Last, Best Look at Pluto’s Far Side and Four Perplexing Spots: 2 Days Out from Flyby

New Horizons' last look at Pluto's Charon-facing hemisphere reveals the highest resolution view of four intriguing darks spots for decades to come. This image, taken early the morning of July 11, 2015, shows newly-resolved linear features above the equatorial region that intersect, suggestive of polygonal shapes. This image was captured when the spacecraft was 2.5 million miles (4 million kilometers) from Pluto. Credit: NASA/JHUAPL/SWRI

New Horizons’ last look at Pluto’s Charon-facing hemisphere reveals the highest resolution view of four intriguing darks spots for decades to come. This image, taken early the morning of July 11, 2015, shows newly-resolved linear features above the equatorial region that intersect, suggestive of polygonal shapes. This image was captured when the spacecraft was 2.5 million miles (4 million kilometers) from Pluto. Credit: NASA/JHUAPL/SWRI
Story updated[/caption]

Today (July 11) we got our last, best and clearest look at a quartet of perplexing dark spots on Pluto’s far side from NASA’s New Horizons spacecraft – now just two days and two million miles (4 million km) out from history’s first ever up close flyby of the Pluto system on Tuesday, July 14.

The four puzzling spots (see above) are located on the hemisphere of Pluto which always faces its largest moon, Charon, and have captivated the scientists and public alike. Pluto and Charon are gravitationally locked with an orbital period of 6.4 days.

Over only the past few days, we are finally witnessing an amazing assortment of geological wonders emerge into focus from these never before seen worlds – as promised by the New Horizons team over a decade ago.

Be sure to take a good hard look at the image, because these spots and Pluto’s Charon-facing hemisphere will not be visible to New Horizons cameras and spectrometers during the historic July 14 encounter as the spacecraft whizzes by the binary worlds at speeds of some 30,800 miles per hour (more than 48,600 kilometers per hour) for their first up close reconnaissance.

And it’s likely to be many decades before the next visitor from Earth arrives at the frigid worlds at the far flung reaches of our solar system for a longer look, hopefully from orbit.

“The [July 11] image is the last, best look that anyone will have of Pluto’s far side for decades to come,” said New Horizons principal investigator Alan Stern of the Southwest Research Institute, Boulder, Colorado, in a statement.

The image of the mysterious spots was taken earlier today (July 11) by New Horizons Long Range Reconnaissance Imager (LORRI) at a distance of 2.5 million miles (4 million kilometers) from Pluto, and just released by NASA. The image resolution is 10 miles per pixel. One week ago it was only 40 miles per pixel.

They were first seen only in very recent LORRI images as Pluto’s disk finally was resolved and are located in a Missouri sized area about 300 miles (480 kilometers) across and above the equatorial region.

But until today they were still rather fuzzy – see image below from July 3! What a difference a few million miles (km) makes!

Latest color image of Pluto taken on July 3, 2015. Best yet image of Pluto was taken by the LORRI imager on NASA’s New Horizons spacecraft on July 3, 2015 at a distance of 7.8 million mi (12.5 million km), just prior to the July 4 anomaly that sent New Horizons into safe mode. Color data taken from the Ralph instrument gathered earlier in the mission.  Credit: NASA/JHUAPL/SWRI
Latest color image of Pluto taken on July 3, 2015. Best yet image of Pluto was taken by the LORRI imager on NASA’s New Horizons spacecraft on July 3, 2015 at a distance of 7.8 million mi (12.5 million km), just prior to the July 4 anomaly that sent New Horizons into safe mode. Color data taken from the Ralph instrument gathered earlier in the mission. Credit: NASA/JHUAPL/SWRI

“The Pluto system is totally unknown territory,” said Dr. John Spencer, New Horizons co-investigator at today’s (July 11) daily live briefing from NASA and the New Horizons team.

“Pluto is like nowhere we’ve even been before. It is unlike anything we’ve visited before.”

Now, with the $700 million NASA planetary probe millions of miles closer to the double planet, the picture resolution has increased dramatically and the team can at least speculate.

Researchers say the quartet of “equally spaced” dark splotches are “suggestive of polygonal shapes” and the “boundaries between the dark and bright terrains are irregular and sharply defined.”

“It’s weird that they’re spaced so regularly,” says New Horizons program scientist Curt Niebur at NASA Headquarters in Washington.

However their nature remains “intriguing” and truly “unknown.”

“We can’t tell whether they’re plateaus or plains, or whether they’re brightness variations on a completely smooth surface,” added Jeff Moore of NASA’s Ames Research Center, Mountain View, California.

“It’s amazing what we are seeing now in the images, showing us things we’ve never seen before,” said Spencer.

“Every day we see things we never knew before. We see these crazy black and white patterns. And we have no idea what these mean.”

Answering these questions and more is what the encounter is all about.

Pluto is just chock full of mysteries, with new ones emerging every day as New Horizons at last homes in on its quarry, and the planet grows from a spot to an enlarging disk with never before seen surface features, three billion miles from Earth after an interplanetary journey of some nine and a half years.

“We see circular things and wonder are those craters? Or are they something else,” Spencer elaborated.

“We saw circular features on Neptune’s moon Triton that are not craters. So we should know in a few days . But right now we are just having an awful lot of fun just speculating. It’s just amazing.”

Until a few days ago, we didn’t know that “the other Red Planet” had a big bright heart and a dark ‘whale-shaped’ feature – see my earlier articles; here and here.

Pluto’s “Heart” is seen in this new image from New Horizons’ Long Range Reconnaissance Imager (LORRI) received on July 8, 2015 after normal science operations resumed following the scary July 4 safe mode anomaly that briefing shut down all science operations.   The LORRI image has been combined with lower-resolution color information from the Ralph instrument.   Credits: NASA-JHUAPL-SWRI
Pluto’s “Heart” is seen in this new image from New Horizons’ Long Range Reconnaissance Imager (LORRI) received on July 8, 2015 after normal science operations resumed following the scary July 4 safe mode anomaly that briefing shut down all science operations. The LORRI image has been combined with lower-resolution color information from the Ralph instrument. Credits: NASA-JHUAPL-SWRI

“When we combine images like this of the far side with composition and color data the spacecraft has already acquired but not yet sent to Earth, we expect to be able to read the history of this face of Pluto,” Moore explained.

New Horizons will swoop to within about 12,500 kilometers (nearly 7,750 miles) of Pluto’s surface and about 17,900 miles (28,800 kilometers) from Charon during closest approach at approximately 7:49 a.m. EDT (11:49 UTC) on July 14.

The probe was launched back on Jan. 19, 2006 on a United Launch Alliance Atlas V rocket on a 9 year voyage of over 3.6 billion miles (5.7 billion km).

Pluto is the last of the nine classical planets to be explored up close and completes the initial the initial reconnaissance of the solar system nearly six decades after the dawn of the space age. It represents a whole new class of objects.

“Pluto is a member of a whole new family of objects,” said Jim Green, director of Planetary Science, NASA Headquarters, Washington, in today’s live Pluto update.

“We call that the Kuiper Belt. And it is the outer solar system.”

New Horizons is equipped with a suite of seven science instruments gathering data during the approach and encounter phases with the Pluto system.

Graphic shows data gathered by New Horizons particle and plasma science instruments from 2 million miles out on July 11, 2015.  Credit: NASA/JHUAPL/SWRI
Graphic shows data gathered by New Horizons particle and plasma science instruments from 2 million miles out on July 11, 2015. Credit: NASA/JHUAPL/SWRI

The New Frontiers spacecraft was built by a team led by Stern and included researchers from SwRI and the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. APL also operates the New Horizons spacecraft and manages the mission.

Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer

Tantalizing signs of geology on Pluto are revealed in this image from New Horizons taken on July 9, 2015 from 3.3 million miles (5.4 million km) away. This annotated version shows the large dark feature nicknamed "the whale" that straddles Pluto's equator, a swirly band and a curious polygonal outline. At lower is a reference globe showing Pluto’s orientation in the image, with the equator and central meridian in bold. Credit:  NASA-JHUAPL-SWRI
Tantalizing signs of geology on Pluto are revealed in this image from New Horizons taken on July 9, 2015 from 3.3 million miles (5.4 million km) away. This annotated version shows the large dark feature nicknamed “the whale” that straddles Pluto’s equator, a swirly band and a curious polygonal outline. At lower is a reference globe showing Pluto’s orientation in the image, with the equator and central meridian in bold. Credit: NASA-JHUAPL-SWRI

Why Don’t We Send Probes “Up” In The Solar System?

Why Don't We Send Probes "Up" In The Solar System?

Wouldn’t it be easier to see what’s outside the solar system if we just send out probes straight up?

Dammit, science people! Why are you always firing probes “outwards”? Then they have to go past all this stuff, like planets and asteroids and crap to escape the solar system. Don’t you realize that if we want to see what’s outside the solar system we just need to shoot them straight up?

Then we don’t have to go past all that junk, and we can finally see what’s between us and the next star system over! Is it thick goo? Is it thin goo? Is it the aether?!

What the heck is wrong with you! It’s so easy. Just go up! Why are we always going out?

Whenever we talk Solar System, we’re always using flat objects for reference. Plates, flying disks, pancakes and pizzas, as it’s arranged in a flat disk known as the plane of the ecliptic.

Formed from a blob of hydrogen gas and dust in the solar nebula. Gravity pulled everything together, and the conservation of angular momentum set the whole thing spinning, faster and faster. The spinning pulled the whole Solar System into the disk we see today, with our star at the center and the planets embedded in the surrounding disk. As a result, the Sun, Moon, planets and their moons all move through a relatively small region in the sky.

This definitely makes things easier to send spacecraft from world to world. NASA’s Voyager 2 was able to visit Jupiter, Saturn, Uranus and Neptune because they were all lined up like dominoes.

When Willie Sutton was asked why he robbed banks, he answered, “that’s where the money is,” and we explore along the plane of the ecliptic because that’s where the science is. Everything in our Solar System is arranged along this flat area, so it makes sense to look along this region.

But wait! As you know, the Solar System isn’t actually flat. Some objects rise a little above or below the plane of the ecliptic. This is known as a planet’s orbital inclination.

Orbit of Mercury
Orbit of Mercury

Of all the planets, Mercury has the greatest with 7-percent. It’s even crazier for the the dwarf planets, Pluto is 17-percent off the plane of the ecliptic, and Eris is 44-percent.

One of the reasons Eris went undiscovered for so long is because it orbits so far outside the planet of the ecliptic. It wasn’t until Mike Brown and his team from Caltech looked far enough outside the usual hiding spaces that they found these additional dwarf planets.

There really isn’t much outside the flat plane of the ecliptic, it’s also much more difficult to get spacecraft to travel above or below. When spacecraft launch, they already have tremendous velocity just from the rotation of the Earth and the speed of the Earth orbiting the Sun.

I realize this is just more “outwardist” propaganda for you. So why no “up”? If you did want to go that way, you need a powerful rocket capable of creating velocity in this direction, or that direction.

If you wanted to escape the Earth’s gravity and explore the Solar System in the regular old way, you’d need to add about 10 km/s in velocity to your spacecraft. But for straight up, you’d need about 30 km/s, meaning more fuel, and compromises to your payload.

It still sounds like I’m making excuses. Here’s the deal, you might be amazed to learn that spacecraft actually have been sent “up”.

Artist impression of the Ulysses spacecraft. Credit: NASA/ESA
Artist impression of the Ulysses spacecraft. Credit: NASA/ESA

The European Space Agency’s Ulysses spacecraft, launched in 1990 had the goal of looking down on the Sun from above. It wasn’t possible to do this just with a rocket, but engineers were able to use a gravitational assist from Jupiter to kick Ulysses into an orbital inclination of 80-degrees, and for the first time, we were able to see the Sun from above and below.

A new European mission is in the works called the Solar Orbiter, and it’ll get into an orbital inclination of 90-degrees to be able to see the Sun’s poles directly for the first time. If all goes well, it’ll launch in 2018.

So, why don’t we go up? Actually, we do. We’re going “up” again very soon. It’s good to go up. It’s always good to get outside of our regular stomping grounds and see our Solar System from new angles and perspectives.

If you could send a probe anywhere in our Solar System, where would you choose?

New Horizons Exits Safe Mode, Operating Flawlessly for Upcoming Pluto Encounter

Latest color image of Pluto taken on July 3, 2015. Best yet image of Pluto was taken by the LORRI imager on NASA’s New Horizons spacecraft on July 3, 2015 at a distance of 7.8 million mi (12.5 million km), just prior to the July 4 anomaly that sent New Horizons into safe mode. Color data taken from the Ralph instrument gathered earlier in the mission. Credit: NASA/JHUAPL/SWRI

Latest color image of Pluto taken on July 3, 2015 shows 4 mysterious dark spots.
Best yet image of Pluto was taken by the LORRI imager on NASA’s New Horizons spacecraft on July 3, 2015 at a distance of 7.8 million mi (12.5 million km), just prior to the July 4 anomaly that sent New Horizons into safe mode. Color data taken from the Ralph instrument gathered earlier in the mission. Credit: NASA/JHUAPL/SWRI
Story updated[/caption]

Despite some hair-raising and unplanned 4th of July fireworks of sorts in deep space which caused NASA’s Pluto bound New Horizons spacecraft to enter “safe mode” due to a computer glitch and temporarily halt all science operations over the weekend, the spacecraft is now fully back on track, “healthy” and working “flawlessly” and set to resume all planned research investigations on Tuesday, July 7, NASA and top mission managers announced at a media briefing held this afternoon, Monday, July 6.

It’s now just exactly one week before the once-in-a-lifetime opportunity for a fast flyby encounter of the ever intriguing binary planet, at the far flung reaches of the solar system. And the great news could not come soon enough given the proximity of the flyby.

“The spacecraft is in excellent health and back in operation. New Horizons is barreling towards the Pluto system,” stated Jim Green, director of Planetary Science, NASA Headquarters, Washington, at the start of today’s news media briefing.

The $700 million mission remains on track to conduct the complex close flyby science sequence in its entirety, as planned over the next week, including the July 14 flyby of Pluto, despite the scary safe mode episode.

“The New Horizons spacecraft and science payload are now operating flawlessly,” Alan Stern, New Horizons principal investigator, Southwest Research Institute, Boulder, Colorado, announced at the media briefing.

NASA unexpectedly lost contact with the New Horizons spacecraft on Saturday, July 4, at about 1:30 p.m. EDT after it suffered a memory related software anomaly and executed a protective operation known as “safe mode.” An anomaly investigation team was formed immediately.

“It’s really a historic time, but also fraught with many decisions and challenges on the way to the July 14 Pluto system encounter,” Green said.

The mission team quickly worked to reestablish contact with the piano shaped spacecraft about 90 minutes after the signal was lost.

“On Saturday we lost contact with the spacecraft. The New Horizons team immediately went into action. Within 90 minutes the signal was reacquired by the team, with the spacecraft in safe mode. They soon found the root cause and corrective actions were immediately taken to get the spacecraft back in business.”

The team worked tirelessly and diligently day and night over the holiday weekend to recover New Horizons back to full operation quickly and in time for the flyby encounter of Pluto on July 14, set for approximately 7:49 a.m. EDT (11:49 UTC) on July 14, said Glen Fountain, New Horizons project manager, Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland.

There are no second chances.

This trio of images are the most recent high-resolution views of Pluto sent by NASA’s New Horizons spacecraft, including one showing the four mysterious dark spots on Pluto that have captured the imagination of the world. The Long Range Reconnaissance Imager (LORRI) obtained these three images between July 1 and 3 of 2015, prior to the July 4 anomaly that sent New Horizons into safe mode. Credit: NASA/JHUAPL/SWRI
This trio of images are the most recent high-resolution views of Pluto sent by NASA’s New Horizons spacecraft, including one showing the four mysterious dark spots on Pluto that have captured the imagination of the world. The Long Range Reconnaissance Imager (LORRI) obtained these three images between July 1 and 3 of 2015, prior to the July 4 anomaly that sent New Horizons into safe mode. Credit: NASA/JHUAPL/SWRI

The software glitch occurred a day after new operating software was uploaded to New Horizons last Friday.

The spacecraft was trying to do two things at once on Saturday, compressing science data and writing command sequences while using up too much flash memory, explained Fountain.

“The computer was trying to do these two things at the same time, and the two were more than the processor could handle,” Fountain said.

“So the processor said ‘I’m overloaded.’ Then the spacecraft did exactly what it was supposed to do. It then switched to the backup computer and went into safe mode. At that point, we lost the downlink from the primary computer. We realized quickly what happened and put a recovery plan in place and recovered.”

Artist view of New Horizons passing Pluto and three of its moons. The ship is about the size of a grand piano and kept warm in the cold of the outer Solar System by  heat release from the radioactive decay of plutonium within the probe's RTGs (Radioisotope  Thermoelectric Generator). Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Artist view of New Horizons passing Pluto and three of its moons. The ship is about the size of a grand piano and kept warm in the cold of the outer Solar System by heat release from the radioactive decay of plutonium within the probe’s RTGs (Radioisotope Thermoelectric Generator). Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

At this moment New Horizons is about 3 billion miles (4.9 billion km) from Earth and less than 6 million miles (9 million km) away from unmasking the secrets of tantalizing Pluto, Charon, its largest moon with which it forms a double planet system, and its four tiny and recently discovered moons. Charon is half the size of Pluto.

The round trip time for signals traveling at the speed of light is 8.5 hours. So it’s a very long time before commands from Earth can reach the spacecraft and for the team to determine their outcome. So the probe has to be able to operate on its own without direction from Earth during the intense and brief flyby period.

Pluto is the most distant and last unexplored planet in our Solar System, and therefore presents enormous complexities to those bold enough to dare the mightiest things.

“We expect a nominal flyby of Pluto from every indication now,” said Alan Stern, New Horizons principal investigator, Southwest Research Institute, Boulder, Colorado, announced at the media briefing.

“This object is unlike any other that we have observed,” Stern said. “Both Pluto and Charon are already surprising us.”

Less than 1 percent of the planned data was lost in the three days that the science instruments were shut off.

“It’s more important to focus on the later science during the flyby,” Stern elaborated.

“There is zero impact to the primary Group 1 highest-priority science objectives. And a minor impact to Group 2 and Group 3 objectives,” Stern elaborated.

“This is a speed bump in terms of the total return that we expect from this flyby.”

“I’m pleased that our mission team quickly identified the problem and assured the health of the spacecraft,” noted Green. “Now, with Pluto in our sights, we’re on the verge of returning to normal operations and going for the gold.”

Credit: NASA/JHUAPL/SWRI
New Horizons trajectory map to Pluto. Credit: NASA/JHUAPL/SWRI

The team said this type of software update will not be repeated and a similar type safe mode event should not recur.

Fountain said that during the encounter period, the probe can switch itself to exit safe mode event within about 7 minutes, depending on the situation, and minimize any science data losses.

New Horizons will swoop to within about 12,500 kilometers (nearly 7,800 miles) of Pluto’s surface.

It will zoom past Pluto at speeds of some 30,000 miles per hour (more than 48,000 kilometers per hour).

Today the team also released the best yet images of Pluto that were taken by the Long Range Reconnaissance Imager (LORRI). The trio of images were between July 1 and 3 of 2015, prior to the July 4 anomaly that sent New Horizons into safe mode.

The images show varying and enigmatic surface features on the different hemispheres of Pluto.

They also show the four mysterious dark spots on Pluto that have captured the imagination of the scientists and the world.

Their nature remains unknown at this time.

The probe was launched back in 2006 on a United Launch Alliance Atlas V rocket.

“We are on our way to Pluto!” Green exclaimed.

Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer

Animation of Pluto rotating from photos taken by New Horizons two weeks before the flyby. Credit:
Animation of Pluto rotating from photos taken by New Horizons two weeks before the flyby. Credit:

What is the Biggest Planet in the Solar System?

Jupiter and Io
Io and Jupiter as seen by New Horizons during its 2008 flyby. (Credit: NASA/Johns Hopkins University APL/SWRI).

Ever since the invention of the telescope four hundred years ago, astronomers have been fascinated by the gas giant of Jupiter. Between it’s constant, swirling clouds, its many, many moons, and its Giant Red Spot, there are many things about this planet that are both delightful and fascinating.

But perhaps the most impressive feature about Jupiter is its sheer size. In terms of mass, volume, and surface area, Jupiter is the biggest planet in our Solar System by a wide margin. But just what makes Jupiter so massive, and what else do we know about it?

Size and Mass:

Jupiter’s mass, volume, surface area and mean circumference are 1.8981 x 1027 kg, 1.43128 x 1015 km3, 6.1419 x 1010 km2, and 4.39264 x 105 km respectively. To put that in perspective, Jupiter diameter is roughly 11 times that of Earth, and 2.5 the mass of all the other planets in the Solar System combined.

But, being a gas giant, Jupiter has a relatively low density – 1.326 g/cm3 – which is less than one quarter of Earth’s. This means that while Jupiter’s volume is equivalent to about 1,321 Earths, it is only 318 times as massive. The low density is one way scientists are able to determine that it is made mostly of gases, though the debate still rages on what exists at its core (see below).

Composition:

Jupiter is composed primarily of gaseous and liquid matter. It is the largest of the gas giants, and like them, is divided between a gaseous outer atmosphere and an interior that is made up of denser materials. Its upper atmosphere is composed of about 88–92% hydrogen and 8–12% helium by percent volume of gas molecules, and approx. 75% hydrogen and 24% helium by mass, with the remaining one percent consisting of other elements.

This cut-away illustrates a model of the interior of Jupiter, with a rocky core overlaid by a deep layer of liquid metallic hydrogen. Credit: Kelvinsong/Wikimedia Commons
This cut-away illustrates a model of the interior of Jupiter, with a rocky core overlaid by a deep layer of liquid metallic hydrogen. Credit: Kelvinsong/Wikimedia Commons

The atmosphere contains trace amounts of methane, water vapor, ammonia, and silicon-based compounds as well as trace amounts of benzene and other hydrocarbons. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, and sulfur. Crystals of frozen ammonia have also been observed in the outermost layer of the atmosphere.

The interior contains denser materials, such that the distribution is roughly 71% hydrogen, 24% helium and 5% other elements by mass. It is believed that Jupiter’s core is a dense mix of elements – a surrounding layer of liquid metallic hydrogen with some helium, and an outer layer predominantly of molecular hydrogen. The core has also been described as rocky, but this remains unknown as well.

In 1997, the existence of the core was suggested by gravitational measurements, indicating a mass of from 12 to 45 times the Earth’s mass, or roughly 4%–14% of the total mass of Jupiter. The presence of a core is also supported by models of planetary formation that indicate how a rocky or icy core would have been necessary at some point in the planet’s history in order to collect its bulk of hydrogen and helium from the protosolar nebula.

However, it is possible that this core has since shrunk due to convection currents of hot, liquid, metallic hydrogen mixing with the molten core. This core may even be absent now, but a detailed analysis is needed before this can be confirmed. The Juno mission, which launched in August 2011, is expected to provide some insight into these questions, and thereby make progress on the problem of the core.

The temperature and pressure inside Jupiter increase steadily toward the core. At the “surface”, the pressure and temperature are believed to be 10 bars and 340 K (67 °C, 152 °F). At the “phase transition” region, where hydrogen becomes metallic, it is believed the temperature is 10,000 K (9,700 °C; 17,500 °F) and the pressure is 200 GPa. The temperature at the core boundary is estimated to be 36,000 K (35,700 °C; 64,300 °F) and the interior pressure at roughly 3,000–4,500 GPa.

Moons:

The Jovian system currently includes 67 known moons. The four largest are known as the Galilean Moons, which are named after their discoverer, Galileo Galilei. They include: Io, the most volcanically active body in our Solar System; Europa, which is suspected of having a massive subsurface ocean; Ganymede, the largest moon in our Solar System; and Callisto, which is also thought to have a subsurface ocean and features some of the oldest surface material in the Solar System.

Then there’s the Inner Group (or Amalthea group), which is made up of four small moons that have diameters of less than 200 km, orbit at radii less than 200,000 km, and have orbital inclinations of less than half a degree. This groups includes the moons of Metis, Adrastea, Amalthea, and Thebe. Along with a number of as-yet-unseen inner moonlets, these moons replenish and maintain Jupiter’s faint ring system.

Jupiter also has an array of Irregular Satellites, which are substantially smaller and have more distant and eccentric orbits than the others. These moons are broken down into families that have similarities in orbit and composition, and are believed to be largely the result of collisions from large objects that were captured by Jupiter’s gravity.

Illustration of Jupiter and the Galilean satellites. Credit: NASA
Illustration of Jupiter and the Galilean satellites. Credit: NASA

Interesting Facts:

Much like Earth, Jupiter experiences auroras near its northern and southern poles. But on Jupiter, the auroral activity is much more intense and rarely ever stops. The intense radiation, Jupiter’s magnetic field, and the abundance of material from Io’s volcanoes that react with Jupiter’s ionosphere creates a light show that is truly spectacular.

Jupiter also has a violent atmosphere. Winds in the clouds can reach speeds of up to 620 kph (385 mph). Storms form within hours and can become thousands of km in diameter overnight. One storm, the Great Red Spot, has been raging since at least the late 1600s. The storm has been shrinking and expanding throughout its history; but in 2012, it was suggested that the Giant Red Spot might eventually disappear.

The discovery of exoplanets has revealed that planets can get even bigger than Jupiter. In fact, the number of “Super Jupiters” observed by the Kepler space probe (as well as ground-based telescopes) in the past few years has been staggering. In fact, as of 2015, more than 300 such planets have been identified.

Notable examples include PSR B1620-26 b (Methuselah), which was the first super-Jupiter to be observed (in 2003). At 12.7 billion years of age, it is also the third oldest known planet in the universe. There’s also HD 80606 b (Niobe), which has the most eccentric orbit of any known planet, and 2M1207b (Lerna), which orbits the brown dwarf Fomalhaut b (Illion).

Scientist theorize that a gas gain could get 15 times the size of Jupiter before it began deuterium fusion, making it a brown dwarf star. Good thing too, since the last thing the Solar System needs if for Jupiter to go nova!

Jupiter was appropriately named by the ancient Romans, who chose to name after the king of the Gods (Jupiter, or Jove). The more we have come to know and understand about this most-massive of Solar planets, the more deserving of this name it appears.

If you’re wondering, here’s how big planets can get with a lot of mass, and here’s what is the biggest star in the Universe. And here’s the 2nd largest planet in the Solar System.

Here’s another article about the which is the largest planet in the Solar System, and here’s what’s the smallest planet in the Solar System.

We have recorded a whole series of podcasts about the Solar System at Astronomy Cast. Check them out here.

Sources:

Mathematics: The Beautiful Language of the Universe

Let us discuss the very nature of the cosmos. What you may find in this discussion is not what you expect. Going into a conversation about the universe as a whole, you would imagine a story full of wondrous events such as stellar collapse, galactic collisions, strange occurrences with particles, and even cataclysmic eruptions of energy. You may be expecting a story stretching the breadth of time as we understand it, starting from the Big Bang and landing you here, your eyes soaking in the photons being emitted from your screen. Of course, the story is grand. But there is an additional side to this amazing assortment of events that oftentimes is overlooked; that is until you truly attempt to understand what is going on. Behind all of those fantastic realizations, there is a mechanism at work that allows for us to discover all that you enjoy learning about. That mechanism is mathematics, and without it the universe would still be shrouded in darkness. In this article, I will attempt to persuade you that math isn’t some arbitrary and sometimes pointless mental task that society makes it out to be, and instead show you that it is a language we use to communicate with the stars.

We are currently bound to our solar system. This statement is actually better than it sounds, as being bound to our solar system is one major step up from being bound simply to our planet, as we were

A defining moment for humanity: Galileo turing his spyglass towards the sky
A defining moment for humanity: Galileo turing his spyglass towards the sky

before some very important minds elected to turn their geniuses toward the heavens. Before those like Galileo, who aimed his spyglass towards the sky, or Kepler discovering that planets move about the sun in ellipses, or Newton discovering a gravitational constant, mathematics was somewhat  limited, and our understanding of the universe rather ignorant. At its core, mathematics allows a species bound to its solar system to probe the depths of the cosmos from behind a desk. Now, in order to appreciate the wonder that is mathematics, we must first step back and briefly look at its beginnings and how it is integrally tied into our very existence.

Mathematics almost certainly came about from very early human tribes (predating Babylonian culture which is attributed to some of the first organized mathematics in recorded history), that may have used math as a way of keeping track of lunar or solar cycles, and keeping count of animals, food and/or people by leaders. It is as natural as when you are a young child and you can see that you have

Ancient Babylonian tablet displaying early mathematics
Ancient Babylonian tablet displaying early mathematics

one toy plus one other toy, meaning you have more than one toy. As you get older, you develop the ability to see that 1+1=2, and thus simple arithmetic seems to be interwoven into our very nature. Those that profess that they don’t have a mind for math are sadly mistaken because just as we all have a mind for breathing, or blinking, we all have this innate ability to understand arithmetic. Mathematics is both a natural occurrence and a human designed system. It would appear that nature grants us this ability to recognize patterns in the form of arithmetic, and then we systematically construct more complex mathematical systems that aren’t obvious in nature but let us further communicate with nature.

All this aside, mathematics developed alongside of human development, and carried on similarly with each culture that was developing it simultaneously. It’s a wonderful observation to see that cultures that had no contact with one another were developing similar mathematical constructs without conversing. However, it wasn’t until mankind decidedly turned their mathematical wonder towards the sky that math truly began to develop in an astonishing way. It is by no mere coincidence that our scientific revolution was spurred by the development of more advanced mathematics built not to tally sheep or people, but rather to further our understandings of our place within the universe. Once Galileo began measuring the rates at which objects fell in an attempt to show mathematically that the mass of an object had little to do with the speed in which it fell, mankind’s future would forever be altered.

This is where the cosmic perspective ties in to our want to further our mathematical knowledge. If it were not for math, we would still think we were on one of a few planets orbiting a star amidst the backdrop of seemingly motionless lights. This is a rather bleak outlook today compared to what we now know

Johannes Kepler used mathematics to model his observations of the planets.
Johannes Kepler used mathematics to model his observations of the planets.

about the awesomely large universe we reside in. This idea of the universe motivating us to understand more about mathematics can be inscribed in how Johannes Kepler used what he observed the planets doing, and then applied mathematics to it to develop a fairly accurate model (and method for predicting planetary motion) of the solar system. This is one of many demonstrations that illustrate the importance of mathematics within our history, especially within astronomy and physics.

The story of mathematics becomes even more amazing as we push forward to one of the most advanced thinkers humanity has ever known. Sir Isaac Newton, when pondering the motions of Halley’s Comet, came to the realization that the math that had been used thus far to describe physical motion of massive

Isaac Newton
Isaac Newton

bodies, simply would not suffice if we were to ever understand anything beyond that of our seemingly limited celestial nook. In a show of pure brilliance that lends validity to my earlier statement about how we can take what we naturally have and then construct a more complex system upon it, Newton developed the Calculus in which this way of approaching moving bodies, he was able to accurately model the motion of not only Halley’s comet, but also any other heavenly body that moved across the sky.

In one instant, our entire universe opened up before us, unlocking almost unlimited abilities for us to converse with the cosmos as never before. Newton also expanded upon what Kepler started. Newton recognized that Kepler’s mathematical equation for planetary motion, Kepler’s 3rd Law ( P2=A3 ), was purely based on empirical observation, and was only meant to measure what we observed within our solar system. Newton’s mathematical brilliance was in realizing that this basic equation could be made universal by applying a gravitational constant to the equation, in which gave birth to perhaps one of the most important equations to ever be derived by mankind; Newton’s Version of Kepler’s Third Law.

You can still see where Kepler's 3rd Law remains, but with the added values of the gravitational constant G, and M and m representing the masses of the two bodies in question, this equation is no longer restricted to just our solar system
You can still see where Kepler’s 3rd Law remains, but with the added values of the gravitational constant G, and M and m representing the masses of the two bodies in question, this equation is no longer restricted to just our solar system

What Newton realized was that when things move in non-linear ways, using basic Algebra would not produce the correct answer. Herein lays one of the main differences between Algebra and Calculus. Algebra allows one to find the slope (rate of change) of straight lines (constant rate of change), whereas Calculus allows one to find the slope of curved lines (variable rate of change). There are obviously many more applications of Calculus than just this, but I am merely illustrating a fundamental difference between the two in order to show you just how revolutionary this new concept was. All at once, the motions of planets and other objects that orbit the sun became more accurately measurable, and thus we gained the ability to understand the universe a little deeper. Referring back to Netwon’s Version of Kepler’s Third Law, we were now able to apply (and still do) this incredible physics equation to almost anything that is orbiting something else. From this equation, we can determine the mass of either of the objects, the distance apart they are from each other, the force of gravity that is exerted between the two, and other physical qualities built from these simple calculations.

With his understanding of mathematics, Newton was able to derive the aforementioned gravitational constant for all objects in the universe ( G = 6.672×10-11 N m2 kg-2 ). This constant allowed him to unify astronomy and physics which then permitted predictions about how things moved in the universe. We could now measure the masses of planets (and the sun) more accurately, simply according to Newtonian physics (aptly named to honor just how important Newton was within physics and mathematics). We could now apply this newfound language to the cosmos, and begin coercing it to divulge its secrets. This was a defining moment for humanity, in that all of those things that prohibited our understandings prior to this new form of math were now at our fingertips, ready to be discovered. This is the brilliance of understanding Calculus, in that you are speaking the language of the stars.

There perhaps is no better illustration of the power that mathematics awarded us then in the discovery of the planet Neptune. Up until its discovery in September of 1846, planets were discovered simply by observing certain “stars” that were moving against the backdrop of all the other stars in odd ways. The term planet is Greek for “wanderer”, in that these peculiar stars wandered across the sky in noticeable patterns at different times of the year. Once the telescope was first turned upwards towards the sky by Galileo, these wanderers resolved into other worlds that appeared to be like ours. If fact, some of these worlds appeared to be little solar systems themselves, as Galileo discovered when he began recording the moons of Jupiter as they orbited around it.

After Newton presented his physics equations to the world, mathematicians were ready and excited to begin applying them to what we had been keeping track of for years. It was as if we were thirsty for the knowledge, and finally someone turned on the faucet. We began measuring the motions of the planets and gaining more accurate models for how they behaved. We used these equations to approximate the mass of the Sun. We were able to make remarkable predictions that were validated time and again simply by observation. What we were doing was unprecedented, as we were using mathematics to make almost impossible to know predictions that you would think we could never make without actually going to these planets, and then using actual observation to prove the math correct. However, what we also did was begin to figure out some odd discrepancies with certain things. Uranus, for instance, was behaving not as it should according to Newton’s laws.

Here you can see that the inner planet is being perturbed by the outer planet, in our situation, that outer planet was Neptune, not yet discovered.
Here you can see that the inner planet is being perturbed by the outer planet. In our situation, that outer planet was Neptune, which had yet to be discovered.

What makes the discovery of Neptune so wonderful was the manner in which it was discovered. What Newton had done was uncover a deeper language of the cosmos, in which the universe was able to reveal more to us. And this is exactly what happened when we applied this language to the orbit of Uranus. The manner in which Uranus orbited was curious and did not fit what it should have if it was the only planet that far out from the sun. Looking at the numbers, there had to be something else out there perturbing its orbit. Now, before Newton’s mathematical insights and laws, we would have had no reason to suspect anything was wrong in what we observed. Uranus orbited in the way Uranus orbited; it was just how it was. But, again revisiting that notion of mathematics being an ever increasing dialogue with the universe, once we asked the question in the right format, we realized that there really must be something else beyond what we couldn’t see. This is the beauty of mathematics writ large; an ongoing conversation with the universe in which more than we may expect is revealed.

It came to a French mathematician Urbain Le Verrier who sat down and painstakingly worked through the mathematical equations of the orbit of Uranus. What he was doing was using Newton’s mathematical equations backwards, realizing that there must be an object out there beyond the orbit of Uranus that was also orbiting the sun,

French mathematician who discovered the planet Neptune by using only mathematics
French mathematician who discovered the planet Neptune by using only mathematics

and then looking to apply the right mass and distance that this unseen object required for perturbing the orbit of Uranus in the way we were observing it was. This was phenomenal, as we were using parchment and ink to find a planet that nobody had ever actually observed. What he found was that an object, soon to be Neptune, had to be orbiting at a specific distance from the sun, with the specific mass that would cause the irregularities in the orbital path of Uranus. Confident of his mathematical calculations, he took his numbers to the New Berlin Observatory, where the astronomer Johann Gottfried Galle looked exactly where Verrier’s calculations told him to look, and there lay the 8th and final planet of our solar system, less than 1 degree off from where Verrier’s calculations said for him to look. What had just happened was an incredible confirmation of Newton’s gravitational theory and proved that his mathematics were correct.

Are There Oceans on Neptune
Neptune is more than just the 8th planet in our solar system; it is a celestial reminder of the power that mathematics grants us.

These types of mathematical insights continued on long after Newton. Eventually, we began to learn much more about the universe with the advent of better technology (brought about by advances in mathematics). As we moved into the 20th century, quantum theory began to take shape, and we soon realized that Newtonian physics and mathematics seemed to hold no sway over what we observed on the quantum level. In another momentous event in human history, yet again brought forth by the advancement in mathematics, Albert Einstein unveiled his theories of General and Special Relativity, which was a new way to look not only at gravity, but

Einstein's Relativity, yet another momentous advancement for humanity brought forth from an ongoing mathematical dialogue. Image via Pixabay.
Einstein’s equation for the energy-mass equivalency, yet another incredible advancement for humanity brought forth from an ongoing mathematical dialogue. Image via Pixabay.

also on energy and the universe in general. What Einstein’s mathematics did was allow for us to yet again uncover an even deeper dialogue with the universe, in which we began to understand its origins.

Continuing this trend of advancing our understandings, what we have realized is that now there are two sects of physics that do not entirely align. Newtonian or “classical” physics, that works extraordinarily well with the very large (motions of planets, galaxies, etc…) and quantum physics that explains the extremely small (the interactions of sub-atomic particles, light, etc…). Currently, these two areas of physics are not in alignment, much like two different dialects of a language. They are similar and they both work, but they are not easily reconcilable with one another. One of the greatest challenges we face today is attempting to create a mathematical grand “theory of everything” which either unites the laws in the quantum world with that of the macroscopic world, or to work to explain everything solely in terms of quantum mechanics. This is no easy task, but we are striving forward nonetheless.

As you can see, mathematics is more than just a set of vague equations and complex rules that you are required to memorize. Mathematics is the language of the universe, and in learning this language, you are opening yourself up the core mechanisms by which the cosmos operates. It is the same as traveling to a new land, and slowly picking up on the native language so that you may begin to learn from them. This mathematical endeavor is what allows us, a species bound to our solar system, to explore the depths of the universe. As of now, there simply is no way for us to travel to the center of our galaxy and observe the supermassive black hole there to visually confirm its existence. There is no way for us to venture out into a Dark Nebula and watch in real time a star being born. Yet, through mathematics, we are able to understand how these things exist and work. When you set about to learn math, you are not only expanding your mind, but you are connecting with the universe on a fundamental level. You can, from your desk, explore the awesome physics at the event horizon of a black hole, or bear witness to the destructive fury behind a supernova. All of those things that I mentioned at the beginning of this article come into focus through mathematics. The grand story of the universe is written in mathematics, and our ability to translate those numbers into the events that we all love to learn about is nothing short of amazing. So remember, when you are presented with the opportunity to learn math, accept every bit of it because math connects us to the stars.

We are connected to the universe through mathematics...
We are connected to the universe through mathematics…

 

Cassini to Perform Its Final Flyby of Hyperion

Enhanced-color image of Hyperion from Sept. 26, 2005. (NASA/JPL/SSI)

On Sunday, May 31, the Cassini spacecraft will perform its last close pass of Hyperion, Saturn’s curiously spongelike moon. At approximately 9:36 a.m. EDT (13:36 UTC) it will zip past Hyperion at a distance of about 21,000 miles (34,000 km) – not its closest approach ever but considerably closer (by 17,500 miles/28,160 km) than it was when the image above was acquired.*

This will be Cassini’s last visit of Hyperion. It will make several flybys of other moons within Saturn’s equatorial plane over the course of 2015 before shifting to a more inclined orbit in preparation of the end phase of its mission and its operating life in 2017.

At 255 x 163 x 137 miles (410 x 262 x 220 km) in diameter, Hyperion is the largest of Saturn’s irregularly-shaped moons. Researchers suspect it’s the remnant of a larger body that was blown apart by an impact. Hyperion’s craters appear to have a “punched-in” look rather than having been excavated, and have no visible ejecta or secondary craters nearby.

Impactors tend to make craters by compressing the surface material, rather than blasting it out. (NASA/JPL/SSI. Edit by J. Major.)
Impacts on Hyperion tend to “punch in” the surface material, rather than blasting it out. (NASA/JPL/SSI. Edit by J. Major.)

Hyperion orbits Saturn in an eccentric orbit at a distance of over 920,000 miles (1.48 million km)…that’s almost four times the distance our Moon is from us! This distance – as well as constant gravitational nudges from Titan – prevents Hyperion from becoming tidally locked with Saturn like nearly all of its other moons are. In fact its rotation is more of haphazard tumble than a stately spin, making targeted observations of any particular regions on its surface virtually impossible.

Images from the May 31 flyby are expected to arrive on Earth 24 to 48 hours later.

As small as it is Hyperion is Saturn’s eighth-largest moon, although it appears to be very porous and has a density half that of water. Read more about Hyperion here and see more images of it from Cassini here and here.

Source: NASA

*Cassini did come within 310 miles (500 km) of Hyperion on Sept. 26, 2005, but the images to make up the view above were acquired during approach.

UPDATE June 1, 2015: the raw images from Cassini’s flyby have arrived on Earth, check out a few below. (Looks like Cassini ended up with the same side of Hyperion again!)

Hyperion on May 31, 2015. Credit: NASA/JPL-Caltech/SSI. (Minor editing by J. Major.)
Hyperion on May 31, 2015. Credit: NASA/JPL-Caltech/SSI. (Minor editing by J. Major.)
Hyperion on May 31, 2015. Credit: NASA/JPL-Caltech/SSI.
Hyperion on May 31, 2015. Credit: NASA/JPL-Caltech/SSI.
Hyperion on May 31, 2015. Credit: NASA/JPL-Caltech/SSI. (Minor editing by J. Major.)
Hyperion on May 31, 2015. Credit: NASA/JPL-Caltech/SSI. (Minor editing by J. Major.)

What is Lunar Regolith?

A boot print on the lunar regolith. Credit: NASA.

When you’re walking around on soft ground, do you notice how your feet leave impressions? Perhaps you’ve tracked some of the looser earth in your yard into the house on occasion? If you were to pick up some of these traces – what we refer to as dirt or soil – and examine them beneath a microscope, what would you see?

Essentially, you would be seeing the components of what is known as regolith, which is a collection of particles of dust, soil, broken rock, and other materials found here on Earth. But interestingly enough, this same basic material can be found in other terrestrial environments as well – including the Moon, Mars, other planets, and even asteroids.

Definition:

The term regolith refers to any layer of material covering solid rock, which can come in the form of dust, soil or broken rock. The word is derived from the combination of two Greek words – rhegos (which means “blanket”) and lithos (which means “rock).

Earth:

On Earth, regolith takes the form of dirt, soil, sand, and other components that are formed as a result of natural weathering and biological processes. Due to a combination of erosion, alluvial deposits (i.e. moving water deposing sand), volcanic eruptions, or tectonic activity, the material is slowly ground down and laid out over solid bedrock.

central Yilgarn Craton, Western Australia.
Picture of Mt Magnet in the Central Yilgarn Craton in Western Australia, which dates to the Precambrian Era. Credit: geomorphologie.revues.org

It can be made up of clays, silicates, various minerals, groundwater, and organic molecules. Regolith on Earth can vary from being essentially absent to being hundreds of meters thick. Its can also be very young (in the form of ash, alluvium, or lava rock that was just deposited) to hundreds of millions of years old (regolith dating to the Precambrian age occurs in parts of Australia).

On Earth, the presence of regolith is one of the important factors for most life, since few plants can grow on or within solid rock and animals would be unable to burrow or build shelter without loose material. Regolith is also important for human beings since it has been used since the dawn of civilization (in the form of mud bricks, concrete and ceramics) to build houses, roads, and other civil works.

The difference in terminology between “soil” (aka. dirt, mud, etc.) and “sand” is the presence of organic materials. In the former, it exists in abundance, and is what separates regolith on Earth from most other terrestrial environments in our Solar System.

The Moon:

The surface of the Moon is covered with a fine powdery material that scientists refer to it as “lunar regolith”. Nearly the entire lunar surface is covered with regolith, and bedrock is only visible on the walls of very steep craters.

Earth viewed from the Moon by the Apollo 11 spacecraft. Credit: NASA
Earth viewed from the Moon by the Apollo 11 spacecraft, across a sea of lunar soil. Credit: NASA

The Moon regolith was formed over billions of years by constant meteorite impacts on the surface of the Moon. Scientists estimate that the lunar regolith extends down 4-5 meters in some places, and even as deep as 15 meters in the older highland areas.

When the plans were put together for the Apollo missions, some scientists were concerned that the lunar regolith would be too light and powdery to support the weight of the lunar lander. Instead of landing on the surface, they were worried that the lander would just sink down into it like a snowbank.

However, landings performed by robotic Surveyor spacecraft showed that the lunar soil was firm enough to support a spacecraft, and astronauts later explained that the surface of the Moon felt very firm beneath their feet. During the Apollo landings, the astronauts often found it necessary to use a hammer to drive a core sampling tool into it.

Once astronauts reached the surface, they reported that the fine moon dust stuck to their spacesuits and then dusted the inside of the lunar lander. The astronauts also claimed that it got into their eyes, making them red; and worse, even got into their lungs, giving them coughs. Lunar dust is very abrasive, and has been noted for its ability to wear down spacesuits and electronics.

Alan Bean Takes Lunar Soil Sample
Alan Bean takes a sample of lunar regolith during the Apollo 12 mission. Credit: NASA

The reason for this is because lunar regolith is sharp and jagged. This is due to the fact that the Moon has no atmosphere or flowing water on it, and hence no natural weathering process. When the micro-meteoroids slammed into the surface and created all the particles, there was no process for wearing down its sharp edges.

The term lunar soil is often used interchangeably with “lunar regolith”, but some have argued that the term “soil” is not correct because it is defined as having organic content. However, standard usage among lunar scientists tends to ignore that distinction. “Lunar dust” is also used, but mainly to refer to even finer materials than lunar soil.

As NASA is working on plans to send humans back to the Moon in the coming years, researchers are working to learn the best ways to work with the lunar regolith. Future colonists could mine minerals, water, and even oxygen out of the lunar soil, and use it to manufacture bases with as well.

Mars:

Landers and rovers that have been sent to Mars by NASA, the Russians and the ESA have returned many interesting photographs, showing a landscape that is covered with vast expanses of sand and dust, as well as rocks and boulders.

A successful scoop of Martian regolith (NASA/JPL-Caltech/University of Arizona/Max Planck Institute)
A successful scoop of Martian regolith performed by NASA’s Phoenix lander. Credit: NASA/JPL-Caltech/University of Arizona/Max Planck Institute

Compared to lunar regolith, Mars dust is very fine and enough remains suspended in the atmosphere to give the sky a reddish hue. The dust is occasionally picked up in vast planet-wide dust storms, which are quite slow due to the very low density of the atmosphere.

The reason why Martian regolith is so much finer than that found on the Moon is attributed to the flowing water and river valleys that once covered its surface. Mars researchers are currently studying whether or not martian regolith is still being shaped in the present epoch as well.

It is believed that large quantities of water and carbon dioxide ices remain frozen within the regolith, which would be of use if and when manned missions (and even colonization efforts) take place in the coming decades.

Mars moon of Deimos is also covered by a layer of regolith that is estimated to be 50 meters (160 feet) thick. Images provided by the Viking 2 orbiter confirmed its presence from a height of 30 km (19 miles) above the moon’s surface.

Asteroids and Outer Solar System:

The only other planet in our Solar System that is known to have regolith is Titan, Saturn’s largest moon. The surface is known for its extensive fields of dunes, though the precise origin of them are not known. Some scientists have suggested that they may be small fragments of water ice eroded by Titan’s liquid methane, or possibly particulate organic matter that formed in Titan’s atmosphere and rained down on the surface.

Another possibility is that a series of powerful wind reversals, which occur twice during a single Saturn year (30 Earth years), are responsible for forming these dunes, which measure several hundred meters high and stretch across hundreds of kilometers.  Currently, Earth scientists are still not certain what Titan’s regolith is composed of.

Data returned by the Huygens Probe’s penetrometer indicated that the surface may be clay-like, but long-term analysis of the data has suggested that it may be composed of sand-like ice grains.  The images taken by the probe upon landing on the moon’s surface show a flat plain covered in rounded pebbles, which may be made of water ice, and suggest the action of moving fluids on them.

Asteroids have been observed to have regolith on their surfaces as well. These are the result of meteoriod impacts that have taken place over the course of millions of years, pulverizing their surfaces and creating dust and tiny particles that are carried within the craters.

False color picture of Eros' 5.3-kilometer (3.3-mile) surface crater, showing regolith inside. Credit: NASA/JPL/JHUAPL
False color picture taken by NASA’s NEAR Shoemaker camera of Eros’ 5.3-kilometer (3.3-mile) surface crater, showing the presence of regolith inside. Credit: NASA/JPL/JHUAPL

NASA’s NEAR Shoemaker spacecraft produced evidence of regolith on the surface of the asteroid 433 Eros, which remains the best images of asteroid regolith to date. Additional evidence has been provided by JAXA’s Hayabusa mission, which returned clear images of regolith on an asteroid that was thought to be too small to hold onto it.

Images provided by the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) cameras on board the Rosetta Spacecraft confirmed that the asteroid 21 Lutetia has a layer of regolith near its north pole, which was seen to flow in major landslides associated with variations in the asteriod’s albedo.

To break it down succinctly, wherever there is rock, there is likely to be regolith. Whether it is the product of wind or flowing water, or the presence of meteors impacting the surface, good old fashioned “dirt” can be found just about anywhere in our Solar System; and most likely, in the universe beyond…

We’ve done several articles about the Moon’s regolith here on Universe Today. Here’s a way astronauts might be able to extract water from lunar regolith with simple kitchen appliances, and an article about NASA’s search for a lunar digger.

Want to buy some lunar regolith simulant? Here’s a site that lets you buy it. Do you want to be a Moon miner? There’s lots of good metal in that lunar regolith.

You can listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?

Reference:
NASA

Rosetta’s View of a Comet’s “Great Divide”

A shadowed cliff on comet 67P/C-G imaged by Rosetta in Oct. 2014 (Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0)

The latest image to be revealed of comet 67P/Churyumov-Gerasimenko comes from October 27, 2014, before the Philae lander even departed for its surface. Above we get a view of a dramatically-shadowed cliff separating two regions on 67P, the high, smooth plateaus of Babi and the boulder-strewn, slumped valley of Aten. Both are located on the larger lobe of the comet, while parts of the Ma’at region on the smaller “head” lobe can be seen in the distance at upper left. (You can see a regional map of comet 67P here.)

The image scale is about 75 cm (2.4 feet) per pixel and the entire image spans 770 meters across – about half a mile. Based on that, the cliff is easily over 190 meters (630 feet) high!

Here's a diagram of the image above in context with the entire comet. (ESA)
Here’s a diagram of the image above in context with the entire comet. (ESA)

It’s thought that the morphological differences in the Babi and Aten regions – in both texture and altitude – are the result of a massive loss of material from Aten at some point in the comet’s history. According to the entry on the Rosetta blog, the entire volume of the Aten “scoop” is equivalent to about 50 Great Pyramids of Giza… a fitting analogy considering the choice to name features on 67P with an ancient Egyptian theme.

See Comet 67P’s Enormous “Cheops” Boulder

The image above is one of a slew of NavCam images that will be released at the end of the month on ESA’s Archive Browser, captured by Rosetta after establishing orbit around 67P.

Source: ESA’s Rosetta blog

NavCam image of 67P/C-G acquired on May 12, 2015. The elongated depression at the center of the illuminated region is Aten. ( ESA/Rosetta/NavCam – CC BY-SA IGO 3.0)
NavCam image of 67P/C-G acquired on May 12, 2015. The elongated depression at the center of the illuminated region is Aten. ( ESA/Rosetta/NavCam – CC BY-SA IGO 3.0)

Could We Live on Jupiter?

Could We Live on Jupiter?

When humans finally travel into space, where will we live? Will we ever be able to colonize gas giants like Jupiter?

NASA and Elon Musk have plans to get your ass to Mars.

It’s not impossible to imagine humans living and working on the Red Planet. Maybe they’ll be crusty asteroid miners making their fortune digging precious minerals out of the inexhaustible supply of space rocks. Pray they don’t dig too deeply. We should go ask Kuato, that creepy little guy knows everything! Except he’s always trying to get you to touch his funny little hands. Pass.

Venus looks like it’s a pretty great place to live, if we stick to the clouds in floating sky cities, plying the jet streams in our steampunk dirigibles. It’ll be fun, but first, does anyone know how to attach a cog to a top hat? Venus, here we come!

We should stay away from the surface, though, that place’ll kill you dead. We’re guessing a crispy shell holding in a gooey center, at least for the first few moments. Once we sort the living in space deal, is there anywhere we won’t be able to go?

We could create underwater cities on Europa or Ganymede, in the vast oceans with the exotic hopefully unarmed, peaceful, vegetarian Jovian whales.Like Jupiter? Could we live there?

Jupiter is the most massive planet in the Solar System. It has a diameter of almost 140,000 kilometers and it’s made mostly of hydrogen and helium; the same materials of the Sun. It has more than 317 times the mass of the Earth, providing its enormous gravity.

If you could stand on the cloud tops of Jupiter, you would experience 2.5 times the gravity that you experience on Earth. Then you’d fall to your death, because it’s a gas planet, made of hydrogen, the lightest element in the Universe. You can’t stand on gas, rookie.

If you tried to bring your Venusian Vernian exploratorium ballooncraft for a jaunt across the skies of Jupiter, it would sink like a copper bowler with lead goggles.

The only thing that’s lighter than hydrogen is hot hydrogen. Let’s say you could make a balloon, and fill it with superheated hydrogen and float around the cloud tops of Jupiter suffering the crushing gravity. Is there anything else that might kill you?

Did you leave Earth? Then of course there is. Everything is going to kill you, always. You might want to write that on the brass plaque next to your ship’s wheel with the carving of Shiva in the center there, Captain Baron Cogsworth Copperglass.

Jupiter's Great Red Spot and Ganymede's Shadow. Image Credit: NASA/ESA/A. Simon (Goddard Space Flight Center)
Jupiter’s Great Red Spot and Ganymede’s Shadow. Image Credit: NASA/ESA/A. Simon (Goddard Space Flight Center)

Jupiter is surrounded by an enormous magnetic field, ten times more powerful than Earth’s. It traps particles and then whips them around like an accelerator. This radiation is a million times more powerful than the Earth’s Van Allen belts. Our big human meat roasting concern during the Apollo days.

If you tried to get near the radiation belts without insufficient shielding. It’d be bad. Just picture jamming your copper and brass steamwork fantasy into a giant microwave.

Is it possible there’s a solid core, deep down within Jupiter? Somewhere we could live, and not have to worry about those pesky buoyancy problems? Probably. Astronomers think there are a few times the mass of the Earth in rocky material deep down inside.

Of course, the pressure and temperature are incomprehensible. The temperature at the core of Jupiter is thought to be 24,000 degrees Celsius. Hydrogen is crushed so tightly it becomes superheated liquid or strange new flavors of ice. It becomes a metal.

The moral, we’re not equipped to go there. Let alone set up shop. So, let’s just stick with fantasizing your adventures as Emperor Esquire Beardweirdy Brassnozzle Steamypantaloons.

In his classic book 2001, Arthur C. Clarke said that “all these worlds are yours except Europa, attempt no landing there”. Well that’s crazy.

Europa’s awesome, we’re totally landing there, especially if we discover alien whales. So, Europa first. Besides, it’s just a book. So, Jupiter is the worst. Do not navigate your airship into that harbour.

What’s the worst possible environment you can imagine to try and live on? Tell us in the comments below.