Okay, where to begin?
With this paper, I want to demonstrate that we are probably living in the most important century for the humankind, as (and this is not only a
) there's no doubt in my mind that the final proof of extraterrestrial life will be found within the century.
Indeed, as scientific technology progress nowadays in an exponential way, there is an increasing volume of clues that undoubtely shows that we will
not have to wait anymore longer for the scientific indeniable proof of extraterrestrial life
outside of solar system to emerge.
I'll try to list these clues here for you, feel free to comment and criticize!
1- Extrasolar planets detection history
- Since the first published, confirmed discovery made in 1988 (Gamma Cephei A
planet) by the
Canadian astronomers Bruce Campbell, G. A. H. Walker, and S. Yang, there was an increasing numbers of discoveries that can be listed as below:
- In 1992, Aleksander Wolszczan and Dale Frail discovered thatthe pulsar
PSR B1257+12 has three
planets (a, b and c)
- In October 1995, Michel Mayor and Didier Queloz of the University of Geneva announced the first definitive detection of an exoplanet orbiting an
ordinary main-sequence star (51 Pegasi b
- Since then, the exoplanet catalog
, regularly updated, never cease to increase the amount of new
discoveries, to gain the number of 548 as of today, including 68 Earth-size
This increasing volume is due to the constant progress of the detection techniques:
2- Methods of detecting extrasolar planets
Any planet is an extremely faint light source compared to its parent star. In addition to the intrinsic difficulty of detecting such a faint light
source, the light from the parent star causes a glare that washes it out. For those reasons, only a very few extrasolar planets have been observed
Instead, astronomers have generally had to resort to indirect methods to detect extrasolar planets. At the present time, several different indirect
methods have yielded success:
The number of various methods
also never cease to increase, until
today, thus the increasing number of discoveries as well.
We can separate them in 10:
- Radial velocity
: with radial velocity, gave better results as of today, with 419 planetary systems, 500 planets and 50 multiple-planets
- Pulsar timing
, note that the main drawback of the pulsar-timing method is that pulsars are relatively rare, so it is unlikely that a large
number of planets will be found this way. Also, life as we know it could not survive on planets orbiting pulsars since high-energy radiation there is
- Transit method (that includes transit timing variation method (TTV) and transit duration variation method (TDV))
, with a result of 121
planetary systems, 128 planets and 10 multiple-planets systems.
- Gravitational microlensing
, with a result of 11 planetary systems, 12 planets and 1 multiple-planets system.
- Direct imaging
, with a result of 21 planetary systems, 24 planets and 1 multiple-planets system.
Direct image of exoplanets around the star HR8799 using a vortex coronograph on a 1.5m portion of the Hale telescope
- Eclipsing binary minima timing
, with a result of 7 planetary systems, 12 planets and 4 multiple-planets systems.
- Orbital phase reflected light variations
- Auroral radio emissions
3- Resizing things....
Our recents discoveries (548 extrasolar planets including 68 potentially Earth-size planets) must be appreciated for what it worth, i-e only a tiny
part of what the reality is probably, and here are the reasons why:
- Distance is still an obstacle: discoveries methods can only be used in a combination way for relatively nearby stars out to about 160 light-years
from Earth (exceptionnally up to 300 light-years):
.... And that's only for our Galaxy, besides the 170 billion (1.7 × 1011) galaxies in the observable universe....
- The above have to be balanced with the fact that the moderns missions, responsible of most of the recent discoveries, has just begun: for example,
as of February 2011, NASA's Kepler mission
had identified 1,235 unconfirmed planetary
candidates associated with 997 host stars, based on the first four months of data
from the space-based telescope, including 54 that may be in
the habitable zone.
1235/54 in only four months.... Let's imagine how much have to be discovered yet, with a planned mission lifetime of at least 3.5 years.
- Transit discoveries method have disadvantages: planetary transits are only observable for planets whose orbits happen to be perfectly aligned from
the astronomers' vantage point. The probability of a planetary orbital plane being directly on the line-of-sight to a star is the ratio of the
diameter of the star to the diameter of the orbit. About 10% of planets with small orbits have such alignment, and the fraction decreases for planets
with larger orbits. For a planet orbiting a sun-sized star at 1 AU, the probability of a random alignment producing a transit is 0.47%.
It let a huge amount of possibilities for Earth-like planets to be discovered outside this range....
4- Upcoming missions increasing our chances
Besides the actual search programs (Kepler, COROT
Spitzer Space Telescop
, New Worlds
, there are several upcoming projects such as PLATO
Terrestrial Planet finder
and the very promising
European Extremely Large Telescope
: a mirror of approximately 42 metres
(138 ft) would allow the study of the atmospheres of extrasolar planets.
Complex form-life means complex molecules to be found, and iIt has been estimated that a telescope with a diameter of 80 meters would be able to
spectroscopically analyse Earth-size planets around the 40 nearest sun-like stars.
As such, this telescope could help in the exploration of extrasolar planets and extraterrestrial life (because the spectrum from the planets could
indicate the presence of molecules indicative of life).
Such an incredible telescope can technically be feasible: this is the Overwhelmingly
The Overwhelmingly Large Telescope (OWL) is a conceptual design by the European Southern Observatory (ESO) organization for an extremely large
telescope, which was intended to have a single aperture of 100 meters in diameter. Because of the complexity and cost of building a telescope of this
unprecedented size, ESO has elected to focus on the 42 meter diameter European Extremely Large Telescope instead.
While the original 100-m design would not exceed the angular resolving power of interferometric telescopes, it would have exceptional
light-gathering and imaging capacity which would greatly increase the depth to which humankind could explore the universe. The OWL could be expected
to regularly see astronomical objects with an apparent magnitude of 38; or 1,500 times fainter than the faintest object which has been detected by the
Hubble Space Telescope.
All proposed designs for the OWL are variations on a segmented mirror, since there is no technology available to build a monolithic 60- or 100-meter
mirror. The operation of a segmented mirror is somewhat more complicated than a monolithic one, requiring careful alignment of the segments (a
technique called cophasing). Experience gained in existing segmented mirrors (for example, the Keck telescope) suggests that the mirror proposed for
the OWL is feasible
The only obstacles are the cost (of around €1.5 billion), and the competition between the various projects of building 30 meters telescopes.
Only a worlwide consensus could lead to the construction of a 80 meters telescope, this is actualy not the case, but there's already a very active
worlwide scientific community, and one of their future challenge will be to convince politics and backers.
Looking back to the eighties, we thought that it would be impossible to build a 30 meters telescope (in a monolothic mirror), but time proved that
scientific ingenuity was able to get around this problem, using the new segmented hexagonal mirrors
So I'm confident that the built of a 80 meters telescope will not be anymore an insurmontable problem in the near future.
I said at the beginning of my talk that this will be the most important discovery of the mankind, and that it will occurs within the century (and to
be honest, I hope that it will happen in my lifetime!
), but let's also hope that this discovery will not be kept under secrecy.
14-5-2011 by elevenaugust because: (no reason given)
edit on 14-5-2011 by elevenaugust because: spelling