Hello Space Fans and welcome to another edition
of Space Fan News.
This week, astronomers at the University of
Kent in the UK have tried to answer the question:
"Could life have survived a fall to Earth?"
It is hypothesized that one way life arose
on Earth was that it was brought here by rocks,
comets and asteroids from other places in
the galaxy.
In other words, life arose somewhere else,
got onboard one of these bodies, then crashed
here on Earth.
It's a theory called panspermia and it is
an idea that's taken pretty seriously by planetary
scientists.
It's pretty well established that soon after
the solar system was formed, the inner planets
took a pounding by meteorites, comets and
all kinds of debris floating around that didn't
become part of a planet.
Even today this is still happening, although
thankfully not as much.
Right now meteorites made of Mars rocks are
found here on Earth, so it is quite plausible
that simple life forms like yeasts or bacteria
could be carried on them.
The thing is, could these life forms survive
the an impact with Earth?
Could they live through the freezing temperatures
and radiation of space?
And what about entering the Earth's atmosphere,
could they survive that?
Well, Dina Pasini and others at the University
of Kent went about answering this by taking
frozen samples of Nannochloropsis oculata,
a type of single-celled ocean-dwelling algae,
and tried to test the conditions which early
life would have had to survive if it did indeed
travel through space.
Using a two-stage light gas gun, which can
accelerate objects up to very high speeds,
Pasini fired frozen pellets of Nannochloropsis
into water, and tested the samples to see
if any had survived.
He said that, "As you might expect, increasing
the speed of impact does increase the proportion
of algae that die, but even at 6.93 kilometres
per second, a small proportion survived.
This sort of impact velocity would be what
you would expect if a meteorite hit a planet
similar to the Earth."
As well as surviving freezing and impacts,
like those experienced when rocks are ejected
from planets or hit them, there are good reasons
to think that the other problems faced by
panspermia are not insurmountable either.
Ice and rocks can provide protection against
radiation, especially if the organism is deeply
embedded inside.
What is more, heating caused by entry into
the atmosphere is unlikely to heat anything
more than a thin layer around the outside
of rocks, forming what is known as a 'fusion
crust'.
So this research suggests that panspermia,
while certainly not proven, is not impossible
either.
Pasini says, "Our research raises several
questions.
If we find life on another planet, will it
be truly alien or will it be related to us?
And if so, did it spawn us or did we spawn
it?
We cannot answer these questions just now,
but the questions are not as farfetched as
one might assume."
Next, also in the 'My Research Raises More
Questions Than It Answers Department", Astronomers
at The University of Texas at Austin believe
they have discovered the answer to a 20-year
debate over how the irritatingly mysterious
"dark matter" is distributed in small galaxies.
Dark Matter is believed to make up 25% of
all matter in the universe, but the irritating
thing is, we can't see it or interact with
it in any way.
The only way we know dark matter must be there
is that we see the gravitational effect it
has on things we can see that are close to
it.
Now, everybody has an opinion on what this
stuff is, but the truth is no one has a clue.
But for the past 20 years, observational astronomers
and theorists have argued over how dark matter
is distributed in galaxies.
Observational astronomers, you know, the guys
who actually look at things with telescopes,
have argued that galaxies have a fairly uniform
distribution of dark matter.
Theorists, with their computer simulations
and supercomputing slide rules, have argued
that dark matter density decreases steadily
from a galaxy's core to its outer edges.
The disagreement is known as the "core/cusp
debate."
So these guys tried to settle the issue by
striking a middle ground and used both data
from telescopes and new computer models.
You know, like a mid-east peace broker.
The project started out "not assuming core
or cusp theory is right," but simply asked
asking 'what is this stuff?.'
These new models allowed them to take this
approach.
They also used telescope observations of several
of the satellite galaxies orbiting the Milky
Way, including the Carina, Draco, Fornax,
Sculptor, and Sextans dwarf galaxies.
And the reason they used dwarf galaxies is
they contain up to 1,000 times more dark matter
than normal matter.
Normal galaxies like the Milky Way don't have
that much, they contain only 10 times more
dark matter than normal matter, so it's better
to look at dwarfs when you can.
The work involved running many supercomputer
models for each galaxy to determine the distribution
of dark matter within it, using the university's
Texas Advanced Computing Center.
He found that in some of the galaxies, the
dark matter density decreased steadily from
the center.
In others, the density held constant.
And some galaxies fell in between.
Wait a minute, what?
However, when all the galaxies' distributions
were analyzed together, the results showed
that on average, the theorists were right.
The researcher said that When you look at
individual galaxies, some of them look wildly
different from expectations.
However, when you average several galaxies
together, these differences tend to cancel
each other out.
This seems to suggest that the theory behind
dark matter in galaxies is correct on the
whole, but that "each galaxy develops slightly
differently."
So here we have a simulation from theorists
and the answer they get supports - surprise
- the theorists.
Hmmm.
Well, at least they used observations as a
starting point to the simulations.
At least the real world was involved somehow.
The researchers say the results do "pose more
questions — questions about dark matter
itself, and how normal matter interacted with
dark matter" to form the types of galaxies
seen today"
So there you go, Dark matter is still irritating,
I don't care what you say.
Finally, work on the James Webb Space Telescope
reached a couple of new milestones this month.
First, the templates that will be used to
construct the tennis-court sized heat shield
are complete.
The template layers are the last step before
manufacturing the final flight sunshield layers.
After successful completion of a manufacturing
readiness review, the team is now ready to
produce the final flight layers.
The sunshield template layers have the same
design and manufacturing processes as the
flight layers.
Each one has been individually shape-tested
to verify that they were built to requirements.
As all five template layers are being subsequently
tested at Northrop Grumman's Space Park facilities
to ensure the membranes meet flight performance
requirements, NeXolve (another contractor)
is beginning manufacturing of the final flight
layers.
Technicians at Northrop Grumman are also practicing
folding and unfolding the five layers by hand
on a test bed.
And also too, the European Space Agency has
completed the Near-Infrared Spectrograph,
one of two instruments that it is contributing
to the JWST.
NIRSpec (as it is called) is a spectrograph
which splits light up into a spectrum and
is designed to detect the light from the very
first stars and galaxies that formed in the
young Universe, roughly 400 million years
after the Big Bang, a time when conditions
were very different to today.
It will also be used to study the early phases
of stellar birth across our Milky Way galaxy,
as well as analyse the atmospheric properties
of planets in orbit around other stars, assessing
the potential for life on worlds elsewhere
in the Universe.
NIRSpec will be shipped to NASA later this
month for integration into JWST's instrument
module, followed by further testing and calibration
as the whole observatory is built up.
We're getting closer folks!
2018 here we come!
Well, that's it for this week space fans,
thank you for watching and as always, Keep
Looking Up!
