On Wednesday December 7, Tiffany Nichols lectured about her research on the process to locate and acquire a site for the Laser Interferometer Gravitational-Wave Observatory (LIGO) as a part of the New York History of Science Lecture Series.
Gravitational waves are often the only indications of violent cosmic events like black hole mergers. When these astronomical events occur, they result in ripples through the very material of space-time that linger for billions of years. Scientists can observe gravitational waves to learn more about the history of the cosmos. The equipment used by astrophysicists to detect gravitational waves is extremely sensitive, and can detect ripples as small as 1/1000th of the width of a proton. But this also leaves it extremely vulnerable to disturbance. This makes decisions about tool design and location vital to proper functioning. Tiffany Nichols, Presidential Postdoctoral Research Fellow at Princeton University, studies the intersection of astrophysics, history, and law which combine in this project studying the history of site location for the Laser Interferometer Gravitational-Wave Observatory, LIGO.
LIGO uses an interferometer to detect tiny displacements of space. A laser beam is sent towards a partially reflecting mirror, so that it splits along two paths, each being four kilometers long. At the end of each arm, the beams are reflected back, recombined, and directed toward a detector. When a gravitational wave passes, the distance between the end mirrors and the central one shift, changing the time it takes the laser to travel along the arms. The recombined beams shift with respect to one another and produce a signal at the detector. These distortions are minuscule in size, hence the precision of the device.
Finding a home for sensitive research like this is much more complicated than just acquiring the land. To emphasize the importance of the location of sensitive astronomical research, Nichols referenced the ongoing issues at the Mauna Loa Observatory, where a volcano is currently erupting, demonstrating just how inseparable a scientific research center is from its location. Power and road access are cut off, meaning work has ceased, further disrupting the research occurring there. Natural events like these must be taken into account when planning the construction of extremely sensitive equipment.
LIGO is one of the most sensitive measuring devices ever created, uniquely susceptible to disruption. This makes finding a home for this kilometers-long device a unique challenge. The site must be absolutely flat or completely evenly sloped, seismically quiet, not anthropogenically active, and there must be a minimum of two sites to corroborate the findings of the other. These criteria are the bases for the title of Nichols’ project, Finding Stillness: Navigation Conflicting Land Interests During the Site Selection of the Laser Interferometer Gravitational-Wave Observatory (LIGO).
After funding for LIGO was secured by the National Science Foundation, physicists were sent out to find sites that fit the criteria and present them to the research team. Initially, many of the physicists headed to military locations, which Nichols added was an interesting insight into their psychological approach to site location.
One of the first seriously considered sites was at the Idaho National Engineering Laboratory (INEL). The site seemed to meet all of the standards, with minimal human and seismic activity in the area, and an absolutely flat plane, plus it had controlled access to further limit possible disruptions. Seismic measurements were conducted, and research began looking into land acquisition. However, INEL also used the site for nuclear waste research, something that didn’t become an issue until researchers conducted a final look through the site and were “accosted by gun-totin cowboys.” As it turned out, INEL had been subject to a random security drill the week before and had failed, hence the increased aggression from security. With the increased interpersonal issues and prospective difficulty with land acquisition, the researchers decided to move on to other options.
The next site considered was an abandoned radar site: the Hawes Radio Relay Site. This location was close to CalTech, one of the primary research centers on the project, which would have made any necessary travel much more convenient. However, land acquisition on this site would have been much more complicated, having to deal with the Air Force and public Bureau of Land Management land. Additionally, being situated in California, it was near a fault line. Despite this, the team continued to seriously look into Hawes. But the next issue they ran into was the possibility of future anthropogenic disturbance from a nearby railhead, private landowners, and mineral prospectors who looked into mining silver on the land for some time. The NASA Jet Propulsion Lab (JPL), another collaborator on the experiment, the prospectors would just give up, but in the end, underestimated their legal savvy. Although no formal plans had been set in motion, the prospectors did at least $100 of survey work on the land each year and filed it with the proper agencies, to maintain their claim on the land in accordance with state law. In the end, the Air Force demolished the radio tower which resulted in serious damage to the building below that the team had hoped to use. This was the end of the Hawes Radio Relay site; no stillness was to be found there.
Next, researchers considered the Maine Blueberry Barrens. While the site was not flat, it was continuously sloping and was seismically and anthropogenically quiet. Here, the team initially thought there was only one owner, but upon further research, they discovered that the land was owned by 12 different parties, and the man they had thought owned the original land was actually renting from the major owner, Renee Cotton. The barrens also provided a uniquely good habitat and rich soil for the grown species of blueberries. And these blueberries send out lateral rhizomes, continuously growing horizontal stems, underground, which meant digging in one area could kill several square kilometers of blueberries, so digging would have to be seriously limited. As the physicists talked more with Cotton, the major land-owner, she introduced involved conditions that would need to be satisfied for her to sell, including LIGO’s sole affiliation with MIT, which would be a serious issue, as CalTech and JPL were also working on the project. Finally, locals began to voice concerns about lasers being used near their residences, and the landowners wanted each of their entire plots to be bought out instead of only sections like the team had offered. The site was abandoned and left to the original blueberry farmers there.
Eventually, two sites were acquired, one in Livingston, Louisiana, and the other at the Hanford Observatory near Richland, Washington. Nichols commented that the Livingston location is, interestingly, actually legally designated as a church for tax and land acquisition reasons. This process of finding stillness was long and involved, with many individuals working together to find a solution. The labor it took to finally find these sites showed an interesting insight into how involved the work is before an experiment even starts, how intertwined a research site is with the land it resides on, and how important it is to acknowledge and appreciate that land.
Gravitational Wave Depiction via Flickr
LIGO Depiction Image via Wikimedia Commons
LIGO Featured Image via Flickr