Revolutionising understanding of the cosmos

Astronomers from the University of Cape Town (UCT) joined global celebrations to mark the first light images of the Legacy Survey of Space and Time (LSST) on Monday, 23 June – another compelling collaboration the university finds itself at the heart of.

It is a project of the Vera C Rubin Observatory, a brand-new astronomy and astrophysics facility under construction on Cerro Pachón in Chile. This undertaking, which will launch later in 2025 and run for the next decade, is set to revolutionise our understanding of the cosmos. In 10 years, the observatory will generate about 60 petabytes, more data than everything that’s ever been written in any language in human history. The Square Kilometre Array (SKA), a radio telescope under construction in South Africa and Australia, will produce more data than this.

“One of the things we will be able to study is how galaxies form. We have theories; we understand that they are formed by smaller galaxies merging, but we can only observe the small galaxies now that are close to us,” said Professor Patricia Whitelock from UCT’s Department of Astronomy and the South African Astronomical Observatory (SAAO), who is the manager of the South African LSST project. “We will now be able to observe small galaxies millions of years ago as they were in earlier stages of the universe. We don’t understand dark energy and dark matter; we know most of the universe is made up of things we cannot see. The overall data from Rubin is going to produce vast amounts of opportunities for studying dark energy and dark matter.”

The 8.4 m Simonyi Survey Telescope at the Vera C Rubin Observatory, equipped with the LSST camera – the largest digital camera ever built – will take detailed images of the Southern Hemisphere sky for 10 years, covering the entire sky every few nights and creating an ultra-wide, ultra-high-definition, time-lapse record – the largest astronomical movie of all time. This unique movie will bring the night sky to life, yielding a treasure trove of discoveries: asteroids and comets, pulsating stars and supernova explosions.

Ten South African scientists, including those from UCT, and their teams will have access to LSST data, enabling groundbreaking research on topics ranging from the origins of the universe to galaxy evolution and the mechanisms behind stellar explosions. South Africa’s award of 10 LSST principal investigator positions and their junior associates, who enjoy the same data access privileges as their counterparts in the United States and Chile, is the result of significant contributions by South African institutions to the Vera C Rubin Observatory collaboration.

Professor Whitelock added: “The students are excited about this. I’m a retired astronomer, but for me the universe is incredibly beautiful and the opportunity to explore it is the greatest opportunity anyone could have. And it is so important that we in Africa are participating in this exploration of the universe. With millions of sources per night, there will be enough for everybody to do something interesting and it’s a matter of finding what you are good at and what you are interested in. To students, I say: join the exploration. You are going to have fun. And you are going to contribute to science and to Africa. I’m looking forward to young people joining the programme and doing things we haven’t even dreamt of.”

PhD students in the astronomy department are enthused about the world of possibilities that await. Anke van Dyk said the next 10 years of the project would see a bringing together of numerous skillsets. “We will have to use modern techniques of artificial intelligence (AI) and machine learning to look and sift through the data to find interesting objects. I’m also interested in wide dwarf spinners, and trying to identify those can be tricky, but with a long time span, we can add all the data together to be able to give us information about finding those types of objects. It’s exciting that South Africa is a world player in this type of science.”

Danile Egbo, whose work centres around radio stars, said: “Part of my research has been discovery, and where it meets LSST is that in my case, I have multiple objects which fall within the transient and variable stars. LSST is going to help, in real-time, to detect new objects and do follow-ups. LSST leads to more discoveries and with that we can liaise it with the archival data that we have and do continuous follow-ups with instruments.”

Good pressure

Kyle Solomons works around star systems called Xray binaries, and the systems are known to undergo outbursts where they become extremely bright. “LSST will assist in terms of me catching them right at the beginning when they become super bright and then follow up with the Southern African Large Telescope (SALT) where we do spectroscopic analysis. It’s good pressure to be part of this. It solidifies us as African scientists as active and intellectual partners and that’s a good thing. The unmatched depth of LSST will allow us to see even faint events even faster than before, opening new discoveries.”

LSST project in numbers:

• 4 m: primary mirror diameter
• 3 nights: time needed for an all-sky imaging
• 15 seconds: exposure time needed to capture an image
• 37 billion: number of celestial objects detected after 10 years
• 15 TB: amount of data collected every night
• 800: number of times the same object will be captured
• 23 F/D: telescope aperture
• 3 200 megapixels: resolution of telescope camera.