Hello Space Fans and welcome to a special south by southwest edition of Space Fan News.
Chemists from the University of California, Berkeley, and the University of Hawaii, Manoa,
have run an experiment that simulates conditions in deep space.
The experiment reveals that the complex building blocks of life could have been created on
icy interplanetary dust and then carried to Earth.
This process of getting the building blocks for life (or even life itself) from other
places in the universe is a key idea that many believe could have jump-started life
here on Earth.
The process is called panspermia.
Well these chemists showed that conditions in space are capable of creating complex dipeptides
– linked pairs of amino acids – that are essential building blocks shared by all living
things.
The discovery opens the door to the possibility that these molecules were brought to Earth
aboard a comet or possibly meteorites, catalyzing the formation of proteins (polypeptides),
enzymes and even more complex molecules, like sugars, that are necessary for life.
While scientists have discovered basic organic molecules, such as amino acids, in many meteorites
that have fallen to Earth, they have been unable to find the more complex molecular
structures that are prerequisites for our planet’s biology.
And since they haven't found any, scientists have always assumed that the really complicated
chemistry of life must have originated in Earth’s early oceans.
But this experiment shows that that may not necessarily be the case.
It is possible that the most basic building blocks that led to life on Earth may well
have had an extraterrestrial origin.
The hawaiian team's experiment consisted of an ultra-high vacuum chamber which was chilled
to 10 degrees above absolute zero, and simulated an icy snowball in space which included carbon
dioxide, ammonia and various hydrocarbons such as methane, ethane and propane.
Then they zapped that chamber with high-energy electrons to simulate the cosmic rays in space.
What happened next is pretty cool, the chemicals reacted to form complex, organic compounds,
specifically dipeptides.
All of which are essential to life.
Then the UC Berkeley guys took the organic residues and analyzed them through the Mars
Organic Analyzer, which is an instrument designed for ultrasensitive detection and identification
of small organic molecules in the solar system.
The analysis revealed the presence of complex molecules – nine different amino acids and
at least two dipeptides – capable of catalyzing biological evolution on earth.
And they all came from the simulated space environment, it appears the oceans aren't
required.
Next, after a decade of careful observations of the Large Magellanic Cloud, the closest
galaxy to our Milky Way, a team of astronomers have made the most precise measurement of
its distance from us so far.
This precise measurement has also allowed astronomers to improve our knowledge of the
expansion rate of the universe, and according to some theories, is a crucial step towards
understanding the nature of the mysterious dark energy that is causing the expansion
to accelerate.
The reason this is such a big deal is that astronomers survey the scale of the Universe
by measuring the distances to close-by objects and then using those objects as standard candles
to pin down distances further and further out into the cosmos.
But this chain is only as accurate as its weakest link.
Up to now finding an accurate distance to the Large Magellanic Cloud (LMC), one of the
nearest galaxies to the Milky Way, has proved elusive.
As stars in this galaxy are used to fix the distance scale for more remote galaxies, it
is crucially important.
But careful observations of a rare class of double star have now allowed a team of astronomers
to deduce a much more precise value for the LMC distance: 163 000 light-years, a number
accurate to within 2%.
Now because we know more accurately how far away the LMC is, we get better distances to
an important class of stars known as Cepheid Variables.
These are really interesting stars: their variability is related to their intrinsic
brightness, or how bright the star would be if it were right next to us.
Cepheid variables are one of the most important yardsticks astronomers use to find out how
far things are in the universe.
If we know how bright something is when it's right next to us, we can easily figure out
how far away it is when we measure it far away.
So this really accurate measurement of the LMC gives us more confirmation of the distances
of these Cepheid variables which we need to get accurate distances to more distant galaxies.
So the way they got this measurement was by observing rare close pairs of stars, known
as eclipsing binaries.
As these stars orbit each other they pass in front of each other.
When this happens, as seen from Earth, the total brightness drops, both when one star
passes in front of the other and, by a different amount, when it passes behind.
By tracking these changes in brightness very carefully, and also measuring the stars’
orbital speeds, it is possible to work out how big the stars are, their masses and other
information about their orbits.
When this is combined with careful measurements of the total brightness and colours of the
stars remarkably accurate distances can be found.
Astronomers are working on their method to get more accurate measurements still - they
think they can get this down to 1% in a few years.
I'll keep you posted.
Finally, if by
some chance you haven't heard, this weekend, I'm
in Austin Texas….
Well, that's it
for this
week Space Fans, thanks for watching and as always, Keep Looking Up.