In 1991, the United States Postal Service released a set of stamps depicting each planet and noting which spacecraft had explored it. Pluto’s stamp featured an artist’s rendition of an uninhabitable planet with no features and the words: “NOT YET EXPLLORED.”
New Horizons successfully reached Pluto and discovered that its moons Charon, Nix, Hydra and Kerberos were more active than predicted, leading scientists to revise their models of its outer region.
What is pluto?
NASA’s New Horizons spacecraft zoomed past Pluto in 2015 and revealed a frigid world that was more dynamic than scientists had predicted. Icy nitrogen cliffs and giant methane ice slabs cover its landscape while deep cracks mar its surface – one spot had an astounding heart-shaped feature which caused observers here on Earth to go into shock!
Scientists presented some of the latest discoveries from New Horizons at this week’s Lunar and Planetary Science Conference, such as evidence that Pluto may once been covered with methane and an explanation for its bladed terrains formation based on Tanguy Bertrand of Ames Research Center and New Horizons co-investigator – she believes some may have been created due to sunlight erosion.
Clyde Tombaugh discovered Pluto 90 years ago as a barely visible dot barely discernible to ground telescopes. Astronomers took another decade before discovering how to photograph it. Pluto’s unique orbit means its surface tilts constantly relative to the Sun; some icy surfaces sublimate and form thin atmospheres when closer to our Sun than at other times, giving rise to sublimation events on Pluto itself and producing sublimated gaseous surfaces nearer us than ever.
What is the spacecraft?
Planetary scientists were inspired by the success of Voyager probes to envision a follow-on mission that could examine Kuiper belt objects and Pluto. New Horizons was officially launched on January 20, 2006 to fulfill this goal.
On July 14, 2015, after an incredible nine-year journey that marked it as the fastest ever to reach our solar system’s outer reaches, New Horizons made history when it arrived at Pluto on July 14. It provided images of a frozen, icy world and its moons revealing unexpected geologic activity such as glaciers, mountain ranges made up of water ice mountains, and dunes which absorb methane gas – as well as glaciers, mountain ranges composed of water ice mountains, and methane gas-absorbing dunes – that revealed many surprises about geologic activity within our solar system!
Data gleaned from the flyby caused scientists to revise models of Pluto and its satellites’ formation significantly, as well as to rethink what constitutes a planet; Pluto is now officially classified as a dwarf planet.
What is the mission?
New Horizons spacecraft reached Pluto in 2015, producing spectacular close-up images of this dwarf planet and its four moons. Of particular note is a region near Pluto’s equator called Tombaugh Regio – named for Clyde Tombaugh who discovered this mission – interrupted by a bright area dubbed by scientists as its heart.
New Horizons collected data about an impressive array of subjects during its nine-year journey to Pluto and the Kuiper Belt, from ice volcanoes and liquid ocean evidence on Charon to whether Pluto might possess methane on its surface.
New Horizons’ journey was an extraordinary test of both ingenuity and patience. To speed its flight, New Horizons used a flyby of Jupiter as a launchpad; over the years it made careful thruster burns to stay on course towards Pluto. Yet engineers managed to reach Pluto and its Kuiper Belt neighbors successfully, sending back breathtaking photographs showing towering water-ice mountains, expansive plains of frozen nitrogen, and many other intriguing features.
What is the future?
After the success of Voyager, planetary scientists turned their focus toward Pluto. Though initially uncertain whether to pursue flyby missions to it, in 1989 a group known as Pluto Underground persuaded Stern and his colleagues that Pluto must be explored further.
The group’s perseverance paid off, as the New Horizons mission successfully reached Pluto. But it was no easy task; funding cuts under both Presidents Bush and Clinton threatened to derail it at every turn.
At present, the only way for a spacecraft to visit Pluto and its moons with a JGA trajectory (jumping from Jupiter’s gravity slingshot to Pluto using thruster burns over years). Unfortunately, such an expensive approach requires a very large launch vehicle, likely only available by 2030 at best. But there may also be low-launch energy VEGA trajectory options which don’t involve jumping from Jupiter – these may shorten trip duration and encounter speeds significantly.