Jupiter is a great big question mark.  Like the king of the gods for whom it is named, the giant planet dominates the solar system, surrounding itself with an entourage of moons and other attendants.  The region of space all around Jupiter is filled with its gravitational field, its magnetic field and its zones of intense radiation.  Its nearer moons are heated by the tidal force of its gravity, allowing them to have inner oceans of water (probably) and sometimes active volcanoes.  Jupiter is our biggest gas giant planet, but we know from our observations of other planetary systems that  there are others that are much bigger.  These enormous planets, Jupiter and its big cousins, are really the main product of planet formation.  They suck up most of the matter that surrounds a planet-forming star, and the crumbs that are left over form the lesser planets.   Jupiter and its cloud of satellites are often called a mini-solar system, with good reason.

One of the main questions that Juno will attempt to answer is, exactly what is Jupiter?  Is there a solid planet down there, or is it just a globe of gas?  You will sometimes hear TV science programs saying that Jupiter has no solid body at its core, but the truth is, we just don’t know.  Understanding that will tell us how the planet formed in the first place.

In its most basic form, the question we’re asking is this: did a rocky core form first, and then attract the rest of the matter around it to form the planet, or did an unstable region of the solar nebula collapse and trigger the planet’s formation?  In the first case, the rocky core should still be there.  In the second case, there will only be gas all the way through, and while it will be extremely compressed at the center of the planet, there will be no rocky core there.

And that’s only one of the topics Juno will be investigating.  In the old myth, Jupiter made a cloud around himself to hide his misdeeds, but Juno was able to pull it aside and see within.  Hopefully, the analogy will prove to be appropriate.

(Just a few days ago, NASA made an announcement that points out our lack of understanding of Jupiter and its atmosphere: one of the iconic stripes has disappeared from the lower hemisphere of the planet.  Scientists confess that they are completely baffled by this event.  When Juno gets there, perhaps it can suggest an explanation of how a feature that has “always” been there can suddenly disappear.)

The Juno probe will be launched in August, 2011, aboard an Atlas V-551 rocket from Cape Canaveral.  The journey will take about five years, with the craft arriving at Jupiter in July of 2016.  The projected mission time (which may be changed, as we know) is one Earth year.  During that time, Juno will orbit Jupiter 32 times in a highly elliptical orbit that will bring it to within 3,000 miles of the planet at closest approach.

The specific goals of the Juno mission are:

1. Measure the amount of water in Jupiter’s atmosphere, which will help us figure out which theory of planetary formation is right, or if we need new theories.

2. Conduct in-depth study of Jupiter’s atmosphere, measuring composition, temperature, cloud motion, etc.

3. Make the first map of Jupiter’s gravity and magnetic fields, which should reveal the planet’s internal structure.

4. Specifically investigate Jupiter’s magnetosphere near the north and south poles, where enormous auroras occur that will hopefully give us new insights into how the planet’s magnetic field interacts with its atmosphere.

Like NASA’s previous Pioneer probes, Juno will spin on its axis to ensure stability and make aiming the craft easier.  Immediately after launch, Juno will be spun up by the rocket motors of its second-stage booster, to which it will still be attached.  When it enters Jupiter orbit, the spinning satellite will sweep space with its instruments once in each rotation.  At three rotations per minute, this means that Juno’s instruments will sweep Jupiter 400 times in the two hours it takes the craft to circle from pole to pole.

Juno will be the first solar-powered satellite made to operate so far from the sun.  Since Jupiter receives 25 times less sunlight than Earth, Juno will need three extra-large solar panels to provide sufficient energy.  These panels will be folded flat against the sides of the probe during launch.  When deployed, they will extend outward from the hexagonal body, giving the craft a span of more than 20 meters.

Thanks to recent technological advances in the field of solar power, Juno’s panels will be 50 percent more efficient and radiation tolerant than solar panels that were used just 20 years ago.  The mission needs only small amounts of electricity, since it will only be in use for about six hours out of each 11-day orbit of Jupiter.  (Juno will be in a highly elliptical orbit, and will only be observing the planet during its closest approach.)  Once it is in its working orbit, Juno will be in total sunlight for the duration of the mission; there will be no time when it is in Jupiter’s shadow.

There are zones of intense radiation around Jupiter which could easily fry the electronics of a space probe, so Juno will have all of its sensitive innards in a shielded vault. Juno is the first space probe to use such heavy shielding, and scientists will be watching carefully to see how well it works.  This line of research is relevant to future missions, since the harsh radiation of space is potentially harmful both to unmanned probes, and to the human crews that will eventually follow them.  To hedge its bets, Juno will try to avoid the worst areas of radiation by making its approaches to Jupiter over the planet’s north pole, dropping below the radiation belts, and then exiting over the south pole.

The smaller planets of the solar system have all seen extensive changes to their atmospheres during their lifetimes.  For instance, we now know that the atmospheres of both Mars and Venus were very different in their early days.  (See our articles on the Mars Express and Venus Express missions.)  But Jupiter, with its enormous gravity, has probably held onto all of the gas that it had at its formation. Planetary scientists will be very interested in studying the big planet’s atmosphere to see what it can tell us about the matter that was around in the solar system’s youth.  Juno will be able to observe that atmosphere in greater detail than ever before, seeing the global structure and motion of gases below the cloud tops for the first time, and mapping variations in the composition, temperature and patterns of motion down to unprecedented depths.

Jupiter has the brightest auroras in the solar system, and Juno will actually take samples of charged particles as it flies over the poles.  Its study of the auroras and the magnetic fields that produce them should increase our understanding of Jupiter and of all other powerful sources of magnetism, such as young stars with their own planetary systems.

So, those are some of the things that Juno will tell us about Jupiter.  This is really basic science, the kind of preliminary investigation that should pave the way for more complex enterprises in the future.  In fact, the mission overview at the NASA website points out that no new technology had to be invented for this mission.  It uses tried-and-true instruments that gather basic information- the kind of stuff that can tell us fundamental things about this giant planet, and about the beginnings of our solar system.

Juno will be launched in August of next year- and of course, you can read all about it here.

Sources:

“Juno: Unlocking Jupiter’s Mysteries” at the NASA website:  nasa.gov/mission_pages/juno/main/index.html

“Juno Mission Overview” at the NASA website:  nasa.gov/mission_pages/juno/overview/index.html

“Juno: Spacecraft and Instruments” at the NASA website: nasa.gov/mission_pages/juno/spacecraft/index.html

“Juno Mission News: Juno Taking Shape in Denver” at the NASA website:

nasa.gov/mission_pages/juno/news/juno20100405.html

In our last article, we took a look at NASA’s JEO and the main object of its observations, the intriguing moon Europa.  In this article, we will look at the ESA’s JGO, which will orbit Jupiter’s largest moon, Ganymede.

As we said above, the opening of the mission, upon arrival at Jupiter, is a collaborative overview of the entire Jovian system.  Because of its enormous gravity pull and magnetic field, the great planet has a big influence over its satellites, and the system must be viewed as a whole.  In particular, the magnetic interaction between all of these bodies is very complex, and will be studied in great detail.

In connection with this, there will be a contribution from the Japan Aerospace Exploration Agency.  JAXA is designing and building a probe called the Jupiter Magnetospheric Orbiter (JMO), which will perform some stand-alone observations of the Jovian magnetic environment, as well as collaborating with the JGO and JEO on multi-point measurements of Jupiter’s magnetic field and its interaction with its satellites.

So far, we haven’t mentioned the JMO because it will travel onboard the JGO until insertion into Jupiter orbit.  At that time, it will be deployed from the JGO and enter a separate orbit.

The Jupiter Magnetospheric Orbiter will be a spinning probe weighing about 400 kg., and it will be carrying a scientific payload of 25 kg.  When it is deployed, the spin axis will be tilted toward Earth.  This craft will employ technology borrowed from three earlier missions: the Nozomi Mars probe, the BepiColombo Mercury probe and the Solar Sail project.  (The BepiColombo and Solar Sail missions were mentioned in earlier articles at this website.  Nozomi was a Japanese unmanned Mars probe which was unfortunately lost due to technical problems, but its failure had nothing to do with the technology that will be recycled for use on the JMO.)  For its post-deployment maneuvers, it will be carrying 60 kg. of propellant.  For all of its other functions, it will be powered by electricity from two “paddle-wheel” solar panels.

(This info comes from the original mission proposal, and may change before completion.  In particular, the proposal expressed the wish to increase the payload weight.  Hopefully they will be successful in this.)

The JMO has an ambitious schedule of observations to make after being deployed from the JGO.  It will perform the first complete survey of the Jovian magnetosphere, mapping lines of magnetic force which run from Jupiter to its moons.  It will also address various questions relating to the interaction of the solar wind with the Jovian magnetosphere, as well as the effects of these interactions on the atmosphere of Jupiter.  As mentioned above, there will be some studies which will be performed in coordination with the JGO and JEO.  The presence of a third point of observation will allow the construction of three-dimensional images of the magnetosphere.

After separating from the JMO, the JGO will first take part in an elaborate series of maneuvers in coordination with the JEO, in which they will conduct a large-scale survey of Jupiter and its moon system.  The JGO’s primary goal is to study the moon Ganymede, but there will also be observations of Callisto, Io and Europa, performed either alone or in cooperation with the JEO.  After that, the JGO will go into orbit around Ganymede for prolonged observations.  (This is a greatly simplified description.  The full itinerary will include an ambitious- and confusing- array of maneuvers, a full discussion of which is far beyond the scope of this humble article.  For those who want more details, the websites of all three space agencies offer fascinating reading.)

Ganymede is Jupiter’s largest moon.  In fact, if this body orbited the sun instead of Jupiter, it would be classified as a planet.  It is larger than either Mercury or Pluto, and is three-quarters of the size of Mars.  It actually has an oxygen atmosphere, though the pressure is too low to support any kind of life known on Earth.

One interesting point about Ganymede, and the subject of some of the study on this mission, is that it is the only moon in the solar system with an active magnetic field.  Like so many other things in the Jupiter system, Ganymede’s magnetism is a result of Jupiter’s gravity.  In our last article, we saw that the big planet’s gravity causes tidal heating in the interiors of its moons, especially the closer ones.  This is the reason why Europa almost certainly has a liquid ocean beneath its surface, and it is also the reason for Io’s excessive volcanic activity.  Here we see another example, for without Jupiter’s gravity, Ganymede would not have its magnetic field.

As we saw in our article on the BepiColombo Mercury probe a couple of weeks ago, a body can only have an active magnetic field if it has a solid inner core with a molten mantle above it.  The molten mantle contains iron, and the heat which keeps it molten causes it to move in convection currents.  The solid core contains iron, too, and the movement of the molten iron mantle around the solid iron core is what makes the electrical current that forms the magnetic field.  Without this movement of iron around iron, electricity will not be generated, and the body will not have a magnetic field.  In the case of Ganymede, it is the tidal heating caused by Jupiter’s gravity that keeps the moon’s mantle liquid, allowing the convection movement that makes the whole process work.

During the time when the JGO is orbiting Ganymede, there will be times when the JEO is also passing close enough to allow coordinated observations involving both probes.  This will allow detailed study, with the JGO performing close study while the JEO observes from farther away.  In this way, it is hoped that they will be able to do precise mapping of the Ganymedan magnetic field.

We already know that Ganymede’s history has been long and complicated.  About forty percent of its surface is highly cratered, darker areas, while the other sixty percent is lighter in color, and is covered by an elaborate pattern of grooves.  The surface of Ganymede is mostly water ice, and these grooves are thought to be caused by tensional faulting of this ice, or by liquid water flowing up from below the surface.  Here, as on Europa, we have the near certainty of large amounts of liquid water beneath the surface.   The presence of liquid water always raises the possibility of life, and here again we get back to the main goal of the entire EJSM/LaPlace mission,  to search for habitable worlds.  This actually encompasses two separate questions: do these worlds have life now, and could they support human beings in the future?

The fourth moon to be examined will be Callisto, and these observations will be conducted primarily by the JGO, though the JEO will take part in some of them.  Callisto is the third largest moon in the solar system, and is almost as big as Mercury.  The unique and interesting thing about Callisto is that it seems to be a geologically dead world, with no visible seismic activity, vulcanism, or anything else to alter its surface.   Unlike the three other moons we have looked at, this one orbits much farther from Jupiter, so the kind of volcanic activity that we saw on Io, for example, is absent here.  Because of this, it is thought that Callisto has the oldest landscape in the solar system, preserving impact craters from the very early history of planetary formation.  All of the other bodies in the solar system have changed since then, but Callisto remains as a snapshot of the system’s childhood.  As you can imagine, this moon will be the subject of much study in the future, and the work that will be done by this mission will pave the way for that research by giving us our first close-up view of the body.

The EJSM/LaPlace mission is a huge undertaking which promises to yield a staggering amount of data.  Even if some of the science doesn’t come off as planned, this project will undoubtedly be one of the most productive and thorough space projects ever.  For years to come, we will be poring over the information that this project will give us.

We have always had our eyes on the moons of Jupiter.  Ever since Galileo looked through his homemade telescope and drew his first crude pictures of them, we have wanted to visit them.  The more we learn about them, the more interesting they get.  These are real worlds, with atmospheres, heat and water.  They may have life, and they certainly will have it in the future, for we will visit these bodies in person someday.  While it is unlikely that hellish Io will ever be settled by humans, it certainly makes an interesting place to study, and the other three Galilean moons will almost certainly feel the tread of human feet someday.  When that happens, it will be a direct result of the knowledge we gain from this mission.

Sources:

Solar System Exploration: Moons and Planets of the Solar System at NASA website:  solarsystem.jpl.nasa.gov/planets/

OPFM: Outer Planet Flagship Mission at website of Jet Propulsion Laboratory, California Institute of Technology:  opfm.jpl.nasa.gov/europajupitersystemmissionejsm/

OPFM: Outer Planet Flagship Mission- Jupiter Ganymede Orbiter (JGO) Concept at website of Jet Propulsion Laboratory, California Institute of Technology:  opfm.jpl.nasa.gov/europajupitersystemmissionejsm/jupiterganymedeorbiterjgoconcept/

Synergy Between JMO, JGO, and JMO at ISAS/JAXA website:  sprg.isas.jaxa.jp/jupiter/pukiwiki/index.php?Synergy%20between%20JMO%2C%20JGO%2C%20and%20JEO

Scope and Purpose: The Europa Jupiter System Mission (EJSM) at ISAS/JAXA website:  sprg.isas.jaxa.jp/jupiter/pukiwiki/index.php?I.%20SCOPE%20and%20PURPOSE

III “The Spacecraft” and III.1: “Current Plan” at ISAS/JAXA website:  sprg.isas.jaxa.jp/jupiter/pukiwiki/index.php?III.%20Spacecraft

II.2.1 “Main Objectives” at ISAS/JAXA website:  sprg.isas.jaxa.jp/jupiter/pukiwiki/index.php?II.2%20Magnetospheric%20and%20Space%20Sciences

IV.1 “The Current JAXA Plan” at ISAS/JAXA website:  sprg.isas.jaxa.jp/jupiter/pukiwiki/index.php?IV.%20Orbit%20and%20Operation

The two main spacecraft in the mission are NASA’s Jupiter Europa Orbiter (JEO) and the European Space Agency’s Jupiter-Ganymede Orbiter (JGO).  While the exact timeline has yet to be released, tentative plans would have the two crafts being launched about a month apart.  They will travel for about six years, and for a while after reaching Jupiter, they will work together.  The first part of the mission is an elaborate dance through the Jupiter system, collaborating on an overview of the giant planet and its system of satellites, which has been called a mini-solar system because of its size and complexity.   After that, the probes will go into their separate orbits around Europa and Ganymede for in-depth study.  During the course of the mission, there will also be flybys of Io and Callisto.

Because this mission is so big, and since it involves two spacecraft, we will divide it into two segments.  In this part, we will look at NASA’s Jupiter Europa Orbiter.  As the plan stands now, this probe will launch in February 2020 aboard an Atlas V 551 rocket.   The course that it will follow will be called the VEEGA course, since it involves one gravity assist maneuver at Venus and two at Earth.  On this trajectory, it will arrive at the Jupiter system in December 2025.  (Dates may change slightly as plans become firmer.)  After entering orbit around Jupiter, it will undertake a 30-month tour of the Jovian system, which will be followed by Europa Orbital Insertion (EOI) for a nine-month science mapping phase.  There will be several highlights in this tour:

1. Four encounters with the moon Io, with a possible volcanic plume flythrough.

2.  Six Europa encounters before the actual insertion into orbit around that moon.

3. Six encounters with Ganymede, to study that moon’s magnetosphere.

4.  Nine encounters with Callisto.

5.  Continuous monitoring of Jupiter and Io’s atmospheres.

After this, the probe will enter a 200 km. orbit around Europa, conduct a one-month mapping survey, then move to a 100 km. orbit for further observations.

The data collected by the JEO will add to the basic information we already know about this body.  Europa is a little smaller than Earth’s moon.  Like Earth, it is thought to have an iron core, a rocky mantle and an ocean of salt water.  However, this ocean is deep enough to cover the entire surface, and the top layer is frozen solid.  Europa is an ice world, its surface riddled with countless cracks.

When we look at Europa, we see evidence of the dominant theme of the Jupiter system: Jupiter.  The enormous planet influences everything here with its gravity.  It is tidal heating which causes Europa’s inner ocean to be liquid instead of solid, and it is Jupiter’s constant tugging on this water that causes the ice above it to be covered with an elaborate pattern of cracks.

Within that inner ocean, there may be life.  Nature has created a perfect environment for it here, containing both water and heat.  Of course, we won’t really know what’s in there until we can put landers down and take some samples, but the JEO will be doing the basic groundwork that will lead to that.  Using the information that comes from this mission, future missions will know where to go on Europa, and what to look for.  Someday a lander will reach this little world, put a periscope down through the ice, and have a look around.  When that happens, will something be looking back?  We won’t know until we try.

The investigation of Europa will follow the overall purpose of the entire EJSM mission: to assess habitability.  Specifically, does Europa support life, or could it in the future?  To simply ask this question is exciting.  We’re talking about exploration, future colonies and the possibility of extraterrestrial life.  The future is here.

But for now, we’re just trying to get a better idea of all the parts involved, and their relationship to each other.  How big is this layer of liquid water, and how big is the solid core beneath it?  How thick is the ice layer above it, and what are the variations in thickness and composition of this ice over the entire moon?  What is the nature of the surface-ice-ocean exchange?  What are the surface features?  How quickly are they changing?  What are the possible sites for future landings?  These are some of the questions that will be addressed by the JEO.

In addition to its ongoing survey of Europa, the JEO will also perform observations of Io, one of Jupiter’s other moons.  In contrast to Europa, Io is a fire world.  It is the most volcanically active body in the solar system, its surface constantly erupting in an ever-changing array of volcanoes, some of which hurl plumes of matter far into space.  Just as Europa’s inner ocean is the result of Jupiter’s gravity, so is Io’s volcanic activity.  The same tidal heating which melts Europa’s ice is more extreme here, generating enough heat to melt magma.  If there is a volcano conveniently erupting in the right direction when JEO flies by, the probe may be able to fly through the plume and take samples.   Even failing that, we should be able to get some spectrographic data from starlight shining through some of the plumes, and we can expect some wonderful pictures of a world that is about as close to Hell as we’ll ever find.

The lifespan of the JEO is uncertain.  It will eventually impact on Europa when it finally succumbs to radiation damage, or when it runs out of fuel for maneuvers.  By that time, it will have added volumes to our knowledge of the solar system’s biggest planet and its moons.

In our next article, we’ll take a look at the other half of the EJSM/LaPlace mission, the European Space Agency’s Jupiter Ganymede Orbiter.  As we said earlier, this probe will be performing some observations in coordination with the JEO, and will also do some “stand alone” science of its own, orbiting Jupiter’s largest moon while the JEO is orbiting Europa.   Watch for part two!

Sources:

Solar System Exploration: Moons and Planets of the Solar System at NASA website:  solarsystem.jpl.nasa.gov/planets/

Mission News: NASA and ESA Prioritize Outer Planets Missions at NASA website:  nasa.gov/topics/solarsystem/features/20090218.html

OPFM: Outer Planet Flagship Mission at website of Jet Propulsion Laboratory, California Institute of Technology:  opfm.jpl.nasa.gov/europajupitersystemmissionejsm/

OPFM: Outer Planet Flagship Mission- Jupiter/Europa Orbiter (JEO) Concept at website of Jet Propulsion Laboratory, California Institute of Technology:  http://opfm.jpl.nasa.gov/europajupitersystemmissionejsm/jupitereuropaorbiterconcept/

News: LaPlace, Studying the Jovian System at website of the European Space Agency:  esa.int/esaSC/SEMPHEWX3RF_index_0.html

Jupiter: Moons: Europa at website of Jet Propulsion Laboratory, California Institute of Technology:  solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Jup_Europa

The New Frontiers program came about following a study in 2001 which was conducted to look at the state of solar system exploration at that time and identify priorities for continued exploration during the 10 year period 2003 to 2013. The study identified five medium class missions that were considered of importance and the New Frontiers program was set up to examine and implement these.

The first mission launched was named New Horizons and its goal is to visit and explore Pluto. It will also visit one or more Kuiper Belt objects during the mission. New Horizons was launched in January 2006 and is scheduled to reach its destination by July 2015. The second New Frontiers mission is named Juno and has been designed to conduct an in-depth study of Jupiter. It is currently scheduled for launch in August 2011. At the end of December 2009 NASA announced that three candidates had been chosen for the third New Frontiers program and these include some exciting possibilities for solar system exploration.

The first potential candidate is named the Sunrise and Atmosphere Geochemical Explorer (SAGE) and would comprise a mission to Venus. On arrival it would release a probe into the atmosphere of the planet which would undertake extensive measurements as it descended to the surface of Venus. Upon landing the probe would conduct studies to assess the composition and mineralogy of the surface material.

The second candidate is called the Origins Spectral Interpretation Resource Identification Security Regolith Explorer or Osiris-Rex for short. This mission would be designed to travel to and orbit an asteroid. Extensive measurements of the asteroid would be taken while the spacecraft was in orbit around it. Samples would then be collected from the surface of the asteroid and these would be returned to Earth. These samples would be used to assist in the study of the formation of the solar system and the origins of the molecules necessary for life.

The third candidate would send a spacecraft to land in an area near the south pole of the moon which would collect lunar material and return it to Earth. This mission is known as Moonrise: Lunar South Pole – Aitken Basin Sample Return Mission. The returned lunar sample would be used to help gain an insight into the early history of the Earth-moon system.

Each of the candidates will now have around a year to complete a detailed concept study which is required to consider the feasibility of implementation, the costs involved and technical plans for carrying out and completing the mission. The teams will receive approximately $3.3 million to undertake the concept study and it is currently proposed that selection of the winning candidate will be made in mid 2011. Planning and preparation for the chosen mission would then take around seven years and the spacecraft has to be ready for launch by no later than the end of December 2018.

Each of the missions represents an opportunity for further study of a celestial body and the winning candidate is sure to advance our knowledge of the solar system. All three are potentially exciting opportunities to learn something new and any one of them would provide scientists with a rich source of data. Only time will tell which of the candidates will be successful and for now the three teams have a year of hard work ahead of them.

The Jupiter flyby was a huge success, allowing observations of the giant planet and its moons in unprecedented detail.  Among other things, information was gathered about the atmosphere and weather of Jupiter.  Data on cloud composition was collected by the visible light, infrared and ultraviolet remote sensing devices, and ammonia was observed welling up from the lower atmosphere to form clouds.  Lightning strikes were observed at the poles, the first polar lightning ever seen off Earth, and from this it was learned that heat moves evenly through water clouds at all latitudes across Jupiter.  New Horizons also made size and speed measurements of waves in the Jovian atmosphere, indicating strong storm activity beneath, and obtained close-up images of the Little Red Spot, a smaller version of the Great Red Spot.  The smaller feature is about half the size of the bigger one, or about 70 per cent of Earth’s diameter.

New Horizons obtained the clearest images yet of the tenuous Jovian rings.  Here clumps of material were observed that may be from a recent impact within the ring system.  The probe got a detailed view of the ring dynamics involved here, with moons Metis and Adrastea shepherding the materials around the rings.  A search for small moons within the rings yielded negative results.

The probe performed observations of Jupiter’s four largest moons, focusing especially on Io, closest to Jupiter and volcanically active.  Eleven volcanic plumes of varying size were seen, three for the first time.  One of these, a 200-mile-high eruption from the volcano Tvashtar, offered a chance to see the structure and motion of the plume as it condensed and fell back to the surface.  Instruments picked up infrared radiation from at least 36 volcanoes on Io with lava temperatures about 1900 degrees Fahrenheit, which is comparable to volcanoes on Earth.  Io is the most active body in the solar system, and more than 20 geological changes had occurred since the Galileo Jupiter orbiter was there in 2001.  Observations of Io while in Jupiter’s shadow showed glowing clouds over many of the volcanoes, a possible source of gas for Io’s atmosphere.

The probe passed down Jupiter’s magnetotail and got the closest-ever look at this region.  Particle detectors indicated that volcanic material from Io moves down the tail in slow-moving blobs.  Scientists are hoping to learn how these gases are ionized, trapped and energized by Jupiter’s magnetic field, and then finally ejected from the system.

New Horizons left Cape Canaveral in January, 2006.  It is the fastest spacecraft ever built, reaching Jupiter in only 13 months.  It is now about halfway between the orbits of Jupiter and Saturn, more than 743 million miles from Earth, and it will fly past Pluto and its moons Charon, Nix and Hydra in July 2015 before going deeper into the Kuiper Belt.

At present, the mission continues to go well.  In November of 2009, the probe was brought out of hibernation to repoint the communications dish antenna in order to keep up with the changing position of Earth around the sun.  This wake-up also provided an opportunity to download several months of stored data, correct a minor bug in the fault protection system software, perform adjustments to refine the craft’s trajectory, and upload instructions for the running of the craft from now until its next scheduled wake up in January 2010.

While New Horizons will not reach its destination until 2015, it will be able to perform some observations of Pluto and its largest moon, Charon, about a year earlier.  It will be taking pictures of the two at that point, and a few months later, it will be able to generate a map of Pluto.

The long approach will give an opportunity to watch seasonal changes in Pluto’s atmosphere.    Since 1989, Pluto has been heading away from the sun.  In 1999, it crossed the orbit of Neptune, once again becoming the outermost of the nine traditional planets.  It is now heading into its 200-year winter, when its atmosphere is expected to freeze and fall to the surface as snow, and because of this, the New Horizons mission will be the last chance to study the atmosphere of Pluto.  The probe will obtain information about its chemical composition, and also allow observations of cloud formation.  Clouds, probably composed of nitrogen or carbon monoxide, have already been observed in the thin atmosphere of Pluto.

Once New Horizons has passed Pluto, it will head out into the Kuiper Belt to find and study some of the mysterious bodies that exist there, which are thought to be icy and comet-like.  The probe will conduct a search for Kuiper Belt bodies, and when it finds them, will modify its own course to approach and observe them.  It is hoped that New Horizons will find six to ten of these bodies to study.

The outermost region of the solar system is a vast, dark area that is only beginning to reveal its secrets.   What else is out there?  Over the next few years, we will begin to find out.

Scientists are taking the search for extraterrestrial life to the high seas with two voyages now taking shape in the lab. If everything goes according to plan in about a decade a mission will launch to send a pair of probes to explore the moons of Jupiter. These probes will concentrate on Europa and Ganymede, and they will focus on exploring the oceans that may lurk beneath the surface.

A few years after the mission to the moons of Jupiter launches, an even more ambitious mission will explore the moons of Saturn. This ambitious probe will explore the polar seas thought to lurk beneath the surface of Saturn’s moon Enceladus. The same mission will also explore the seas of Titan, long considered a leading candidate for extraterrestrial life.

These modern missions will use a decidedly old fashioned approach to space exploration ”“ namely a hot air balloon that will hover over the deserts and mountains of the satellites, along with a boat designed to float on an ocean of liquid hydrocarbon.

This unique mission was first announced in February of 2009 as a joint venture of NASA and European Space Agency. Both the mission to Jupiter and the mission to Saturn are now in their critical early planning stages, but once those missions lift off they will provide a unique view of some of the most promising locations in the hunt for extraterrestrial life.

As it stands now the plan is for the Europe Jupiter System Mission, or EISM, to lift off early in 2020. The mission will proceed in two stages, with the NASA sponsored Jupiter Europa Orbiter and the European Space Agency’s Ganymede Orbiter due to be launched within a month of one another. The two spacecrafts will plot a parallel course for Jupiter, taking six years to reach their respective destinations. Once the probes reach the moons of Jupiter they will explore several of the planet’s satellites before each probe moves on to its primary target ”“ Europa and Ganymede respectively.

What makes these probes unique is the fact that they will explore not only the surface of each satellite but the depths of the moons as well. As far back as the Voyager space missions scientists have suspected that the frozen crust of these satellites hides a liquid ocean, and the presence of a liquid ocean could greatly boost the chances that extraterrestrial life is lurking within the confines of our own solar system. While other exploration has focused on the possibility of life on planets orbiting distant stars, these upcoming missions take a much more local approach to the hunt for life beyond the bounds of Earth.

In order to complete their missions the orbiters will be equipped with special radar designed to penetrate the thick polar ice covering the moons of Jupiter and Saturn. If this crust of ice is relatively thin ”“ only a few kilometers ”“ that ice penetrating radar may even be able to peer into the deep ocean beneath the surface. But even if the ice sheet is too thick for direct observation these probes are expected to shed new light on the features of these moons, providing scientists with a wealth of new information that could lead to clues about not only the existence of life but the formation of the solar system.

by beconrad

The art/science of studying the stars was engaged by several ancient populations like Maya, Incas, Egyptians and Greeks, and soon grew in importance to the point where those who practiced it were highly regarded and respected in their own society. The reason for this is evident: this science could provide, even from its first, rudimentary structure, an explanation to phenomena strictly connected to their life, such as the alternating of day and night or the cycle of seasons, and provided an essential instrument for activities such as agriculture and navigation.

The history of Astronomy is in part — from its origins to the invention of the telescope by Galileo Galilei, in 1610 — also the history of astrology. In prehistoric ages, the most advanced tribes were familiar with the motion and trajectories of just a few, visible objects like the sun, the moon and some of the brightest stars. The most commonly cited example of such knowledge is the Stonehenge complex, residing in Great Britain, which is thought to have served as a monumental calendar.

Chinese astronomy was born before 2000 BC and is still cited nowadays for its great tradition of carefully, a-critic documentation. From the documents in our possession we know that in their time they were already aware of events such as the passage of comets, or even the explosion of a Supernova star.

A few civilizations in central America also reached astonishing results, but unfortunately they didn’t manage to share they knowledge with other populations. Maya and Inca tribes would often build pyramids and temples, which were devoted to the Gods of the Sky. Their religion was strictly related to the planet Venus and, based on estimations of its motions, they managed to create an incredibly precise astronomical calendar, finding out, among other things, that the planet would accomplish five complete orbital revolutions in the time span of exactly 584 days.

Babylonians soon showed exceptional knowledge in the matter of astronomy, which would later be inherited by Egyptians and Indians. In their case, the desire to perfect this science at all costs came, rather than an actual need, from skeptical reasons that linked the motion of stars and planets to good or bad luck (solar and lunar eclipses were thought to bring extremely bad luck, and this conception would persist until relatively recent times). Even lacking any sort of precise instrumentation, Babylonians managed to find out many things about the apparent motion of planets, basing their observation on the position of a few bright stars on the sky: they therefore discovered the orbital revolution time of many planets, among which Venus, Mars, Jupiter and Saturn, only mistaking by a few days, and reporting the results of their calculations on special tables, most of which are well-preserved and can still be seen now in astronomical museums.

Egyptians’ immense and astonishing knowledge regarding astronomy relies, once more, on their ability to forge precise calendars describing the motion of stars and planets. As their life cycle was strictly linked to that of the Nile river, astronomy was given a central role by this society from the very beginning. Around 3000 BC, Egyptians were already used to dividing their day and night time in regular intervals of 12 parts each: day time would be measured by sundials, while night time would be measured by observing the relative position of 24 bright stars. Measuring this way, their ‘hours’ would have a different duration depending on the season, but still averaging 60 minutes each.

It was only with Greek astronomy, though, that a stress was posed on developing theories that would explain the birth of the Universe and its mechanics: Anaximander thought the planet Earth was a cylinder at the center of the Universe, while the stars would rotate around it in all directions; Plato had at a first time a theory, extremely advanced for its time, that put the Sun at the center of the Universe, but he later withdrew it to favor an Earth-centric theory similar to that of Anaximander; Eudoxus of Cnidus, finally, advanced a theory that was later approved by Aristotle, according to which the Universe was made of concentric spheres, rotating one inside another, where the Earth would be in the center.

The Aristotle conception of the structure of the universe was meant to last, with minimal variations, until the year 1500 AD, when Nicolaus Copernicus — which many consider the father of modern astronomy — advanced a theory that put the Earth orbiting in perfect circles around the Sun, together with all the other planets: this approach could in fact solve many of the contradictions that those who supported Aristotle had to face. A few decades later, John Kepler refused yet another innovative model of the universe from his mentor Tycho Brahe, and later became famous for formulating the three laws of star mechanics that were named after him, which are considered valid still nowadays.

In 1610, Galileo Galilei invented the telescope, after a long period of research and experimentation. As soon as he pointed it at the stars, a never seen before universe appeared in front of his eyes: the Moon had a surface full of craters, Jupiter was surrounded by four satellites, while the Milky Way suddenly appeared as nothing but a huge mass of countless stars. In 1632, after publishing his book ‘Dialogo sopra i due massimi sistemi del mondo’ [On the main two models of the Universe] in which he was openly exposing the results of his observations, he was forced by the Catholic Church to abjure not having made those discoveries.

A few decades later, while researching innovative techniques to build more and more powerful telescopes, an important debate took place between the scientist Huygens and Newton over the nature of light: the first said it was a wave, while the second thought it was made of physical ‘atoms’ (photons). The debate that was destined to be solved once and for all just a few decades ago (light is, indeed, both a wave and a physical object). Huygens studied advanced optics as well, and managed to build a telescope that could noticeably minimize the chromatic aberration in observations, which led him to discover Saturn’s rings and its moon, Titanus.

Just a few years later, Cassini and Romer found out that phenomena such as solar eclipses would happen just several minutes after they were expected: this led them to think that light could actually travel at a finite although extremely high speed, rather than to an infinite speed: their estimation put the speed of light at 230,000 km per hour (the actual speed of light is 300,000 km/h).

Starting from the 19th century, following the Industrial Revolution, the continuous development of innovative techniques and instruments for the observation of the sky led to a series of discoveries that quickly contributed to our knowledge. Nowadays, the main purpose of astronomy is to study the life cycle of stars and galaxies, the origin and future of the Universe, obscure objects like pulsars and black holes, and methods to measure interstellar distances with increased precision.