From UC Santa Cruz: “Lick Observatory commemorates Apollo 11 experiment on 50th anniversary”

UC Santa Cruz

From UC Santa Cruz

July 22, 2019
Tim Stephens

The retro-reflector array can be seen in this NASA photo in front of the lunar module, between the flag and the astronaut, who is placing a seismograph on the lunar surface.

The first precise measurement of the distance from Earth to the moon was achieved on August 1, 1969, in a landmark experiment involving Lick Observatory astronomers and the Apollo 11 astronauts.

To commemorate this achievement on its 50th anniversary, a bronze plaque in the lobby of the Shane Telescope Dome at Lick Observatory will be dedicated on Thursday, August 1, as part of the IEEE Milestones Program, which honors significant technical achievements and innovations in electronics and computing. (The event is by invitation only due to space limitations.)

Researchers used Lick’s 120-inch Shane Telescope [below] to fire a powerful laser at the moon and detect the light that bounced back from a retro-reflector array placed on the lunar surface by the Apollo 11 astronauts. By precisely timing the delay between short pulses of light from the laser and the return signals from the moon, the researchers were able calculate the distance with unprecedented accuracy.

The Shane Telescope at Lick Observatory was used to fire a powerful laser at the moon and detect the signal returned from the retro-reflector array placed on the lunar surface by the Apollo 11 astronauts. (Photo by Laurie Hatch)

By the time a laser pulse reached the moon, its light was spread out over an area about 2 miles in diameter, so the amount of light that came back to the telescope from the small (18 by 18 inches) reflector array was just a few photons.

“It was a big technological feat to detect such a small signal,” said Elinor Gates, staff astronomer at Lick Observatory. “At the time, our Shane Telescope was the second largest in the world, and that gave Lick an advantage for detecting the signal.”

Joseph Wampler, now a professor emeritus of astronomy and astrophysics at UC Santa Cruz, coordinated the experiment for Lick Observatory. The team at Lick overcame numerous technological challenges to get the Lunar Laser Ranging Experiment (LURE) to work. Wampler recalled that the agreement with NASA to use the Lick facilities happened in February 1969, leaving little time to prepare before the Apollo 11 mission in July.

“The optical system coupling the telescope to the lasers had to be designed and built, a system for guiding the telescope using a TV camera was also needed, optical benches for the lasers had to be cleared through the Defense Department before they could be purchased, and finally, the dome housing the Shane Telescope required substantial modification,” he said.

To accommodate the lasers, their optical benches, and the telescope guiding system, a pit was dug below the Shane Telescope and lined with tile. The tiled pit is still there, known to Lick astronomers as “the swimming pool.” Parts of the mirror system for directing the laser beams are also still installed on the telescope.

Multiple teams

According to Wampler, NASA was worried that when the Apollo astronauts left the moon, their rocket exhaust would leave the retro-reflector array covered with dust. Therefore, several teams were funded to try to detect it during the few hours that the astronauts remained on the moon after deploying the array. Two teams using different laser systems were working at Lick Observatory, and other teams were working at the McDonald Observatory in Texas and the Mount Haleakala Observatory in Hawaii. It soon became apparent that Soviet scientists were also trying to hit the LURE target with their own laser.

The initial attempts were frustrated by a number of problems, including the moon’s position low on the horizon. Also, the high-powered ruby-crystal laser systems were prone to catastrophic equipment failures, complete with explosions and fried electronics. The first successful signal detection was achieved on August 1 using a KORAD laser system. Just a few days earlier, an equipment failure had sent Hal Walker, KORAD’s field operations manager for the project, driving 350 miles from Mt. Hamilton to KORAD’s labs in Santa Monica to get replacement parts.

Gates, who will lead a tour of the Shane Telescope after the dedication of the plaque, said the LURE experiment was one of the first pieces of history she learned about when she started working at Lick Observatory 20 years ago. “Lick’s successful part in the Apollo 11 mission is a point of pride, even for those of us who are too young to remember the moon landing,” she said.

At Lick, the laser ranging activities ended in August 1969, but observations have continued at other observatories, and subsequent Apollo missions (14 and 15) deployed additional retro-reflector arrays on the moon. LURE is the only Apollo experiment that is still returning data from the moon.

In addition to the first precise measurements of the distance to the moon, these experiments have provided important information about the moon’s orbit and variations in its rotation, as well as improving our knowledge of continental drift, changes in the Earth’s rotation rate, and the precession of its spin axis.

After the plaque dedication, a reception and talks will be held in Santa Clara, where Michael Bolte, professor of astronomy and astrophysics at UC Santa Cruz and former director of UC Observatories, will discuss Lick Observatory’s role. Hal Walker will talk about his role in the experiment in a conversation with Seth Shostak of the SETI Institute.

The Institute of Electrical and Electronics Engineers (IEEE) History Center administers the IEEE Milestones Program. In addition to the plaque at Lick Observatory, the program will install a pedestal-mounted plaque in Santa Monica at the site where KORAD Lasers developed the ruby-crystal laser that was successfully used at Lick.

For additional information about the August 1 events, contact Brian Berg, the IEEE Region 6 History Chair and Milestone Coordinator, at

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UCSC Lick Observatory, Mt Hamilton, in San Jose, California, Altitude 1,283 m (4,209 ft)


UC Observatories Lick Autmated Planet Finder, fully robotic 2.4-meter optical telescope at Lick Observatory, situated on the summit of Mount Hamilton, east of San Jose, California, USA

UCO Lick Shane Telescope
UCO Lick Shane Telescope interior
Shane Telescope at UCO Lick Observatory, UCSC

Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

UC Santa Cruz campus
The University of California, Santa Cruz, opened in 1965 and grew, one college at a time, to its current (2008-09) enrollment of more than 16,000 students. Undergraduates pursue more than 60 majors supervised by divisional deans of humanities, physical & biological sciences, social sciences, and arts. Graduate students work toward graduate certificates, master’s degrees, or doctoral degrees in more than 30 academic fields under the supervision of the divisional and graduate deans. The dean of the Jack Baskin School of Engineering oversees the campus’s undergraduate and graduate engineering programs.

UCSC is the home base for the Lick Observatory.

Lick Observatory's Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building
Lick Observatory’s Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building

Search for extraterrestrial intelligence expands at Lick Observatory
New instrument scans the sky for pulses of infrared light
March 23, 2015
By Hilary Lebow
The NIROSETI instrument saw first light on the Nickel 1-meter Telescope at Lick Observatory on March 15, 2015. (Photo by Laurie Hatch) UCSC Lick Nickel telescope

Astronomers are expanding the search for extraterrestrial intelligence into a new realm with detectors tuned to infrared light at UC’s Lick Observatory. A new instrument, called NIROSETI, will soon scour the sky for messages from other worlds.

“Infrared light would be an excellent means of interstellar communication,” said Shelley Wright, an assistant professor of physics at UC San Diego who led the development of the new instrument while at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics.

Wright worked on an earlier SETI project at Lick Observatory as a UC Santa Cruz undergraduate, when she built an optical instrument designed by UC Berkeley researchers. The infrared project takes advantage of new technology not available for that first optical search.

Infrared light would be a good way for extraterrestrials to get our attention here on Earth, since pulses from a powerful infrared laser could outshine a star, if only for a billionth of a second. Interstellar gas and dust is almost transparent to near infrared, so these signals can be seen from great distances. It also takes less energy to send information using infrared signals than with visible light.

Frank Drake, professor emeritus of astronomy and astrophysics at UC Santa Cruz and director emeritus of the SETI Institute, said there are several additional advantages to a search in the infrared realm.

“The signals are so strong that we only need a small telescope to receive them. Smaller telescopes can offer more observational time, and that is good because we need to search many stars for a chance of success,” said Drake.

The only downside is that extraterrestrials would need to be transmitting their signals in our direction, Drake said, though he sees this as a positive side to that limitation. “If we get a signal from someone who’s aiming for us, it could mean there’s altruism in the universe. I like that idea. If they want to be friendly, that’s who we will find.”

Scientists have searched the skies for radio signals for more than 50 years and expanded their search into the optical realm more than a decade ago. The idea of searching in the infrared is not a new one, but instruments capable of capturing pulses of infrared light only recently became available.

“We had to wait,” Wright said. “I spent eight years waiting and watching as new technology emerged.”

Now that technology has caught up, the search will extend to stars thousands of light years away, rather than just hundreds. NIROSETI, or Near-Infrared Optical Search for Extraterrestrial Intelligence, could also uncover new information about the physical universe.

“This is the first time Earthlings have looked at the universe at infrared wavelengths with nanosecond time scales,” said Dan Werthimer, UC Berkeley SETI Project Director. “The instrument could discover new astrophysical phenomena, or perhaps answer the question of whether we are alone.”

NIROSETI will also gather more information than previous optical detectors by recording levels of light over time so that patterns can be analyzed for potential signs of other civilizations.

“Searching for intelligent life in the universe is both thrilling and somewhat unorthodox,” said Claire Max, director of UC Observatories and professor of astronomy and astrophysics at UC Santa Cruz. “Lick Observatory has already been the site of several previous SETI searches, so this is a very exciting addition to the current research taking place.”

NIROSETI will be fully operational by early summer and will scan the skies several times a week on the Nickel 1-meter telescope at Lick Observatory, located on Mt. Hamilton east of San Jose.

The NIROSETI team also includes Geoffrey Marcy and Andrew Siemion from UC Berkeley; Patrick Dorval, a Dunlap undergraduate, and Elliot Meyer, a Dunlap graduate student; and Richard Treffers of Starman Systems. Funding for the project comes from the generous support of Bill and Susan Bloomfield.