Pluto Space At P-3

When I was born, we had not yet sent a rocket to orbit the Earth.

When I was still too young for school, Luna 3 sent us our first picture of the lunar far side, grainy and static-filled as it was.

Farside-Luna-3

Photo: Roscosmos

When I was in kindergarten, we had no clue what the planets really, REALLY looked like. Many people still thought there were canals on Mars, or at least a thick atmosphere and possibly plant and animal life. We knew Jupiter had a big red spot, Saturn had rings, and Venus had clouds.

When I was in second grade, Mariner 2 flew by Venus and we confirmed that it was HOT and completely cloudy, the atmosphere totally opaque. It was the first time that anyone had sent any kind of spacecraft to another planet successfully. It wasn’t until 1970 that the Russian Venera 7 spacecraft became the first to reach the surface of Venus, 1975 before Venera 9 sent back the first images from the surface of Venus, and 1978 before the Pioneer Venus Orbiter gave us our first, simple radar map of the surface.


When I was in fourth grade, Mariner 4 flew by Mars and scientists were literally stunned to see that the surface of Mars was heavily cratered, looking more like the Moon than the Earth.

Mariner 4 - JPL

Photo: JPL / NASA

Think about that for a second. We now know so much about Mars that grade school kids know that it has a whisper-thin atmosphere, valleys that dwarf the Grand Canyon, and the biggest volcano in the Solar System. There are people in their late thirties that remember seeing Viking on Mars as a kid. But until July 15, 1965, fifty years ago, we didn’t have a clue that it was anything like what it really is.


In my senior year of high school, Mariner 10 was the first spacecraft to use a gravity assist from another planet, slingshotting around Venus to get to Mercury. It returned the first photos of Mercury, which up until that time had been just as mysterious and unknown as Mars’ details had been. Even from the biggest telescopes on Earth, Mercury had been nothing but a bright crescent with an occasional blobby smudge visible. Being so close to the sun we knew that it would be hot, but we didn’t know we would find some of the coldest places in the solar system there. (There are polar craters on Mercury that never see the sun. Ever. They’ve almost certainly got ice in them.) We didn’t know if Mercury had an atmosphere or not. (It doesn’t.) Instead of a pinpoint with smudges, Mercury was revealed to be cratered and barren, similar to the Moon, but different in its own ways.

Mariner 10 image of Mercury - JPL

Photo: JPL / NASA


Just before I got out of high school, Pioneer 10 was the first spacecraft to fly by Jupiter. Our vision of the giant planet got tantalizingly better.

Pioneer 10 - Jupiter

Photo: JPL / NASA

The next year Pioneer 11 followed past Jupiter, with even better detail.

Pioneer 11 - Jupiter

Photo: JPL / NASA

After its Jupiter flyby, Pioneer 11 went on to pass Saturn in 1979.

Pioneer 11 - Saturn

Photo: JPL / NASA


When I was in college, Voyager 1 flew by Jupiter, with Voyager 2 following it by four months. The Voyager spacecraft expanded our view of those two planets and their moons by many orders of magnitude.

Voyager 2 Jupiter

Photo: JPL / NASA

Seen up close and in incredible detail, Jupiter showed itself to be one of the most complex, dynamic, and beautiful planets.

Voyager 1 at Jupiter - JPL

Photo: JPL / NASA

Jupiter’s Great Red Spot is not just a storm (a storm almost three times bigger than the entire Earth) but part of a complex of storms and vortices, spinning off smaller (Earth-sized) storms and swallowing others.

Voyager 1 Jupiter System

Photo: JPL / NASA

The moons of Jupiter turned out to be as varied and complex as the family of planets orbiting the sun.

converted PNM file

Photo: JPL / NASA

Io is a frozen volcanic hell, hundreds of degrees below zero on the surface but spewing plumes of sulfur and other molten rocks high into space. These were the first active volcanoes ever seen other than on Earth.

Voyager 1 Callisto - JPL

Photo: JPL / NASA

Callisto is an icy moon, heavily cratered.

Voyager 1 Ganymede - JPL

Photo: JPL / NASA

Ganymede is also an icy moon, but with very little cratering. This means that the surface must be actively regenerated by some process, probably from turnover between the surface and a huge ocean trapped underneath the ice.

converted PNM file

Photo: JPL / NASA

Europa was the most mysterious of all of the Galilean moons. Relatively smooth and covered in ice, it’s also covered by a spiderweb of cracks. What’s causing the tan or brown color? Gravitational data from the Voyagers indicated that Europa could have an ocean under the ice that contains even more water than on the entire Earth.

Could that ocean, kept warm by tidal forces, protected by the ice above, and fed with minerals from ocean vents, could it be a safe harbor for life to develop? The Galileo spacecraft in the late 1990s gave us more indications that it could, so now we’re planning a dedicated mission to Europa to launch in the 2020s.

Voyager 1 Jupiter Ring - JPL

Photo: JPL / NASA

Jupiter has a ring! No, four rings! We had no idea that they were there until the Voyagers saw it in 1979.

Voyager 2 Saturn

Photo: JPL / NASA

Then the Voyagers flew by Saturn in 1980 and 1981. Again, our theories about the planet and its moons got turned on their heads repeatedly.

Voyager 1 Saturn's Rings

Photo: JPL / NASA

From Earth, our biggest telescopes of the 1970’s showed three rings with gaps between them. Pioneer 11 had shown that the ring structures were more complex, but didn’t give us a detailed view.  Voyager showed the rings to have complex structures far beyond anything ever imagined, including structures or “spokes” that form and dissolve as the rings rotate. Three rings? Nope. Dozens.

Voyager - Enceladus & Cassini Enceladus jets

Photo: JPL / NASA

Enceladus is an icy moon with parts cratered and parts smooth. The smooth areas were once cratered, but some process has re-formed them. Later, when the Cassini spacecraft got to Saturn it discovered that the cracks in Enceladus’ icy surface are venting into space (right part of picture above). It’s water being vented, and it contains dust and simple organic compounds.

Does Enceladus have an ocean under the ice that might contain life? We know the water’s there, we know the chemicals are there, we know a heat and energy source is there. First, Europa, now Enceladus?

Voyager 1 - Dione

Photo: JPL / NASA

Dione is a mix of ice and rock, heavily cratered, but also with stripes and rays of some material stretching halfway around the moon.

By the time of Voyager, we thought that all of the moons would look like our Moon, Mars, and Mercury. But none of the moons of Jupiter or Saturn are simple, and they’re all unique.

Voyager 1 Titan

Photo: JPL / NASA

Titan is the biggest moon in the solar system and the Voyagers found it to be covered in a thick, opaque atmosphere. But closer examination showed complex layers in the thick, methane atmosphere.

Voyager 2 Iapetus

Photo: JPL / NASA

Iapatus is a small moon of Saturn, but it’s jet black on one hemisphere and blindingly white on the other, with a ridge of mountains running around the planet between the two halves like the seams on a baseball. We’ve gotten much better pictures from Galileo, but we’re still baffled.

Voyager 2 Tethys

Photo: JPL / NASA

Tethys is mostly ice and rock with lots of craters – and some huge, deep, long canyons that wrap huge distances around the moon. Again, a unique place.


Voyager 2 Uranus

Photo: JPL / NASA

Voyager 1 flew off into interstellar space after leaving Saturn, but Voyager 2 was flung toward Uranus, arriving in 1986. Uranus seems almost featureless, but close examination shows the upper atmosphere to have some of the highest winds in the solar system. We won’t use radar to map the surface like we did with Venus – Uranus is a gas giant like Jupiter and Saturn, although smaller.

Voyager 2 Neptune

Photo: JPL / NASA

After Uranus, Voyager 2 was targeted to Neptune. In 1989 it gave us our only closeup views, showing tremendous storms and winds in the atmosphere. The colors seen at Jupiter aren’t seen, possibly because the much lower sunlight levels and much colder conditions leave the chemicals in the atmosphere with too little energy to mix into complex organic and inorganic compounds.


Following the initial burst of planetary exploration in the 1960s through the 1980s, we have gone back to many of the planets. MESSENGER went to orbit Mercury and mapped it in great detail over its six-year mission. Magellan spent over four years using radar to map the surface of Venus. Galileo orbited through the Jupiter system, and dropped a probe into Jupiter’s upper atmosphere. Juno is on its way to Jupiter, arriving there in 2016. Cassini has been orbiting Saturn since 2004 and should continue its mission until September 2017. Cassini dropped the Huygens probe into Titan’s atmosphere and landed it on the surface in 2005.

Mars has practically been infested with rovers, landers, and orbiters. We first landed on Mars in 1976 with Viking 1 and Viking 2, followed by Pathfinder, Spirit, Opportunity (now in the 4,185th day of its 90 day mission!), Phoenix, and Curiosity. We’ve been orbiting Mars since Mariner 9 in 1971, and we currently have five functional spacecraft in orbit (Mars Odyssey, Mars Express, Mars Reconnaissance, Mangalyaan, and MAVEN).

We’ve flown spacecraft to comets, asteroids, Vesta, and Ceres. We’ve landed on comets and orbited them.

What’s my point?


We have lived in a truly golden age of space exploration, a time when our view of the universe around us has changed more radically than at any time since Copernicus and Galileo discovered that the Earth was not at the center of the universe.

It’s almost impossible to understand how different our view of our solar system and the universe was when I was starting school some 50+ years ago. (Okay, so that’s for a large value of “+”.) We didn’t know what galaxies were. We knew very little about the other planets, or even our own Moon. Hell, we even knew very little about our own Earth, having just discovered the Van Allen radiation belts!

Throughout this whole age of discovery, I can remember time after time, sitting with family, watching and listening in awe as our view of the universe shifted yet again.

At first it was with my parent and siblings. The first views of the craters of Mars. The first view of the lunar far side. The first pictures from Jupiter and Saturn.

Later it was with my kids, whooping and hollering with the first pictures from Pathfinder, Spirit and Opportunity, MESSENGER, Galileo, Cassini, Huygens, Dawn, and Rosetta.

The memories of those images and experiences still fill me with wonder and awe. I was lucky enough to see it all. My kids haven’t ever seen people walking on the moon, but they’ve known their whole lives that it was done. The view of the universe they started with was vastly different from the one I started with.

In three days (P-3 is Pluto minus three days), on Tuesday morning, New Horizons will zip by Pluto at over 30,000 miles an hour, snapping pictures and taking data as it goes. Over the next year we’ll get those pictures trickling back down to us, for the last time showing us a major body of the Solar System for the first time in detail.

Is it the end of an era? Perhaps. But it’s also the beginning of a new one.

Fifty years ago we had nine planets, a few asteroids, the occasional comet, and a handful of moons. Now we have eight planets, a growing list of possibly hundreds or even thousands of dwarf planets, tens of thousands of asteroids, and almost a hundred moons. Most importantly, beyond Pluto there are hundreds of thousands of small, icy bodies that we’re only now starting to discover.

Now we’re not taking our first glances at the planets, but we’re still exploring them all. Digging, drilling, zapping, and sampling on Mars, with the goal of walking around with people there in my lifetime. Building bigger and more complex spacecraft to explore the gas giants, their moons, and to look for life there as well. Ways to go back to the moon with people and machines, to mine and explore, and to go beyond to look at asteroids and comets with human crews.

Our view of our celestial neighborhood will never be the same. It will continue to get even better.

 

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