One of the great challenges in searching for life on other planets is that we still have so much to learn about life on our own Earth. Amazingly, that is true not only at the micro level of biochemistry and genetic codes, but at the macro level as well. You would think that there would be little left to learn about elephants, bears, penguins, and jaguars–the creatures sometimes lumped together by jaded zoologists as “charismatic megafauna”–but you would be wrong.
The new series “Hostile Planet” (its second episode premieres tonight at 8PM EDT on National Geographic) offers abundant evidence in that regard. At first glance, it looks like something you have seen before, another documentary show about nature, red in tooth and claw. It does indeed showcase quite a few megafauna of the charismatic variety. But the settings, the visuals, and above all the behaviors caught on camera are a revelation.
Giving an additional twist to the formula, the host of the show is Bear Grylls, an adventurer and survivalist best known for shows like Man vs Nature and Survivor Games. Here he flips the roles, presenting the animals as the precarious survivors–or not, as is often the case.
Astronomers have been grappling with the mystery of dark matter for a long time, and I mean a looong time. The history of dark-matter investigations goes back at least to 1906, when physicist Henri Poincaré’s 1906 speculated about the amount of “matière obscure” in the Milky Way. Or really, it goes to back to 1846 and the first successful detection of dark matter: the discovery of the planet Neptune, whose existence had been inferred by its gravitational pull well before it was actually observed.
Since then, scientists have identified many different dark components in space: collapsed stars, interstellar dust, hot gas, planets, black holes. Unfortunately, none of those can account for the genuinely invisible dark matter that seems to make up 26 percent of the mass of the universe, outweighing all ordinary matter more than five to one. Failure to identify dark matter has gone on so long that some people have started to wonder if the whole concept is amiss. The recent discovery of two galaxies that seem to contain no dark matter at all hasn’t helped. As often happens these days, some wags on Twitter immediately started joking that dark matter sounds like the fictitious “aether” that physicists sought in the 19th century.
But those jokes miss the exciting truth–in fact, they get it exactly backwards. Dark matter is real. It just may be even stranger and more complicated than we thought.
I’m a longtime fan of cosmic disaster scenarios. Not because I’m particularly gloomy (according to my friends and family, I’m actually more of a goof), but because they are fabulous ways to illustrate the workings of the universe. They are also great for making you appreciate the delicate set of contingencies that allow us to exist right now, right here on Earth. I wrote one of the first Armageddon-science articles, entitled “20 Ways the World Could End,” which was published for the 20th anniversary of this magazine, and followed it with a sequel a decade later.
Some potential cosmic catastrophes are modest enough that we could potentially avert them–an asteroid on an Earth-collision path being a prime example. Some of the scenarios are so unlikely that they are hardly worth considering–for instance, a stellar-mass black hole barreling straight toward our solar system. But there’s one disaster that falls into the sweet spot. It’s something that we know has happened in the past, possibly with significant impact on our planet, and there’s nothing we can do to prevent the next one. I’m talking about a nearby supernova (and mindful, too, that “disaster” literally means “bad star”).
Science fiction is a genre committed to the concept of “run before you can walk.” Long before anyone knew whether heavier-than-air flight was possible, writers were imagining travel to other planets. By the time interplanetary space probes were a reality in the 1960s, the storytellers had long since moved on to thinking interstellar.
Today, two or three generations of happy nerds have grown up in a world saturated with science fiction TV shows and movies featuring the word “star” in their titles. When we hear astronomers discuss the detection of possible Earthlike planets around other suns, then, it’s only natural that we want to go there and take a look. We’ve been conditioned to imagine that it’s possible.
In truth, it’s not–at least, not yet. But there may be a way to cheat a little, to get the benefits of interstellar travel without going the full distance. To find out how that might work, I called up Slava Turyshev, a research scientist at NASA’s Jet Propulsion Laboratory who has spent many years thinking about how to bend the rules of space exploration by exploiting the rules of bent light.
“Any man’s death diminishes me, because I am involved in mankind, and therefore never send to know for whom the bell tolls; it tolls for thee.” The quote is so familiar that most people have no idea where it originally comes from (I’ll admit, I had to look it up myself to be sure: It is Mediation XVII from John Donne’s Devotions upon Emergent Occasions.) In recent years, though, the words have taken on new meaning, at least for those of us who are devoted to astronomical exploration. Any space robot’s death diminishes us as well, it seems.
So it was with the Cassini spacecraft’s terminal plunge into Saturn in 2017; one popular Twitter feed, called @CassiniNooo, was devoted entirely to screaming “noooooo” as the final day approached. And so it was again earlier this month when NASA officially declared the death of the Opportunity rover, which had spent more than 14 years exploring Mars on what was designed to be a 90-day mission. The eulogies were passionate and moving. People also tried to make sense of why they were so upset. They offered a lot of plausible explanations, but I think they missed out on the most interesting one.
It has been a great week for humans banging on things around the solar system. Japan’s Hayabusa2 probe touched down and grabbed a sample of asteroid Ryugu; NASA’s InSight is hammering into the surface of Mars; and a private Israeli spacecraft named Beresheet is heading toward an April landing on the Moon. But we are just beginners at the game. Nature has been banging and moving things around in the solar system for billions of years–and doing it with impressive efficiency.
Case in point: a rock nicknamed Big Bertha, and officially known as NASA catalog #14321. It was collected during the Apollo 14 mission by astronaut Alan Shepard, who picked it out because it contained an unusual-looking fragment. His instincts were spot-on. That chunk of Big Bertha really isn’t like the surrounding Moon rocks, most likely because it did not originate there. According to a study by David Kring of the Lunar and Planetary Institute and his colleagues, the fragment actually started out on Earth.
This is the first clear example of terrestrial material traveling to another world–and more evidence of the interplanetary highway running through the solar system.
It was a New Year’s Eve like no other. First of all, the big celebration started a half hour after midnight. Children were waving mini-flags, surrounded by throngs of giddy planetary scientists. And four billion miles away, one billion miles past Pluto, the New Horizons spacecraft was flying past an enigmatic object called 2014 MU69–better known by its nickname, Ultima Thule.
When radio signals from New Horizons finally reached Earth the next morning, they revealed that the mission was a smashing success. The first images of MU69 showed that it is a double-lobed object, apparently created from the delicate joining of two primitive planetary building blocks, or planetessimals. It was everything the mission scientists had hoped for. The only thing that felt off about the triumphant event was the object’s name: not only because some people objected to the Nazi mythology attached to Ultima Thule, but because of the name’s literal meaning of “beyond the known world.”
The moment that New Horizons reported back, MU69 became part of the known world. The probe had lived up to its name, pushing back the horizon of human understanding, so that it can be pushed back farther, again and again, in the future. There is no final frontier anywhere in sight, and that is what truly made the New Year’s encounter so exciting.
Novelists have “It was a dark and stormy night.” For planetary scientists, the equivalent cliche is, “We expect to be surprised.” The story of every new space mission seems to begin that way. No matter how intensely researchers study some solar-system object, no matter how they muster the best resources available on Earth, they are inevitably caught off-guard when they get to study it up close for the first time. And no matter how worn and familiar that cliche may sound, it also rings true every time. Nature’s creativity surpasses human imagination, time after time.
Even by those standards, the flight of the New Horizons probe past Ultima Thule tonight is something special. In the words of Alan Stern, the mission’s principle investigator and spiritual leader, “We’ve never, in the history of spaceflight, gone to a target we know less about.” It’s a type of object never seen up close before, a small (30 kilometers wide) member of the Kuiper Belt. Even more exciting, it belongs to the so-called “cold classical” region of the Kuiper Belt, meaning that it probably has remained largely unchanged for more than 4 billion years, frozen in deep storage 6.5 billion kilometers from the Sun.
Will it look battered from ancient collisions? Will it be covered with organic molecules from the early solar system? Will it resemble Pluto’s moons, or look like a fresh comet, or like something else entirely? Nobody knows.
Some two billion years ago, the first photosynthetic algae evolved the ability to respond to light—the brilliant Sun by day, the spectral Moon by night. Around 700 million years ago, primitive eye-pits appeared; then, during the Cambrian era, arthropod-like creatures gazed at the sky through true eyes, sensing the lunar rising and setting with their arthropod-like comprehension. So it continued, into the succeeding chapters of life featuring mammals, primates, hominins, and Homo sapiens, the last of them plotting the Moon’s movements and mapping the pockmarked terrain of Earth’s companion.
Then, 50 years ago, the perspective flipped. Apollo 8 took off on a figure-eight pattern around the Moon and, on December 24, 1968, three NASA astronauts peered out at the first Earthrise in the history of life. Most of the reminiscences now popping up across the media focus the Earth itself, seen gibbous and gorgeous from afar. But the true power of the image comes from its juxtaposition of two views never seen before: our blue planet, wrapped with air and water and hope, contrasted with the extraordinary gray desolation of the Moon.
Many years ago, this magazine was owned by the Walt Disney Corporation, and I would sometimes get one of the company’s songs stuck in my head: “It’s a Small World,” the relentless musical accompaniment to the ride of the same name at Disney World in Florida. That song has popped up in my brain again recently, but in a very different and more majestic context. We are entering a new stage in the exploration of the solar system, one that inverts the theme of much that came before. Big is out and small is in.
The hot destinations in space right now are comets and asteroids–including asteroid Bennu, now coming into view of the ambitious OSIRIS-REx probe. The most innovative robotic explorers are the size of a briefcase. And in NASA’s latest pivot, the long-term plan to send humans back to the Moon and on to Mars is set to begin on a decidedly modest scale, with a set of low-budget, privately built lunar explorers. Cue the mental music: “It’s a Small Solar System (After All).”