Angelle Tanner

Angelle Tanner, a post-doctoral scholar at JPL and Caltech, studies planets in distant solar systems, called extrasolar planets. The golden prize in this field is to find a planet similar to Earth - the only planet we know that harbors life. While more than 350 extrasolar planets have been detected, most are gas planets, with no solid surface. Many are located in orbits closer to their parent star than Mercury is to the sun. In other words, not very similar to Earth.

Here’s Tanner’s short list of what she and her colleagues would love to find in another planet - the elements that might enable life on another world. With the powerful tools scientists have now and with new technology and missions coming soon, the odds are going up for finding an Earth-like planet, if one is out there.

Tanner’s top five “holy grails” of extrasolar planet research are hoped-for findings that she predicts will happen within the next 15 years.

1. First planet that weighs the same as Earth

Artist’s concept of an extraolar planet.
Image credit: NASA/JPL-Caltech

Although most planets discovered have been giant gas planets with no surface, a handful of rocky planets, called super-earths, have also been detected. Super-earths are akin to Earth in their rocky make-up, but with a mass up to 10 times that of Earth.

There is no reason these planets could not host an atmosphere or even life as we know it. The discovery of a true Earth clone – Earth-like in size and make-up — could happen within a year or two. NASA’s recently launched Kepler mission has the ability to find planets as small as Earth.

2. First Earth-sized planet in the ‘habitable zone’

The so-called habitable zone is the area around a star where a rocky planet could have the right temperature to have liquid water on its surface. In our solar system, Earth sits in the habitable zone. Venus sits just inside the habitable zone and is too hot while Mars is just outside and too cold. Finding an Earth-sized planet is this geographically desirable location is the next big step in extrasolar research. One super-earth has already been detected near to its parent star’s habitable zone and it is only a matter of time — using existing technologies –- before a planet is found in this friendly environment. Ground-based telescopes and NASA’s Kepler mission are searching stars within a few hundred light years of Earth right now.

3. First atmosphere on a rocky planet

A planet’s atmosphere, along with other factors, helps determine whether a planet could sustain life. For the past few years, astronomers have studied the atmospheres of Jupiter-like, extrasolar planets. These gas giant planets have hydrogen-rich atmospheres inhospitable to life as we know it. However, many of the techniques developed for studying gas giants could be used to study the atmospheres of super-earths. This would mark an important step in beginning to understand the environment of rocky planets.

4. First hint of habitability and life

Once astronomers have enough Earth-sized planet atmospheres to study, they will be looking for biosignatures – indicators in a planet’s atmosphere that the planet might be hospitable to or even support life. Some of the molecules they will be looking for include water vapor, methane, ozone and carbon dioxide. NASA’s James Webb Space Telescope, scheduled to launch in 2014, will provide scientists with the sophisticated instruments needed for these potential observations on super-earths orbiting small stars. Assuredly, astrobiologists will be studying such data for years to come since potential life may, or may not be, in a form we expect. Keeping an open mind is critical.

5. The unexpected

The final grail — the unexpected. The history of science is marked with findings that were never predicted. As in all fields of science and exploration, it’s what we don’t know that will be the most exciting.

For more information about extrasolar planets, visit planetquest.jpl.nasa.gov

by Tracy Drain
Systems Engineer

The Kepler mission, which will look for Earth-like planets, is nearing its scheduled March 6 launch date.

At our flight readiness review on February 4th, our deputy principal investigator, David Koch, took a few minutes to talk about the history of Johannes Kepler, the project’s namesake. Koch recapped Kepler’s tremendous contributions to the realm of astronomy 400 years ago, and reminded us all why our mission is so appropriately named for that great scientist. He also touched on the more recent history of the mission, reminding us how our science principal investigator, William Borucki, wrote his first paper on the possibility of detecting planets using the transit method back in the ’80s, and then in 1992 first proposed the mission that would later become Kepler. While I already knew most of those details, there was something special about hearing them again during that milestone review just one month away from launch. It gave a deeper, richer context to what we were all doing and made me even more excited about seeing this mission succeed. (If you are reading this David, thanks so much for doing that!)

Now here we are, less than a week away from launch. The entire team has been working so hard these last several weeks. The assembly, test and launch operations team has run the final major checkouts on the spacecraft at the Kennedy Space (I don’t think it’s Spaceflight) Center in Florida, and the spacecraft is now all buttoned up on top of the Delta II launch vehicle.

Image above: Workers attach the two-part payload fairing over the Kepler spacecraft in preparation for launch. The cover, designed to jettison shortly after launch, protects the spacecraft from the friction and turbulence as it speeds through the atmosphere during launch. Image credit: NASA

The operations team has completed the final, full-up operational readiness test to rehearse the launch and early operations period. We’ve also completed the last pre-launch ground segment integration test and the commissioning operational readiness tests, which together validated the tools and procedures that we will use during that roughly two months of checkout after launch. We’re now in the home stretch: signing off the last few test reports, closing out the final action items — dotting and crossing those proverbial i’s and t’s.

And so we are nearly ready to go. In just a few days I will head off to Boulder, Colo., where I will join the part of the team located at the mission operations center to support launch and commissioning operations. We’re gearing up for an exciting campaign; I can hardly wait for this new phase to begin!

by Dan Coe
Astronomer

Planets, stars, buildings, cars, you and I, we are all made of the same basic stuff - atoms, the building blocks of matter. The late Carl Sagan famously said “we are star stuff,” as the heavy elements in our bodies were all forged in supernovas, the explosions of dying stars. In a real scientific sense, we are one with everything we see in the night sky.

We have since learned that everything we see is awash in another kind of matter, a “dark” matter, made of particles yet to be discovered. Dark matter is all around us, but we cannot see it. Some estimate that a billion dark matter particles whiz through your body every second, but you cannot feel them. We now believe that the universe contains five times more dark matter than ordinary matter. While we all may be made of star stuff, we find that the universe is mostly made of something very different.

Why do we believe that dark matter exists? How can we study something that we cannot see or even feel? And how can we unravel the universe’s greatest mystery - what is this dark matter?

The idea of dark matter was born at Caltech in 1933. (Just three years later, JPL would be born there as the “rocket boys” began their first launch experiments.) In observations of a nearby cluster of galaxies named the Coma cluster, Fritz Zwicky calculated that the collective mass of the galaxies was not nearly enough to hold them together in their orbits. He postulated that some other form of matter was present but undetected to account for this “missing mass.” Later, in the 1970’s and ’80’s, Vera Rubin similarly found that the arms of spiral galaxies should fly off their cores as they are orbiting much too quickly.

In this Hubble image, the galaxy cluster Abell 2218 reveals its dark matter by lensing background galaxies into giant arcs. Image credit: NASA/JPL.

Today dark matter is a widely accepted theory, which explains many of our observations. My colleagues and I at JPL are among those working to reveal and map out dark matter structures. Dark matter is invisible. But astronomers can “see” it in a way and you can too, if you know what to look for! For instance, if you have a wineglass on a table and you look through the glass, the images behind it are distorted. So too when we look through a dense clump of dark matter, we see distorted and even multiple images of galaxies more distant. Matter bends space according to Einstein’s Theory of General Relativity, and light follows these bends to produce the distorted images. By studying these “lensed” images, we can reconstruct the shape of the lens, or in our case, the amount and distribution of dark matter in our gravitational lens.

Our observations of dark matter in outer space force particle physicists to revise their theories to explain what we see. Hopefully through their efforts, physicists will soon produce dark matter in the lab, catch and identify a small fraction of that which passes through us, and ultimately explain the relationship between dark matter and “star stuff.”