Pint-Size Sky Watchers

While monster telescopes get the attention, the little guys quietly — and cheaply — rack up cosmic finds.

HATSouth telescopes search for dim planets orbiting the stars in Chile’s Atacama desert sky. (Gáspár Bakos)
Air & Space Magazine

If Gáspár Bakos ever needs to condense his job description into an elevator pitch, it might go something like this: Travel the world, dodge snakes, discover new planets.

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The Hungarian-born Princeton astronomer is doing a bit of repair work on an overcast spring afternoon in Arizona’s Santa Rita Mountains, poking into an electronics box that controls one of five small telescopes he oversees at the Smithsonian’s Fred Lawrence Whipple Observatory near Amado, 35 miles south of Tucson. The cluster of telescopes forms most of HATNet, the Hungarian-made Automated Telescope Network, which hunts for planets in other star systems. Two more telescopes are in Hawaii, and a second network, HATSouth, spreads from Namibia to Chile to Australia. Together, these little telescopes are able to search wide swaths of the sky to make voluminous catalogs of cosmic objects.

Bakos is in Arizona because the top of one of the box-shaped telescope enclosures refuses to open. To keep the remotely operated telescopes running, he sometimes travels 100,000 miles a year. His journeys bring him close to the many varied objects of the universe, not to mention a menagerie of creatures on this planet as well.

“One time this telescope had a black widow inside,” Bakos recalls, jabbing his finger at the spot in the Whipple telescope where he found the nasty visitor. “Namibia has snakes. They’ve never gotten into the telescopes, but they’re all over the place. This site [in Arizona] has the sun spider, which is as bad as a scorpion. It has a gigantic mouth, which is really scary, with a lot of teeth in it.”

For those who operate small telescope networks, there’s no such thing as “not my job.” “It’s like working at a small business, because if something needs to be done, you do it,” says Ed Beshore, who recently left his post as head of the University of Arizona’s Catalina Sky Survey, which hunts for asteroids and comets that come close to Earth’s orbit, to become deputy principal investigator for OSIRIS-REx, a NASA asteroid sample-return mission scheduled to launch in 2016. “I’ve swept the floors at the observatory, I’ve ripped the telescope apart and pulled the mirrors out and pulled the cameras off, I’ve written software, and I’ve written grant proposals.”

Networks of small telescopes are contributing to science in ways most astronomers couldn’t have envisioned just a couple of decades ago. They have increased by 60 times the number of known asteroids in the solar system, discovered several dozen extrasolar planets, cataloged thousands of exploding stars, and helped solve some of the mysteries of the most powerful blasts in the universe. Though they’re called “networks,” the telescopes aren’t wired together; they’re just a collection of instruments that are all assigned the same task. These telescopes are generally 40 inches in diameter or smaller, and by working in groups they are especially suited to record changes in large areas of the sky over periods of days, weeks, or even years. “Historically, we’ve always gone deeper—to the very edges of the universe, or nearby but very faint, and that’s the role of giant telescopes,” says David Charbonneau, a Harvard astronomer and lead scientist for MEarth, another Whipple-based project, which uses a set of eight identical 16-inch telescopes to hunt for planets around small, cool stars known as M dwarfs. “But the time domain has been neglected,” he says. “The idea of studying stars and seeing how they change is fairly new,” enabled over the past couple of decades by the advent of these small, wide-field-of-view telescope networks.

Whipple is home to not only the small telescopes of HATNet and MEarth, but also one of the largest telescopes in the world, the giant MMT. Its primary mirror spans more than 21 feet. “There was this trend in the ’90s that bigger telescopes were always better,” says Bakos, pointing over his shoulder at the MMT. But in the last couple of decades, “the opinion of the [scientific] community changed, and I think they now see small telescopes as essential things in astronomy. I think there’s more funding going into these now, there’s more time given to them, just more understanding of how important they are.” In the field of exoplanets, for example, giant telescopes have done much of the legwork, confirming they exist and pinning down what to look for; now droves of inexpensive, small telescopes can be dedicated to simply finding them all.

Each project at MMT must compete with many other proposals for just a few nights of observing time. HATNet, on the other hand, is made up of four telescopes that are just four inches in diameter, plus a fifth, TopHAT, that is a relatively beefy 10 inches across and performs follow-up work on ambiguous HATNet images. In fact, the whole cluster of telescopes, each one enclosed in what looks like a white barbecue grill, would fit comfortably atop MMT’s mirror. The group has been working on a single project for eight years, discovering more than 40 exoplanets and almost 1,000 candidates.

“The amount of time you have on a small telescope is orders of magnitude more than you could have on a big one,” Bakos says; he can set the HATNet telescopes to gaze in one direction for as long as he wants, having them collect as many exoplanets as he thinks the little mirrors will find. The MMT is used for everything from projects that hunt for the exotic, like quasars and dark matter, to in-depth study of common stars and even exoplanets, so “you get a few nights per year. But [the HATNet] telescopes are dedicated to just this one thing. They’re small and cheap, and one can afford to dedicate them to one field.”

Some of the first small telescope networks were put to work looking for changes not in distant stars but inside our own solar system. They take snapshots of the same area of sky every few minutes or hours and look for objects that have moved against the background of stars, indicating the objects are close by. The goal is to find near-Earth objects (NEOs): asteroids or comets that approach or cross Earth’s orbit and thus have the potential for a collision.

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