hazardous IIIb range for 5-500 mW lasers. Such lasers can cause permanent eye damage with direct exposure for periods of as little as 1/100th of a second.

Safety distances for a 5mW green laser. (Wikimedia Commons graphic under a Creative Commons Attribution-ShareAlike 30 License).
Safety distances for a 5mW green laser. (Wikimedia Commons graphic under a Creative Commons Attribution-ShareAlike 3.0 License).

It’s also worth noting that actual reported cases of laser injuries are fairly rare. A 2004 paper from the Archives of Ophthalmology cites 15 injuries worldwide each year, while a recent 2012 paper in PLoS ONE estimates “220 confirmed laser eye injuries have occurred between 1964 and 1996,” for an average of 6.9 laser injuries per year.

The Code of Federal Regulations limits output for green laser pointers to 5mW in the visible range and 2mW in the infrared. 75% of the tested devices exceed this standard for infrared emission as well. Note that there have been anecdotal reports that even the point source generated by a laser (say, by shining it against a wall) can be excessively bright. This recent NIST study was the first time we’d seen a back up argument for this. Many of the cheaper handheld lasers sold online (think in the 20$ USD range) may forgo the infrared filtering component all together.

So in lieu of an outright ban on laser pointers, what can be done? Joshua Hadler cites the need for a better accountability for laser manufacturers. “By relying on manufacturers’ traceability to a national measurement institute such as NIST, someone could use this design to accurately measure power from a laser pointer.” Mr. Hadler also notes that a simple test bed for laser pointers can be built using off the shelf parts for less than $2,000 USD. We’re surprised there’s not “an App/Kickstarter for that…” already. (Would-be designers take note!)

In the end, we’d hate to see these crucial tools for astronomy outreach  banned just because a very few individuals were irresponsible with them. Through accountability from production to application, we can assure that laser pointers remain a vital part of the amateur astronomer’s tool kit.