When New Horizons Principal Investigator Alan Stern was asked what he expected to see on Pluto, he responded, "Something wonderful."
He was right.
There is something powerful and overwhelming at seeing the world that has enthralled me for almost a decade suddenly take center stage worldwide. Suddenly, everyone is tweeting Pluto images, real and comical, sharing posts about Pluto on Facebook and other social media, marveling at this small planet that never stops surprising us.
Sharing in the joy of counting down to the flyby moment, waiting the long hours for the signal the spacecraft survived, and then taking part in the jubilation when that signal was received are experiences that that will stay with me and with those around the world who shared them, both at APL and online, forever.
New Horizons fly its nominal course, as the team that had been searching for hazards did not find any. None of the alternate Safe Haven Bail Out Trajectories (SHBOTs) that would have led to a slight reduction in the collection of science data, was needed.
The last image of Pluto sent back by the spacecraft before the flyby was a vivid picture prominently featuring the heart-shaped bright area on the encounter side.
Some described the image as Pluto’s “love note” to Earth. It was taken using the Long Range Reconnaissance Imager (LORRI) on Monday, July 13, at approximately 4 p.m. EDT when the spacecraft was about 476,000 miles (768,000 km) from Pluto’s surface. Pluto filled nearly the whole frame in the image.
The "rain of data" from the flyby, so far only one to two percent of the total taken on July 14, is literally one surprise after another. Who knew that both Pluto and Charon are geologically active worlds? One of the biggest surprises was the lack of craters, especially on Pluto.
That lack means the surface is young. Just what drives geology on both worlds is uncertain. Tidal forces from giant planets cause such activity on some of these planets’ moons, but there is no giant planet near the Pluto system to generate such effects.
The iconic heart-shaped region, unofficially dubbed "Tombaugh Regio" after Pluto discoverer Clyde Tombaugh, is covered in carbon monoxide ice. At its southern boundary sit exotic mountains 11,000 feet high, which scientists believed to be made of water ice.
In the center-left of Tombaugh Regio is an area of craterless plains divided into irregularly-shaped segments ringed by narrow troughs. This area has been nicknamed "Sputnik Planum" after the first satellite launched into space by the former Soviet Union in 1957.
Other parts of the plain show small pits, which some scientists believe were formed by ice that sublimated, transforming directly from solid to gas.
One possible explanation for geological activity on both worlds is heat produced by radioactive decay of elements in these worlds’ rocky interiors. Pluto’s interior could harbor potassium, thorium, and uranium, all of which produce heat via radioactive decay.
“The discovery of vast, craterless, very young plains on Pluto exceeds all pre-flyby expectations," noted Jeff Moore, leader of the mission's Geology, Geophysics, and Imaging (GGI) team.
Pluto's atmosphere extends 1,000 miles from its surface. Tens of thousands of miles beyond the planet, New Horizons detected a region of cold, ionized gas, confirming Pluto's atmosphere is being lost to the solar wind.
A prominent crater in its southern hemisphere is much longer and deeper than the Grand Canyon and is estimated to be 60 miles across.
The strange, dark "anti-polar cap" near Charon's north pole is diffuse, stretching about 200 miles long. In color, this region appears reddish, fueling early speculation that the area is covered by material blown off the surface of Pluto.
A zoomed-in image of a region near Charon's equator reveals a mountain appearing to rise out of a trough. The strange feature, about 240 miles (390 km) long, is completely baffling scientists. It has been nicknamed the “mountain in a moat."
The feature has geologists "stunned and stumped," Moore said.
The next batch of data to be sent back by New Horizons will be released on Friday, July 24 at a media conference.
Here are two animation produced by the mission team, "Frozen Plains in the Heart of Pluto's Heart"
and "Animated Flyover of Pluto's Icy Mountains and Plains":
Scientists are not the only ones fascinated by enigmatic Pluto. Artists, writers, musicians, graphic designers, etc., inspired by Pluto, have spent the last week creating beautiful works of art honoring the little planet that could, its five moon, and the spacecraft that flew more than three billion miles to see the system's wonders.
Here is just one of many such sites, this one titled "PlutoVerse": https://storify.com/ridingrobots/plutov
Over the last week, I have written detailed descriptions of New Horizons' findings for Spaceflight Insider, which you can read at the following links:
One of the most memorable experiences was meeting Annette Tombaugh-Sitze and Alden Tombaugh, the daughter and son of Clyde Tombaugh, discoverer of Pluto. In a strange way, Clyde got to visit his planet, as a small amount of his ashes are on board New Horizons.