By Professor Richard Easther
This week, the University of Auckland (where I work) announced it is joining the Large Synoptic Survey Telescope collaboration. So what is the LSST, what will it do, and why are we so excited about it?
Firstly, the LSST is, as the name suggests, a telescope. Currently under construction in the Chilean Andes, it is scheduled to see “first light” in 2019 and will become fully operational in 2021. The telescope’s mirror is just over 8 metres in diameter, which is big – but it’s not size that makes the LSST special.
A telescope is a bucket for catching light from the night sky, and this one will funnel that light into the world’s biggest digital camera; a gigapixel monster the size of a small car. Each image the camera takes will cover a patch of sky fifty times bigger than the full moon; and each fifteen-second exposure lets it see objects that are most of the way to the edge of the visible universe. And the camera will take images all night long, every night for a decade, visiting and revisiting each patch of sky again and again and again.
Traditional telescopes make pointed observations: you point the telescope at what you want to see, but if I need to point the telescope at what I want to see, we have to take turns. What makes the LSST special is that hundreds of astronomers can gather by the banks of the river of data flowing from its camera. The data is digital, so its uses are limited not the number of hours in a night, but by bandwidth, computing power and, ultimately, our imagination. Different digital nets cast into this digital river will catch different fish. An astronomer searching for tiny, icy worlds at the edge of our solar system can weave algorithms to sieve these objects from the torrent of information. Others will pan for gold in the form of tell-tale signals of worlds circling distant suns, or fingerprints left by dark matter as it shaped the galaxies, or even echoes of the Big Bang itself. In the wealth of images the LSST will capture, there will be something for almost every astronomer and astrophysicist.
The LSST’s broad sweep
The LSST won’t make other telescopes obsolete – there are countless objects we need to observe more carefully than regular visits by the LSST will permit, and many instruments analyse light in ways that cannot be done with a digital camera, no matter how big. Not only that, we will most certainly turn to conventional telescopes to follow up on millions of interesting objects first detected by the LSST’s broad sweep.
But the LSST’s power and versatility make it one of a handful of global mega-projects in astronomy and astrophysics over the coming decade. In their most recent decadal review, United States astronomers named the LSST as the top priority for ground-based astronomy, and astronomers from all over the world are signing up to get involved with it. (It’s in good company with other major astronomical projects, including three or four traditional optical telescopes, each an order of magnitude more powerful than anything operating today; the SKA radio telescope project; and space-based missions like the JWST, a successor to the Hubble that is due to launch in 2018.)
Getting involved with the LSST is a dramatic step for the University of Auckland; it ties together our research efforts in astronomy and fundamental physics and plugs our students and staff directly into a huge international collaboration doing some of the best science in the world. Not only that, the LSST is a national opportunity, as astronomers from other New Zealand institutions can join the LSST collaboration under the agreement we have negotiated. And best of all, while LSST is a billion-dollar enterprise, the project’s funding structure means that it’s surprisingly affordable for individual institutions to get involved.
Big data from space
Besides astronomy, taking part in the LSST puts us at the forefront of a separate scientific revolution – data science. Analysing the information that will pour out of the LSST is far beyond the ability of individual human beings, or even big groups of people working together. Astronomers are learning how to use tools like machine learning and deep neural networks to prepare for the the LSST; in fact, projects like the LSST don’t just use data science but are likely to drive its development in new and unpredictable directions. The same fancy software that lets a computer tell a cat from a dog can be trained to tell a spiral galaxy from an elliptical galaxy. And because the LSST gives us a movie of the night sky and not just a static image, we can look for a points of light that change from image to image, and distinguish the tell-tale signals of objects ranging in size and distance from flying rocks that might one day hit the earth through to exploding stars at the edge of the universe.
All in all, the LSST is going to be a big deal for New Zealand astronomy in the 2020s, so watch this space. And in the meantime, watch this space on a mountaintop in Chile:
Professor Richard Easther is a cosmologist and head of the physics department at the University of Auckland