Iowa State University professor of physics and astronomy Steve Kawaler visited SCSU last week to talk about the Kepler telescope discoveries of new planets.
Kawaler gave his first presentation in the Wick Science building at 7 p.m. last Monday, April 6. The presentation was titled “Revealing Habitable Worlds: Ushering in a New Era for Exoplanets (and Stars) with the Kepler Space Telescope.”
Kawaler started with the motivation behind searching for other planets, and what goes into the overall search.
Kawaler talked about finding planets around stars. From Earth, it’s difficult to find these planets, “even from the darkest place on Earth,” he said. However, when you start looking for these planets while in space, the exploration becomes easier, he said.
Growing up, Kawaler said that he was “fascinated” about by searching for other planets during the “space race.” As he came to find out, searching for UFOs or “aliens” from outer space was more on the fringe side of science, he said.
Although, after the publication of “Searching for Interstellar Communications,” co-authored by Philip Morrison, in the general science journal Nature in 1959, the ideas of searching for distant planets and life through broadcast media became a reality, he said.
“That’s crazy talk,” Kawaler said. “But in fact, the case was very clear, and this was the start of the scientific search for life beyond Earth.”
After that, astronomer Frank Drake took on the challenge of finding life beyond Earth. In his search, Drake created the “Drake Equation,” which is the fourth famous scientific equation in science, Kawaler said. Generally, the Drake Equation takes the big questions surrounding the search, and breaks them into smaller ones, he said.
“This has been the guiding principle for the search of extraterrestrial life since Frank [Drake] wrote it down in 1961,” he said. Part of the overall search deals with habitable planets, he said. On Earth, the water is what fuels life.
Looking for water is key, but he said that habitable planets need to fall into the “habitable zone” too. This means that the planet needs to be a certain distance from its host star. Kawaler compared it to a camp fire; the brighter the star, the farther the planet needs to be to have the right temperature.
In addition to its distance, size plays a role in sustaining life. A planet that’s too big will develop an atmosphere that can’t support life, but a planet that’s too small risks its atmosphere escaping altogether.
“So, it’s beginning to look like the three bears, right?” he said. “You want a planet that’s not too close, not too far, not too big and not too small, it has to be just right.”
“Earth is barely in the habitable zone of our own solar system,” he said. “This habitable zone is a narrow place.”
Finding planets within the zone can be difficult, especially so when searching around stars, he said. He compared the search to looking for a small candle that’s standing next to a set of stadium lights from orbit. He said that the sun “out shines” the reflection from the planets.
Kawaler said that one way to find planets is using the reflex orbital motion—looking at the way orbiting planets will “tug” at the star, which causes it to wobble. Taking measurements from the motion and the star’s mass, you can find out the mass of planet, he said.
“As of today, this has been a very successful technique, and it is the technique that first found planets around other stars,” he said. “Nearly 600 planets have been found this way.”
However, this method isn’t as simple as the Transit technique. This method looks for the shadow caused by a planet passing around the star, much like an eclipse, and then measuring the brightness of the star, he said.
“This has been a much more successful way to find planets,” he said. Kawaler said that 1,200 planets have been found this way, mostly from space. Finding planets from Earth poses some challenges, especially since “in order to get the size of the planet, you need to know the size of the star,” and it requires looking at many stars, over a long period of time according to Kawaler.
“The best way to do this, is to look for brightness variations, using a telescope in space,” he said. “And that’s why Kepler was built.”
Designed by Bill Borucki, the Kepler telescope is much like a video camera “about the size of a dinner plate,” Kawaler said. The $600 million telescope looked at a single field of view continuously for four years. The goal was to look at 150,000 stars every minute or every half hour to find the right distance between stars and planets.
Kepler’s goal was to find “E.T.’s home,” he said. “Kepler succeeded in its mission, wildly successful.”
After its launch on March 6, 2009, the first few planets that Kepler found were larger than Jupiter and close to their host star, Kawaler said. Continuing on, Kepler has found a number of planets between the sizes of Earth and Neptune, and In February 2014, Kepler confirmed hundreds of planets, including about 100 in the habitable zone, he said.
“It’s an amazing result,” he said. “Nobody’s really anticipated finding as many planets around multiple stars as Kepler has found.”
Kawaler then went on to talk about Asteroseismology, which deals with the measurements of vibrations given off from stars. This is much like the quakes on Earth, and the vibrations are similar to sound waves, he said.
“So, Kepler, not designed to do Asteroseismology, is doing it anyways,” he said. “It’s looking for planets, but it’s taking these measurements at the same time.”
“By measuring the frequency of vibrations of these stars, you can measure their size,” he said. “One year of Kepler data is the equivalent to over 200 years of trying to do that from the ground.”
He said the Kepler data is open to the public for free.
Kawaler went onto give specific examples of data and planets picked up by Kepler. Artists’ interpretations of distances planets showed on the presentation slides, showing Earth-like planets textured and colored a variety of ways.
Kawaler finished up his presentation in just over an hour, leaving enough time to take questions from the audience.
He gave another talk last Tuesday, April 7, titled, “The Kepler Mission’s ‘Other’ Legacy: Space-based Asteroseismology” at 4 p.m.
Kepler did eventually face problems, causing it to break down. However, Kepler was stabilized and repurposed, with the help of sunlight. Now, Kepler (K2) was fixed and continued to find planets, and although not as well as it used to, it’s operating and is expected to for another three years.
Transiting Exoplanet Survey Satellite (Tess) is a follow up to Kepler, which will be able to look at half a million stars to look for planets and is expected to launch in 2018. Kawaler said that NASA “has a lot of things on the drawing board,” and space exploration is continuing.
Todd Vaccaro, an SCSU professor of physics and astronomy, said “we’re going to get tons more data” from Kepler. “The greatest thing that people don’t realize is that Kepler has been repurposed,” and that’s it’s continuing its mission, he said.
“The goal is to find habitable planets, and then follow up with studies,” he said. “What we’ll probably find is E.T.’s home. Finding E.T. is a whole other matter altogether.”