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New Horizons for Solar System Exploration: To Pluto and Beyond

To quote the late sci-fi author Douglas Adams, “Space is big, really big.  You just wouldn’t believe how hugely, vastly, mindbogglingly big space is.  You might think it’s a long way down the road to the chemist but that’s just peanuts to space.”  It takes a really long time to traverse the vast distance of even interplanetary space from Earth to Mars.  The recently deceased comet ISON spent the better part of a year travelling between Jupiter to the Sun before its demise in the Sun’s inferno.  Jupiter is roughly 778,000 kilometers from the Sun and Saturn is nearly twice that far away at 1.4 billion kilometers away.  Twice the distance from the Sun to Saturn is Uranus sitting a whopping 2.8 billion kilometers from the Sun.  Even further still is icy Neptune, so far away it’s existence was predicted before it was directly observed sits an incredible 4.8 billion kilometers from the Sun.  At this point in the solar system the Sun is nothing more than a small point of light almost appearing as just another background star in the Milky Way.  But the orbit of Neptune is just the seashore of the cosmic ocean that is our solar system.  Far beyond the orbit of Neptune lies a huge area known as the Kuiper Belt which is home to an unknown number of tiny icy worlds.  The most well-known of the Kuiper Belt objects (KBO) is the dwarf planet Pluto.  Until 2006 Pluto was recognized as the ninth planet in the solar system but was downgraded to dwarf planet when astronomers began discovering objects in its neighborhood that were both larger and smaller.  Pluto lies a mindbogglingly 5.8 billion kilometers from the Sun.  Together with its large moon Charon, Pluto marks the beginning of unexplored territory in our solar system.  No human spacecraft has ever visited Pluto.  Much of Pluto’s characteristics are unknown to us.  The same goes for all of the KBO’s in Pluto’s neighborhood.

Artists conception of New Horizons probe at Pluto

Artists conception of New Horizons probe at Pluto

NASA is on the verge of changing that.  The New Horizons spacecraft which was launched in January 2006 is just a year away from the beginning of its mission at Pluto.  New Horizons is travelling at about 1 million miles per day as it speeds into uncharted waters so to speak.  Currently approaching the orbit of Neptune, New Horizons is approximately 4 billion kilometers from the Sun.  The probe will arrive at its closest approach of Pluto on July 14, 2015 but the science will begin well before that in January 2015.  New Horizons is equipped with many instruments to help scientists analyze Pluto.  One such instrument is the Long Range Reconnaissance Imager (LORRI) which is essentially a long focal length telescope with a CCD imager to take high resolution images of the Plutonian surface beginning in January 2015.

An Historic Mission

Pluto is part of a vast unexplored trans-Neptune region of the solar system called the Kuiper Belt.  The inhabitants of the Kuiper Belt are thought to be the leftovers of planetary formation when rocky and icy bodies were being flung around the solar system.  These icy worlds didn’t quite form into full-fledged planets but they are worlds nonetheless.  Only five human spacecraft have ever traveled in this cold void before.  New Horizons is the first spacecraft to be sent to directly study a new body since the Voyager probes thirty years ago.  For my generation (milllennials) this is akin to the Apollo 11 moon landing in its scientific value.  I can’t think of any mission that is more important to the understanding of our solar system than New Horizons.

The unknown face of Pluto taken by Hubble.

The unknown face of Pluto taken by Hubble.

The Science

New Horizons will provide scientists with a smorgasbord of priceless data about Pluto and the KBO’s nearby.  Besides LORRI New Horizons is equipped with an ultraviolet spectrometer (ALICE) which will be used to analyze Pluto’s atmosphere, an optical/infrared instrument (RALPH) that will be used to create maps of the surfaces of Pluto and Charon, a particle detection instrument (PEPSSI) used to detect molecules escaping from the atmosphere, a particle instrument (SWAP) to measure the solar wind at Pluto, a radio instrument (REX) to observe the atmosphere and a student created instrument to collect dust particles that have traveled from the inner solar system.  The only thing we know about the surface of Pluto is from Hubble which provide a low resolution map that can only resolve surface features that are hundreds of kilometers in size.

One of the more interesting observations New Horizons will make is the study of Pluto’s atmosphere.  Pluto’s orbit is highly inclined to the ecliptic, the plane all the planets orbit in, and is highly eccentric (oval shaped).  This means that Pluto’s distance from the Sun varies greatly depending on where it is in its orbit.  The vast distance change is thought to cause molecules in Pluto’s atmosphere to condensate and sublimate and be lost to space.  The ALICE, PEPSSI, and REX instruments on New Horizons will measure the constitution of Pluto’s atmosphere and the rate at which it is being lost to space.

Beyond Pluto

Once New Horizons has completed its mission objectives for Pluto and Charon it will move on to studying some nearby KBO’s if any are in the vicinity.  So little is known about the Kuiper Belt and its citizens so any information on these icy worlds is practically invaluable.  The mission is slated to end in 2026 but if the spacecraft is still operational NASA has targeted the edge of the solar system just like with the Voyagers 1 and 2 missions.  Hopefully New Horizons will be able to reach the heliopause (the region where the solar wind from the Sun begins to interact with interstellar particles) and map this boundary point.  With the data from Voyager still inconclusive it is necessary to continue to explore this strange region of space.  The spacecraft is predicted to be inoperable by 2038 signally the end of its lifetime.  By then New Horizons will have contributed a massive volume of science and radically changed the way we view our solar system’s outer reaches.  Who knows what we’ll see when it finally reached Pluto next July?  Besides the data New Horizons provides, the probe is fulfilling our human curiosity and our desire to explore.  Space is the last frontier and there sure is a lot out there!

Geyser Erupts on Europa: Jovian Moon May Have Ice Geysers

Big news came from the Hubble Space Telescope today.  Observations from the famous telescope made in ultraviolet light show a large plume of hydrogen and oxygen spewing from, Jupiter’s moon, Europa’s south polar region.  Europa is one of Jupiter’s four largest moons, known as the Galilean Moons, after their discoverer Galileo Galilei in the 17th century.  The plume is guessed to be water gushing from cracks in the ice that covers the entire surface of Europa.  This is the first observation of geysers on Europa although it has been suspected for some time now.  

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Image of Europa with actual Hubble data superimposed on top to show where the plume was observed. Photo by NASA, ESA, and L. Roth (Southwest Research Institute and University of Cologne, Germany)

Europa is roughly the same size our our moon and is covered with ice.  This has been known for centuries since Galileo discovered the moon in 1610.  Europa is easily visible in binoculars and small telescopes and is extremely bright.  It was correctly guessed that Europa was covered in a layer of ice because it reflects a very high amount of sunlight.  Ice is one of the most reflective materials, about 70% of sunlight is reflected back off the surface.  The spacecraft we have sent to Jupiter such as Voyagers 1 and 2 and the Galileo probe confirmed the existence of an icy surface.  

The surface of Europa is interesting because it doesn’t contain any craters or any marks of impacts like the vast majority of moons in the solar system.  That means that Europa is constantly re-making its surface.  The same way glaciers and tectonic plates reform the surface of Earth, giant cracks along the surface of Europa indicate that the surface is geologically active.  Where there is surface tectonics there should be geological events such as volcanoes or geysers.  That’s what Hubble confirmed today.

The observations from Hubble showed a massive plume of water gushing from the moon’s south polar region.  The plume extends approximately 200 km (125 miles) into space.  Europa has no atmosphere and much less gravity than Earth so the vapor is able to spew well beyond the surface of Europa.  The water from the geyser was blasted from beneath the icy surface at a whopping 700 kilometers per hour (1,500 mph).  That’s three times faster than a commercial jet!  Two questions remain to be answered:  How do we know the geyser is shooting out water and where does that water come from?

A Veritable Waterworld

The existence of water on Europa has actually been known for a long time.  To know how this works we have to know a little bit about Europa’s orbital properties.  Europa orbits Jupiter, the solar system’s largest planet.  Jupiter’s gravity is so intense that it actually effects the insides of its closest moons.  Europa’s orbit is slightly elliptical, meaning that it isn’t a perfect circle, an ellipse or oval-shaped orbit.  Most celestial bodies have slightly elliptical orbits but Europa’s is more pronounced.  When Europa is closer to Jupiter the massive gravity of the planet literally squeezes the moon and stretches the rocky core.  This pressure and friction creates heat under the icy surface and has created a subsurface ocean on Europa.  It is guessed that Europa actually contains more water than Earth as Europa’s ocean is global, there are no landmasses.  NASA and the European Space Agency hope to eventually send a probe to Europa to explore this massive subsurface ocean because where water exists the possibility of life also exists.

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Artists conception of a cutaway of Europa showing the icy surface, subsurface ocean, and metallic core. Photo by NASA / JPL

The Giant Plume

We’ve answered where the water comes from, but how are scientists sure it is indeed water that was spewed from the surface and how does such a tiny moon have geysers that powerful?  Hubble doesn’t just do visible light observations.  The telescope is also equipped with a camera that can image in ultraviolet light.  The actual images taken by Hubble don’t show what we think of as a geyser like Old Faithful in Yellowstone National Park.  What Hubble observed was actually individual hydrogen and oxygen atoms in the plume.  Since Europa has no atmosphere the hydrogen and oxygen atoms were in space.  Jupiter, like Earth, generates an magnetic field in its solid metal core.  When the water from the geyser interacts with the electrons from Jupiter the water separates into its constituent hydrogen and oxygen atoms which glow in ultraviolet light.  That’s the best possible explanation for why Hubble observed these two individual atoms.

But where did the geyser come from?  Well as we saw earlier about Europa’s elliptical orbit, the moon is closer at some points and further away at others.  As Europa moves closer to Jupiter it is squeezed and crunched by Jupiter’s immense gravity.  Then as Europa moves further away from Jupiter cracks in the ice open up and allow the subsurface water to rise up and spew out.  As it so happens, Hubble recorded these observations while Europa was moving away from Jupiter so it makes sense that the cracks in the icy surface were opened up.

Teeming With Life?

The prospect of life swimming in Europa’s ocean has long been intriguing.  The discovery of geysers on Europa make the question even more worth exploring.  As we see from geysers on Earth, a lot of power in needed to blast material out from under the surface.  On Earth this comes from heat and pressure that builds up beneath cracks in the Earth’s crust.  When the heat and pressure becomes too great water and gases burst forth in a steaming awesome display of geological activity.  

One of the theories of how life began involves water and heat in the prehistoric oceans of Earth.  Hydrothermal vents on the ocean floor mix heat and amino acids to create the first organic materials.  To this day life thrives around hydrothermal vents despite the extremely alien conditions.  We know there is heat in Europa’s oceans due to the gravitational heating of the core from Jupiter and there’s water which is a universal solvent.  Could the mixing of amino acids, water, and heat have occurred on Europa as well?  The prospect is certainly intriguing and worthy of further exploration.  Curiosity is one of humanity’s definite traits so hopefully in a decade or two we will have a spacecraft on its way to Europa to explore the subsurface ocean and attempt to find evidence of life.  Imagine fish (or something totally alien) swimming around on the moon of a distant planet!  How that would change our views of life and its frequency throughout our galaxy! 

Hubble’s Hidden Treasures

Unless you’ve lived under a rock for the last 20 years (or on another planet) you’ve seen a plethora of beautiful images from the Hubble Space Telescope.  Many of Hubble’s images are some of the most iconic and awe-inspiring pictures of all time.  Since 1990, Hubble has been constantly observing the visible universe collecting scientific data for astronomers that has been used to determine the origin of our universe and further explore the vastness of the cosmos.  Hubble’s archive, however, is massive and many thousands of images have never been seen by anyone, save only a few scientists.  For a while now the scientists at the European Space Agency have been processing the data from the Hubble vault and producing mind-blowingly beautiful pictures of the data and releasing them as the Hubble Picture of the Week.  But the vault is just too large and there are thousands of hidden treasures still inside Hubble’s vault waiting to be unearthed.

The folks over at Spacetelescope.org have created a contest called Hubble’s Hidden Treasures to help plumb the depths of  riches of the archive of the world’s most well known telescope.  Between now and May 31st you can access the Hubble Legacy Archive website to search for images that Hubble has captured.  The browser-based image processing tools allow you to then adjust the basic properties of the image such as contrast, zoom, color balance, and more to turn the image into a spectacular photograph.  Prizes will be given away for the top images once the contest is over.

For those who own professional-grade image processing software there’s a contest for you too!  You can enter Hubble’s Hidden Treasures 2012 Image Processing Contest.  It works the same way as the normal contest but you can download the data from the Hubble Legacy Archive to your computer and use your favorite image processing software to create truly stunning photos.  For more information on both of these contests go to www.spacetelescope.org and happy imagulating!

Amazing Hubble

The Hubble Space Telescope really is an amazing piece of machinery!  We are approaching the 22nd anniversary of Hubble next month so I believe a little tribute is in order.  For the last 22 years Hubble has been constantly blowing our minds with stunning images of our solar system, our galaxy, and the universe.  Named after the great 20th century astronomer Edwin Hubble, the HST was charged with unlocking the mystery of Edwin Hubble’s greatest project:  the expansion of the universe.  The observatory has since succeeded with remarkably accurate precision.

Without a doubt, Hubble is the great triumph of the Shuttle era.  From its infamously defective mirror correction mission and several repair and upgrade missions over the years, all made possible by the Space Shuttle; Hubble has proven to be tougher and more effective than anyone could have imagined in 1990 when it was launched.  With Hubble we have peered into the furthest visible depths of the universe and seen what we could have previously only imagined.  We owe so much of our knowledge of the universe to the images and data Hubble has sent back to us.  We’ve more accurately determined the rate of expansion of the universe, estimated the age of the universe, discovered ancient supernovae, and discovering that galaxies may have black holes at their centers.  Some of the most stunning images of our universe have come from Hubble.  The HST is known for its incredibly sharp visible light images.

The most recent image to be released by Hubble is one of Messier 9, a globular cluster about 5,500 light years from the galactic center in the constellation Ophiuchus.  The recently captured image is the most detailed ever taken of M9.  The photo shows a myriad of differently colored stars, which number in the thousands.  One can clearly observe several different types of stars in the cluster.  The hotter bluish stars crowd the center of the cluster while the cooler red/orange stars are scattered mostly around the edges.  M9 has a total luminosity of roughly 120,000 times that of our Sun while only occupying the space of a pin point at arm’s length in the sky.  At 25,800 light years from Earth M9 is one of the closer globular clusters to Earth.  Globulars are interesting to astronomers because they contain some of the oldest stars in the galaxy and are a remnant of the galaxy’s infancy and formation.

M9 from Hubble Credit: NASA/HST

There are countless other images sent back from Hubble and I’m sure you’ve seen many of them.  Needless to say, Hubble surely ranks up near the top of NASA’s greatest hits.  The telescope is expected to remain in orbit and functional until at least 2014.  Hubble’s successor, the James Webb Space Telescope is expected to be launched by 2018 but delays and budget concerns have plagued the project for several years now.  Whenever Hubble de-orbits it will surely be remembered as one of mankind’s greatest scientific instruments.  Long live Hubble!

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