I spent the past week at Pluto central–aka, the Johns Hopkins University Applied Physics Lab in Laurel, Maryland–watching images and data come in from the New Horizons spacecraft. You don’t need me to tell you how incredible those first views are. They’ve been covered widely in the science media, including right here on this site, and have thoroughly (and gratifyingly) crossed over into the mainstream. I even got a chance to talk about them on Fox News. But there is a lot more to the story than the new landscapes of Pluto, stunning as they may be.
First and foremost, there is the enormous amount of scientific surprise embedded within those images. Alan Stern, the principal investigator and prime mover behind New Horizons, routinely declared that we should all be prepared for surprises when we got a first look at Pluto. What he added, in his quieter moments, is that we should be prepared even for unpleasant surprises. Pluto might look just like Neptune’s moon Triton. Worse, it might be an inert ball of ice, covered with ancient craters and decorated only with dark, carbon-rich discolorations. Of course, that turned out not to be the case. Stern’s eye-popping reaction, shown up above, says it all.
As the New Horizons probe closes in on Pluto–now less than two days away!–there have been a lot of thoughtful articles looking back at the people responsible for the discovery of this remarkable little world. They have focused mostly on Clyde Tombaugh, the man who spotted Pluto amidst a sea of stars in 1930. Some articles have also told the story of Venetia Burney, the 11-year-old girl who gave Pluto its name, or Percival Lowell, whose obsession with finding “Planet X” inspired Tombaugh’s search. In all these stories, though, one name is conspicuously missing: Vesto Slipher.
It was Slipher who initiated the planet search and who directed its outcome. He was probably the first to set eyes on Pluto. He was also a meticulous deep-sky observer who collected the first evidence of the expanding universe, more than a decade before Edwin Hubble’s landmark publication that led to the modern idea of the Big Bang. So why is there no Slipher Space Telescope? Why have you never even heard of him and his connection to Pluto?
Therein lies a tale.
In space exploration, there are a million ways that things can go wrong and just one way that they can go right. When the New Horizons probe skims less than 8,000 miles past the surface of Pluto on July 14, it will happen only because a large team of scientists, engineers, and mission planners managed to eliminate all the wrong and navigate their way to the right, a process that has taken more than 40 years to fully unfold.
The engineers have become so good at fixing problems that most of the time the public has no idea what they are up against—until something goes wrong, as happened to New Horizons last weekend, when a software glitch caused the probe to shut down into “safe” mode. For a moment, this was a news story. Then, once again, the engineers stepped up and solved the problem (caused by an obscure timing flaw in a command sequence sent to the probe in preparation for flyby). Within three days, all was back to normal. As New Horizons principal investigator Alan Stern says, “In terms of science, it won’t change an A-plus even into an A.”
But software problems are hardly the only glitches that nearly derailed the mission to Pluto. Politics and personalities can go wrong, too, and they frequently did.
“The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka’ but ‘That’s funny…'” That quote, delivered by the brilliant science writer Isaac Asimov, keeps popping into my head as I look at the remarkable new images of Ceres. NASA’s Dawn spacecraft has been orbiting the dwarf planet since March 6, scrutinizing a landscape that is not quite like anything humans have ever seen before.
One detail on Ceres jumped out almost immediately: a bizarre white spot, drastically brighter than its drab surroundings. As Dawn got closer, the probe’s camera showed that the white spot is actually a patch of at least eight smaller white areas; there are also smaller white spots and extended light-ish splotches scattered across Ceres’s 950-kilometer-wide 590-mile wide globe. What are they? No idea, except not alien landing lights (they don’t show up in the dark). Subsequent images revealed a solitary, 3-mile-high mountain; long ridges and apparent streamers of impact debris; giant frozen surface flows; and craters with unusual distorted, vaguely hexagonal shapes.
The initial scientific reaction to these Ceres images boils down to three simple words that Asimov would well recognize: “That looks funny.”
There’s a general rule in media reporting called Betteridge’s Law: Whenever a headline poses a question–especially a sensational one–the answer is “no.” I’m going to break the law this time. An orbiting laser cannon is not only an intriguing technology but, yes, it’s one of the most promising ways to clean up the ever-thickening cloud of dangerous debris surrounding the Earth.
And just to be clear, space junk is a danger. There are about 25,000 human-made objects larger than your fist flying around in orbit, and about half a million pieces bigger than a dime. If you include millimeter-scale shrapnel, the number of rogue bits reaches deep into the millions. Typical speeds in low-Earth orbit are about 30,000 kilometers per hour (18,000 miles per hour), ten times the velocity of a rifle bullet. You see the problem: A little impact can pack a big wallop.
Through most of its life, NASA’s scrappy Messenger probe was something of a unsung hero. The first spacecraft ever to orbit Mercury didn’t have the you-are-there immediacy of a Mars rover, the daredevil appeal of landing on a comet, or the romance of visiting a beautiful ringed planet. But with today’s death–the result of a long-anticipated crash into the planet it studied–we can clearly see what an incredibly successful explorer Messenger was.
Mercury has long been a solar-system enigma. It is not particularly small (roughly halfway in size between Mars and the moon), and it is not particularly far away (third closest planet to Earth after Mars and Venus), but the first planet from the sun is devilishly hard to study. Seen from Earth it hangs low in the sky; from space it hugs so close to the solar glare that the Hubble telescope cannot aim at it. Astronomers were so stymied that they didn’t even know how quickly Mercury rotated until 1965, when they found out, not by looking but by bouncing radar signals off its surface.
If you are old enough to remember news stories from 1990 (or if you are a devoted student of astronomy), you’ll recall that the Hubble Space Telescope was not always regarded as the technological triumph that NASA is loudly celebrating today, on its 25th anniversary. The orbiting observatory debuted as a king-size disaster: the telescope that couldn’t see straight, built with a mirror that was ground perfectly…but perfectly incorrect.
The story of how the error was discovered and ultimately fixed has been told many times, most recently in a beautiful retrospective by my colleague Ian Sample at The Guardian. But today it is hard to appreciate the magnitude of Hubble’s turnaround–the depth of the scientific despair right after launch, and the many resurrections that transformed Hubble into the most famous and productive observatory in history. Since Hubble may not live to celebrate a 30th anniversary, there is no time like the present to tell the tale.
The new image of Ceres that NASA released today is doubly thrilling. It unveils more of the landscape of this mysterious in-betweener world–an object classified both as a giant asteroid and as a dwarf planet, a type of object never before observed up close. But it also taps into the unique significance of the crescent shape, both to our culture and to our science.
The crescent is one of the most recognizable icons in astronomy. It is the signature element of the oldest known representation of the heavens, the 4,000-year-old Nebra Sky Disc; it appears on numerous national flags; and it is a staple of the artwork in children’s books. For the scientist, the crescent holds special significance far beyond that, however. To observe a crescent, you must be farther from the sun than the object you are viewing. For any body that is farther out than Earth–that is, for all of the solar system other than Mercury, Venus, and the moon–space probes are the only way to see a crescent.
In short, a crescent is the no-brainer test of exploration: It tells you in one glance that humans have gone to an exotic place in space.
You don’t have to wonder what is on Alan Stern’s mind. The planetary scientist and former NASA associate administrator is a relentless champion of all things Pluto; he is both the principal investigator and the prime mover behind the New Horizons mission, which will fly past Pluto and its moons this July 14. In advance of the encounter, Stern’s passion is building to a white heat, and he is letting everyone know it.
The excitement is infectious. Pluto is looking far more interesting than researchers realized just a few years ago. Ironically, its scientific importance has skyrocketed in the years since the International Astronomical Union demoted Pluto to “dwarf planet.” Recent theoretical models indicate that the Kuiper Belt–the population of objects, including Pluto, that orbits beyond Neptune–is key to understanding the early evolution of the outer solar system. It is home to multiple big, round objects that record the movements of water and organic chemicals at the time when Earth was forming.
Call these things in the Kuiper Belt dwarf planets, call them planets (or call them “Plutoids” and duck before Stern comes after you), whatever. They are major players in the sun’s family, many of them larger than any asteroid, and Pluto is the brightest and most complex of them all. Stern is a Pluto obsessive, but more and more it looks like the science is on his side: Pluto really is something special, and the New Horizons encounter promises to be a unique experience. Here, Stern makes his case–and reveals surprising details about another great mission that almost happened.
If you pay attention to news about space exploration, you may have seen some skeptical stories about NASA’s proposed Asteroid Redirect Mission. (And even if you don’t follow such things, you might well have been dismayed by headlines announcing a “less ambitious asteroid mission” that is “unlikely to get funded.”) This is not another one of them.
I think the asteroid mission is a cool idea, and an important one. I think it will advance the cause of space exploration in several meaningful ways. And it is exactly the kind of medium-scale, focused mission that could revitalize the whole idea of sending humans on grand adventures beyond Earth orbit–if only it can make its way past the naysayers, political opponents, and misguided scientific skeptics who threaten to derail it before it even gets started.