Hello Space Fans and welcome to another edition of Space Fan News.
This week, analysis from a new galaxy survey suggests that dark matter may be less dense
and more smoothly distributed throughout space than previously thought; and in spite of the
Schiaparelli crash earlier this year, the European Space Agency approves funding for
ExoMars rover in 2020.
There’s some interesting news this week regarding our never-ending quest to figure
out what the heck dark matter is, you know that elusive stuff that we know is there because
we can see its effects on things we can see, like star motions within galaxies and the
rotation rates of galaxies.
Astronomers at ESO’s Paranal Observatory used data taken with the Very Large Telescope
as part of the Kilo Degree Survey (KiDS) and found that the dark matter that is distributed
throughout the large scale structure of the universe, is smoother - or less clumpy - than
they thought.
This flies in the face of earlier data taken with the European Space Agency’s Planck
Satellite which precisely mapped the cosmic microwave background and compared the tiny
fluctuations in the CMB with the large scale structure of the universe and came to the
conclusion that dark matter was rather clumpy and helped sculpt the cosmic web we see today.
This result just goes to reinforce my annoyance with dark matter.
Here are two very accurate surveys of the universe, one done on the ground a covers
a huge area of sky, and another one in space and covered the entire sky, done at unprecedented
accuracies and we get two different result with respect to the distribution of dark matter.
For every one new thing we learn about Dark Matter, two new things pop up that leave us
wondering about what they heck this stuff is.
But we are narrowing it down, it’s just gonna take us some time.
The result announced this week from ESO came after astronomers poured over data from one
of the largest surveys ever: the Kilo Degree Survey.
This program looked at two areas of extragalactic sky, some 750 square degrees each, in four
visible light filters.
At the same time, the companion VIKING project on the neighboring VISTA telescope will cover
the same area in five near-infrared bands.
The exposure times were chosen so that they could see galaxies out to about a redshift
of 0.7, which corresponds to a time when the universe was about seven billion years old.
Using those exposure times, KiDS was able to collect light from some 15 million distant
galaxies which were used to help figure out where the dark matter is in the area of sky
observed by the survey.
Because the image quality was so good, astronomers were able to employ a technique called cosmic
shear, which wins the prize for me in the new jargon of the week contest because I had
never heard of it before I read this story.
Usually to infer the existence of dark matter in galaxy clusters or to even see other really
faint galaxies, astronomers use gravitational lensing created by the gravity fields of the
galaxies in the cluster.
In cosmic shear, it’s the large scale structure of the universe itself, the cosmic web of
galaxies over the entire universe, that’s doing the lensing.
Now if you think that’s hard to detect you’d be right.
By comparison to a gravitational lens of a cluster of galaxies, this effect is microscopic.
Very wide and deep surveys, such as KiDS, are needed to make sure that the very, very,
very weak cosmic shear signal is strong enough to be measured and can be used by astronomers
to map the distribution of the matter doing the gravitating.
This study takes in the largest total area of the sky ever to be mapped with this technique.
The finding that dark matter is less clumpy was a surprise result and has implications
for our wider understanding of the Universe, and how it has evolved during its almost 14-billion-year
history.
Such an apparent disagreement with previously established results from Planck means that
astronomers may now have to reformulate their understanding of some fundamental aspects
of the development of the Universe.
We’re still very early in our search for answers when it comes to dark matter, so I’m
not too discouraged that these results and the ones from Planck don’t agree.
Science is messy and we need as many observations as we can get to help us toss out theories
that don’t fit what we see and put in new ones that better match the data.
That’s just how science works.
I’m confident we’ll figure out dark matter, but until then, it’s proving to be most
annoying in its elusiveness.
Next, remember last October we talked about the demise of the Schiaparelli lander that
was part of the EXO Mars mission?
Well as I said back then, it was a pathfinder mission meant to test out technology and techniques
that will be needed for a future rover to be built by the European Space Agency in cooperation
with the Russian Roscosmos program.
Well during the ESA council meeting in Lucerne, Switzerland last month, ESA decided to go
ahead with funding for the 2020 EXOMars mission that Schiaparelli was designed to test.
The second stage of this two-part program will cost 1.3 billion euro, and is due to
land a rover on the Red Planet in 2021 to drill into the Martian soil and look for biochemical
traces of living or dead microbes.
At the Switzerland meeting, the member nations also agreed to increase ESA’s budget by
1% and this EXOMars mission is expected to eat up that whole increase.
So even though the lander was lost this year, the second part of the mission, the Trace
Gas Orbiter did successfully arrive and is currently circling the Red Planet.
Next year it will start sampling the planet’s atmosphere for trace gases including methane
, which may indicate the presence of life (or is it MEEE THANE since this is a European
mission?).
Well that’s it for this week Space Fans, thanks to all SFN Patreon Patrons who keep
this show on YouTube, it simply wouldn’t happen without your support.
Thank all of you for watching and as always, Keep Looking Up!