The conventional wisdom of space exploration suggests that robotic probes are both more scientifically efficient and cost effective. Not so, argues a professor of planetary science.
Astronaut Edwin E. Aldrin Jr., lunar module pilot, poses beside the deployed flag of the United States during the Apollo XI moon landing July 20, 1969. [Reuters]
When the Space Shuttle Atlantis rolled to a stop in July 2011, NASA bid farewell to the nation's symbol of manned spaceflight. The Obama administration has scrapped NASA's plan to return humans to the Moon by 2020, which was behind schedule because of technical and budgetary problems. As financial constraints threaten the possibility of future ventures into outer space, many in the astronomical community are advocating for the increased use of unmanned robotic
space, arguing that they will serve as more efficient explorers of planetary surfaces
than astronauts. The next giant leap, then, will be taken with robotic feet.
At the core of Crawford's argument is that human beings are much better at performing the type of geological fieldwork that makes planetary exploration scientifically valuable: they're faster and significantly more versatile than even the most advanced autonomous probes. "People who argue for robotic exploration argue for more artificial intelligence, the capacity for robots to make more complex decisions that somehow leads to increased efficiency," explains Crawford. "But one of the things that make them cheap is miniaturization.You can make robots more intelligent and efficient to a certain point, but they wont get smaller and therefore cheaper." With miniaturization, he explains, comes a depletion in the number of scientific instruments a probe can carry, the number of samples it can collect, and its ability to cover more ground. " [Mars rovers] Spirit and Opportunity are fantastic things on Mars, but the fact that they've traveled as far in eight years as the Apollo astronauts traveled in three days speaks volumes." At a certain point, the costs of developing 'smarter' (but not better equipped) autonomous rovers will exceed the meager gains in scientific collection and outstrip existing scientific budgets.
The advantages of human over robot explorers are recognized in the planetary sciences community: a 2005 report by the Commission on the Scientific Case for Human Space Exploration noted that "the expert evidence we have heard strongly suggests that the use of autonomous robots alone will very significantly limit what can be learned about our nearest potentially habitable planet." Steve Squyres, the Principal Investigator for the Mars Exploration Rovers Spirit and Opportunity, conceded in his book Roving Mars that "[t]he unfortunate truth is that most things our rovers can do in a perfect sol [a martian day] a human explorer could do in less than a minute." But Crawford also expresses concerns over the capacity of robots for "making serendipitous discoveries."
"We may be able to make robots smarter, but they'll never get tot he point where they can make on the spot decisions in the field, where they can recognize things for being important even if you don't expect them or anticipate them," argues Crawford. "You can't necessarily program a robot to recognize things out of the blue."
The other downside of a shift towards robotic exploration is the decline of samples, the real meat of the planetary sciences. Robotic expeditions have always been one-way trips: the probes go, land, take readings, and don't come back. But the collection and prolonged study of planetary samples are real drivers of scientific knowledge, which Crawford measures in terms of published scientific literature:
Several things are immediately apparent from Figure 2. Most obvious is the sheer
volume of Apollo's scientific legacy compared to the other missions illustrated. This
alone goes a long way to vindicate the points made above about human versus robotic
efficiency. The second point to note is that the next most productive set of missions
are the lunar sample return missions Lunas 16, 20 and 24, which highlights the
importance of sample return. Indeed, a large part of the reason why Apollo has
resulted in many more publications than the Luna missions is due to the much larger
quantity and diversity of the returned samples which, as we have seen, will always be
greater in the context of human missions. The third point to note is that, despite being
based on data obtained and samples collected over 40 years ago, and unlike the Luna,
Lunokhod, or Surveyor publications, which have clearly levelled off, the Apollo
publication rate is still rising. Indeed, it is actually rising as fast as, or faster than, the
publications rate derived from the Mars Exploration Rovers, despite the fact that data
derived from the latter are much more recent. No matter how far one extrapolates into
the future, it is clear that the volume of scientific activity generated by the MERs, or
other robotic exploration missions, will never approach that due to Apollo.
"We're still benefiting from the scientific legacy of those few soil samples brought by the Apollo mission, but we can only do this because we went to the Moon, got these samples, and came back," says Crawford. "If we sent a rover to Mars along with a return vehicle, that would enormously increase its scientific impact, but that's hasn't been implemented yet because its still incredibly expensive. If a mission goes to Mars, lands in one place, bring back half a kilogram of Mars rocks, it will be immensely valuable, but compared to Apollo, which not only visited six sites (and many hundred of sites with the help of the lunar rover) but came back with 382 kilograms of lunar material, it sort of pales in comparison."
While robotic probes find a permanent home on a planetary surface, sending manned expeditions inherently means planning for a return trip. Would a manned trip to Mars, replete with a sample-laden return vehicle, yield a similar explosion in scientific literature? Crawford thinks so. "A Martian expedition would be 5 or 10 times more expensive than Apollo in real terms, but not so much more expensive that it would negate the added benefit of being able to collect samples. They'll bring back a much larger quantity and diversity of samples than a robotic mission, and this is especially important with regards to Mars: there are reasons for wanting more lunar samples, but Mars is a much bigger and much more geologically diverse planet, with a much more complicated geology so much more inconceivably complicated history than the Moon, we won't get a full sense of its history or evolution just by scraping around on the surface with these smalls robot probes."
The scientific impact of these moon rocks is compelling: our whole
chronology of the solar system is built on the radiometric dating of the
Apollo samples. "The top scientific benefit is that it's been possible
to date areas of the lunar surface. We have this curve that plots crater density versus age, which we can use to get an estimated age of
virtually anywhere else in the Solar System," explains Crawford.
"The last major eruption of Olympus Mons [on Mars] was 400 million years
ago, and the only way we have this measurement is because of Apollo
So why, then, are scientists resigned to sending probes and rovers to the corners of the galaxy? Scientists, argues Crawford, tend to look at the enormous costs for Apollo, which nobody will ever be able to afford again, as an artificial baseline for gradual streamlining of space exploration. This is the wrong approach to take "There's lots of collective amnesia as to how efficient Apollo really was, which is really the only example of exploring the surface of another planet," explains Crawford. "An enormous amount was achieved in a very short total contact time with the lunar surface."
Planners feel the microscopic formations in Mars meteorite ALH84001, found in Antarctica, and the highly diverse samples of rocks believed to have been strewn about by ancient rivers seen at the Mars Pathfinder landing site, provide a strong motive for sending human exobiologists and geologists to the Red Planet. [Pat Rawlings/NASA]
But Crawford recognizes that, despite its benefits for scientific research, manned missions are subject to domestic forces and rarely undertaken for the sake of science alone. The United States was willing to shoulder the enormous costs of the Apollo mission because of the geopolitical and economic interests (namely, besting the Soviet Union), an argument advanced most recently by science communicator Neil DeGrasse Tyson.
"Science was the beneficiary of a human spaceflight mission that was undertaken for geopolitical purposes," explains Crawford. "The total costs is large, but the best way for scientists to look at it is not 'this is a science function.' They need to look at Apollo as the confluence of geopolitical, industrial, and social factors. You need all of these things to spend the money necessary."
Crawford's theory, then, is not necessarily targeted towards the general public: he recognizes the difficulty of justifying an expensive manned mission with no immediate economic benefit (although he notes notes that the 1987 NASA procurement of $8.6 billion generated a turnover of $17.8 billion and created 209,000 private sector jobs, according to an article in Nature), especially in the throes of an global economic downturn. His main argument, then is those scientists consigning themselves to a future of interstellar probes are shooting themselves in the foot. Ventures like the James Webb Space Telescope may hit the ceiling for government expenditures on purely scientific ventures, but researchers and scientists can -- and should -- try to make the case for manned spaceflight in other contexts, if only for the sake of maximizing the scientific gains made from planetary exploration.
"Humans bring a net benefit to space exploration that, in my opinion, outweighs the costs," says Crawford. "But people need to realize that the overall case for manned spaceflight is multifaceted, a totality woven out of these different strands, of which science is one. Industry, innovation, inspirational value -- all of these factors must be addressed before manned spaceflight can return."
The most personally moving, and most fundamentally patriotic, moment of the Democratic National Convention was the appearance by the bereaved parents of Army Captain Humayun Khan, and the statement about the meaning of their son’s life and death, and about the Constitution, by Mr. Khizr Khan.
After Khizr Khan spoke, politicians and commentators on most networks said they were moved, humbled, inspired, choked up. (Commentators on Fox did not say these things, because their coverage cut away from the Khans for Brit Hume and Megyn Kelly, plus a Benghazi ad.)
How the election looks to backers of the Republican nominee
Perhaps the hardest thing to do in contemporary American politics is to imagine how the world looks from the other side. I’ve made no secret of why, as a Republican, I oppose Donald Trump and what he stands for. But I’ve also been talking to his supporters and advisors, trying to understand how they see and hear the same things that I do, and draw such very different conclusions. What follows isn’t a transcription—it’s a synthesis of the conversations I’ve had, and the insights I’ve gleaned, presented in the voice of an imagined Trump supporter.
“You people in the Acela corridor aren’t getting it. Again. You think Donald Trump is screwing up because he keeps saying things that you find offensive or off-the-wall. But he’s not talking to you. You’re not his audience, you never were, and you never will be. He’s playing this game in a different way from anybody you’ve ever seen. And he’s winning too, in a different way from anybody you’ve ever seen.
Not the people—the term. How generational divisions have driven down voter turnout over the last century of American politics.
Throughout the 2016 U.S. presidential election, pundits and activists have debated how to get more Millennials involved in politics, always stressing their distinctive character. But it was actually this tendency to slice up the electorate into unique generations that drove young people from politics in the first place.
In the 19th century, children, youths, and adults “mingled freely together” at rowdy campaign rallies, lured by the holy trinity of booze, barbecue, and bonfire. Older citizens introduced young people to politics, helping to drive voter turnouts to their highest levels in U.S. history. “It’s the ‘big fellow,’” observed the Republicans canvassing in pool halls and saloons in the 1880s, who does the best job getting “the ‘little fellow”’ into politics.
Narcissism, disagreeableness, grandiosity—a psychologist investigates how Trump’s extraordinary personality might shape his possible presidency.
In 2006, Donald Trump made plans to purchase the Menie Estate, near Aberdeen, Scotland, aiming to convert the dunes and grassland into a luxury golf resort. He and the estate’s owner, Tom Griffin, sat down to discuss the transaction at the Cock & Bull restaurant. Griffin recalls that Trump was a hard-nosed negotiator, reluctant to give in on even the tiniest details. But, as Michael D’Antonio writes in his recent biography of Trump, Never Enough, Griffin’s most vivid recollection of the evening pertains to the theatrics. It was as if the golden-haired guest sitting across the table were an actor playing a part on the London stage.
“It was Donald Trump playing Donald Trump,” Griffin observed. There was something unreal about it.
Last night, in her overall very successful acceptance speech, Hillary Clinton said with ruthless precision about her opponent:
Ask yourself: Does Donald Trump have the temperament to be Commander-in-Chief?
Donald Trump can't even handle the rough-and-tumble of a presidential campaign.
He loses his cool at the slightest provocation. When he's gotten a tough question from a reporter. When he's challenged in a debate. When he sees a protestor at a rally.
Emphasis added, as it was in her delivery:
Imagine—if you dare, imagine—imagine him in the Oval Office facing a real crisis. A man you can bait with a tweet is not a man we can trust with nuclear weapons.
I can’t put it any better than Jackie Kennedy did after the Cuban Missile Crisis. She said that what worried President Kennedy during that very dangerous time was that a war might be started—not by big men with self-control and restraint, but by little men—the ones moved by fear and pride.
A collection of books recommended by The Atlantic’s editors and writers
The Atlantic’s editors and writers share their recommendations for summer reading—new titles, old favorites, and others in between.
By Yaa Gyasi
In her first novel, Yaa Gyasi cleverly weaves the intergenerational tale of a family through a series of short, but interrelated stories set in what’s now Ghana during the mid-18th century. The two women at the center of the novel, Effia and Esi, are half-sisters who wind up on vastly different paths. One is captured during a battle between tribes, sold, and winds up on a slave ship bound for the U.S. The other—separated from her village and married off to a British slaver—ends up living on top of the dungeons that hold her own kin and hundreds of others who would also become slaves. The novel traces the lineage of these women through the tales of their children, and their children’s children, and so on—up until the present day.
Last month, my wife and I found ourselves in a disagreement about whether or not our apartment was clean enough for guests—the type of medium-sized disagreement that likely plagues all close relationships. In the midst of it, there was a lull and, feeling exhausted all of a sudden, I got up and left the living room. In the bedroom, I immediately fell face down into the sheets. The next thing I knew it was 20 minutes later and my wife was shaking me awake. I hadn’t meant to fall asleep; I just felt so fatigued in that moment that there was nothing else I could do.
This wasn’t new for me. A few weeks earlier, I had come into conflict with an acquaintance over some money. We were exchanging tense emails while I was at my office, and I began to feel the slow oozing onset of sleep, the same tiredness that came on when, as a child, I rode in the backseat of the car on the way home from some undesired trip. A sleepiness that overtakes the body slowly but surely and feels entirely outside of your control.
It’s a staple in American homes, but at what environmental cost?
As Hurricane Katrina raged through New Orleans in 2005, neighborhood after neighborhood collapsed from flooding. Of the houses that stood, many still had to be bulldozed due to mold within the walls. But one building, a plantation-home-turned-museum on Moss Street built two centuries before the disaster, was left almost entirely unscathed.
“The Pitot house was built the old way, with plaster walls,” says Steve Mouzon, an architect who helped rebuild the city after the hurricane. “When the flood came, the museum moved the furniture upstairs. Afterwards, they simply hosed the walls—no harm done.”
The other houses weren’t built the old way. “All the homes around the Pitot house were lost because they were built with drywall,” says Mouzon.
Learning how to bond with my daughter, who found comfort in the familiarity of being alone, has come through understanding reactive attachment disorder.
My hands hover over the computer keyboard. They are trembling. I hold down the shift key and type the words with intention, saying each letter aloud: “R-e-a-c-t-i-v-e A-t-t-a-c-h-m-e-n-t D-i-s-o-r-d-e-r.” The words “reactive attachment disorder” are memory beads I gather into a pile and attempt to string along on a necklace.
I think back to when Judith, my neighbor who is a psychiatrist, offhandedly threw out the term the first time she met Julia. We were talking about babies who start their lives in orphanages, and she mentioned the disorder. She wasn't suggesting that my daughter Julia showed any signs, but she’d said it was a well-known problem with children who’d been adopted from Romanian orphanages in the '80s and '90s. I remember nodding my head and thinking, Shut up, Judith. We got Julia young. It shouldn't be an issue.
A federal appeals court finds the impact of the state’s voting law can only be explained by “discriminatory intent.”
Updated on July 29 at 9:30 p.m.
DURHAM, N.C.—The Fourth Circuit Court of Appeals struck down key portions of North Carolina’s strict 2013 voting law on Friday, delivering a stern rebuke to the state’s Republican General Assembly and Governor Pat McCrory. The three-judge panel in Richmond, Virginia, unanimously concluded that the law was racially discriminatory, and it blocked a requirement that voters show photo identification to vote and restored same-day voter registration, a week of early voting, pre-registration for teenagers, and out-of-precinct voting.
“In what comes as close to a smoking gun as we are likely to see in modern times, the State’s very justification for a challenged statute hinges explicitly on race—specifically its concern that African Americans, who had overwhelmingly voted for Democrats, had too much access to the franchise,” wrote Judge Diana Gribbon Motz.