Wednesday, January 12, 2005

Betting on a new Earth!

When, if ever, will humans discover another Earth?

That has been the subject of many a good discussion.
Here in Denmark my friend Jan Holst Jensen and I have discussed
it many times.
Now however, the time has come where we commit our
prediction to this blog - for some future laughs!


The planet we are talking about must not only look like Earth in size and color - we think it must have an atmosphere,
perhaps even a diverse landscape where life can find many different
niche's. In some distant future it should be possible for
humans to settle the place. It short, it should be VERY Earthlike.
Obviously, all other kinds of planets will also be extremely
interesting, but here we are talking about Earth II.

So, when are we going to see it? After endless discussions -
Finally, in 2002 we made a bet on it (the winner gets the prestige of being right). The projects that began to emerge at that time made us confident that it will be possible to settle the question in our lifetime.

So here we go:
Jan Holst Jensen: - The Kepler Mission will find such a planet more or less immediately after launch. That is in 2007 - 2008. And Kepler might not even be necessary, some lone astronomer might beat Kepler... So Jan is betting on 2009 (Where Kepler have made three observations
of Earth II).

Simon Laub: Was a little bit more cautious, even though he certainly shares the enthusiasm. Simon thinks you will have to monitor a system for some time to be sure - and that the task will be a little more
difficult than just picking a winner immediately after the Kepler launch.
So he is betting on 2012.

We both thinks that the Terrestrial Planet Finder mission will be necessary to be absolutely sure - but both thinks that the smoking gun will be there before this mission. Which allows us to stand up for these early dates.

The bet is now committed to this blog. everybody should feel
free to comment or give their own bet to this blog. We should have
a winner in less than 20 years ! :-)


So far the facts are:

Kepler is planned for launch in the fall of 2007, it will monitor 100,000 stars similar to our sun for four years. The results will be extremely important either way. If Kepler detects many habitable, Earth-size planets, it could mean the universe is full of life.
When a planet passes in front of its parent star, as seen by us, it blocks a small fraction of the light from that star. If the dimming is truly caused by a planet, then the transits must be repeatable. Measuring three transits all with a consistent period, duration and change in brightness provides a rigorous method for discovering and confirming planets - planets even smaller than the Earth.

Kepler will help answer the questions:

What fraction of stars have planetary systems?
How many planets are there in a typical system, and
What are their masses and distances from the central star?
How do these characteristics depend on the mass of the star, its age and whether it has a binary companion?"

What will Kepler find? That's the exciting part, because we don't know. Borucki has estimated that if Earth-sized planets are common, the mission will uncover roughly 50 of them in orbits comparable to our own. Thousands of closer-in and/or larger planets could be found. Even bulky moons around some of the Jupiter-sized planets discovered with the wobble technique might block enough starlight to make their presence known. All such worlds are potential abodes for life.

After Kepler the Terrestrial Planet Finder will continue its work

The Terrestrial Planet Finder (TPF) will use a small collection of high sensitivity telescopes (probably 4 large 3.5-meter telescopes). It will measure the temperature, size, and the orbital parameters of planets as small as our Earth in the habitable zones of distant solar systems. Also, TPF's spectroscopy will allow atmospheric chemists and biologists to use the relative amounts of gases like carbon dioxide, water vapor, methane and ozone to find whether a planet might support life. Launch is anticipated between 2012-2015.


Jan Holst Jensen (Cph, Denmark)
Simon Laub (Aarhus, Denmark)

Tuesday, January 11, 2005

The ET message is in our genes!

Although many planets have been discovered outside the solar system, so far none of them looks anything like our planets.
Typically, these planets are are much heavier than Jupiter, and
most are so-called "hot jupitors" that orbit closer to their star than does the Earth.
A new Earth has not been found yet. And certainly
not a new Earth with aliens beaming radiosignals to us.
Still, all the new exo-planets tend to make you optimistic.
That ET signal can't be far away? Or?

For more than 40 years, mankind has been
using radio telescopes to pick up signals from
alien civilisations.
And so far the silence has been deafening......

Which might not be that much of a surprise.
After all, Alien civilisations could be million of years ahead
of us. Either they should continue to send signals
in our direction for aeons, hoping that
we would one day build a radio telescope. Or they
have only transmitted sporadically, in which case we
have an about zero percent chance of tuning in
at the right time.

So, if the ETs really want to contact us it would be
much better for them to leave some kind of superstructure
on our planet or in its vicinity - which would then
"phone home", when we are evolved enough to be interesting
(2001, A Space Odyssey).
Certainly a nice idea, but it also
has its problems - such artefacts on a planet surface
might be overlooked (by the dummies) or eroded away over the aeons.
A better solution would be to have messages inserted
into something that is small, cheap, self-repairing and self-replicating.
And which is always close to the species (dummies)
you want to contact. Something that keep copying the information
over immense durations and despite whatever unforseen environmental hazards might pop up.

And we have such things - they are called cells!
So, according to Apollo astronaut Rusty Schweickard the place to
look for messages from ET is in DNA.
Obviously, there are mutations in the DNA - so ET
would probably incorporate messages in parts that are highly conserved.
Unfortunately, such parts are normally essential coding parts
that control the most vital parts of an organism.
Inserting messages in non protein coding parts - socalled "junk DNA" - have a better chances of being not harmful for the organism.
But such parts are also likely to accumulate lots of mutations
over the aeons, that would destroy the message?
Fortunately, highly conserved sequences of "junk DNA"
have recently been discovered.

So, that could be a nice spot to locate the primer for
how to go online to the Encyclopedia Galactica.