The NASA Outer Planets Research Program has selected UAB to help research the composition of Titan and Enceladus, two of the 52 moons orbiting Saturn, and discern the kind of life those celestial bodies may house.
Perry Gerakines, Ph.D., associate professor of physics, was awarded a three-year, $408,000 grant for the project, “Vacuum Ultraviolet Spectroscopy of Icy Mixtures Relevant to the Outer Solar System.” Gerakines will work with Amanda Hendrix, a Cassini UVIS instrument scientist from the Jet Propulsion Laboratory, to measure the vacuum ultraviolet spectra of thin ice films.
Saturn’s rings stretch across this scene with the small moon Epimetheus and the smog-enshrouded satellite Titan, which UAB researcher Perry Gerakines will be studying.
Hear about researching distant moons.
“We want to understand what the Saturn system is made of because we want to understand the history of our solar system,” Gerakines says. “The chemistry around Saturn is a lot different from Earth. Understanding the origins of the materials on these moons tells us about the origin of Saturn and the origin of the solar system and the origin of the materials in the solar system — where they’ve come from, why they are the way they are and how they got to be that way.”
Gerakines will conduct measurements of ices similar to the ones NASA scientists expect on the surface of the moons. Gerakines and Hendrix then will compare the lab results to the measurements Cassini has made.
“It’s like we’re making up this book of spectra, and then we will compare this book to what we actually see around Saturn in order to identify what may be there,” Gerakines says.
Titan similar to Earth?
NASA launched the Cassini orbiter and the Huygens probe in 1997 equipped with an array of sophisticated instruments and cameras able to collect images in varying conditions and light spectra, from visible light to the infrared.
The Cassini spacecraft entered orbit around Saturn to begin the first in-depth, up-close study of the ringed planet and its domain in June 2004. Cassini is reaching the end of its planned four-year tour of the Saturn system but now will conduct an extended mission called the Cassini Equinox Mission.
Saturn’s rings, moons and its dynamic magnetosphere along with Titan’s surface and atmosphere continue to give scientist a treasure trove of information about our galaxy’s history.
Cassini’s observations of Titan have given scientists a glimpse of what Earth might have been like before life existed. They now believe Titan, which is similar in size to Mercury, possesses many parallels to Earth, including lakes, rivers, channels, dunes, rain, snow, clouds, mountains and possibly volcanoes.
“Titan’s atmosphere is full of brown haze that is made up of interesting hydrocarbon particulates, like smog in the Earth’s atmosphere,” Gerakines says. “The surface has always been hidden because of this haze, but Cassini now is enabling us to see the surface of Titan. We’ve already found hydrocarbon liquids, which is exciting because people always have wondered can life exist inside such a liquid.
“Does life need water, for example? And maybe life could exist at these low temperatures on Titan, so things like methane and ethane are actually liquids on Titan,” he says. “It’s very interesting.”
The bright white moon Enceladus also interests scientists. While it’s much smaller than Titan, Enceladus has a warm spot at its southern pole producing geysers that spew ice crystals, giving evidence of liquid water beneath its surface.
It is now thought the geysers, which shoot out at a distance three times the diameter of the satellite, feed particles into Saturn’s most expansive ring. “Somehow, Enceladus is staying warm on the inside and spraying this water out of cracks in the southern region,” Gerakines says. “That leads to many possible ramifications.”
Properties of the moons
Gerakines hopes that he and NASA scientists will be able to learn about the properties of the ices — such as how grainy they are and what they are made of — by looking in detail at the ultraviolet spectrum of these objects.
Gerakines and a graduate student will build a UV spectrometer and any other equipment needed to make the ice. The measurements of the ices will occur in the UV spectrometer, which will calculate the amount of ultraviolet and visible light transmitted or absorbed.
“We hope to show that the vacuum ultraviolet spectra obtained by Cassini reveal the presence and physical properties of trace ice components such as carbon dioxide, ammonia, or methane on the surfaces of Saturn’s moons,” he says.