What happened to Air France Flight 447? More than two years after the crash that took 228 lives, a new interim report from France's air accident investigation agency (BEA), based on cockpit voice and data recordings recovered in May, reveals how a combination of faulty instrument data and pilot errors sent the plane into a stall from which it never recovered.

The problems began shortly after 2 a.m., a little over three and a half hours into the flight, when the autopilot and auto-thrust disengaged, probably due to bad air speed data from the plane's iced-over Pitot probes. According to the BEA report, the two copilots who were in the cockpit at the time had no training in manual aircraft handling at high altitude, and their choices showed it: They tipped the nose of the plane up, causing it to lose lift and speed as it climbed, instead of down, which would have increased the speed and prevented a stall.

Why do airplanes fly? Find out with NOVA's interactive on the physics of flight.

For more on how lift and drag work, check out this interactive from NOVA's web site.

The BEA report bears out much of the expert speculation in NOVA's Crash of Flight 447, which focused on the failure of the airspeed-sensing Pitot probes and the ubiquity of autopilot, which has left many pilots without extensive hands-on training flying manually in challenging conditions. Yet, as the New York Times points out, "Investigators found that the loss of valid speed readings lasted for no more than a minute of the plane's terrifying four-minute descent." Even if the air-speed data had been lost entirely, the pilots could have saved the plane, BEA director Jean-Paul Troadec told reporters.

The BEA's full report will be out in early 2012.

Not to get all philosophical on you, but sometimes we at NOVA ask ourselves, what does science tell us about how to live our lives? What can it teach us about how to be better human beings? Better caretakers of our environment, our planet, each other? The best answer I know is captured in this excerpt from Carl Sagan's book Pale Blue Dot. A few months back, illustrator Adam Winnik set those words to his own animation, and the result is joyful, sad, sweet, and wonderful. Winnik writes that Sagan's words have changed his life. Check out the video, and let us know how science has changed your perspective.

Pale Blue Dot - Animation from Ehdubya on Vimeo.

Close your eyes. Inhale. Exhale. Ahh. Can you feel your autonomic nervous system modulating itself?

It probably sounds like a weird question. But according to researchers like Harvard Medical School professor Sat Bir S. Khalsa, yoga and meditation practices might actually produce measurable changes in the activity of the autonomic nervous system--the bodily system that regulates, among other things, respiration, pulse rate, and digestion--as well as in brain activity and even gene expression. Researchers like Khalsa believe that these physiological effects, collectively dubbed the "relaxation response," lie at the root of yoga's touted health benefits, and that understanding the relaxation response may prove invaluable in the quest to develop new and improved treatments for sleep disturbances, anxiety disorders, and even some learning difficulties.

A yoga class. Via the Wikimedia Commons, Creative Commons Attribution-ShareAlike 2.0.

Of course, if you're a self-described Type A personality like me, it's easy to view this type of on-demand relaxation as little more than a yogic pipe dream. But curious about how the other half lives, on March 2nd, 2011, I decided to attend a presentation by Khalsa at the Harvard Graduate School of Education entitled Yoga: Practice and Research. I had seen advertisements for the talk plastered around the school, where I am currently studying educational neuroscience, and I was intrigued. Khalsa's evidence-based approach seemed like the perfect way for this high-strung science nerd to enter into the elusive world of yoga and meditation. The promise of attending an actual yoga class following Khalsa's lecture was an added perk. Would I bear witness as my fellow students soared to higher planes of consciousness? Would I finally experience, firsthand, relaxation in its purest form? Only time would tell.

Khalsa began his talk by briefly discussing yoga's history. My fellow attendees and I learned that artifactual evidence suggests that yoga originated in India as many as 5000 years ago. In its traditional form, yoga encompasses rhythmic breathing patterns, physical exercise--including the characteristic, sometimes pretzel-like poses known as "asanas"--and a range of mental activities which, according to Khalsa, lead to a state of "relaxed, focused attention." Although historically yoga has been practiced as a kind of mysticism, with the ultimate goal of reaching a state of "enlightment," in recent years increasing attention has been paid by researchers and the media to yoga's therapeutic potential, both medical and psychological. This positive attention may help to explain yoga's meteoric rise to popularity far beyond the Indian subcontinent. As of 2008, nearly 16 million Americans actively participated in yoga, with a majority of novice practitioners citing wellness or "stress management" as their main motivation for taking up the practice.

As a dyed-in-the-wool data-lover, I found these statistics compelling, but not convincing. Popularity aside, I wondered about the scientific evidence supporting yoga's espoused health benefits. I thus listened with eager ears as Khalsa proceeded to discuss some research findings related to yoga's effects on the body. Surprisingly, I quickly discovered that yoga research is nothing new. A number of landmark studies dating back to the 1930s have looked at the effects of yoga and, relatedly, meditation, on everything from heart rates to brain waves.

While some of these studies yielded conflicting results--it appears that even expert yogis cannot, alas, temporarily stop their own hearts from beating--others provide strong evidence for the existence of the relaxation response. As early as the 1950s, scientists had discovered that yoga and meditation reliably produce a cascade of physiological effects, including decreased oxygen consumption, slowed breathing, increased blood flow to the limbs, and changes in patterns of brain activity associated with attention. Described in a 1971 article as reflecting a "wakeful hypometabolic physiologic state," these effects appear to account for the feelings of subjective calmness and well being reported by yoga and meditation practitioners.

Across the last three installments of the Preventing the Unpreventable series, we have explored the scientific challenges of working with the HIV virus, a brief history and status update of HIV vaccine research, and the perspectives of HIV vaccine trial participants. In the fourth and final installment of our series, we turn to the future, and to you.

Researchers believe that the scientific community may be within ten years of finding a safe and effective HIV vaccine. They remain optimistic that the recent modest success of the Thai Trial (see Part III) has reinvigorated hope that an HIV vaccine is indeed possible. Though each discovery takes years to develop from initial concept through multiple stages of testing, scientists believe they are at least moving in the right direction.

"[HIV/AIDS] is one of the most tremendous challenges of our generation," said Linsey Baden, M.D., of the Brigham and Women's Hospital in Boston.

In this way, as the scientific community collaborates in the search for the HIV vaccine, such a tremendous generational challenge also requires the support of communities of all types, around the world. We all must commit to fighting HIV/AIDS. The scientists and trial participants we spoke with all agreed on one thing: all of us have roles to play in the future of HIV vaccine research, even if those roles are not in the lab.

Joseph Caputo learned about HIV and AIDS while in high school, when HIV and homosexuality were inextricably linked in the public consciousness.

"Coming out in high school, the only place you could learn about being gay was the library and the Internet," he said. "All the books at the library were about gay men having AIDS. So from a very young age, I thought that if I was gay, it would mean I would get sick."

Over a decade later, while the public perception had changed, Caputo felt the desire to contribute to the fight against HIV. "I was watching Angels in America and I realized I wanted to do something to get involved," he said. "I don't have money, but I could give my time and my body to research."

Caputo is one of the tens of thousands of men and women who have participated or are currently participating in HIV vaccine field studies and clinical trials worldwide. These individuals are literally the "life of a trial."

HIV-negative volunteers such as Caputo receive treatments, often over the course of many years, that scientists design to prevent HIV infection. Researchers hope that participants who are given the vaccine will contract the virus at a lower rate than control subjects, who receive a placebo treatment instead. All trial subjects are routinely tested for HIV to gather data comparing the treatment group and placebo group, and track success over time. Caputo is currently involved in a study run from Boston.

In the third part of our video blog series Preventing the Unpreventable, we spoke with Caputo and another volunteer, Benjamin Perkins, who currently works in community HIV/AIDS outreach at Fenway Health. (To learn about the scientific challenges of the HIV virus, read Part I, and to find out about today's progress toward finding a safe and effective vaccine, check out Part II).

After serving on community advisory boards, promoting the cause as an HIV/AIDS activist, and working in the field, Perkins said, "I felt like it was a natural progression to roll up my sleeves-figuratively and literally-and do my part."

For both participants, their involvement in HIV vaccine trials has allowed them to feel they are members of the tremendous community of people around the globe contributing to the collective HIV/AIDS activism and advocacy effort.

"Hopefully, the kid today, wandering about the high school library, won't have to go through some of the things that I've gone through," said Caputo.

After 30 years of research, billions of dollars in spending, and millions of lives lost, are we any closer to finding a vaccine for HIV? In Part II of Preventing the Unpreventable, Inside NOVA's video blog series on the search for an HIV vaccine, we find out why some AIDS researchers are optimistic about the future. (For more on why HIV is such a formidable opponent, check out Part I of this series).

Almost every day, scientists from around the world release new findings about the biological structure of the HIV virus and its various subspecies, clinical test results that confirm or dispute the direction of vaccine development, or creative new vaccine concepts for eliciting immune response. Progress is happening in real time. So, where are we now?

Getting a potential vaccine to clinical trial is costly, logistically difficult, time-consuming, and ethically fraught. To drive progress toward that goal, large-scale organizations such as the HIV Vaccine Trials Network, the International AIDS Vaccine Initiative, and the U.S. Military HIV Research ProgramNational Institutes of Health and the Indian Council of Medical Research to private foundations, organizations including government agencies, non-profits, philanthropic foundations, and pharmaceutical companies, are joining forces to share research findings and build a collective database of HIV knowledge, all aimed at preventing HIV infection.

The journey to find the HIV vaccine has been a long one. Why?

We asked a few of today's leading HIV/AIDS specialists about the scientific challenges of working with the HIV virus and development of a safe and effective vaccine.

Not only does the human-specific HIV attack the very system (the immune system) that typically helps to ward off viruses, but it constantly changes, adapting to the body's antibodies. This is called adaptive immunity.

Some other unique challenges in working with HIV include:

• Most vaccines protect against disease, not infection. However, the HIV infection does not result in AIDS (the disease) for an extended period of time.
• A partial (or dead) HIV virus loses its potency, and thus cannot be used for a vaccine. Yet, using a live virus is too dangerous. Therefore, scientists must develop synthetic viruses that model the structure and ideally elicit similar immune responses as the actual virus. Synthetics, while more complex, are significantly safer, and are commonly used in other vaccines like the flu vaccine.
• While most vaccines guard against infection contracted primarily through gastrointestinal or respiratory tracts (the flu, for example), a great majority of HIV infection occurs through the genital tract, which responds only weakly to infection.
• HIV may be encountered by a single individual multiple times in various and diverse forms or strains; this is called biodiversity. Therefore, successful vaccine concepts must ward off many different viruses at once.
• Typical vaccines mimic natural immunity seen in patients who have recovered from infection, but there are no recovered HIV/AIDS patients.

Come back later this week as we take a look at what it takes to develop an HIV vaccine and the progress that has been made to date.

* * *

Lindsey R. Baden , M.D., is Director of Infectious Diseases, Dana-Farber Cancer Institute; Director of Clinical Research, Division Infectious Diseases, Brigham and Women's Hospital; and Assistant Professor of Medicine at Harvard Medical School.

Dan H. Barouch, M.D., Ph.D. is the Chief of the Division of Vaccine Research, Department of Medicine, Beth Israel Deaconess Medical Center; and an Associate Professor of Medicine at Harvard Medical School.

Ken Mayer M.D., is the Medical Research Director and co-chair of the Fenway Institute at Fenway Health.

This is Part One in the four-part blog series Preventing the Unpreventable: The Search for the HIV Vaccine written by Devon Dickau, who interned at NOVA in the spring of 2011 before graduating from the Harvard Graduate School of Education's program in Technology, Innovation and Education.

Health and Human Services Margaret Heckler declared that a vaccine for the deadly HIV virus, the virus that causes AIDS, would be widely available within 2 years.

What went wrong? This year, as we mark the 30th anniversary of the first AIDS diagnosis, more than 33 million people worldwide are infected. Since the 1980's, AIDS has become a global pandemic, revealing debilitating social stigmas, orphaning children, and destroying developing economies. And thus we spend almost $1 billion each year in pursuit of a vaccine that can prevent HIV-with little progress. But, why? How can we dedicate vast resources, time and brainpower with such a modest result?

This four-part blog series will try to answer those questions. We will delve into some of the scientific and social challenges to developing the vaccine, take a look at the milestones of the past decades, and come face-to-face with scientists and people who inspire the optimism driving the continuous search to prevent the seemingly unpreventable.

Part 1: Meeting the Challenge

Part 2: Where Are We Now?

Part 3: Life of a Trial

Part 4: The Future and You

This post is part of the four-part blog series Preventing the Unpreventable: The Search for the HIV Vaccine written by Devon Dickau, who interned at NOVA in the spring of 2011 before graduating from the Harvard Graduate School of Education's program in Technology, Innovation and Education.

The final flight of the space shuttle marks the end of an era, leaving a vacuous trail to an uncertain future. Its absence will bring into focus potentially wrenching decisions ahead for the future of human spaceflight.

As an engineering achievement, the space shuttle is without peer, designed and built by the geniuses that sprang from the Apollo program. The sight, sound and feel of a space shuttle launch can only be understood by direct experience. The space shuttle is not just a rocket. It is a complex, reusable space transportation system--part rocket, part plane and part mini space station--that has enabled a crew of up to seven astronauts to conduct missions to learn how to live and work in space for weeks at a time, performing scientific experiments, deploying and repairing satellites of every conceivable type, assembling and supporting space stations and then returning back to Earth. The space shuttle has unique capabilities--such as the ability to grapple and service large satellites, perform major repairs on the space station, and return significant-sized cargo back to Earth--that will never be replaced and will probably be sorely missed someday. Although versions of these features could be built into future systems, it will come at a cost, and they're not likely to match the capability and versatility of the space shuttle. The shuttle's main task over the past decade has been to support the assembly of the International Space Station (ISS), which is now complete.

The space shuttle, though, is also a cultural icon. Just look around and take note every time you see a reminder of the space shuttle. Whether it's on TV, in the movies, on license plates, or on a kid's toy--it's just about everywhere. Symbols are important, and the space shuttle is an important symbol. To me, it symbolizes American ingenuity and technological prowess and a core belief that we are explorers and risk-takers looking to the next frontier. The space shuttle has also inspired countless young students to study engineering and science, probably its greatest legacy.

But the space shuttle program has fallen far short of its original goal of providing routine, low-cost access to space. The space shuttle was born in the waning days of Apollo. After planting flags on the moon to win the space race, NASA set its sights on making transportation to space routine, affordable and accessible. While these goals were laudable, in practice they were unachievable. The total cost of the space shuttle program since its inception in the early 1970s is estimated to be $174 billion. That's an average of about $4 billion each year, or about $1.3 billion for each of the 135 flights. While the space shuttle's unique capabilities were indeed impressive, the shuttle's costs were prohibitive, and the rationale for sending humans into space sometimes seemed conjured up simply to justify the program's existence. For the past decade or so, the quip was that we have the space shuttle to support the space station and we have the space station because we need somewhere to go with the space shuttle.

As a kid, I lived through several turning points for America, events that had a real impact on history: the beginning of the Space Race, the Cuban Missile Crisis, the escalation in Vietnam. It was hard to appreciate their uniqueness at the time, but one nice thing about getting older is that you have enough perspective to recognize a "historic moment" as it's happening--you can reflect on it in the present. So it is now with the final flight of the space shuttle.

Although American astronauts will still go into orbit, they'll have to hitch a ride with the Russians. We're outsourcing human spaceflight, which is somewhat ironic given that it was our fear and distrust of the Russians that got America into space in the first place.

I've always believed that exploring space is something worth doing, so I'm ambivalent about this. Certainly the shuttle has plenty of negatives: it's expensive and inherently dangerous. That's why the Columbia Accident Investigation Board recommended that it should not keep flying indefinitely.

There's also the question of its larger purpose. The shuttle can't explore new frontiers and distant worlds; it's a taxi, an SUV for moving people and stuff to low earth orbit.

I think that's why I never really felt passionately about the shuttle. I grew up watching Mercury, Gemini, and Apollo launches. Each seemed to do a bit more, go a bit farther--an inspired, and inspiring, steady progression toward eventually landing on the Moon.

The Moon--what a goal! Bold, daring, ambitious. Who cared what politics originally motivated it? For the first time ever, someone would leave our planet and journey to another world. The endeavor seemed noble, and the vast distances and extreme difficulties lent it a monumental scale.

And no part of Apollo seemed as monumental as the Saturn V moon rocket. Weighing thousands of tons, it would rise off the earth and propel three men to a speed of seven miles per second. Everything about it defied the imagination: too big for any road, its stages had to be moved by barge...the building to assemble it was so cavernous it had its own weather inside...the giant crawler that moved it could carry it miles and climb up a hill without tipping it more than a few inches...on and on.

Compared to this, the shuttle seemed boring and pedestrian. Smaller and less powerful, it wouldn't visit other worlds. Even its name acknowledged lesser expectations; it would simply "shuttle" back and forth between the earth and some nearby orbit, never venturing more than a few hundred miles from the planet--not a journey so much as a commute.

But my perspective on the shuttle changed. Making the Nova show Hubble's Amazing Rescue, I was lucky enough to spend two years following the astronauts and engineers working on the final repair of the Hubble Space Telescope.

With that experience, I got to know more. I spent time with people who work on and fly the shuttle. I got to see one, Atlantis, up close, close enough to touch it. And I saw it launch, carrying seven people who I had gotten to know and like.

As we approach the last flight of the space shuttle, many have suggested that we are witnessing the end of U.S. human spaceflight. That is certainly not the case: Now that the International Space Station, the shuttle's single most valuable contribution to research, is finally ready, the next decade of U.S. human spaceflight activity will be focused on utilizing this unique space laboratory. It is when we look farther into the future, to 2020 and beyond, that we face the possibility there will be no U.S. program of human space exploration, and thus that the U.S. government human spaceflight program will come to an end after work on the space station phases out.

For the past forty years, the space shuttle has been the centerpiece of the U.S. space program. In recent years, it has been used almost exclusively to launch the various elements of the International Space Station (ISS) and to assemble them in Earth orbit through numerous astronaut spacewalks. (It was that task, in fact, that was among the primary drivers of the shuttle's design in the 1970-1971 period.) For the next decade, rotating six-person crew from the fifteen ISS partner nations will operate the facility and carry out a wide variety of scientific and engineering experiments. It is certainly embarrassing that for the time being U.S. astronauts will be traveling to and from the ISS in Russian space taxis. But there will be Americans working in space for at least ten years to come.

The Columbia Accident Investigation Board in its 2003 report called the fact that there was no replacement for the space shuttle in sight a "failure of national leadership." Eight years later, there is still no replacement, although current plans call for an industry-NASA partnership to develop, by mid-decade, one or more small spacecraft and their associated launch vehicle to carry crews to the ISS. One can only hope that the nation's leaders will support this effort, and that it will be successful, sooner rather than later. It will be hard for the United States to sustain its position as the world's leading space country if there is an extended period during which it has to depend on others for human access to space.

Then what? The tougher question is whether the United States will commit to traveling beyond Earth orbit; no human has done so since the final Apollo mission, Apollo 17, in December 1972. In 2004, President George W. Bush laid out what remains a worthy goal: to "implement a sustained and affordable human and robotic program to explore the solar system and beyond." The first step was to have been a return to the Moon by 2020, but the program to develop the capabilities to achieve that goal, called Constellation, was deemed in 2009 by an expert panel "unexecutable." Last year the Obama administration cancelled the program, thereby abandoning the "Moon by 2020" goal, but the president called for a continuing commitment to space exploration, saying, "If we fail to press forward in the pursuit of discovery, we are ceding our future and we are ceding that essential element of the American character."