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Unlocking the Universe: How the Rubin Observatory Will Transform Astronomy

By Mahitha Ramachandran

A new era of astronomy research is about to be ushered in by an observatory in the desert mountains of north-central Chile. This observatory, once known as the Large Synoptic Survey Telescope, but now more commonly called the Vera C. Rubin Observatory, will soon begin a decade-long deep survey of the entire southern hemisphere sky. Throughout these 10 years, it will produce data that will open the door to exploring previously unanswerable questions about our universe.

The observatory will hold the Simonyi Survey Telescope, an 8.4-meter diameter ground-based optical telescope with an extraordinarily wide field of view, as well as a 3,200-megapixel optical camera, the largest digital camera ever constructed for astronomy. The enormity of this camera and the quality of the images it will produce is difficult to overstate. According to the Rubin Observatory’s official website, the camera is the size of a small car, weighs over three tons, and will “produce images so large that 1,500 high-definition TV screens would be required to view each one.” This camera, and its accompanying telescope, are truly a colossal (and expensive – the project’s total funding continues to change but now sums to over $500 million) technological achievement. It is only natural to ask, “Why?” What exactly do we need an enormous, extremely high-quality camera and telescope for?

To understand the purpose and value of the Rubin Observatory, we need to understand what a survey is. It is typical to think of a telescope as a device that observes particular objects, such as a star, nebula, or galaxy cluster. For many telescopes, such as the James Webb Space Telescope, this is true. However, the work of a survey telescope like the Simonyi is very different; rather than focusing on a specific object, it collects images and data of the entire night sky over a specific duration of time. These surveys allow scientists to track both large-scale and minuscule changes, anomalies, and constants over the interval of time in various regions of the sky. The more survey data that is collected, the more insight the data analysis can provide. Thus, a bigger, better survey telescope and camera paired with a 10-year-long survey period promises to reveal quite a lot about our universe.

This is the premise of the Legacy Survey of Space and Time (LSST). Using the Simonyi Survey Telescope and LSST camera, the LSST will be a monumental survey of the southern hemisphere’s night sky. Each night, it will take around 2,000 30-second exposures of various regions of the sky, each the size of about 40 full moons. Through high precision focusing and rapid repositioning of the enormous telescope, it will be able to cover the entire southern sky every 3–4 nights, and will repeat this for a decade. This process will produce an unprecedented depth of data on the night sky: approximately 20 terabytes of data each night, resulting in an estimated 60-petabyte database at the end of ten years (1 petabyte is equal to 1 million gigabytes). Thus, the great challenge—and potential—of the LSST lies in building and maintaining the software to process and manage all this data.

Of course, processing the stream of data from the LSST will be well worth the challenge. Scientists working on LSST anticipate discovering around 20 billion galaxies, 17 billion stars, 10 million supernovae, and 6 million Solar System objects. The Rubin Observatory was designed to specifically maximize discoveries in four main areas: 1) understanding the nature of dark matter and dark energy, 2) creating an inventory of the Solar System, 3) mapping the Milky Way Galaxy, and 4) exploring “transients,” or objects which change in a property such as position or brightness over time, in the optical sky.

Essentially, there is a wide variety of research that will become possible through LSST data. For instance, the ability to study dark matter through its gravitational effect on galaxies will dramatically increase with the influx of LSST images. Another example is the LSST’s unique ability to detect stellar streams around the Milky Way, allowing astronomers to discover new ones and use them to map out our galaxy’s formation. There is so much more that the LSST will make possible. In fact, professors and research faculty right here in Pitt’s Department of Physics and Astronomy are involved in this endeavor.

“A lot of current research [here] is focusing on the software that aims to tackle the tremendous amount of data,” Dr. Tianqing Zhang, Research Assistant Professor at Pitt said. Dr. Zhang is involved in various LSST-related projects; he went on to explain that for Rubin, even a simple operation, such as finding the median of a dataset, will be hard. “With Rubin, you could easily have a dataset that is in the order of hundreds of terabytes, which would never fit into any memory of a computer system. Sorting data when it cannot fit into the memory is a computer science challenge. There are a lot of challenges like that which are driving software development, and Pitt and CMU are a big part of that.”

At Pitt, Dr. Jeff Newman, Dr. Brett Andrews, and Dr. Zhang are involved in developing code to estimate distances of the new galaxies LSST will detect using a technique called photometric redshift. Dr. Michael Wood-Vasey and Dr. Mi Dai study supernovae, an example of a transient; they are preparing for the transient research which LSST data will make possible. These projects are a few examples of Pitt’s involvement with Rubin.

“A lot of the questions posed to the community by Rubin are completely new,” said Dr. Zhang. “It’s very exciting to see it all coming together.”

The Rubin Observatory is almost ready for use. Currently, the timeline has various components ready for testing throughout the second half of 2024 and the System First Light (an astronomy term for the first official use of a telescope) is scheduled for January 2025. The LSST is then set to begin 4–7 months after that. It is an exciting time to be an astronomer, astrophysicist, or even simply a space enthusiast. So much of our universe is unknown, but the Rubin Observatory and LSST are a testament to our natural wonder and constant pursuit to unravel those mysteries. If you share in that wonder at all, keep an eye out for news about Rubin and the new age of astronomy just around the corner.