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Space Exploration

Plus Ultra [1]


On the 14th of July, NASA’s New Horizons probe will reach Pluto. Stop and think about what you just read.

In a little under four weeks, humankind will have arrived at the furthest of the classical nine planets[2] in our solar system, a ball of rock and ice so far away that our Sun is no bigger than a star in our own night sky[3]. It is, on average, almost 6 billion kilometers away: which means that the light from the Sun that reaches the Earth in 8.3 minutes takes 5.5 hours to shine upon the dwarf planet.

This will be the first visit by NASA to the Pluto-Charon neighborhood and New Horizons will take full advantage to increase our knowledge of this fascinating, but largely unknown body and its satellites[4]. The probe will then continue its investigation of the Kuiper Belt, a vast disk of asteroids and comets analogous to the Martian-Jovian belt, but many thousands of times larger and far more distant.


New Horizons continues the magnificent tradition of going farther and faster than humanity ever has in the peaceful pursuit of knowledge. The National Aeronautics and Space Administration was created in 1958 in the midst of the Cold War, in fear of a tiny beeping ball launched by the Soviet Union, with the goal of ensuring that the United States would not lose “the Space Race.” Project Mercury was launched to catch up on the Soviet lead and America proved it had “the right stuff”.

In 1961, President John F. Kennedy challenged America to “go to the Moon in this decade and do the other things, not because they are easy, but because they are hard.[5]” This committed NASA to Projects Gemini[6] and Apollo, the costliest scientific endeavor ever undertaken by the nation[7]. Though President Kennedy died shortly after issuing his historic challenge, his successors realized his dream: on the 20th of July, 1969, Buzz Aldrin and Neil Armstrong successfully landed on the surface of the Moon. These two Americans were the first human beings to ever set foot on a world other than our own. NASA subsequently sent 10 more astronauts to the Moon’s surface before cancelling the Apollo program in 1972[8].

Even while competing in the Space Race and struggling to overcome the monumental challenges posed by the Moon landings, the brightest minds America produced were dreaming with wonder of the further reaches and explorations beyond the Moon. The Inner Planets awaited us: our sister world, Venus; swift Mercury, gravitationally locked so that an observer on the surface would experience only one day in 6 Earth months; and the Red Plant, Mars, where future human colonies will ensure the continuity of our species.

Even as President Kennedy was making his historic speech at Rice University, the United States became the first nation to successfully send an object to another planet: Mariner 2 rendezvoused with Venus on the 14th of December 1962.


Scientists and engineers at NASA and the Jet Propulsion Laboratory continued to push the envelope, each mission building upon the last, establishing new firsts in human history until the achievements seemed to become routine and lose their wonder.

Mariner 4 visited Mars and took the first photographs of another planet:


Mariner 10 became the first human object to use the gravity of another object to “slingshot” itself onto a new trajectory as the spacecraft flew by Venus and used that body to alter its flight path into one that would lead it to Mercury.


Before the Inner Solar System was conquered, NASA was already planning its campaign for the Outer Planets. The first Pioneer program had been designed to send probes to the Moon (Pioneer 1 to 5) and ended in 1960. The name was resurrected in 1965 for a series of solar weather missions (Pioneer 6 to 9). But Pioneer 10 and 11 were designed with a different mission in mind. They would be the first human objects to traverse the asteroid belt and explore the region beyond including the giants of our system: Jupiter and Saturn.


Pioneer 10 not only gave us our first close-up view of the Jovian system, it was the first spacecraft to achieve escape velocity from our solar system. Unless it collides with another object, Pioneer 10 will sail through the interstellar medium forever.


Although both Pioneer 10 and 11 achieved escape velocity and were launched earlier, it is actually Voyager 1 that became the first human spacecraft to leave the heliosphere, the region of space formed by the outward pressure of the solar wind meeting and equaling the outside pressure of interstellar space. It is truly the region between stars. With a recession velocity of 17 kms per second, Voyager 1 is the fastest human spacecraft.


Voyager 2 was launched before Voyager 1, but with a slower velocity it was soon passed by its sister ship. The second Voyager probe gave us our first detailed look at Uranus, with its unique axial tilt, and Neptune, with its geologically active moon Triton. The probe was also the first that carried instruments specifically designed to measure the medium of space beyond the heliosphere, another first for mankind.


NASA ambitions and curiosity were not yet sated. In 2007, the Dawn spacecraft was launched with a new ion propulsion system. These engines permit the craft to execute a greater velocity change than any previous unmanned spacecraft after launch and thus to visit the two largest objects in the asteroid belt, Vesta and Ceres. After visiting Vesta in 2011, Dawn entered orbit around Ceres in March 2015, becoming the first human craft to orbit (not merely fly by) more than one non-Earth body.


Historians will look back at the decades after 1957 and marvel at what we have accomplished. With less computing power than a modern smartphone and the same technology found in the first generation Chevy Camaro, NASA sent 15 men to the Moon, returning them safely to Earth, and launched vessels that would visit every one of the 7 planets[9] in our Solar System and beyond. It is a feat even more daring and audacious than crossing the Atlantic Ocean on a 60-ton caravel measuring only 50 feet from prow to stern. Columbus[10] defied the warnings of the Ancients to pass the Straits of the Gibraltar in search of new worlds and his discovery launched a European Golden Age that shaped the modern world. NASA’s achievements – assisted and complemented by other space agencies – will help usher in a Golden Age that all mankind can share in. We stand on the very cusp of it.


Remember to look up at the night sky and marvel.


Sources and Notes

[1] Latin for “Further Beyond”

[2]  Pluto was formally kicked off the list of planets by the International Astronomical Union because of the discovery of a satellite, Charon, which is more than half as large as Pluto itself; as well as the discovery of Eris, which is smaller but denser than Pluto. The former ninth planet also has a highly eccentric orbit which leads scientists to believe that it was a late capture by the Sun rather than part of the original formation of the solar system. There might be many more such objects beyond Pluto’s orbit all the way out to the Oort Cloud, that are simply too faint to detect.

[3] At 0.8088 arc minutes, the angular diameter of the Sun as viewed from Pluto is bigger than the closest star and about a third of the diameter of Neptune. The Sun would also be 150 to 450 times brighter than the full moon on Earth, depending on where Pluto was in its orbit.

[4] It is referred to as the “Pluto-Charon” system because the barycenter of their orbit lies outside either body in a point of space between them. There are four more moons orbiting Pluto: Styx, Nix, Kerberos and Hydra.

[5] President John F. Kennedy, “We Choose To Go To  The Moon,” Rice University, 12 September 1962. The quote is from the Rice speech, but the President had already laid out the challenge before a Joint Session of Congress on 25 May 1961.

[6] Gemini was a series of 10 manned flights designed to expand on the Mercury program and explore the effects of longer duration flights, space rendezvous techniques, extravehicular activities (space walks) and precision Earth landings.

[7] The Apollo Program cost approximately 205 billion in 2014 dollars. The International Space Station, the next most expensive, cost NASA approximately 160 billion in 2014 dollars. Skylab cost approximately 12 billion 2014 dollars. The Space Shuttle program, though slightly more expensive than Apollo, was not a purely scientific venture, so I have excluded it. All costs are taken from the Congressional Budget Office.

[8] On the 19th of December, 1972, the Apollo 17 capsule safely splashed down in the Pacific Ocean. It was the last time mankind has left low Earth orbit…for now.

[9] Again excluding Pluto, now a dwarf planet or planetoid.

[10] I say Columbus with all due respect to the Portuguese navigators who had accomplished the equally impressive feat of rounding Africa and entering the Indian Ocean years before him. I also acknowledge the great Viking navigators who settled Iceland, Greenland and possibly discovered Newfoundland, and the even more impressive accomplishments of the Polynesians who spread across the vast Pacific Oceans on their sea-going catamarans.

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