Future Search for Earthlike Planets & Life
(Top Posts - Science - 022709)

Compilation of several posts in a thread begun
on February 27, 2009:

- - -

As for current knowledge, a vast expansion of
our knowledge of our universe has been made
via the exploits of the Hubble Space Telescope:

- - -
October 14, 2008

A view of the edge of the universe
- - -

- - -
Extensive links to Hubble photos
- - -

- - - - - - - - - - - - - - - - - - - - - - - -

Exciting advancements are coming in the ability
of humankind to search for earthlike planets, to
expand our knowledge regarding our universe,
and to probe back to the beginnings of the very
first stars and galaxies in our universe:

 o Kepler Mission

 o James Webb Space Telescope

 o European Extremely Large Telescope

 o Thirty Meter Telescope

 o Giant Magellan Telescope

- - -
Kepler Mission: A search for habitable planets
- - -


Importance of Planet Detection

The centuries-old quest for other worlds like our
Earth has been rejuvenated by the intense excitement
and popular interest surrounding the discovery of
hundreds of planets orbiting other stars.

There is now clear evidence for substantial numbers
of three types of exoplanets; gas giants, hot-super-
Earths in short period orbits, and ice giants.

The following websites are tracking the day-by-day
increase in new discoveries and are providing infor-
mation on the characteristics of the planets as well
as those of the stars they orbit:

Extrasolar Planets Encyclopedia

New Worlds Atlas

 Current Planet Count Widget

The challenge now is to find terrestrial planets (i.e.,
those one half to twice the size of the Earth), especially
those in the habitable zone of their stars where liquid
water and possibly life might exist.

The Kepler Mission ... is specifically designed to survey
our region of the Milky Way galaxy to discover hundreds
of Earth-size and smaller planets in or near the habitable
zone and determine how many of the billions of stars in
our galaxy have such planets.

Results from this mission will allow us to place our solar
system within the continuum of planetary systems in the

Graphic: Kepler Spacecraft and Photometer


Video: Kepler Mission

- - - end excerpts - - -

- - -
The James Webb Space Telescope
- - -


The James Webb Space Telescope is NASA's next
orbiting observatory and the successor to the Hubble
Space Telescope.

A tennis court-sized telescope orbiting far beyond
Earth's moon, Webb will detect infrared radiation and
be capable of seeing in that wavelength as well as Hub-
ble sees in visible light.

Infrared vision is vital to our understanding of the uni-
verse. The furthest objects we can detect are seen in
infrared light, cooler objects that would otherwise be
invisible emit infrared, and infrared light pierces clouds
of dust, allowing us to see into their depths.

Webb will unleash a torrent of new discoveries, opening
the door to a part of the universe that has just begun to
take shape under humanity's observations.


In 2013, the Webb telescope will launch into space,
sailing to the distant, isolated orbit where it will begin
its quest. Supernovae and black holes, baby galaxies
and planets' potential for supporting life - Webb will
help reveal the answers to some of the biggest myster-
ies of astronomy.

Video: Webb Space Telescope [from another website]

- - - end excerpts - - -

- - -
February 24, 2009

Dome Big Dome: Giant Observatories Augur New Era
of Cosmology

When a new generation of giant ground-based telescopes
comes online in the next decade, human eyes will see what
no one has seen before

by Bruce Lieberman
- - -


Four centuries ago Galileo pointed his spyglass toward the
heavens and astronomy changed forever. As the world cele-
brates the 400th anniversary of the telescope, another cos-
mological revolution is coming: The Giant Magellan Tele-
scope (GMT), Thirty Meter Telescope (TMT) and Euro-
pean Extremely Large Telescope (E-ELT)-all expected
to see first light by 2020-will dwarf the biggest observa-
tories in use today.

The largest, the 42-meter (138-foot) E-ELT, will gather 15
times more light than today's 10-meter (33-foot) optical
telescopes. TMT, with its 30-meter- (98.5-foot-) diameter
primary mirror, and GMT, delivering the resolving power
of a 24.5-meter (80-foot) reflector, will also outclass any
current optical telescope.


This next generation of big telescopes follows the leap in
technology achieved with the W. M. Keck Observatory
on Mauna Kea, Hawaii, in the 1990s.


"There's plenty of science to occupy multiple versions
of these telescopes. Having one of these to be shared for
the whole world-that would be a shame, actually, because
there's more than one telescope worth of things to be doing."

But size isn't everything. These telescopes will rely on adap-
tive-optics technology that incorporates a deformable (shape-
changing) mirror to cancel out atmospheric turbulence. That
is expected to make these scopes perform as well as any
space-based visible-wavelength observatory-including the
Hubble Space Telescope.

Collectively, they are expected to illuminate an epoch when
the first stars and galaxies lit up the void more than 12 billion
years ago, probe the atmospheres of exoplanets, and unveil
the exotic physics of supermassive black holes at the center
of the Milky Way as well as distant galaxies.

For Avi Loeb, a theoretical physicist and professor of astro-
nomy at Harvard University, these instruments will allow
researchers to add the missing pages from astronomy's
"photo album of the universe."

"In order to probe deeper into the universe, you really need
bigger and bigger telescopes," Loeb says. "Modern tele-
scopes allow us to see galaxies when the universe was a
billion years old. We would like to see the very first galaxies.


Closer to home, obtaining spectra from planets orbiting other
stars could be within the reach of these next-generation tele-
scopes ...

With unprecedented angular resolution and light-collecting
capacity, the new telescopes should be able to focus the
light of stars so sharply that astronomers will be able to dis-
cern planets close enough to the star where Earth analogues
might be found ... Spectral analysis of such planets may re-
veal biomarkers such as oxygen, methane and nitrous oxide.

GMT, TMT and E-ELT are expected to work in partnership
with space telescopes and other ground-based observatories.
For example, NASA's James Webb Space Telescope, sche-
duled to launch in 2013, will catalogue some of the universe's
most distant objects in the infrared. The three optical tele-
scopes will then examine those objects in more detail.


- - - end excerpts - - -

- - -
February 27, 2009

Are You Out There, ET? Searches for Habitable
Planets Are About to Get a Boost

A Q&A with stellar and planetary scientist
Alan Boss about the holy grail of extrasolar
planet research--finding Earth-like planets

- - -


Next week brings a milestone in the search for
extraterrestrial life with the scheduled launch
Friday of NASA's Kepler satellite. The mission,
named for 16th- and 17th-century German astro-
nomer Johannes Kepler, will study a group of
stars for three-plus years in search of subtle,
periodic dips in stellar brightness-the telltale
signs of planetary orbits.

Although more than 300 planets outside the solar
system have already been found using this method,
among other techniques, Kepler's strength will lie
in its instruments' sensitivity to smaller, cooler
planets more hospitable to life and more like our

With any luck, Boss says, Kepler should indicate
that billions of habitable planets exist in our galaxy
alone, with an almost unfathomable tally of sex-
tillions across the entire universe.


[An edited transcript of the interview
with Boss follows.]

Your new book is called The Crowded Universe.
What does the title mean?

The point of the book is to show why one can
claim that the universe is likely to be teeming with

I make the argument throughout the book that we
already know that Earths are likely to be incredibly
common-every solar-type star probably has a few
Earth-like planets, or something very close to it.

To my mind, at least, if one has so many habitable
worlds sitting around for five billion or 10 billion
years, it's almost inevitable that something's going
to start growing on the majority of them.

If they've got water on them, and they've got some
comets coming in dumping in some amino acids
and other interesting prebiotic chemicals, how are
you going to keep those things from growing some
sort of life?

Life is so tenacious and willing to seek out a toehold
anywhere it can, my feeling is that it is going to orig-
inate anywhere it has a chance. It may not necessarily
be little creatures like in a Steven Spielberg movie,
but there will be some kind of archaealike or bacteria-
like microbes crawling around or bubbling along.

Those are going to be creating output like oxygen
and methane, and those are things we can see in the
atmosphere. We may not be able to tell if a planet
has intelligent life or dinosaurs, but we can at least
tell if it has slime mold. So we're going for the slime

The Kepler satellite, which will seek out those habita-
ble planets, launches March 6. What do you think it
is going to tell us?

I'm betting it's going to tell us that Earths are quite
common. Kepler's going to be looking at 100,000
stars for three or four years. We expect that Earth-
like planets will have their orbits aligned in such a
way that basically one out of 1,000 can be seen by

So if every single star has one Earth-like planet, that
means that Kepler will see roughly 100 Earths. But if
it turns out that we're wrong and, say, only one out
of 100 stars has an Earth-like planet, then Kepler might
find one Earth-if it's lucky-or it might find zero. And if
Earths only occur around one out of 1,000 stars, we'd
have to be really lucky for Kepler to find anything at

So Kepler basically assumes that it should be able to
find some Earths as long as they occur at roughly a
1 percent rate or higher. There's a very good chance
that Earths are available essentially all the time, but
we can be a little bit conservative and say that Kepler
should find dozens of Earths.

If Kepler does find a number of Earth-like planets, then
we'll know how many there are in general because Kepler
will have searched such a large sample.

And then we'll know how to go about planning the next
phase of the search, which is to search the nearby stars.

Kepler's going to be searching stars hundreds of light-
years away all in one direction of the sky. It's sort of
like after looking at another neighborhood in another
city, we want to then look at our own block. Kepler
will tell us how many houses we have to search on our
block to look for life.


Assuming our assumptions of planet formation aren't
way off, how long will it take before Kepler turns up
some Earths?

We'll find the hot Jupiters quickly and maybe a few hot
super-Earths within the first year, I would guess. But the
real treasure is the Earth-like planets-and, by definition,
you can't get them until you've run for at least three or
four years.

You're looking for one-year orbital periods, roughly,
for solar-type stars, and the first time the transit occurs,
you think, "That's interesting." You've got one blip. You
need at least two blips to say, "Now I have an orbital
period, let's see if there's a third blip at the right time."

So if you get the third blip you say, "Hmmm, that looks
good, I've got blips that are separated by roughly the
same amount of time, maybe I'll just be really cautious
and wait for a fourth blip." And if you do that then you're
up to a few years of observing time. So my feeling is that
by 2013 we'll have some Earths to announce.

- - - end excerpts - - -

- - -
3 March 2009

Tunguska-like Space Rock Just Misses Earth
(came within 44,750 miles of Earth,
one-fifth of the distance between
Earth and the Moon)
- - -

- - - - - - - - - - - - - - - - - - - - - - - -

Exoplanets Detected To Date

- - -
3 March 2009

Looking for worlds like this one

NASA's Kepler mission is the best shot yet at
detecting an Earth-sized planet elsewhere in the
- - -



The future for other exoplanet-spotting missions
is currently unclear. NASA will shortly decide on
whether to go ahead with a Transition Exoplanet
Survey Satellite to seek transiting planets around
the nearest and brightest stars in the sky.

Elsewhere, one version of a 2009 spending bill
wending its way through Congress suggests that
$20 million may be allocated to continue develop-
ment of SIM Lite, a scaled-down version of the
Space Interferometry Mission, which would look
for Earth-like planets around nearer stars.

More ambitious space-based missions are unlikely
to fly in the near future: the Terrestrial Planet Finder
in the United States, and Darwin in Europe, have
been deferred indefinitely for budgetary reasons.

That leaves planet-hunters keen to see what Kepler
can do.


- - - end excerpt - - -