New Horizons Gets USPS Stamp of Pluto Approval

It's been a long time coming, but the US Postal Service has released its designs for its 2016 stamps and one set rightfully features the biggest space story of 2015 -- NASA's New Horizons mission to Pluto.

It's been a long time coming, but the US Postal Service has released its designs for its 2016 stamps and one set rightfully features the biggest space story of 2015* - NASA's New Horizons mission to Pluto.

Top 10 Space Stories of 2015: Readers' Choice

In 2006, when the spacecraft was being prepped for its near-decade long odyssey to the outer solar system, principal investigator Alan Stern made sure a 1991-minted Pluto stamp was attached to the body of the spacecraft. That stamp, which included the type "Pluto - Not yet explored", had become a planetary exploration "call to arms", according to an Astronomy Magazine interview.

Indeed, Pluto was the final "classical" planet of the solar system to be explored, but on July 14, 2015, that changed dramatically when New Horizons blasted through the Pluto system, revealing the dwarf planet in all it's astonishing glory. Suddenly, the "planetary debate" was forgotten and Pluto and it's incredible system of moons wowed the world. Pluto has become the most fascinating, mysterious and awe-inspiring world, proving that the frozen outermost reaches of the solar system is a surprisingly dynamic place.

ANALYSIS: Why Pluto Was Turned Into Pop Art

And with this revolutionary moment for planetary science comes a USPS stamp to commemorate the NASA mission.

"The New Horizons project is proud to have such an important honor from the U.S. Postal Service," said Stern in a USPS news release. "Since the early 1990s the old, ‘Pluto Not Yet Explored' stamp served as a rallying cry for many who wanted to mount this historic mission of space exploration. Now that NASA's New Horizons has accomplished that goal, it's a wonderful feeling to see these new stamps join others commemorating first explorations of the planets."

The stamps include an artist's impression of the spacecraft and the now iconic composite observation of Pluto at close approach captured by New Horizons' Long Range Reconnaissance Imager (LORRI) with data from the Ralph imaging instrument.

PHOTOS: New Pluto Pics Show Beautiful, Complex World

But that's not all, another set of stamps featuring all the planets of the solar system will also be released alongside a collection commemmorating the sci-fi phenomenon "Star Trek."

You can preview all of 2016′s stamps on the USPS website.

*The New Horizons flyby of Pluto was voted the number one space story of 2015 in a Discovery News readers' poll.

Every year, Discovery News turns to our faithful readers to see which space stories excited you the most and 2015 has been yet another incredible year for astronomy, spaceflight, planetary science and solar system discovery. After pulling together the nominations by considering web traffic over the past 12 months,

the selection was put up for a vote

across social media and the top 10 quickly became obvious -- with a very clear winner. Can you guess which stories made it into the top 10? Read on to find out.

(Want to compare this year's top 10 with last year? Read "

Top 10 Space Stories of 2014: Readers' Choice


With NASA's Dawn mission arriving at Ceres and New Horizons flying past Pluto, 2015 will forever be known as the "Year of the Dwarf Planet." But Ceres will forever be known as the dwarf planet we visited


. In March, the mission, that had made the slow transit from massive asteroid Vesta,

arrived in Ceres orbit

, revealing a fascinating, pock-marked surface. A puzzle quickly presented itself -- what the heck are those bright spots? Although Dawn is orbiting the tiny world closer than ever,

these bright patches still perplex scientists

, highlighting just what a mysterious and fascinating place Ceres is.

PHOTOS: Ceres Delights: Dawn's Latest Dwarf Planet Views

Sure, it's a movie, but it's a movie that starred Matt Damon and co-starred SCIENCE! Not only did "The Martian" become a box office success, it was a rare movie that pleased scientists and the general public alike. There were a

few scientific missteps

, but overall, it was a science fiction movie that realized that scientific accuracy can drive a great story forward without having to unnecessarily stray into scientific fantasy.


The Martian: Science vs. Fiction

Tour 'The Martian' Movie Set... On Mars

While many of the headlines focus on its younger roving cousin, Curiosity, NASA's Mars Exploration Rover Opportunity is still exploring the Red Planet despite 10 years of dusty wear and tear. The veteran robot

has even completed an extraterrestrial marathon this year

, proving that

years of steady progress

, despite

recently suffering more "amnesia" problems

, can pay off. Be sure to keep an eye on this mission, it's not done with Mars quite yet.

MORE: 10 Years On Mars: Opportunity’s First Sols

The NASA/ESA Hubble Space Telescope is nothing short of a scientific and cultural phenomenon. Since 1990, the powerful space telescope has been pushing the boundaries of astronomical breakthroughs, refining our understanding of our place in the cosmos. And this year it celebrated its

quarter of a century

in space -- an incredible feat. As we look forward to the launch of NASA's James Webb Space Telescope (scheduled for 2018), we can only hope that Hubble's successor will have the longevity of the world's most famous space telescope.


Hubble at 25: The Space Telescope by the Numbers

Hubble at 25: What's Next for the Space Telescope?

Hubble at 25: Space Telescope's Top Science Discoveries

Hubble at 25: Brief History of the Hubble Space Telescope

NASA's six-wheeled rover Curiosity

continues to wow the world with incredible images and science from the slopes of Mount Sharp in the center of Gale Crater. The robotic geologist has not only revealed the stunning array of surface features the region has to offer, but it has also discovered potential for past habitable environments and

an abundance of evidence for past liquid water flowing on Mars' surface

. It is a mission of epic proportions and has been a Reader's Choice favorite since it landed on the Red Planet in 2012 -- we can't wait to see what adventures Curiosity has in store for us in 2016.

PHOTOS: Curiosity Plays in Sandy Martian Dunes

After a decade of orbiting Saturn, NASA's Cassini mission has started

its farewell tour

. Having most recently carried out its final flyby of enigmatic moon Enceladus, the spacecraft will begin maneuvers in 2016 that will ultimately see the mission fly through the planet's ring plane. Then, the spacecraft

will conclude its "Grand Finale"

, burning up in Saturn's atmosphere. 2015 has been a huge year for Cassini, revealing more incredible science about Saturn's system of moons, rings and dynamic atmosphere and we look forward to more science and beautiful images like this one

before mission end


MORE: Cassini's Final Flyby of Ice Moon Enceladus

This story rapidly became 2015's viral story of the year because...


Actually, it's

probably a cloud of comets

, but the mere hint of

a possible alien megastructure orbiting a star some 1,500 light-years away

was enough to throw the internet into a spin. But the best thing about this story is that NASA's Kepler space telescope was thrown into the limelight and the stunning science of exoplanet detection became an international talking point. Since the original detection of the weird transit signal discovered by citizen scientists of the Planet Hunters project, the SETI Institute has turned its powerful Allen Telescope Array at Tabby's Star

to find no transmitting aliens

. Still, it doesn't mean it's


aliens, it just means there are far more likely explanations.

MORE: Has Kepler Discovered an Alien Megastructure?

Ahhh, water on Mars. Yes, we already know that there's water ICE on Mars, but this time it's different. Well, it MIGHT be different. Way back in 2011, some strange seasonal channels were spotted by NASA's Mars Reconnaissance Orbiter on Martian slopes. Though they looked like channels created by flows of liquid water, scientists urged caution -- Mars' atmosphere is so cold and thin, only short-lived water ice should exist, right? But after orbital analysis this year, the chemical residue of these channels was analyzed, revealing that these channels may well be caused

by gushing liquid water

. However, this water isn't your fresh mountain spring variety --

it's highly toxic water

laced with perchlorates,

if it is indeed liquid water...

MORE: So Liquid Water Flows on Mars -- Now What?

Commercial access to space has been ramping-up in recent years and 2015 has seen some of the biggest advances.

Orbital Sciences has bounced back

after its

Antares rocket explosion

in 2014 and, though suffering its own huge setback with

a Falcon 9 rocket explosion

in June, SpaceX returned with a

dramatic launch and 1st stage rocket return this month

. Add these historic advances to

Blue Origins own suborbital rocket return

and we have seen 12 exciting months of commercial spaceflight successes not only to resupply the space station, but also to launch satellites and refine rocket technology. Next stop Mars?

Who knows


MORE: Lesson of SpaceX Rocket Landing: Try, Try, Try Again

It's been a long wait, but in July, NASA's New Horizons mission flew through the Pluto-Charon system for its

historic and long awaited flyby

. The spacecraft, which took nearly a decade to reach the outer solar system, is now blasting through the Kuiper Belt and mission scientists are

steering it toward a Kuiper Belt object (KBO)

for another flyby in 2019. But its Pluto flyby was just the beginning -- the spacecraft recorded so much data that it continues to beam back detailed information about the dwarf planet,

its weirdly dynamic surface

, it's

crazy assortment of moons

and some

perplexing mysteries along the way

. This has been a historic year; we're finally seeing Pluto up-close and in high-definition for the first time since it was discovered by American astronomer Clyde Tombaugh in 1930.

PHOTOS: Dive Onto Pluto's High-Resolution Landscape