Somewhere far out in our Milky Way galaxy, thousands -
perhaps millions - of pale
blue dots are orbiting their
suns just as Earth does ours, and in two weeks a new American
spacecraft will fly off to seek them out.
Carrying a powerful telescope and one of the most sensitive
cameras ever launched into space, the NASA ship named Kepler will
hunt for terrestrial-size “exoplanets” whose orbits lie in what
astronomers call the “habitable zones” of their distant solar
systems.
The $591 million, 3 1/2-year mission, described Thursday by NASA
officials in Washington, is set to launch from Cape Canaveral on
March 5, weather permitting.
“We hope to find hundreds of such planets,” said space physicist
William J. Borucki, who leads the mission’s science team at the
Ames Research Center in Mountain View.
Finding that many, he said, would increase the odds that life in
some form or another exists and evolves on other planets throughout
the Milky Way.
“If we don’t find any, it will mean that a planet like Earth,
with its life, must be very rare indeed, and so there will be no
‘Star Trek,’ ” he said.
The spacecraft is not designed to seek out evidence of life
itself - only to detect the existence of Earth-like planets in
parts of their solar systems where life might be possible, Borucki
said.
“Kepler is not designed to find E.T.,” he said, “but it’s hoping
to find E.T.’s home.”
Astronomers discovered the first known exoplanets in 1995, and
since then more than 335 have been found. Most of them are “gas
giants” larger and more massive than Jupiter; others known as “ice
giants” are orbiting so far from their suns that they must be
eternally frozen; and some known as “super-earths” - perhaps 10
times the mass of Earth - have gravity so powerful it would be hard
to think of life existing on them.
Astronomer Debra Fischer of San Francisco State University, a
pioneer in discovering exoplanets, said the Kepler flight will
determine just how frequently Earth-size planets exist in habitable
zones in the Milky Way. Fisher, who is not part of the mission
team, said the venture is bound to be a “key driver” for future
NASA spacecraft that will target specific planets to probe for
evidence of some form of life. Specifically, the long-term goal
would be to seek life-sustaining atmospheres and signs of liquid
water - a crucial component of life.
“The 15- to 20-year vision of astronomers is a mission to take a
picture of a pale blue dot orbiting a nearby star,” Fischer
said.
Although the mission, in development since 2001, is assigned to
operate for 3 1/2 years, the spacecraft will carry enough fuel to
operate its telescope and camera for at least six years, according
to Jim Fanson, the project manager at NASA’s Jet Propulsion
Laboratory in Pasadena.
Kepler’s orbit will trail Earth’s path around the sun as it
surveys more than 100,000 stars at distances ranging from 30 to
1,000 light-years in what is essentially a census-taking quest to
count the number of Earth-like planets circling suns in orbits
neither too close nor too far, too hot nor too cold, for life to
exist.
The extraordinarily powerful camera, capable of imaging 100
million stars at once, is so sensitive that it can sense and
measure the slight dimming of a target star’s light as a planet
passes in front it - an event known as a transit.
Fanson said it would be as if Kepler were to look down from
space at a small town on Earth at night and its camera detected the
dimming of a porch light as someone passed in front of it.
But as Borucki explained, Kepler must measure the faint dimming
of a star’s light during at least three successive transits of a
planet - and also measure the planet’s orbital distance from its
star. Then the spacecraft can signal back to Earth that it has
detected a planet the right size and on the right orbit to qualify
as a potential candidate for future close-up investigation.
According to the astronomers on Kepler’s scientific team, the
mission will observe at least 100,000 stars in its first three
years and could detect about 50 planets in “habitable zones” around
those stars if most are roughly the size of Earth. Their
calculations indicate that Kepler could detect about 150 such
planets if most of them are at least one-third larger than Earth,
and about 640 planets if most are more than twice the size of
Earth.
That’s only a rough estimate, and the number could vary from
many more hundreds to zero, the astronomers concede.
Kepler spacecraft
What: A 3 1/2-year NASA mission to seek out
so-called exoplanets in the Milky Way galaxy where conditions might
make life possible.
Launch: 7:48 p.m. PST, March 5, weather
permitting
Source:
http://www.amosatlantis.com/2009/03/nasas-new-mission-to-seek-earth-like-planets/
AmosAtlantis comment:
I believe that all along, NASA is doing a great job in space
exploration. I have been a “fan” of NASA since young. How I wish
that we could live to see the future. Space and time is going to be
the next big thing in time to come, just like the computers and
internet now.
