Searching For E.T. In An Electronic Dead Zone
The hills of Green Bank, West Virginia are tranquil and serene. But peeking out of a shallow valley is something quite unnatural—the huge ivory dish of the Green Bank Telescope (also referred to as GBT, or the “Great Big Thing” by locals). It is the largest fully steerable radio telescope in the world, with a huge ear that can listen to 85 percent of the sky.
The massive dish is like a basin, but instead of water it collects radio signals from space. Astronomical signals can be incredibly weak (the telescope often measures signals on the order of 10-29 Watts/m2/Hertz, or milli-Janskies). In order to be able to pick those distant transmissions out of Earthly electronic noise, the observatory must sit in radio silence.
Green Bank Observatory lies within the national radio quiet zone—a 13,000 square mile region of Virginia and West Virginia that is protected from radio frequency interference. “Within that region anyone that puts a fixed license antenna has to talk to us,” Karen O’Neill, Green Bank site director, explained in a video. The observatory helps locals within the zone design special cell towers and antenna that don’t disrupt the observatory’s research.
“The energy given off by a single snowflake hitting the ground is much more powerful than the radio signal an astronomer is trying to receive,” says Michael Holstine, an engineer and business manager at Green Bank. “Any manmade transmitter, electronic device, unintentional transmitter basically overwhelms the usable signal for the observer.”
Past a certain point on the Green Bank Observatory campus, you must abandon all of your precious electronics. There can be no radio signals emitted from your cell phone, microwave heating up dinner, or digital camera—so when SciFri visited the sanctuary in February, photos had to be snapped on a low-tech, real-film disposable camera. The result were these blue-tinted, looming views of GBT. Sleet and cobalt clouds cast a gloomy grey over the usually gleaming white reflector surface of the telescope.
It’s easy to feel minuscule beneath the towering latticed structure. The GBT stands taller than the Statue of Liberty at 485 feet and can fit an entire football field in its 2.3-acre reflector. Its tremendous size is needed to collect those faint signals in space.
The telescope is used to monitor pulsars, find gravitational waves, view comets, and map diffuse clouds of gas. GBT has been involved in the search for extraterrestrial intelligence (SETI) since the 1960s, and now is currently working on the Breakthrough Listen project, an intensive search for extraterrestrial intelligence, spending hundreds of hours per year searching for potential signs of intelligent life.
Karen O’Neil is director of the Green Bank Observatory in Green Bank, West Virginia.
Michael Holstine is business manager of the Green Bank Observatory in Green Bank, West Virginia.
As Science Friday’s director and senior producer, Charles Bergquist channels the chaos of a live production studio into something sounding like a radio program. Favorite topics include planetary sciences, chemistry, materials, and shiny things with blinking lights.
IRA FLATOW: This is Science Friday, I’m Ira Flatow. The search for extraterrestrial intelligence is a key theme of movie depictions of astronomy. But in the real world, SETI generally hasn’t received tons of funding. But two years ago, investor and science philanthropist Yuri Milner said he wanted to pour $100 million into SETI research as part of the Breakthrough Listen project. Science Friday’s Charles Bergquist visited the Green Bank Observatory in West Virginia, one of the places that’s listening for E.T.
CHARLES BERGQUIST: As you wind through the hills of the Potomac highlands in eastern West Virginia, you pass a few antique stores, farms, an occasional logging truck, and signs for a ski resort further up the road. At a certain point, radio reception falls away.
SPEAKER 1: A lot of static there, the scan.
VOICE ON RADIO: We’ll send you a notice–
SPEAKER 1: That’s station 550 AM here. That’s the radio scanning.
VOICE ON RADIO: We provide to you an additional–
SPEAKER 1: And we’re back to 550. We’ve got one station on the AM band here.
CHARLES BERGQUIST: And as you enter the town of Green Bank, West Virginia, population 143, you might notice something unusual. The rim of a huge dish peeking over the hills behind the elementary school.
MIKE HOLSTEIN: To travel for many miles through just a very natural environment, and then come up on this really high tech view, this outer space-y vision, it’s just beautiful.
CHARLES BERGQUIST: That’s Mike Holstein, an engineer responsible for the business operations of that outer space-y– the Green Bank Telescope, or GBT. While it looks a bit like the backyard satellite dishes some people use to get TV reception, the GBT is huge. They call it a 100-meter telescope, but that really doesn’t do it justice.
MIKE HOLSTEIN: It’s big. It’s made up of about 2,200 panels, each panel being about the size of a mattress. So the reflector surface is 2.3 acres.
CHARLES BERGQUIST: That 2.3 acres collects faint radio signals across a wide swath of the electromagnetic spectrum– wavelengths from 2.6 millimeters up to three meters– and focuses them down on to instruments sitting in a spot just a few inches in size. Dr. Karen O’Neil is the director of the Green Bank Observatory. She says every minute on the telescope is spoken for. For projects like one that looks at the wispy clouds of gas around galaxies.
KAREN O’NEIL: People who do computational astronomy have built these beautiful maps that everybody sees, showing the universe’s clumps and filaments all connected together. And they’re absolutely gorgeous. But they’re computer simulations. We need to go get the data to show that these computer simulations are right. It’s the only telescope in the world that can detect this diffuse gas. There is no other telescope that has a combination of sensitivity and instruments to go and do it.
CHARLES BERGQUIST: Closer to home, it can look at individual planets. It’s been used to take pictures of comets. And it can look for the energy given off by the vibrations of specific molecules– things like basic sugars floating in space.
KAREN O’NEIL: We found these just out anywhere that you have a lot of energy in space. We discovered you could have basic sugars.
CHARLES BERGQUIST: The telescope has also detected prebiotic molecules and, recently, chiral molecules– the left or right handed molecules necessary for life as we know it on Earth. But if those molecular building blocks are common, what about intelligent life? The Observatory has a history with the search for extraterrestrial intelligence, or SETI. Astronomer Frank Drake first set down the equations scientists use to ballpark the probability of finding intelligent life during a 1961 meeting here. And now O’Neil says a massive 2,000 hours a year of telescope time is going to the SETI project Breakthrough Listen, an effort to repeatedly observe many star systems searching for signs of intelligence.
KAREN O’NEIL: Truly one of the hardest questions to ask is to look for a signal. You have no idea what it’s going to look like, at a frequency you have no idea where it’s going to come in at. And then to try to say, I think I’ve got one. So it’s a very, very difficult problem. It’s a very, very challenging problem. It’s a very, very fun problem to try to do.
CHARLES BERGQUIST: But Earth brings additional challenges to that search– technical challenges caused by humans.
MIKE HOLSTEIN: The energy given off by a single snowflake hitting the ground is much more powerful than the radio signal that the astronomer is trying to receive. So any man-made transmitter or electronic device, unintentional transmitter, basically overwhelms the usable signal for the observer.
CHARLES BERGQUIST: The problem is particularly acute when it comes to looking for SETI signals because researchers are looking for transmissions that might be very like signals from our own earthly technology. Just a lot farther away. The lack of radio reception on my drive into town was because the Observatory lies in a National Radio Quiet Zone, that strictly regulates transmissions.
Close to the telescopes, electronics use is restricted even more. Only diesel engines are allowed past a toll gate at the Observatory because the spark plugs in regular gas engines give off too much electrical noise. On a tour of the site, I have to turn my recorder off before it goes anywhere near the front side of the telescope. And digital cameras also make too much radio noise. I have to pick up a disposable film camera to get some snapshots. And forget about the “Can you hear me now?” guy. Cell phones are supposed to be turned off and left in your vehicle by the front gate.
MIKE HOLSTEIN: The radio astronomer unit of measurement is called a Jansky. And a Jansky is 10 to the minus 26 watts per square meter per Hertz. The GBT is operating in milliJanskys. Your cell phone that may operate at one watt, let’s say, when it transmits or is trying to handshake with a tower, is a billion billion million times more powerful than the signal that the radio astronomer is trying to receive.
CHARLES BERGQUIST: And there’s definitely no Wi-Fi in the dorm rooms.
MIKE HOLSTEIN: Absolutely, the biggest challenge in today’s world for us is Wi-Fi. Wi-Fi modems, Wi-Fi everything. You know, cars now are Wi-Fi hot spots. So vehicles that are traveling up and down the main road are just transmitters. You know, 2.4 gigahertz. 2.4 gigahertz, unfortunately is the prime band for pulsar observations.
CHARLES BERGQUIST: He’s plotted the frontage of the property with a stand of pine trees, hoping to damp down interference from passing cars. The grounds are studded with weird looking sculptures of metal pipe that are actually sensors to monitor for radio interference. And there’s a van that can hunt for sources of interference. Maybe someone’s home Wi-Fi network, or the automatic door opener at the new grocery store down the road. But so many things have some kind of wireless connection these days. And the problem is getting worse.
MIKE HOLSTEIN: Everyone is so connected at these frequencies with every device. 20 years ago, it wasn’t even a concern. These days, it’s a major concern for radio astronomy. How to mitigate that is just– it’s been a challenge that I’m not sure we can win.
CHARLES BERGQUIST: In other words, he’s hoping that the first signs of extraterrestrial intelligence won’t be drowned out by someone streaming Arrival on their iPad. In Green Bank West Virginia, I’m Charles Bergquist for Science Friday.