Experience the Amazing Unmanned Journeys to Explore the Universe
In Incredible Stories from Space, veteran space journalist Nancy Atkinson shares compelling insights from over 35 NASA scientists and engineers, taking readers behind the scenes of the unmanned missions that are transforming our understanding of the solar system and beyond. Weaving together one-on-one interviews along with the extraordinary sagas of the spacecraft themselves, this book chronicles the struggles and triumphs of nine current space missions and captures the true spirit of exploration and discovery. Full color images throughout reveal scientific discoveries and the stunning, breathtaking views of our universe, sent back to Earth by our robotic emissaries to the cosmos.
-Travel along with the first mission to Pluto
-Explore Mars alongside the Curiosity Rover
-Join the unprecedented hunt for extrasolar planets
-Unlock the mysteries of the cosmos with the iconic Hubble Space Telescope
-Discover the latest findings in our solar system
-See the future of space exploration with a preview of upcoming missions
|Publisher:||Page Street Publishing|
|Product dimensions:||6.00(w) x 9.00(h) x 0.70(d)|
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Incredible Stories From Space
A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos
By Nancy Atkinson
Page Street Publishing Co.Copyright © 2016 Nancy Atkinson
All rights reserved.
UNLOCKING PLUTO'S SECRETS: NEW HORIZONS
THEY SAID IT COULDN'T BE DONE
In typical Alan Stern style, he squeezed in time for a phone call during a drive between meetings while making a quick stop at home, too. A ratty Bluetooth connection left Stern's voice barely audible over background road noise and traffic, then car and house doors slamming, briefcases and drawers opening and closing. All the while he discussed his spacecraft's incredible, almost inconceivably successful mission to the far reaches of the solar system to study distant Pluto and its moons in July 2015.
"We did it," Stern said succinctly, never one to ramble on, talking about how he now responds to those who said the New Horizons spacecraft could never be built on time, on budget and still succeed. "We don't need to say anything more."
Stern, the principal investigator — and chief instigator — of the New Horizons mission, had been pushing for a mission to Pluto since the late 1980s.
"The first ten years we couldn't even get out of the starting blocks," he said. Other missions to Pluto had been proposed but were either canceled or not seriously considered. Frustrated, Stern started lobbying other scientists and even members of Congress, resulting in the National Academy of Sciences ranking a mission to Pluto as the highest priority for the first decade of the 2000s.
New Horizons' mission to Pluto was initially approved in 2001, but then in 2002 it looked as though NASA would have to scrap the mission for budgetary reasons. But space advocacy groups like The Planetary Society and others petitioned Congress to keep the mission alive, in part by using the power of letters from children. Seemingly, kids have always been enamored with the planet with the cartoon character name, even though Pluto is actually named after the Roman god of the underworld.
The plan worked and the mission to Pluto was reinstated. But still there were naysayers.
"When New Horizons was selected in 2001, people told us, 'you won but you lost,'" Stern recalled. "They said no one can build a mission at this price, one fifth the cost of the Voyager mission in the 1970s. No one has built an outer planet mission in this timeframe, just four years. Then, it's a ten-year journey to Pluto and you've only got one spacecraft, so there's a significant chance of failure. It just can't be reliably done."
But, Stern contends, the New Horizons team resolved to make it happen. "They pulled off something few people appreciate. It took dedication from 2,500 people around the country who worked all day plus nights and weekends for over fifteen years to make this dream come true. It's the stuff of history."
The dream was sending a spacecraft to explore Pluto and its moons. "Exploration always opens our eyes," Stern told me back in 2005, just months before New Horizons would launch. "No one expected it when previous missions found river valleys on Mars, or a volcano on Io, or lakes on Titan. What do I think we'll find at Pluto and Charon? I think we'll find something wonderful, and we expect to be surprised."
Stern's prediction — and his dream — came true.
New Horizons was the fastest spacecraft ever launched using a souped-up Atlas V rocket with extra boosters.
"We built the smallest spacecraft we could get away with that has all the things it needs: power, communication, computers, science equipment and redundancy of all systems, and put it on the biggest possible launch vehicle," said Stern. "That combination was ferocious in terms of the speed we reached in deep space."
The baby grand piano–size spacecraft sped away from the Earth at 36,000 miles per hour (about 58,000 km/hour), going nearly a million miles (1,609,344 km) a day in its 3-billion-mile (4.8-billion-km) journey to Pluto. But at that blazing speed, slowing down and going into orbit around Pluto would be impossible. Therefore, this first reconnaissance of the Pluto system would be a flyby mission, somewhat of a throwback to the early space missions like Mariner and Voyager that made the first flybys of Mars, Jupiter, Saturn, Uranus and Neptune in the 1960s, 70s and 80s.
New Horizons launched on January 16, 2006, and zoomed past the Moon's orbit in just nine hours. That same journey took the Apollo astronauts three days. Then New Horizons made the 500-million-mile (800-million-km) journey to Jupiter in just 13 months — faster than any of the seven previous Jupiter-bound missions — as the spacecraft swung past the giant planet for scientific studies and an all-important gravity assist in February 2007, boosting New Horizons' speed to 52,000 mph (83,600 km/h).
Despite its speed, it took nearly nine-and-a-half years for New Horizons to cross the expanse of the solar system and reach the region around Pluto. The true mission would start about five months out, before what's called closest approach, so in total there would be a six-month-long reconnaissance as New Horizons approached, flew by and then looked back at the Pluto system, with closest approach on July 14, 2015.
Since New Horizons' journey takes it so far from the Sun, solar panels wouldn't be feasible to provide enough electrical power. Instead, a radioisotope thermoelectric generator (RTG) produces heat from the natural decay of non-weapons-grade plutonium-238, and the heat is converted into electricity. The heat also keeps electronics and other parts of the spacecraft from freezing in the cold depths of space.
After Pluto, New Horizons continues on to explore the Kuiper Belt, a region out past Neptune, about 30 to 50 times Earth's distance from the Sun, or 2.5 to 4.5 billion miles (4.5 to 7.4 billion km) away, where Pluto is located. This belt is similar to the asteroid belt found between Mars and Jupiter; however, some objects in the Kuiper Belt tend to be more icy rather than rocky. This is where icy short-period comets (such as Halley's Comet) originate.
The spacecraft carries a robust payload of imagers, spectrometers and other scientific instruments to map the surface of Pluto and its moon Charon, study their composition and analyze any atmosphere around either body.
At launch, New Horizons was billed as the "first mission to the last planet." But that designation changed just seven months later.
PLANET OR NOT?
Several things changed, actually, while New Horizons was in flight.
When the spacecraft launched, Pluto was classified as a planet. But ever since its discovery in 1930 by astronomer Clyde Tombaugh, the distant little Pluto was always considered a bit of an oddball: it didn't fit in with the rocky terrestrial worlds of the inner solar system, and the tiny, icy, 1,473-mile (2,370-km)-wide world definitely didn't match up with the gas giants of the outer solar system. Pluto's orbit was unique, what astronomers call an eccentric orbit due to its highly elongated and angled path around the Sun compared to the relatively circular and flat orbits of the other planets.
Of course, Pluto was so far away even the best pictures available taken by the Hubble Space Telescope were just pixelated blobs. No one really knew what Pluto was like. One of New Horizons' goals was to understand how Pluto and its moon Charon fit in with everything else.
Decades before the mission, Stern and other planetary scientists theorized that Pluto wasn't alone out there in the far reaches of our cosmic neighborhood. It didn't make sense that the solar system would abruptly run out of material after Pluto. Plus, since the Kuiper Belt was thought to be the birthplace of comets, why couldn't other objects be there, too?
In a paper published in 1991, Stern proposed there could be hundreds of smaller yet-unseen icy bodies like Pluto and Triton — Neptune's moon and a virtual twin of Pluto, and thought to be a Kuiper Belt Object (KBO) that wandered out of the belt, captured by Neptune's gravity. Stern used the term dwarf planet in his paper to indicate a new subclass of planets that might be needed to properly classify Pluto and the large KBOs they expected to find.
Just a year later in 1992 came confirmation with the first true discovery of a KBO, a tiny object about 100 miles (161 km) across. Since then, astronomers have found hundreds of KBOs, and scientists now estimate there could be thousands of such bodies. This put Pluto into context, as it seemed to be just one of a much larger class of tiny, icy bodies. And because KBOs are thought to be unaltered since the birth of the solar system 4.5 billion years ago, studying Pluto would provide clues to the conditions that prompted planets to form. That led to Stern's push for a mission to Pluto.
A decade later, with the advent of better telescopes and other improved observation techniques, scientists found bigger objects more like Pluto. Astronomers Mike Brown and Chad Trujillo from Caltech discovered an object about half the size of Pluto named Quaoar (pronounced kwa-war, named for another ancient god), followed in quick succession by Sedna in 2003, Haumea in 2004, and Eris and Makemake in 2005. Eris was the clincher, as it was about the same size as Pluto.
The debate that had been simmering for years now heated up in earnest: should all these large KBOs be classified as planets, too? Or would it be better to instigate a new class of planets that encompassed Pluto and it's nearer, more similar companions?
Curiously, at that time there wasn't an official definition of a planet. But with the new KBO discoveries, it seemed time to create one, as well as decide what to do with Pluto and all these new objects. The International Astronomical Union (IAU) is usually the arbiter and decision-making body in cases like this, so in August of 2006 at an IAU Assembly meeting, it was put to a (controversial) vote.
There were three choices:
1. Add Eris, Makemake and the largest asteroid Ceres to the planet club, bringing the total number of planets in our solar system to twelve.
2. Keep the total at the familiar nine, and not really address the new discoveries.
3. Drop the number of planets down to eight, kicking Pluto out and creating a new class of objects called dwarf planets.
The difference — and the kicker — between Stern's use of that term in 1991 and the IAU's word choice in 2006 was that the IAU said dwarf planet wasn't just a subclass of planets; it wasn't a planet at all. The IAU's definition inferred Pluto and its pals were a completely different type of object.
To help make the decision, the IAU also created the definition of a planet, with an object needing to meet three requirements:
1. It is in orbit around the Sun.
2. It has enough mass and gravity to pull itself into a spherical shape.
3. It has cleared the neighborhood around its orbit.
While Pluto meets two of these criteria, it fails on the third. Clearing the neighborhood means the planet has become gravitationally dominant; there are no other bodies of comparable size other than its own moons in its vicinity in space. Since Pluto shares its orbital neighborhood with other KBOs, that demotes Pluto to the newly created classification of dwarf planet.
This set off a war of words between astronomers and planetary scientists, with Stern at the forefront of the fight for Pluto to retain its planetary status.
"Astronomers aren't experts in planetary science, and they basically passed a bunch of BS off on the public back in 2006 with a planet classification so flawed that it rules the Earth out as a planet, too," Stern said. "A week later, hundreds of planetary scientists, more people than at the IAU vote, signed a petition that rejects the new definition. If you go to planetary science meetings and hear technical talks on Pluto, you will hear experts calling it a planet every day."
Stern, along with other scientists who had been studying Pluto for most of their careers, took the reclassification as a direct insult. To this day, this group of scientists — sometimes called the Pluto Mafia — as well as many other scientists, still reject the IAU's definition of a planet both in terms of defining a dwarf planet as something other than a type of planet and in using orbital characteristics rather than surface features and other fundamental properties to define a planet.
But while Pluto was demoted in scientific terms, the public seemed to embrace Pluto even more. Lovers of Pluto as a planet protested and aired complaints. Stern and the Pluto Mafia held their ground, hoping that New Horizons might one day change the classification defining their favorite little world.
The other change that occurred during New Horizons' flight was the discovery of four more moons orbiting Pluto. Charon, the largest, had been discovered in 1978 and is almost half the size of Pluto. The two bodies actually orbit each other around a common center of gravity, and therefore Pluto and Charon were sometimes referred to as a binary planet (today they are sometimes referred to as a double dwarf planet system).
In 2005, as New Horizons scientists used the Hubble Space Telescope to search the region around Pluto to help prepare for the mission, they discovered two new tiny moons at Pluto, now named Nix and Hydra. Then in 2011, Kerberos was found between the orbits of Nix and Hydra, and in 2012, another little moon named Styx was found.
The discovery of all these moons made the New Horizons team realize there could potentially be more moons and possibly a ring or debris field generated by a theoretical impact in Pluto's busy system billions of years ago. Any debris would pose a hazard for the spacecraft, and so the team began a thorough search using Hubble and later, New Horizons' instruments. Also, they needed a plan for mitigating any potential strikes by debris, so that task was put on the already long to-do list as New Horizons moved steadily towards Pluto.
Hal Weaver is the project scientist for New Horizons and Stern's longtime colleague and friend. I visited him in his office in early 2016 at the Applied Physics Laboratory at Johns Hopkins University in Laurel, Maryland — where New Horizons was built and where the spacecraft's Mission Operation Center is located.
Weaver mused how psychological testing has shown that while everyone thinks they can multitask, most people aren't good at it.
"Alan is the exception," he said. "He's the one person I know who is able to handle many, multiple projects at once."
In addition to starting and overseeing New Horizons, Stern is an associate vice president at the Southwest Research Institute (SwRI) in Boulder, Colorado, an organization that does research in several areas, including planetary science and astrophysics. He also was the principal investigator on an instrument on the Lunar Reconnaissance Orbiter (which you'll read about later here) called LAMP, and another called Alice on ESA's Rosetta mission to a comet. He's a consultant to various universities and aerospace firms. In 2007 and 2008, he directed all of NASA's space and earth science programs as a NASA associate administrator. Additionally, he cofounded a company called World View to take tourists to the edge of space in high-altitude balloons, and another company, Golden Spike, which helps coordinate commercial missions to the Moon. He also helped start Uwingu, an organization that raises money for astronomy research by unofficially and somewhat controversially selling the naming rights to exoplanets and craters on Mars. He also is a proponent of suborbital research and has helped design instruments for studies on board future flights of private companies like Virgin Galactic. Stern trained as an astronaut in the 1990s but never had the chance to fly, so he hopes to be on board several suborbital science flights.
Because of all this and more, Stern was listed among TIME magazine's 100 most influential people in the world in 2007 and is a candidate again for the same honor in 2016.
"I'm not sure how Alan does it all," Weaver said. "I think his administrative assistant has an administrative assistant! But he's an amazing guy. Period. You can't find anyone who is more energetic than he is. He is involved in so many things I can't keep up with it ... or him."
Weaver himself feels like he hasn't had a spare minute since joining the New Horizons team in 2002. There was a rush to make sure New Horizons launched by 2006 to exploit an advantageous alignment between Jupiter and Pluto. The gravity assist from Jupiter would shave three years off the travel time to the outer solar system.
"There was a lot of incentive to get the spacecraft ready to launch on time," Weaver recalled, "but that required meetings almost every day throughout the development period. It was unbelievable. I just remember so many Sunday morning meetings as we were putting all the instruments together and integrating them on the spacecraft."
Another confirmed workaholic, Bill Gibson from SwRI was the payload manager, and he notoriously scheduled Sunday morning meetings. No problem for Weaver and Stern, at least.
"Alan and I are early birds so we were always up. And we love weekends because that just gives us time to do more work," Weaver laughed.
Excerpted from Incredible Stories From Space by Nancy Atkinson. Copyright © 2016 Nancy Atkinson. Excerpted by permission of Page Street Publishing Co..
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Table of Contents
Introduction Riding Along on the Journeys to Space 7
Chapter 1 Unlocking Pluto's Secrets: New Horizons 10
Chapter 2 Roving Mars with Curiosity 34
Chapter 3 Changing Everything: The Remarkable Hubble Space Telescope 57
Chapter 4 Traveling Between Two Worlds: Dawn 78
Chapter 5 Hunting for Planets: Kepler and the Search for Other Worlds 101
Chapter 6 Unveiling Secrets of a Ringed World and its Icy Moons: Cassini-Huygens 123
Chapter 7 Downloading the Sun 24/7: The Solar Dynamics Observatory 144
Chapter 8 Rising to the Occasion: The Mars Reconnaissance orbiter and Hirise 161
Chapter 9 Shooting The Moon: The Lunar Reconnaissance Orbiter 180
Chapter 10 Seeing the Future: Missions and Discoveries to Watch 202
Epilogue Why Explore Space? 214
About the Author 218
Recommended Further Reading 218