The Large Synoptic Survey Telescope - A New Way to Scan the Sky
by Seth Shostak, Senior Astronomer
It will be the mother of all telescopes, and you can bet it will do for astronomy what genome sequencing is doing for biology.
The clumsy, if utilitarian, name of this mirrored monster is Large Synoptic Survey Telescope, or LSST. You can’t use it yet, but a peak in the Chilean Andes has been decapitated to provide a level spot for placement. This robotically operated sky-eye, with an aperture of 8.4 meters, should be up and running six years from now.
OK, but so what? After all, there are many new telescopes rolling down the pike these days, some of which will boast far larger optics than the LSST.
The difference is in the way this scope will sponge data from the sky, and distribute it to the world. The LSST will be the first instrument designed from the pedestal up to work fast, to pile up petabytes of data, and to quickly notice any cosmic phenomena that go bump in the night.
That last point is important. Generally speaking, most stuff you see in the heavens doesn’t change very quickly. The stars look the same from night to night. Nebulae and galaxies are dully immutable, maintaining the same overall appearance for thousands or millions of years. Indeed, only the Sun, moon and planets – together with the occasional comet, asteroid or meteor – seem dynamic.
The principal reason for the universe’s poker face is that its constituents are far away. Stars careen through space, and galaxies spin at speeds thousands of times faster than a jet plane. But given their distance, you’d need the patience of Job to notice much change in their appearance or position.
Nonetheless, we know of celestial circumstances that do change quickly. Stars can explode in minutes. Nearby asteroids capable of cratering your neighborhood can traverse the sky in hours. And surely the most interesting of all are the things we don’t know about: fast phenomena that have escaped our attention simply because astronomers have always used still cameras to photograph the cosmos.
According to Mario Juric, the LSST’s Data Management Project Scientist, this new telescope will sport a massive, three-ton digital camera with a wide enough field of view to snap photos of the entire southern sky roughly every three days. Since the current plan is to operate the LSST for at least a decade, that means every object visible to this instrument will be imaged nearly a thousand times. Of course, those photos can be viewed in sequence, like a time-lapse film. As Juric says, “It’s a robot telescope that will make a movie of the sky.”
And this flick won’t be dull. Juric estimates that ten million transient objects will be photographed each clear night. Many of these will be asteroids prancing through our solar system, and the LSST will catalog millions of them, including 80 percent of the larger ones – rocks as big as a football field or more. Knowing the orbits of these dangerous projectiles will prompt us to deflect those coming our way. To know them is to shove them.
That’s a nice bit of insurance against collision catastrophe, but the truly revolutionary thing about the LSST is what it will do for fundamental astronomy. It’s a safe bet that this telescope will discover multitudes of extraordinary events such as colliding neutron stars or other exotica worthy of intense, and immediate, study by others. So part of the LSST’s design is to send out electronic alerts within 60 seconds of sensing one of these fast-action, “bump in the night” events.
With this laundry list of extraordinary capabilities, and its formidable cache of data, the LSST will revolutionize astronomy. Yes, that’s a cliché, but sometimes clichés are appropriate.
Juric notes that, historically speaking, “astronomy has always been a data-starved science.” That’s because the most interesting research topics are inevitably on the edge of visibility, and consequently require using the largest telescopes.
The result is a bottleneck. In the not-so-good old days, a working astronomer might get a few nights a year on a world-class instrument, and could generally observe a few dozen or a few hundred objects. Sure, there were published surveys that cataloged reasonably big swaths of the sky, but those data were not always adequate to address the kinds of interesting questions scientists cook up. So big-time astronomers were often intimately dependent on big-time telescopes.
The LSST may cause a breakup of that exclusive relationship. After its first decade of operation, this new scope will have an image collection of about 20 billion galaxies and 17 billion stars. The data set will tally hundreds of millions of gigabytes. That’s truly big data, and the good news is that anyone will be able to scour through it – via the laptop in their office, or using their smart phone while waiting for the bus.
So here’s the big shift: For four hundred years, the relationship between astronomers and their telescopes has been as fundamental as that between a psychiatrist and his couch. But once the LSST starts digitizing the sky, it will alter the paradigm dramatically. Scientists will interact with data, not with an instrument. Rather than acquiring photos or spectra to prove or disprove their ideas, they will be free to trawl immense quantities of data, and see what falls out.
It will be as if biologists and zoologists suddenly had access to detailed information for every single species on Earth (and thousands of examples of each). Think of the sort of investigations even amateurs could make.
The LSST will be a game changer, and it could very turn out that the biggest discoveries about the past, present and future of the cosmos will come not from tweedy astronomers, but from the keen and curious non-specialists sitting at home, faced off against their laptops. Galileo would have been stupefied.
Originally published on Huffington Post