Faraway Planets Orbiting Distance Stars

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Questions for NASA's Origins Program:

Where did we come from? Are we alone?

NASA artist's concept of an Earthlike planet
NASA artist's concept of an
Earthlike planet near a distant star
Between now and the 2020s, NASA's Origins Program will build more powerful telescopes that astronomers need to stare at other stars that might have life nearby. They will continue to search for Earthlike planets orbiting those stars.

Since we understand some of the conditions that brought life Earth, scouting out similar planets with physical conditions like those on Earth should increase the odds of finding life, scientists say.

Warm wet planets. With current technology, astronomers can uncover the orbital infleunces of only very large planets like Jupiter. Those probably don't harbor life. After all, Jupiter is composed completely of gas and has no solid surface where life might form. Of course, that raises the question, is a solid surface necessary for life? Astronomers are hungry to find smaller planets, like Earth or Mars, with conditions more favorable to life as we know it.

Origins Program will look for warm, wet, Earthlike planets around other stars. That requires telescopes of such extraordinary size and cost as to be impractical.

A parent star shines brightly -- like our Sun -- so a planet nearby appears to us to be quite dim. NASA says its somethinglike looking for a firefly in front of a searchlight.

Interferometry. To get around the problem, NASA will build a "virtual telescope" using a technique known as interferometry. Light gathered by multiple telescopes will be combined in the "virtual telescope" to produce a sharper, more detailed image.

Origins projects will include:
  • Space Interferometry Mission with launch of a satellite to Earth orbit between 2005-2010;

  • Keck Interferometer, which already is working on the ground in Hawaii, are expected to find even smaller planets;

  • Terrestrial Planet Finder, an ambitious project with multiple telescopes on separate satellites flying in formation. Those telescopes working together would snap family portraits of entire solar systems outside of our own and analyze their electromagnetic spectra for the chemical fingerprints that scientists suggest life would leave on the reflected light from a planet.
NASA artist's concept of the Terrestrial Planet Finder
NASA artist's concept of
the Terrestrial Planet Finder
What the spectrum reveals. If you used special instruments to look back at Earth from a long way out in space, you would note the presence of oxygen, ozone, carbon dioxide and other chemicals in our planet's atmosphere. NASA says that would suggest Earth has living things.

Similarly, the flotilla of satellites to be called Terrestrial Planet Finder will look for telltale chemical signatures of life on Earth-sized planets around other stars.

How does that reveal life? Scientists know that life on Earth requires water. It also needs certain other chemicals to be on hand along with an energy source. Life does appear to be surprisingly hardy. After all, scientists have found it surviving in extremely hostile environments, such as those boiling, toxic thermal vents on the floor of oceans.

Of course, if life is found elsewhere in the Universe, who knows if it will be like what we see on Earth? That's what drives the planets hunters. Their search is an exciting, profound adventure.

Learn more about planet hunting:

Introduction to Planet Hunting

NASA JPL Planet Quest      3D Atlas of the New Worlds

Observatories on the Ground      Observatories in Space

What is the Electromagnetic Spectrum?



Introduction to Planet Hunting
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