I’m writing this from more than 8,000 feet (around 2,500 meters, for the more metric-ly inclined) above sea level, in the control room of one of the twin 6.5–meter Magellan telescopes at Las Campanas Observatory, near the southern end of Chile’s Atacama Desert. I’m tagging along on a night of observing with Jackie Faherty and Chris Tinney as they measure distances and chemical compositions of exotic objects known as brown dwarfs. For the next three Science Today entries, I’ll try my best to tell the story of this one night of observing and to give a sense of what Faherty and Tinney are attempting to learn about these tiny, faint stellar wannabes.

The night’s work starts in the afternoon. The instruments require calibration, which can take place long before the sky gets dark. Because the observations will involve taking both images (basically photographs) and spectra (a “fingerprint” of the light) of the brown dwarfs, they will use both the FourStar camera and the FIRE spectrograph. Astronomers have a more fastidious approach to their images than, say, your average Instagram user, so they carefully characterize the camera’s responsiveness and uniformity. For the spectrograph, they create a map of how the light splits into its constituent wavelengths using the equivalent of neon billboard lights aimed at the instrument.

At sunset, a few clouds in the southwest cause some concern: astronomers prefer their sunsets dull, unimpressive, and cloud-free. The worry passes, however, and as the sky darkens, the work begins in earnest.

Only four days from full, the moon brightens the sky considerably. For astronomers who observe in visible wavelengths (what we see with our eyes), this would ruin a perfectly good night. Consequently, many seek out “dark time,” defined as the first few nights before or after the new moon. Luckily, brown dwarfs show up best in infrared light, so tonight’s observations can take place in the “bright time,” three to five nights before or after the full moon. Indeed, the astronomers appreciate not having to deal with pitch-black observing conditions: “It’s inconvenient. You can’t see the clouds, and you trip over things,” Tinney notes.

A little more calibration occurs as the sky darkens, including pointing and focusing the telescope, and then the observations begin. “The focus at the beginning of the night changes rapidly because the temperature is dropping,” Faherty explains. “So we take shorter exposures, and continually monitor the images for out-of focus stars, which look like little donuts.”

Ultimately, Faherty and Tinney want to determine each object’s precise location in the sky—a process known as astrometry—as well as its light fingerprint—a process known as spectroscopy.

Particularly for this kind of project, astronomers need excellent “seeing,” which refers to “the blurring the atmosphere produces,” as Tinney describes succinctly. More blurring means the light gets spread out over a larger area of the detector, making precision work on faint brown dwarfs far more challenging.

Astronomers describe the quality of seeing in terms of the apparent angular diameter of a star. Optimal observing conditions at Las Campanas can yield seeing of 0.4 arcseconds or better—equivalent to the diameter of a penny observed from a distance of twelve miles (nearly twenty kilometers). This evening started with seeing around 0.5 arcseconds, but as the night wears on, the seeing drops to nearly 0.3 arcseconds! A great night! (Or perhaps simply observational karma: on Faherty’s last visit to the Magellan telescope, the seeing averaged 1.4 arcseconds, and the observatory shut down because of high winds. C’est l’astronomie.)

Amazingly, these high-quality observations can translate into even more impressive precision when it comes to locating the brown dwarfs relative to the other stars in the image. The resolution of the detector (about 0.16 arcseconds per pixel for FourStar) combined with good seeing means they can pinpoint an object’s location down to a few milliarcseconds—that’s right, 4% the apparent size of the object itself! Such excellent conditions also make it possible to tease apart the atmospheric properties of some of the faintest compact sources in the vicinity of the Sun.

Tomorrow, I’ll share a little more about brown dwarfs and the particular challenge that Faherty and Tinney plan to address, and on Wednesday, I’ll give a summary of how the evening’s work went and what it could mean for the next steps in brown dwarf science.

Ryan Wyatt is the director of the Morrison Planetarium and Science Visualization at the California Academy of Sciences.

Image:  Karl Schultz

Besides the 1960 and 2010 earthquakes there have been several other large quakes. Science News provides the reason:

Off the western coast of South America, the Nazca plate of Earth’s crust dives beneath the South American plate, pushing up the Andes and building up stress that gets relieved occasionally in powerful earthquakes.

In 1835, Charles Darwin was in the area and experienced a large magnitude-8.5 earthquake. Though there have been five other great earthquakes since then, none have ruptured in the same area that shook in 1835, a locality now known as the Darwin gap. Scientists, aware that the Darwin gap has been accumulating pressure for over 100 years, had been expecting a large quake in that gap.

But the 2010 quake was north of the Darwin gap. According to New Scientist, researchers studying the area after the recent quake

used tsunami, GPS and radar data to assess the amount of land movement during last year’s quake. By feeding this into a model, they were able to estimate the amount of slippage on the fault and the variation in the release and accumulation of stress along it.

And, the results were striking (from Scientific American):

When pressures build up enough, they snap and cause a quake. Some areas, deep below ground to the north of Concepcion, slipped almost 20 meters in the 2010 earthquake but the area of the “Darwin gap” barely moved.

So rather than relieving and reducing the possibility of another large earthquake in the area, this most recent quake may have increased the possibility of another magnitude-7 or -8 earthquake occurring in the near future. The researchers published their findings in this week’s Nature Geoscience:

…increased stress on the unbroken patch may in turn have increased the probability of another major to great earthquake there in the near future.

Image credit: R. Stein, Lorito et al/Nature Geoscience 2011

NASA’s long experience in training and planning for emergencies in human spaceflight along with its protection of humans in the hostile environment of space could have some direct benefits that will be useful to the rescue—especially when it comes to the medical and emotional needs of the miners.

Two physicians, a psychologist and an engineer, all from NASA who were freshly returned from the topside of the mine, took part in the conference, each remarking what an incredible job the Chilean miners and topside team have done and are continuing to do.

The team stressed the importance of keeping a routine down below, which includes work shifts, leisure time, scheduled meals, weekly contact with family members and times for light and darkness to create circadian rhythms for the miners as they wait for rescue that will likely be months away.

Incredibly, the miners had established a hierarchy among themselves in the 17 days before they were found. The Chilean officials are supporting that hierarchy and leadership, which the NASA team also commended.

NASA’s role there last week, and as this disaster continues, is simply an advisory role and to listen, as Dr. J.D. Polk, one of the physicians said, “colleague to colleague.”

Dr. Michael Duncan, the deputy chief medical officer and leader of the team, called this an “Apollo 13 on the ground”, and Dr. Polk confirmed that this operation is unprecedented in scope— “never have there been so many people trapped so deeply for so long.”

Dr. Al Holland, the psychologist, stressed that there will be good days and bad days and it is important to form a community both below ground and in the tent city where the miners’ families are waiting to reunite with loved ones.

He also stressed how important it is that the miners have contact with their families, but not too much. On a weekly basis, contact will give the miners something to look forward to, but were it to be on a more frequent basis, the family members may take on the miners’ problems and vice-versa, the miners taking on problems outside the mine.

One item that NASA helped the Chileans prepare for is when the miners come out of the mine. According to Dr. Duncan, the work will just be beginning when they come out—there will need to be lots of rehabilitation, recovery and reintroductions to family and society. The miners will have celebrity status in their country, and there will be lot of pressures on them from society and media wanting their time.

In the meantime, the miners will have to continue their meaningful work, both for their survival and emotional health. Supplies are sent down 24 hours a day in Palomas—torpedo-like containers four inches in diameter and two meters long. These are able to fit into the three six-inch diameter holes that are drilled to where the miners are, 2,300 feet below the surface. Food, water, medical supplies, games, books, sleeping cots and even an iPod that gets sent back up for recharging come to the miners through these palomas.

The miners will be removing tons of rubble in shifts over the next few months, assisting the various drills that will get them safely out of the mine. Making that work possibly the most meaningful of all.

Creative Commons image by desierto_atacama

NASA’s Jet Propulsion Laboratory distributed a news release yesterday stating that Saturday’s shaking could have shortened the Earth day by 1.26 microseconds (in case you’re wondering, a microsecond is one millionth of a second).

“Could have shortened” because scientists can only measure Earth days with accuracy up to 20 microseconds. The estimate is based on a calculation “using a complex model,” according to the press release.

The findings seem plausible to local earthquake scientist Wayne Thatcher of the US Geological Survey in Menlo Park. He uses GPS and satellite data to measure the displacement around earthquake faults and volcanoes in the western US. “If a large enough earthquake occurs, there’s a redistribution of mass of the Earth around the fault. It can be enough to adjust the rate of rotation.”

The redistribution of mass—or movement of Earth’s figure axis—is about 3 inches according the JPL calculations.

Thatcher likens it to the spin of a figure skater—if the skater brings their arms or legs out, it will change the speed of their rotation.

Using the same calculations, JPL’s Richard Gross was also able to measure the effect of the 2004 magnitude 9.1 Sumatran earthquake. While that earthquake was larger than the Chilean earthquake by a factor of 3 or 4, the redistribution of mass was less. Due to the location, it was only 2.76 inches.

This information is fascinating, but will the newly shortened days cause people to over-sleep?

Don’t set those alarms any earlier, Thatcher says we’ll be fine. “No one except us scientists will notice the difference.”