A small slice of time

The night sky is now a little clearer.

With the ultimate goal of creating a comprehensive map of the universe, the 10-year Legacy Survey of Space and Time project passed a major milestone in October when its testing camera at the NSF-DOE Vera C. Rubin Observatory captured its first images of the night sky.

“With on-sky images obtained with our engineering camera, Rubin Observatory demonstrated that the Simonyi Survey Telescope and Rubin software frameworks are operational,” said University of Washington Professor Željko Ivezić, the observatory’s construction director.

As the team makes regular updates, its members are “excited about our next milestone: integrating our main camera, the largest astronomical camera ever constructed, with the telescope,” Ivezić said.

That main imager is the much larger LSST Camera, which will be capable of obtaining images 21 times bigger than the test camera’s. Work is now ongoing to prepare this camera for installation on the Chile-based telescope with the aim of having it up and running by the end of January. A commissioning period of approximately six months will follow, with the first public release of astronomical images expected in mid-2025.

The LSST camera’s size and resolution are needed for “cosmic cinematography,” said Harvard Professor of Physics and of Astronomy Christopher Stubbs, who is currently working with the telescope’s team in Chile and was Rubin’s inaugural project scientist.

Explaining the project, which was conceived roughly 30 years ago, he said: “Astronomers had built large-aperture telescopes, which collect a lot of light to look at things that are faint. Astronomers had built wide-field telescopes that can look at a lot of things at the same time. The idea here was to put those two things together and make a wide-field, large aperture telescope that can look at lots of faint things all at once.”

By scanning the sky every few nights for 10 years with such a powerful telescope and camera, the observatory will garner “a time-lapse image of the sky every single night and look for everything that changes or moves,” Stubbs said.

The project, which is funded by the U.S. National Science Foundation and U.S. Department of Energy’s Office of Science, breaks ground on two fronts. The first, said Stubbs, is philosophical, as the team plans to “make all the data immediately available to the entire community of scientists, [with] education outreach for K through 12th grade, and participating countries and institutions.”

“The idea of completely wide-open data set is a new way of doing business,” he said.

The project is revolutionary in another way as well, said Stubbs, author of “Going Big: A Scientist’s Guide to Large Projects and Collaborations.” Previously, “people would point the telescope at their favorite object,” a particular galaxy or star. The wide field of the new telescope and its camera makes such a tight focus unnecessary. “The same stream of images will serve a wide span of scientific appetites, ranging from finding potentially hazardous killer asteroids in the solar system to mapping out the structure of our Milky Way to finding exploding stars halfway across the universe” he said.

The breadth and duration of this 10-year project may help unlock other secrets, such as the nature of dark matter and dark energy. Dark matter, Stubbs said, is the name we give to “90 percent of the mass of the Milky Way.”

“We infer its existence from its gravitational effect on things,” said Stubbs. So far, however, scientists have been unable to exactly define dark matter. Dark energy is a similar catch-all term for a force not yet identified, but which is making the universe expand “faster and faster and faster,” he said.

“With this instrument and system, which can do a super-precise job on calibration, we’re optimistic about our ability to look at dark matter and dark energy with unprecedented resolution.”

Ideally, the project will shed light on these mysteries and more. “This is the first instrument that we’ve really engineered from scratch to maximize our ability to study open questions in fundamental physics with astrophysical tools,” Stubbs said.

“The initial plan is to collect data for a 10-year period and process that through computer centers in California and in France, and then disseminate those results as broadly as we possibly can and empower both the formal astronomical community and informal education to make the most of this data set.”