Pluto has proven itself to be a diverse, dynamic and fascinating world packed with strange phenomena that planetary scientists are having problems fully explaining. And now they've found an icy oddity that highlights one of the key processes that is believed to shape this dwarf planet's surprisingly young surface.

PHOTOS: Dive Onto Pluto's High-Resolution Landscape

In recent high-resolution images sent back to Earth from NASA's New Horizons mission, which buzzed Pluto on July 14, 2015, a rather obvious chunk of ice appears to have been ripped away from Pluto’s surface. The upper layers of methane ice are missing from a western plain called Piri Planitia, a feature that is enriched with water ice.

Below Piri Planitia is a very old cratered terrain called Vega Terra, which is separated from the young plain by a series of cliffs (or "scarps"). Some of these scarps appear to have broken off, creating isolated hills (or "mesas"). But what has caused this discontinuity? Why has the methane ice-rich surface layers been cut off by the cliffs, giving way to a lowland plain rich in water ice?

ANALYSIS: 'X' Marks the Convective Spot on 'Lava Lamp' Pluto

According to mission scientists, the answer probably lies in how various ices in extreme environments react to being heated.

As we can probably guess, Pluto is a cold place. Though it's frozen, it is far from static. Chemicals that would normally be in a gas or liquid state here on Earth become solid layers of ice on Pluto. When the world receives even the tiniest amount of heating, volatiles — such as methane or ammonia ice — sublimate.

Sublimation occurs when the atmospheric pressure or temperature (or both) are very low. Water ice, for example, at sea level pressures on Earth will melt into a liquid and then boil into a vapor (or gas) when heated. On Pluto, because it's so cold and the pressures are a near vacuum, liquid water is not possible and heated water ice will sublimate directly from a solid into a gas. And it appears that's what's happening with the methane ice in Piri Planitia; it's sublimating into Pluto's thin atmosphere, likely contributing to the dwarf planet's atmospheric cycles of surface ices and exposing water ice-rich layers below.

NEWS: Pluto's Weirdly Young Surface Doesn't Make Sense

It's almost as if Pluto is getting a rejuvenating facial scrub; over millions of years, as its surface is gently heated by our distant sun, the surface layers of ice are sublimated away, creating young-looking regions curiously free of ancient impact craters.

Source: NASA

Originally published on Discovery News.

This article was originally published at The Conversation.The publication contributed the article to Spacecom's Expert Voices: Op-Ed & Insights.

Last week, SpaceX held another successful launch of its Falcon 9 rocket. Unfortunately, its landing was not quite as successful as the one in December (it crashed into the ocean).

SpaceX isn't alone in trying to develop reusable launch vehicles. Other private companies such as Blue Origin and Virgin Galactic are also in the race to achieve the dream of consistently landing a rocket after hurtling it into the heavens. Each success — and failure — gets us a little closer.

But how significant is the creation of reusable rockets? And where will we go from here? Are we finally close to the future once promised by the Jetson's FX-Atmos "flying car" or Han Solo's Millennium Falcon: a world of personal, space-bound transports that can leave your garage, reach orbit and beyond, and return home in time for dinner?

What else stands in the way?

The final frontier

The "democratization of space exploration," spurred by NASA encouraging private companies to develop and manage complete launch systems, is igniting a new age of space development and awakening a spirit of exploration and technology innovation that’s been absent from our culture for far too long.

This resurgence of interest is reflected in NASA's latest call for astronaut applications: 18,300 hopefuls applied for just 14 positions.

And in the private sector, venture capitalists are showing the same enthusiasm by investing US$1.8 billion in space startups in 2015, compared with an average of $193 million a year over the previous 15 years. The increased demand for space access is further spurring on private companies to develop more efficient reusable rocket launch systems.

Today's space companies aren't the first to set their sights on such a rocket. This great feat of engineering was originally achieved in 1993, when McDonald Douglass tested the Delta Clipper Experimental (DC-X), a prototype single-stage launch vehicle. NASA later canceled the project.

Now, it seems, the conditions are ripe once again to pick up where the DC-X left off. The private sector has started to take up this challenge, and the race is on to enhance all our lives with cheap space travel.

This future begins with the reusable rocket.

What does a reusable launch vehicle get us?

Imagine what life would be like if, after each trip to Grandma's, we had to throw away the car. Even with the benefits of mass production, the cost to an individual would be prohibitive, especially if there exist reasonable alternatives like horses or walking. Such automobiles could be employed only by governments, extremely wealthy enthusiasts or perhaps by a few skilled specialists who lived for the challenge.

This is pretty much the situation with current spacecraft technology. Not even the Space Shuttle program achieved the lofty goal of reliable reusability, although it tried very hard. The shuttle was such a complicated system that every time it returned to Earth, intense maintenance had to be performed and systems rebuilt or overhauled, making it three times as expensive as that of an expendable rocket. For example, a shuttle launch cost $450 million to $1.5 billion, compared with $110 million for a Russian Proton rocket with about the same lift capacity.

Truly reusable launch vehicles would significantly reduce the cost of getting material and people into orbit and enable new uses of space with far-reaching socioeconomic consequences that will ultimately reduce our impact on Earth’s environment, such as space-based energy collection, mining and manufacturing.

In order to get an idea of the savings, the retail price of a Falcon 9 rocket is around $60 million to build and launch (including fuel). Given its total lift capacity of 13,150 kilograms to low-Earth orbit, this translates into a price tag of about $400,000 to ferry a 90-kilogram (198-pound) person into space. But if you had to pay only for fuel, about $300,000 a launch, the price tag drops drastically to just $2,000 for the same person. That's not far from the cost of flying from New York to Sydney, which makes a future family vacation to a Bigelow B330 Space Habitat a viable alternative to Disney World.

At the pace things are going, we project that within 10 years the space industry will achieve the goal of a fully reusable launch vehicle. Companies and municipalities, small and big, are all starting to look into ways of taking advantage of this complete disruption in, or better yet creation of, the commercial space market.

So our next question is this: what do we need to make the Millennium Falcon — that is, a single-stage-to-orbit completely reusable spacecraft — a reality?

A little physics can help us see exactly what needs to happen and exactly how far we are from this goal.

Rocket Science 101

Space travel is all about speed. The old adage, "What goes up must come down," is true only to a point. If you throw something up fast enough, it won't come back down; it will have escaped Earth's gravity. The question is, exactly how fast is fast enough?

A simple application of Newtonian gravity theory tells us that if we achieve a speed of 11 kilometers per second — the equivalent of a plane flying 25,000 mph straight up — we are not going to fall back to Earth. Scientists and engineers refer to this speed, which depends on the physical properties of the Earth, as our planet's escape velocity.

A rocket tries to achieve that speed by taking mass and throwing it out the back as fast as possible. Thanks to Newton's third law — which states that for every action there is an equal and opposite reaction — this propels the rocket forward.

The ratio between the change in velocity needed to escape the Earth's pull (known as delta-v) and the speed at which the rocket sends stuff out the back (exhaust velocity) is the most important number in rocket science. It determines how much mass needs to be expelled and how much energy is necessary to get to space. The smaller we can make the ratio, the better.

In addition, the propellants and fuels are themselves massive, and the rocket needs to carry these things with itself, making it heaver and harder to accelerate.

So we need propellants and fuels with a high energy content and low mass.

Now we can begin to appreciate the enormous feat of engineering that private companies and governments have achieved by not only launching a rocket but learning to land it as well.

The maximum achievable exhaust velocities for the rockets we've been using since the dawn of space travel are much less than the Earth’s escape velocity (about 4 km/s or 9,000 mph), forcing us to come up with ingenious and costly multistage launch techniques to get even a modest payload into space.

In summary, in order to leave the surface of the Earth with the grace and apparent effortlessness of the Millennium Falcon, we need to achieve speeds in excess of the escape velocity, 11 km/s. In order to do that without carrying a fuel tank that far exceeds the size of our ship, we need to achieve exhaust speeds significantly higher than the escape velocity, something not possible with the chemical fuels we use.

So where do we go from here?

So in order to make the Millennium Falcon a reality, we need a new type of fuel, as chemical-based engines are severely limiting.

Thanks to Albert Einstein, we know that there is energy stored in mass itself. Using his famous E = mc² equation, we know that exhaust speeds up to the speed of light are achievable, and way more than necessary to escape Earth’s gravity.

A sustainable exhaust speed of 1,000 km/s, less than 1 percent of the speed of light, would pretty much enable our dream ship. Its fuel-to-mass ratio would be about the same as that of your typical car.

The next question is: how do we get access to the energy stored in the mass (fuel and propellant) sufficient to achieve those speeds? The answer lies in nuclear reactions or, better yet, matter-antimatter reactions. In short, we need to put a mass reactor, nuclear or matter-antimatter, on board our ship. Think of the Enterprise's "warp core," for all those Star Trek fans out there.

Nuclear rockets may seem farfetched, but various versions have already been proposed and prototypes have even been built. The Nuclear Engine for Rocket Vehicle Application (NERVA) project, a joint NASA-Atomic Energy Commission program, developed a flight-certified nuclear-based rocket engine that meets all the requirements for a manned mission to Mars.

What is interesting, and perhaps a little sad, is that this was done in 1968, over four decades ago! The NERVA engine achieved exhaust velocities pretty close to Earth’s escape velocity, around 10 km/s. The program was tied to NASA's manned Mars exploration program and, since it was unable to justify the expense of going to Mars, was scrapped in 1972.

More recently, NASA has been developing electric propulsion systems that can generate large effective exhaust velocities that are limited only through the strength of the electric field. Effective exhaust velocities of 90 km/s are already achievable. But this is just the propulsion part. The solar panels, batteries or fuel cells that are currently used as power sources for these engines limit their usefulness. Electricity generated from nuclear power could solve this problem.

Back to the future

With the renewed interest in space exploration and innovation, we challenge inventors and entrepreneurs to consider looking at advanced nuclear/antimatter-powered rocket systems. This could enable us to achieve the dream of a space car in our garages in half a century.

The key to all the recent advances in space exploration technology has been combining older proven technologies with modern computing capabilities, materials and fabrication processes. NASA's push to get technologies into private hands will accelerate this process.

Back in 1972, we were at 1 percent of the needed exhaust speed. It's not too much of a stretch to propose that, after 40 years of advances, we need only revisit the designs with fresh and entrepreneurial eyes to make it possible for a Han Solo — or, to be more contemporary, Rey Skywalker — to jump into the Falcon and speed off to somewhere far, far away.

Virgin Galactic rolled out its new SpaceShipTwo on February 19, 2016, at the Mojave Air and Space Port.

Fredrick Jenet, Associate Professor, University of Texas Rio Grande Valley and Volker Quetschke, Associate Professor, University of Texas Rio Grande Valley

This article was originally published on The Conversation. Read the original article. Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google +. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Space.com.

A gorgeous total solar eclipse, a Mars lander's second chance and the secrets of Mercury's crust — here are the most amazing things that happened in the universe this week!

Lucky skywatchers capture total solar eclipse

The moon completely blotted out the sun for viewers in Indonesia and the North Pacific Ocean March 8/9 during a total solar eclipse, and Space.com readers sent in epic photos of the celestial event. [Full Story: Amazing Total Solar Eclipse Photos Show 'Black Hole in the Sky']

Plus: Alaska Airlines passengers chased the eclipse in a plane, and the DISCOVR satellite grabbed an awesome viewof the moon's shadow crossing Earth.

Planetary families can span generations

A newly-captured image of a dying star system reveals a dusty shroud that could be fertile for new planet formation — suggesting stars could form new planets not just early in their lives but sometimes later, too. Such a star could potentially form planets multiple times over its life. [Full Story: Could New Planets Form Around Old Stars, Too? (Video, Images)]

Second chance for InSight

NASA's InSight Mars Lander missed its March launch date after a leak in a vacuum chamber surrounding a key instrument couldn't be fixed quickly enough, but the agency will give it another chance: instead of scrapping the mission, officials rescheduled it to May 2018. The lander is built to probe Mars' interior structure. [Full Story: NASA Aims to Launch Troubled Mars Lander in May 2018]

Asteroid wildcard slips safely by

An asteroid predicted to pass by Earth March 8 did so a day early, surprising scientists. The near-Earth asteroid flew by 2.54 million miles (4.09 kilometers) distant from the Earth, Minor Planet Center researchers said. [Full Story: Slippery Asteroid Surprises Scientists With Early Earth Flyby]

Primordial Mercury crust unmasked

Data from the final orbits of NASA's MESSENGER spacecraft revealed that the carbon coating Mercury's surface is nothing new: Rather than being deposited by comets, as previously thought, the carbon actually came from remnants of the planet's primordial crust, formed by a cooling global ocean of super-heated magma. [Full Story: Mercury's Carbon-Rich Crust is Surprisingly Ancient]

Opportunity rover might spy ExoMars newcomer

The European Space Agency's ExoMars 2016 mission, launching Monday, March 14, will put an orbiter around the Red Planet and drop a prototype lander down to the surface. That lander will touch down in Meridiani Planum, where NASA's Opportunity rover landed in 2004 — and Opportunity may be positioned to document the new lander's descent. [Full Story: NASA Rover on Mars May Have Ringside Seat to Europe's ExoMars Mission]

Destructive star keeps destroying

A white dwarf star, spotted shredding a planetesimal in October, is at it again (still): The core of the dead star now seems to be orbited by 10-15 huge clouds of gas and dust from disintegrating rocks. [Full Story: Real-Life 'Death Star' Continues to Destroy Alien Worlds]

One-Year Ceresversary

A year after NASA's Dawn probe made it to the dwarf planet Ceres, giving us our first close-up views, it has returned detailed maps and some answers about Ceres' mysterious bright spots. On the other hand, it's raised even more questions about the unusual mountain called Ahuna Mons. [Full Story: One Year at Ceres: NASA Probe Hits Milestone at a Dwarf Planet]

Astronaut honored with space station delivery craft

NASA's Rick Husband, an astronaut who died in the space shuttle Columbia disaster, will be honored with a namesake supply spacecraft launching to the International Space Station March 22. The Cygnus craft will deliver supplies and experiments to astronauts aboard the station. [Full Story: Orbital ATK Names Space Station Freighter for Fallen Columbia Astronaut]

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