Pluto fly-by is Sagan's dream come true
By Amanda Jermyn

The late Carl Sagan was a great proponent of sending a fly-by mission to Pluto. Several canceled missions later, and years after Sagan’s passing, his dream finally came true. After a journey of nine and a half years and three billion miles, NASA’s New Horizons spacecraft reached the dwarf planet Pluto on July 14th, 2015.

This feat of nuclear powered engineering was designed and built by the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, which operates the craft and manages the mission for NASA. Because of Pluto’s great distance from Earth, it takes radio transmissions four and a half hours to travel between the two, which results in challenges in operating the craft. In addition, the great distance means that when the radio signals arrive, they are very weak, so the data transmission rate is rather slow. As a result, it will take until late 2016 for us to receive all the data stored on the craft’s recorders.

In the meantime, however, since the July flyby, a mere 7,800 miles above Pluto’s surface, we are already receiving some stunning new data that is helping to unlock the mysteries of the dwarf planet and its moons. The new detailed photos we’ve received so far show a surprisingly diverse terrain, with high mountains and smooth plains of exotic ices. According to MIT’s Richard Binzel, an investigator on the New Horizons mission, “Active processes must be occurring on Pluto to give that diverse range of features. We have a lot of new mysteries to solve.”

Amongst the many mysteries is the discovery of a mountain range, rising as high as 11,000 feet. The lack of craters in the area indicates that the mountains are no more than 100 million years old, very young in astronomical terms, and these mountains may still be in the process of forming. Unlike the icy moons of the giant planets, Pluto can’t be heated by gravitational interactions with a larger planet because there is none close by, so it’s not clear what process is responsible for these features.

The latest data from New Horizons provides vivid images of Sputnik Planum, an area in the heart-shaped region of Pluto, which show evidence of nitrogen ice flows, along with carbon monoxide and methane ices. The data also reveals an atmosphere dominated by nitrogen. However, Pluto’s small mass allows hundreds of tons of nitrogen to escape into space per hour. So there has to be a source to replenish the nitrogen in both the atmosphere and ice flows. Recent research by Kelsi Singer of the Southwest Research Institute and Alan Stern, Principal Investigator on the New Horizons mission, suggests that geological activity is helping to bring nitrogen up from Pluto’s interior to replenish the supply. This research has since been bolstered by the latest images from New Horizons that show land forms that suggest heat is rising beneath the surface, with troughs of dark material collecting or bubbling up between flat sections of crust. Just as with the mountains observed on Pluto, it’s not clear what process is responsible for such internal heating but possibilities include geysers and ice volcanoes. However, why the internal heating occurs at all remains a mystery.

Another intriguing discovery is that Pluto has a long plasma tail of ionized gas caused by its atmosphere being blown into space by the solar wind. In addition, complex hydrocarbons are responsible for the reddish color of Pluto’s surface. It’s moon Charon is covered in chasms and craters. The data keeps streaming in, surprising and amazing us. Given that most of the data stored on the spacecraft’s recorders has yet to reach Earth, what wondrous discoveries might still await us?

In other astronomy news, on Sunday, September 27th, there will be a lunar eclipse visible in the Springfield area starting at 9:07pm and ending at 12:27am, September 28th. An eclipse-viewing program will take place from 6:30pm to 11:30pm on September 27th at the Springfield Science Museum. The museum galleries will be open from 6:30pm till 9:00pm and there will be planetarium shows and a special presentation about lunar and solar eclipses by Richard Sanderson. At 9:00pm, participants will move outdoors to view the eclipse, using telescopes provided by the Springfield Stars Club, until the total phase ends. The cost is $5 for adults and $3 for children aged 17 and under.

Also, join the Springfield Stars Club on Tuesday, September 29th at 7pm at the Springfield Science Museum for a talk by Richard Sanderson entitled “A Review of Summer Astronomy Events.” The talk will include a review of the September 27th lunar eclipse. Sanderson is curator of physical science at the Springfield Science Museum and manages the museum’s Seymour Planetarium and Observatory. He is an astronomy writer and co-author of the 2006 book, “Illustrated Timeline of the Universe.” Refreshments will be served, and the public is welcome. The meeting is free of charge for members, with a suggested donation of $2 per non-member.

On Friday, October 2nd, at 7:30pm, the Stars Club and the Springfield Science Museum will host “Stars over Springfield,” an astronomy adventure for the whole family. Astronomy educator Jack Megas will speak on “Observing the Fall Sky.” A fee of $3 for adults and $2 for children under 18 will be charged.