Friday, February 13, 2015
Center for Student Services 360 (Workshop Space) – Center for Student Services

Backpocket Barnburner: A Lightning Quick Overview of Educational Theory

01/21/2015 14:04:11
Lori Dajose
Caltech Professor of Astronomy George Djorgovski and chemist Bruce Brunschwig are among the 401 newly elected fellows of the American Association for the Advancement of Science (AAAS) for 2014.
AAAS
01/21/2015 15:08:53
Kimm Fesenmaier
SPIDER, an instrument carrying six Caltech-made telescopes, just landed after 16 days drifting in the wind above Antarctica searching for signs of inflation in the earliest moments of the universe.

SPIDER Experiment Touches Down in Antarctica

Created by: 
Teaser Image: 
Frontpage Title: 
SPIDER Experiment Touches Down in Antarctica
Slideshow: 
Credit: Jon Gudmundsson (Princeton University)

Each of SPIDER's six telescopes (one shown here, at left, on a lab bench) includes a pair of lenses that focus light onto a focal plane (at right) made up of 2,400 superconducting detectors. Three of the telescopes measure at a frequency of 100GHz, while the other three measure at 150GHz.

Credit: Credit: Steve Benton (University of Toronto)

Like bullets in a revolver, the six SPIDER telescopes slide into the instrument's cryostat (shown here without the telescopes). The cryostat is a large tank of liquid helium that cools SPIDER to temperatures near absolute zero so the thermal glow of the instrument itself does not overwhelm the faint signals they are trying to detect.

Credit: Steve Benton (University of Toronto)

Before SPIDER launched, many members of the team signed an out-of-the-way spot on the payload, wishing "Spidey" well and telling it to make them proud. Bill Jones, the project's principal investigator from Princeton University, also affixed a small photo of the late Andrew Lange.

Credit: Jeff Filippini

Jeff Filippini, a postdoctoral scholar who worked on the SPIDER receiver team at Caltech, stands in front of the instrument as it was being readied for launch.

Additional Caltech researchers involved in the project include professors of physics Jamie Bock and Sunil Golwala, postdoctoral scholar Lorenzo Moncelsi, and research staff members Peter Mason, Tracy Morford, and Viktor Hristov. Becky Tucker (PhD '14) and Amy Trangsrud (PhD '12) worked on the project as graduate students. The JPL team includes Marc Runyan, Anthony Turner, Krikor Megerian, Alexis Weber, Brendan Crill, Olivier Dore, and Warren Holmes.

Credit: Jeff Filippini

Prior to launch, the team laid out the parachute and hang lines in front of SPIDER, seen in the distance. The long-duration balloon that would carry SPIDER into the sky is attached to the end of the parachute shown here in the foreground.

Credit: Jeff Filippini

SPIDER and its balloon, ready for launch.

Credit: Jeff Filippini

SPIDER launched successfully on New Year's Day! Watch a video of the complete launch.

"One of the amazing things about ballooning is there is this moment where you're on the ground doing calibration work, really not in the deployment environment, and then you launch, and you start getting data back. That sharp dividing line between before and after the launch is really remarkable," says Filippini. "So many things can go wrong, and by and large, they didn't."

Credit: John Ruhl (Case Western Reserve University)

Sixteen days after launch, the team brought SPIDER back down to the ice because wind patterns suggested that the instrument might otherwise drift northward off the continent and not return to a safe recovery location. SPIDER landed in a remote area of Antarctica, more than 1,000 miles from McMurdo Station. The team is working on plans to recover the hard drives and payload.

Body: 

After spending 16 days suspended from a giant helium balloon floating 115,000 feet above Antarctica, a scientific instrument dubbed SPIDER has landed in a remote region of the frozen continent. Conceived of and built by an international team of scientists, the instrument launched from McMurdo Station on New Year's Day. Caltech and JPL designed, fabricated, and tested the six refracting telescopes the instrument uses to map the thermal afterglow of the Big Bang, the cosmic microwave background (CMB). SPIDER's goal: to search the CMB for the signal of inflation, an explosive event that blew our observable universe up from a volume smaller than a single atom in the first fraction of an instant after its birth.

The instrument appears to have performed well during its flight, says Jamie Bock, head of the SPIDER receiver team at Caltech and JPL. "Of course, we won't know everything until we get the full data back as part of the instrument recovery."

Although SPIDER relayed limited data back to the team on the ground during flight, it stored the majority of its data on hard drives, which must be recovered from the landing site. The researchers carefully monitored the experiment's flight path, and when wind patterns suggested that the winds might carry the experiment over the ocean, they opted to bring SPIDER down a bit early. It touched down in West Antarctica, more than 1,000 miles from McMurdo Station.

Jeff Filippini, a former postdoctoral scholar at Caltech and member of the SPIDER team who is now an assistant professor at the University of Illinois, Urbana-Champaign, says the landing site is near a few outlying stations. "We are negotiating plans for recovering the data disks and payload," he says. "We are all looking forward to poring over the data."

The team originally proposed SPIDER to NASA in 2005. It is an ambitious instrument, and there were many technical challenges to getting it off the ground. Political challenges also played a role: in October 2013, after the team had completed full flight preparations in the summer and transported SPIDER to the Antarctic by boat, the U.S. government shut down, canceling all Antarctic balloon flights. SPIDER had to be shipped back to the United States.

"But our team persevered," says Bock. "We used that extra time to make improvements and to fix a few problems. It is great to finally see all of our worries resolved and the hard work paying off."

A second SPIDER flight is planned for some time in the next two to three years, depending on how the hardware fares this time around.

The SPIDER project originated in the early 2000s with the late Andrew Lange's Observational Cosmology Group at Caltech and collaborators. The experiment is now led by William Jones of Princeton University, who was a graduate student of Lange's. The other primary institutions involved in the mission are the University of Toronto, Case Western Reserve University, and the University of British Columbia. SPIDER is funded by NASA, the David and Lucile Packard Foundation, the Gordon and Betty Moore Foundation, the Canadian Space Agency, and Canada's Natural Sciences and Engineering Research Council. The National Science Foundation provides logistical support to the team on the ice through the U.S. Antarctic Program.

Exclude from News Hub/Caltech Today: 
Yes
Saturday, January 24, 2015
Center for Student Services 360 (Workshop Space) – Center for Student Services

The personal side of science

Wednesday, February 4, 2015
Center for Student Services 360 (Workshop Space) – Center for Student Services

Meet the Outreach Guys: James & Julius

01/16/2015 10:02:43
Lori Dajose
The 2015 Rossi Prize has been awarded to Fiona Harrison, the Benjamin M. Rosen Professor of Physics at Caltech, for her "groundbreaking work on supernova remnants, neutron stars, and black holes enabled by NuSTAR." The award is the top prize in high-energy astrophysics.
Wednesday, February 18, 2015
Center for Student Services 360 (Workshop Space) – Center for Student Services

HALF TIME: A Mid-Quarter Meetup for TAs

01/07/2015 10:05:43
Ramanuj Basu
Caltech researchers discover a light signal that hints at an extremely close pair of super-massive black holes.

Growing Snow in Pasadena

Created by: 
Tags: 
Teaser Image: 
Frontpage Title: 
Growing Snow in Pasadena
Slideshow: 
Credit: Ken Libbrecht

Needles

All snowflakes are broadly categorized as either columns, which are long and thin, or plates, which are flat. Needles are considered a type of column and form only when the temperature is near 23 degrees Fahrenheit and the humidity level is high.

Credit: Ken Libbrecht

Columns

Columns like these—whether hollow or solid—typically appear at around 23 degrees Fahrenheit. Unlike needles, they can appear at varying levels of humidity and also at temperatures below 8 degrees Fahrenheit.

Credit: Ken Libbrecht

Stellar Dendrites

Plate-like snowflakes, such as this stellar dendrite, typically appear under conditions of very high humidity—but only when the temperature is near 5 degrees Fahrenheit. For the record, Libbrecht employs no Photoshop trickery to create his colorful images. Instead, he shines colored lights in from different angles behind the crystal. The ice acts like a complex lens and bends the light to accentuate structural details.

 

Credit: Ken Libbrecht

Stellar Plates

Snowflakes such as this stellar plate are common at lower levels of humidity, usually at temperatures between 26 degrees Fahrenheit and freezing, or below −14 degrees Fahrenheit. Why plates fail to form between these temperature ranges—or, more generally, why snow crystals grow into such different shapes at different temperatures—remains a scientific mystery.

 

Credit: Ken Libbrecht

Sectored Plates

Libbrecht created this sectored plate snowflake in his lab when the weather outside was frightful—for snowflakes, anyway. "It was summer and about 95 degrees outside when this crystal was growing," he said. Inside the lab, this flake grew at temperatures between 5 and 8 degrees Fahrenheit, and varying levels of humidity.

Credit: Ken Libbrecht

Capped Columns

The capped column starts out as a columnar crystal growing near 21 degrees Fahrenheit. If the crystal then falls into colder air, plates may grow from both ends of the column. The final crystal looks like a spool of thread with a hexagonal center column.

 

Credit: Ken Libbrecht

Bullet Rosettes

The capped bullet rosette forms in much the same way as a capped column but has at least three sections sprouting from a common center. This one grew columns at 21 degrees Fahrenheit, then Libbrecht lowered the temperature to 8 degrees Fahrenheit to create conditions favorable to the formation of plates on the ends.

Body: 

For a city so proud of its mild, sunny winters that it created the Rose Parade to tout its climate, Pasadena—or, at least, Caltech—has become, somewhat paradoxically, renowned for its snowflakes.

Every year, when flurries begin falling across the country, members of the media begin flocking to speak with Caltech physicist and snowflake guru Ken Libbrecht, who literally wrote the book—or, rather, books—on the science and beauty of the frozen crystals. In his lab, he creates countless snowflakes to investigate and explain how subtle changes in temperature, pressure, and humidity give rise to an impressively varied menagerie of intricate snowflake forms.

In recent years, we have showcased his research in articles that explain the physics of snowflake formation in clouds and even how to grow your own snowflakes at home. This year, we are pleased to share some of his most recent micrographs documenting the fascinating and beautiful results of his investigations.

Displayed below are some of Libbrecht's images that show representative samples of some common types of snowflakes: needles, stellar dendrites, stellar plates, columns, sectored plates, capped columns, and bullet rosettes.

To learn more, visit Libbrecht's comprehensive site. It features sections on the science, aesthetics, and history of snowflakes—and it also answers the age-old question of whether any two snowflakes are alike. (Spoiler alert: they aren't.)

Exclude from News Hub/Caltech Today: 
Yes

Pages