NASA's Stratospheric Observatory for Infrared Astronomy, also known as SOFIA. (Photo: NASA)

The new SOFIA observatory isn't your average NASA project. Engineers took a 30-year old 747 airplane, cut a hole in the side and installed a 17-ton telescope. Most telescopes are either on the ground or somewhere in orbit, but SOFIA falls somewhere in the middle, flying around at about 40,000 feet.

I got the chance to hitch a ride on one of its recent research flights as the plane left Moffett Field at the NASA Ames Research Center. It's definitely not the kind of flight where you get a bag of peanuts and movie.

The researchers take advantage of the nighttime sky, so we left at dusk for 10-hour tour flying zigzags across the Pacific Ocean. Each leg of the journey is carefully calculated so the telescope can pinpoint a far away star. The plane interior is packed with computers and equipment. It also lacks insulation since much of it was removed to install the telescope, so it's both cold and loud inside.

At four in the morning, the astronomers are still hard at work. If they're as tired as I am, they certainly aren't showing it.

"For me, this is very exciting," says Ian McLean, a professor at the University of California-Los Angeles. He usually works on the ground. "All my career has been ground-based astronomy. So, it's only my second flight."

McLean says there's a good reason to do astronomy in the stratosphere. The atmosphere is thinner, which means it's easier for the telescope to see the stars. "It's almost as good as space," says McLean. "Not quite, but almost."

And unlike the Hubble Space Telescope, this telescope lands everyday, which means the scientists can update and fix the equipment. "By the time you get a mission into orbit, the technology you're using is relatively old. Here we can stay state of the art all the time," says McLean. NASA began developing SOFIA in 1997 and almost cancelled the project at one point. It flew its first science mission in November 2010 and now costs about $80 million a year to operate.

Searching for a "Holy Grail"

McLean says the SOFIA telescope could show astronomers something that's considered a Holy Grail in their field: seeing a star being born. It happens in huge, dusty clouds – stellar nurseries, as Mclean calls them. "The cloud is huge, light years across and it's gradually contracting to form a whole nursery of stars."

Inside NASA's SOFIA Observatory, somewhere over the Pacific Ocean.

But there's a problem. Astronomers can't see what's happening inside the clouds because, once again, they're made of dust and it's hard to see through.

"We don't mean dust bunnies, but we mean little, tiny little grains of solid material. Doesn't matter how big a telescope you have, you can't see inside it," McLean says.

That's why SOFIA looks at a special kind of light called infrared light. If you look through a telescope on the ground, you're looking at the visible light from space – the light our eyes can see. Infrared light is invisible to us, but it penetrates space dust, which means the telescope can see through the dust too.

"You get to see what you can't see with your eye. It's like a window has been opened," says McLean. They're looking for exactly how stellar nurseries give birth to young stars. McLean says catching a star as it's forming can reveal clues about how own solar system formed.

But star birth isn't the only thing these researchers want to see. They're also looking at the way stars die.

A Star on the Way Out

As the plane makes as sharp right turn, the telescope focuses on an object called NGC 7027. It's a planetary nebula – also known as a dying star. Mclean and his team are capturing an infrared image of the nebula, which is about 3,000 light years away. They can also see what it's made of.

"It has a distinctive shape. It's oval. There's a hole in the middle and that's because it literally is a shell of gas that came off the star," says McLean.

7027 is dying because the star has run out of fuel – the same fate that our sun will face in about five billion years. As it dies, the star casts off its outer layers, shedding huge amounts of material to form a cloud around it. But it's not entirely a sad story.

"It won't be wasted," says McLean. "The material that was thrown off by that star in its dying phase, somewhere, millions, perhaps billions of years from now, will find its way into a new star and the planets that form around it."

From dead stars come new stars – and planets like our own. The oxygen and nitrogen in our bodies were once formed inside a star. "The cosmos is within us," as astronomer Carl Sagan once said. "We're made of star stuff."

As sky begins to lighten, we descend towards the Dryden Aircraft Operations Facility in the Mojave Desert, where the plane is based. The SOFIA telescope is now flying twice a week. Astronomers from around the world are lining up to get onboard.

The earth at night as viewed from a space, in a composite image from NASA.

The world is not as dark as it used to be. Streetlights, parking lot security lights, office building lights, and neon signs shine all through the night. Light pollution can come directly from light bulbs, or it can bounce off of dust and water droplets in the air, creating a bright haze called skyglow. This 24-7 illumination can be seen from space, and it has negative effects on humans and wildlife. But there are ways to dim the lights and reduce their effects—and save energy in the process.

Astronomers have long aware of the problems associated with nighttime illumination—it makes stars disappear. Big telescopes are built away from big cities for this reason, although bright lights have a way of encroaching. QUEST blogger Ben Burress talks about light pollution and astronomy here and here.

Non-astronomers are affected by nighttime lighting, too; exposure to light at night affects our circadian rhythm, the 24-hour cycle deep inside our bodies. Seeing light at night can cause sleep disorders. And long-term exposure to light at night has been linked to breast cancer, because light inhibits the production of melatonin, which slows the growth of cancer cells.

Exposure to light affects animals, too. Anyone who has sat next to a porch light on a summer evening knows that moths are drawn to light—along with a multitude of other insects. Outdoor lights disturb insects’ nighttime navigation, and affect their feeding and mating. Lizards are often found feeding on the tasty insect snacks that gather around lights. Often, these lizards are not normally nocturnal—staying up at night gives them access to a “night-light niche” and an abundant food source. It also creates the opportunity for interactions between animals that would never meet in the dark conditions of previous centuries. Some lizards get a double benefit, basking in the warmth given off by artificial lights (incandescent lights are really inefficient; most of the energy they use goes to producing heat, not light).

Night lights make birds sing at odd hours, and mess with their mating and migration schedules. During migration, birds are drawn to the light from tall buildings and towers, resulting in deadly collisions.

Sea turtles are perhaps the most famous example of animals affected by light. Hatchlings swim towards the light—historically the horizon above the ocean. But now that beaches are backed by well-lit condos and hotels, baby turtles crawl further onshore instead of out to sea. There is evidence that sea turtles are drawn to light with short wavelengths, and using bulbs with longer wavelengths or using filters that cut out short light wavelengths reduces the number of baby turtles crawling in the wrong direction.

Simple fixes, like different bulbs or shades that focus light on the ground, can do a lot to re-darken the night sky, as does turning off unnecessary lighting. Dimmer, more efficient bulbs that provide enough light for human needs—but not too much—are a step in the right direction, and can save on energy costs. Dark sky conservation and stricter lighting ordinances will help.

I was surprised by the negative health effects of exposure to nighttime lighting—something to keep in mind as I work late into the night, basking like a lizard in the glow of my computer screen.

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(left) A cell imaged with an optical microscope. (right) The same cell imaged by allowing the cell to absorb UCNPs and then irradiating it with infrared light. Each nanocrystal is one thousand times smaller than the width of a human hair. Image courtesy of PNAS.

Thus proceeds Michael Crichton's 2002 thriller, Prey, as the protagonists face off against a malicious swarm of flesh-hungry nano-robots that are the offspring of a most unholy marriage of biological, computer science, and engineering research efforts.

Real science capabilities lag somewhat behind, but researchers succeeded recently in demonstrating an exciting new class of nanoparticle with potential applications in biological imaging. The new crystals, more formally known as lanthanide-doped upconverting nanoparticles (UCNPs), were fabricated and studied under the direction of principle investigators Bruce Cohen and James Schuck at Lawrence Berkeley National Laboratory's Molecular Foundry, and results were published on June 18^th in a paper by Shiwei Wu and others in the Proceedings of the National Academy of Sciences (PNAS).

Happily, while Crichton's nanoparticles coordinated an attack on a your vital organs, these particles behave more like benign light bulbs. After allowing a living cell to absorb the UCNPs, researchers shine infrared laser light on the cell, and the nanocrystals within light up like a Christmas tree in red or green arrays of dots. These, in turn, can easily be spotted using an optical microscope and used to map out particle distributions within a cell, yielding information impossible to obtain by other methods.

The method, known as single-molecule imaging, has been demonstrated using other nanoparticle types, but UCNPs are unique because of their uncommon brightness and stability, and because they are powered by infrared light. This is both good for the studied cells, because infrared light is less damaging than visible or X-ray frequencies, and good for the people measuring them, because it can probe more deeply into tissue than other types of light. In fact, one prospect for future research is the imaging of entire animals.

Reflecting on the research effort's long-term goals, Cohen commented that cross-disciplinary sharing of ideas is crucial. "In general, we'd like to bring nanoscience to the larger scientific community, especially biology, where few researchers have had much exposure to it," he said. "Our goal is to make interesting and useful new materials that will let them do all sorts of experiments that would otherwise be impossible."

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