Rooftops of Caltech

Of all the fascinating research, communication, and innovation that takes place on campus, some of the most interesting is hidden—often in plain sight—where most members of the community never go: on the rooftops of campus buildings. Here, we catalog a few of Caltech's notable building superstructures and reveal what they do

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Moore Laboratory
Radio Telescope

The Caltech Radio Frequency and Microwave Group uses the 6-meter telescope atop Moore Laboratory for educational purposes as well as to test amplifiers, feeds, spectrometers, software, and receivers. The telescope was designed and built at JPL as part of a prototype of a deep space network array to receive data from distant spacecraft. It was moved from JPL to Moore Lab in 2005 and dedicated by then JPL director Charles Elachi, professor of electrical engineering and planetary science, emeritus.


Baxter Hall
(and other locations)
Solar Panels

About 5,000 solar panels—located atop Baxter Hall, parking structures, and other buildings—provide the campus with as much as 1.4 megawatts of electricity. Tom Shaffer, energy and LEED-EBOM program manager, says the panels provide about 2 percent of the campus's power annually.

See box at the bottom of the page for additional details about the campus's solar power generation.

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Chandler Café
Rooftop Aeroponics Towers

The aeroponics garden provides fresh herbs and vegetables for use at Chandler Café to reduce produce purchase and improve the facility's carbon footprint by creating a roof-to-table supply chain. The towers went up in June 2017 and their first crops include lettuce, onions, and tomatoes. Condensed water from air conditioning units supplies all the water the garden requires.

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Millikan Library
Earthquake Shaker

A synchronized vibration generator, or “shaker,” is installed on the roof for forced vibration tests to simulate the effects of earthquakes. Thomas Heaton, professor of engineering seismology and director of the Earthquake Engineering Research Laboratory, says the shaker—which consists of two sets of lead weights that are spun around a central axis—was installed in the 1970s. By controlling the rate of spin of each set of weights, researchers can create linear twisting shaking motions on demand. The building itself is peppered with seismometers that help observe and document the mechanical properties of the building and see how they change over time. 


Cahill Center for Astronomy and Astrophysics
Rooftop Observatory

The Cahill Rooftop Observatory includes a permanent 14-inch Celestron telescope, which can be coupled with a camera, as well as portable 8- and 10-inch telescopes. The portable telescopes, along with two smaller Galileoscopes and a 3.5-inch Questar can be checked out by users for events or observing trips. 


Linde + Robinson Laboratory

The white dome houses a coelostat (SEE-luh-stat), a solar observatory that uses mirrors to project an image of the sun down to the main lobby. Built in the 1930s but not completed until 1968, the solar telescope had lapsed into obsolescence by the early 1980s.  In the early 2010s, the observatory received upgrades that helped make the entire building more efficient and environmentally friendly with the addition of arrays of small mirrors in the shaft at the basement and subbasement levels to divert daylight into fiber-optic bundles feeding ceiling lights in the adjoining laboratories. Sunlight from the telescope also feeds a spectrometer that measures greenhouse gases over Pasadena, aids in the study the fluorescence of plants, and helps our understanding of solar photochemistry. 

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South Mudd

Egill Hauksson, research professor of geophysics, says the microwave and radio antennas on South Mudd receive seismic data from scores of Caltech/USGS monitoring stations across Southern California. One of the microwave antenna carries data from stations hosted by Southern California Edison and the Los Angeles Department of Water and Power. Other structures atop the building include satellite antennas that allow Caltech scientists to communicate with the outside world following a major damaging earthquake, a ham radio antenna for emergency communications, and microwave dishes belonging to local news stations to facilitate direct broadcasting from the building's media center.

For Caltech, Solar Panels Make Dollars and Sense

Lined in rows atop buildings across campus are more than 6,000 solar panels, which together provide as much as 1.9 gigawatt-hours per year for the Institute.

According to the US Energy Information Administration, that’s enough to power 2,085 average American homes for one year.

The panels provide about 2 percent of Caltech's annual power, but their impact is greater than that number implies. That's because the panels are optimized to maximize energy production at times when electricity is the most expensive to purchase from the grid, says Tom Shaffer, energy and LEED-EBOM program manager in Facilities Management.

The number of buildings that can support solar panels is somewhat limited, since the presence of mechanical and research equipment such as exhaust fan and fume hood vents can preclude their placement on certain rooftops. At this point, about 72 percent of the eligible rooftops on campus have solar panels installed.

The current rooftop locations housing solar panels are:

  • North Wilson Parking Structure
  • South Wilson Parking Structure
  • Braun Gym
  • Cahill Center
  • Baxter Hall
  • Watson Laboratory
  • Annenberg Center
  • Holliston Parking Structure
  • IPAC Laboratory
  • Child Care

At the time of its installation in 2008, the array on the Holliston Parking garage—Caltech's first such installation —was the largest solar-energy facility within the city of Pasadena.

Fall 2017, FeaturesJon Nalick