(Published on September 18, 2016)
By Benjamin Vermette
History has been made on July 14, 2015. For the first time ever in humanity’s history, a man-made spacecraft flew through the dark and cold territory of the only major celestial object at the very edge of our solar system, the dwarf planet Pluto. At their farthest points, Pluto is 7.5 billion kilometers from Earth which means light, which travels at roughly 300 000 kilometers per second, needs about seven hours to make a single Earth-Pluto trip, a trip that took the NASA’s New Horizons probe more than nine years (and this is still the fastest space-probe ever built).
An artist's depiction of the New Horizons' proximity to Pluto and Charon. (wikipedia)
New Horizons: An Engineering Beauty
Launched on January 19, 2006, the New Horizons probe took off with one main objective in mind: rewriting history books. Mapping the surface and composition of Pluto and Charon (Pluto’s biggest moon), looking for rings and additional moons around Pluto, searching for an atmosphere on Charon and characterizing the neutral atmosphere of Pluto and its escape rate were only secondary objectives. About nine hours after launch, it reached the Moon’s orbit, a feature that took the Apollo modules more than three and a half days. It was just beginning its journey to the dwarf-planet Pluto.
To get to the edge of the solar system, New Horizons gathered unique systems designed by renowned engineers:
· This grand-piano-sized probe uses 16 small hydrazine-fuel thrusters mounted around the spacecraft. The thrusters were designed in different sizes so the Pluto-explorer craft could perform major manoeuvres just as well as small ones;
· X-band communications system was equipped on New Horizons so it could relay science data and status reports to Earth in exchange of commands based on precise radiometric tracking;
· A single radioisotope thermoelectric generator (RTG) is enough to provide, on average, the 230 watts needed for the electrical systems onboard the space-probe to get power. The RTG gets power through the natural process of radioactive decay of plutonium dioxide. As a matter of fact, the U.S. Department of Energy provided New Horizons 24 pounds of plutonium dioxide just before launch.
The NASA New Horizons spacecraft is literally a combination of the most high-end technologies for every system needed. That’s why it’s surprising when you learn the total cost was only $700 million. It’s the most cost-effective space machine ever built. New Horizons is the future.
New Horizons’ Journey, From A To Z
On September 21, 2006, only about seven months after a Mars flyby, New Horizons took the first images of Pluto at a distance of roughly 4,200,000,000 km, or 28.07 Astronomical Units, which means 28.07 times the distance of the Earth from the Sun. The pictures were taken using the Long-Range Reconnaissance Imager (LORRI), a (very) long-distance camera critical for tracking distant targets to help specialists manoeuvre the probe through the Kuiper belt objects.
LORRI also took a picture of Jupiter on September 6, 2006, before the whole New Horizons spacecraft received a gravity assist from the gas giant, with its closest approach being on February 28, 2007. Using Jupiter’s gravity, New Horizons saw its speed increased by 23 km/s (83,000 km/h). That meant the probe would arrive three years earlier to Pluto.
This wonderful technological achievement, otherwise called New Horizons, spent most of the rest of its journey in hibernation mode, waiting for the big day, July 14, 2015.
At 11:49:57 a.m. UTC on a Tuesday, July 14 2015, a gold-coloured space-exploring machine built by man brushed past the frontier of our solar system, more precisely at 12,500 kilometers above Pluto’s surface. After nine and a half years of hard work and patience, New Horizons was there!
This historical flyby gathered a lot of scientific data; some of which is still classified by NASA (no, there are no aliens on Pluto), other data that is still being processed by New Horizons and will be sent home soon, and breathtaking close-up Pluto pictures.
Close up photo of Pluto's surface captured by the New Horizons spacecraft. (nasa.gov)
This is one of the close-up pictures of Pluto’s surface, and guess what this image brought? Questions! 11,000-foot icy mountains on Pluto: How? According to NASA geologists, they formed 100 million years ago. This makes them the youngest mountains in the solar system! Ah, science! Numerous pictures were taken, of Pluto, Charon and its other moons. You can find them on the NASA website. (nasa.gov)
Cool. So, New Horizons flew by Pluto. Where is it going next?
On August 28, 2015, the NASA’s New Horizons’ team announced their jewel’s next destination. Nearly a billion and a half kilometers beyond Pluto lies a small Kuiper Belt object (KBO) dubbed 2014 MU. It’s kind of an ancient KBO that is believed to have formed where it orbits right now. New Horizons is expected to reach its new target on January 1, 2019.
Is Pluto A Planet?
The good old debate persists, after its first apparition on September 13, 2006, when Pluto was demoted to a ‘dwarf-planet’. There are three basic criteria given by the International Astronomical Union that a celestial object, mainly from our solar system, must meet to earn the official title of ‘planet’:
1. The object must be in orbit around the Sun. Pluto is, no doubt;
2. The object’s gravity must be massive enough to put it in a shape of hydrostatic equilibrium. Basically, this means the object is symmetrically rounded into a spheroid shape, which means, obviously, Pluto meets the second criterion as well;
3. The object must have cleared the neighbourhood around its orbit. That means the planet must be gravitationally dominant of its orbital zone. Pluto fails that third criterion. It isn’t gravitationally dominant. Pluto is only 0.07 times more massive than the mass of the objects in its orbit (Earth is 1.7 million times the mass of the objects in its orbit, which includes the Moon, the Space Station, etc.).This is why it was demoted.
However, a lot of definitions of planet exists, and a lot of people think Pluto should be given back its status of a planet because it meets all of the criteria of their favourite planet definition. Since the Pluto flyby on July 14, the debate is more intense than ever. As a matter of fact, the debate became so explosively acute that a petition is out to declare Pluto a planet again:
Wait! Before signing the petition, remember: if Pluto falls out of its orbit and falls towards the Sun, its ice will melt and it will form a tail which is strange behaviour for a planet. (Friendly reminder: it’s a comet’s behaviour.)
Our solar system is like any other solar system in the galaxy, and our galaxy is like any other galaxy in the Universe. But for us, it’s special. Our solar system is a vast and convoluted cosmic ocean, the only one which, as far as we know, has the right capacities to harbour life, and humanity has relatively just started to sail on it. Yet, we have discovered so many astonishing facts about it that our only motivation to keep navigating its interplanetary vacuum is our quest for knowledge; nothing about patriotic pride and nothing about a certain ‘space race’. Only since July 14, can we declare, as an intelligent civilization in being, that every major island of our own cosmic ocean has been explored, and this is something to be proud of.
