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What Were the Science Breakthroughs of 2009?

What was the most important science story of 2009? Or, what was the most significant underreported story?

Answers were given via phone and e-mail, and have been edited for space and clarity.

Neil DeGrasse Tyson

Astrophysicist, American Museum of Natural History; Host, NOVA scienceNOW

This past year, the universe continued to brim with mysteries, while cosmic discovery proceeded unabated. The planet count outside our solar system rose through 400. We’ve found water on the moon. And we serviced the venerated Hubble Space Telescope one last time, giving it a literal and figurative new lease on life. But none of these stories struck me with quite the force as did the December 30th Associated Press story by Vladimir Isachenkov “Russia may send spacecraft to knock away asteroid.”

That asteroid is Apophis, named for the Egyptian god of death and destruction. Discovered five years ago, it’s the size of the Rose Bowl and orbits the Sun on a path that crosses Earth’s orbit once every seven years. Apophis will eventually collide with Earth. In the meantime, we will experience two close approaches. One on Friday the 13th in April 2029, and the next one on Thursday the 13th in April 2036. The first will bring Apophis closer to Earth than our orbiting communication satellites. The second carries a several-in-a-million chance of colliding with Earth’s Pacific Ocean, causing trillions of dollars in tsunami-triggered damage to the West Coast of the United States.

What distresses me most about this AP story is not the asteroid itself, but that a space-faring nation (not us — not the U.S.) has decided to take the lead on an important space mission and, as a courtesy, asked if we want to join them. But isn’t that what we used to do for other countries?

Meanwhile, the Large Hadron Collider, a primarily European, international collaboration at CERN in Switzerland, now probes states of matter beyond all experimental limits previously probed by American labs. Add to these stories the widespread paranoia across America that the world will end in 2012 because an extinct Mayan civilization from half a millennium ago said so, and that we still need court cases to decide whether or not evolution by natural selection should be taught in our public schools, and I’m left fearing the future of America’s leadership on the world stage of science and technology.

This leadership, as any historian will tell you, drives the economic strength and security of nations. The fall is not from a cliff. More like a slow, downward slide — almost imperceptible from day to day. But as the years pass America will have descended from leaders to players to merely followers as we fade to insignificance, at best hitching a ride on the innovations of others.

Kenneth R. Miller

Professor of Biology, Brown University

Let me start with the most underreported story. I think that’s the rapid advance that has been made in producing what are known as induced pluripotent stem cells. The technology has galloped ahead this year in showing very clearly that it’s possible to take ordinary skin cells from the human body and reprogram them so that in nearly every respect they behave like stem cells.

The foundations for this work were laid in 2007 and 2008, however, there were concerns about the technology. In the early experiments, a virus was used to transform the cells, and the virus permanently altered the DNA in the cells being transformed. And several of the genes that had to be introduced to carry out the transformations were genes that were associated with cancer. But by the end of 2009, every one of those problems was solved. It’s no longer necessary to use viruses, potential cancer genes don’t need to be used, and finally, you don’t need make a permanent change in the genetic structure.

At this point, the basic technology that’s emerged involves using proteins. The proteins can be introduced to a cell, do the reprogramming, and are eventually broken down and discarded. And the cells that result behave like embryonic stem cells in every way that matters. This has brought us much, much closer to using these technologies in clinical applications. That to me is very exciting.

And the reason I think this is underreported is that we still have these debates and discussions about embryonic stem cells. And here right in front of us is a technology that is on the verge of changing that debate. [Although] It’s still a debate that we should be having, if only because it will be necessary to continue working on embryonic stem cells in order to fully understand how the reprogramming is happening. Embryonic stem cells are the gold standard, and the only way to understand how they work is by continuing to do research.

In terms of understanding evolution, I think the most important story of the year is the Ardipithecus fossil — the new human ancestor that looks as though it predates Lucy. What’s exciting is the number of arguments it settles, and the new insights into the forces that were acting on human evolution millions of years ago.

Finally, one thing that I take some delight in — as a biologist and the father of two girls, one of whom is also a biologist — is this year’s Nobel prizes. The prizes in chemistry and in physiology or medicine were both divided into three parts this year. And of those six total prizes given, half were given to women [Ada Yonath of Israel in Chemistry, and Elizabeth Blackburn and Carol Greider of the U.S. in Physiology or Medicine]. This is the first time ever that two women have shared credit for one of those Nobel prizes. And it really signifies that women have taken their place in the biological sciences.

Donald Kennedy

Former Editor-in-Chief, Science Magazine; Professor Emeritus, Stanford University

Because I was editor-in-chief of Science magazine, I pay attention to the magazine’s “breakthrough of the year.” And this year it was the remarkable discovery of the hominid higher primate Ardi [Ardipithecus ramidus].

It’s a real breakthrough. It is clearly older than Lucy [the Australopithecus that lived 3.2 million years ago and was discovered in 1974]. It’s the result of an investigation that lasted decades, not just years, and it gives us the firmest possible picture of how close we can get to the branch point [on the evolutionary tree] between a line that led to chimps and other great apes, and a line that led to Australopithecus and to us.

Also, sometimes in this whole rather competitive business of finding hominid fossils and evaluating them, there are early claims and then later rebuttals — people are always ready to argue about the latest new thing. This is a refreshing change from that — it’s a carefully studied find, and it’s hard to find disagreement about its significance.

I’ll also mention a couple of dark horses. One of them, because I’m deeply concerned about climate change, is new information about mass loss from the Greenland glacier, which can be measured now by satellite observations. It turns out that the mass loss from 2000 to 2008 was about 1500 gigatons. And since 2006, high summer melt rates have increased mass loss to 270 gigatons per year. That is doubtless going to increase the estimates that were originally made by the Intergovernmental Panel on Climate Change on prospects for sea level rise by the end of the century.

Finally, I’m always sympathetic to plant scientists, because they don’t get as much attention or support from the federal agencies. And we all depend on plants — the more we know about them, the better we’ll be able to think about biofuels, for example, or improving agriculture. There’s a very important plant hormone called abscisic acid that controls a number of things, like the time leaves drop and flowers bud. And for years we knew about this ubiquitous and important hormone [which also helps plants respond to drought and other stresses] but we didn’t know how it worked and where it linked, the receptor sites. This year scientists figured that out, and it opens lots of possibilities for more research.

Charles Petit

Science Journalist; “Head Tracker” of the Knight Science Journalism Tracker

This year saw several science news gushers, and one must hack away to find the truly exciting news. To start, it is easy to eliminate two of the biggest stories as measured by lines of copy and minutes of broadcast. One is the 200th anniversary of Charles Darwin’s birth celebrated worldwide. It was an event but not news. We knew it was coming, it went as planned, and we knew Darwin’s legacy already.

We can also cast aside, as news but not an event, the blizzard of breathless reports that greeted briefly famous Ida, the 47-million-year-old primate fossil Darwinius masillae from Germany. She was marketed as a paradigm-buster under the slogan “this changes everything.” The exquisitely preserved skeleton would supposedly rewrite evolutionary theory. The excitement lasted hardly a day before it collapsed under the weight of pure hype — and scoffing from experts.

Here are three big events that do pass the test of being news that mattered as events. The second also-ran is the Copenhagen Climate Conference. It must be mentioned largely because it focused attention on climate change, our time’s most difficult scientific challenge. But as the meeting failed to move the ball forward on policy or public understanding, much less the underlying science, we must turn elsewhere.

This leads to the first also-ran: the successful startup, at last, of the Large Hadron Collider particle physics machine under the French-Swiss border. As pure narrative, it gained riveting dramatic arc from the explosions and melted magnets that derailed the first effort to get it going. It got spice from loony theories that it would unleash black holes that would devour Earth. A few people may even have learned some physics from all the coverage. And now it is working just fine, breaking records for the energy with which it tortures fundamental particles. But really, one cannot call it the top story of the year, because it’s hardly done anything yet. We have to reserve the blue ribbon for when and if the thing overturns laws of physics, provides new ones, or both.

The winner? A piece of pure, sublime, impractical, mind-stretching science. Paleontologists from Ethiopia and the U.S., led by U.C. Berkeley’s Tim White, released their reconstruction of Ardipithecus ramidus (Ardi) — a tree-climbing primate that stood upright 4.4 million years ago in what was then a forested North Africa. The bones, crushed and mixed up, required in some cases 15 years of painstaking work to chip them from the hard sedimentary rock that held them. The genus stands — as firmly as things can be in ever changing science — at the root of the human family tree. It is not what paleoanthropologists expected. It is nothing like a chimp. But it is the oldest creature we know in any detail at all that we can call “us.” She is the more fitting news celebration of Charles Darwin’s birth.