Hello Space Fans and welcome to another edition
of Space Fan News
This week, ESA astronomers controlling the
venerable Herschel Space Telescope turned
it off this week and essentially threw it
away.
The science mission Herschel was designed
for ended back in April when it exhausted
its supply of liquid helium, which kept its
detectors cool enough to make infrared observations
of the early, distant universe.
It was designed to operate for three and a
half years and lasted four, so the mission
is heralded as a scientific success.
Still, when it ran out of helium, there was
little that could be done scientifically,
except one thing.
They could use Herschel to study how a spacecraft
dies.
In an emotional ceremony this week, engineers
sent the final commands to Herschel which
fired rocket thrusters to drain its fuel tank
and move the spacecraft into a safe disposal
orbit.
While it did that, they watched the spacecraft
helplessly struggle to regain control while
its antennas and power-generating solar panels
drifted away from their lock on the Earth
and the sun.
This burn was important because they needed
to move the spacecraft to a safe disposal
orbit around the sun.
It had been in orbit at the L2 point, which
is very valuable real estate for space telescopes.
It's a place that keeps anything that's there
in the same orientation with the sun and the
Earth in its orbit around the sun.
Lots of spacecraft, including the James Webb
Space Telescope, will be sent there.
So to get it out of the way, they fired the
thrusters and watched it die.
Sad to see such a great telescope go.
Still, there is a lot of data to be combed
through and discoveries to be made, so Herschel
isn't through showing us new things about
universe.
With a space telescope like this, everyone
knows you only have a finite amount of time
to make observations before the helium runs
out, so people were more concerned about taking
as much data as possible as quickly as possible
before spending a lot of time analyzing.
That part - the data analyzing part - gets
underway now.
Astronomers will be sifting through Herschel
data for years to come.
The Herschel Space Telescope is the largest
we've launched so far, it's comparable to
JWST with a primary mirror of 3.5 meters,
which is 50% larger than Hubble and about
half the size of the JWST segmented primary.
It was also an infrared telescope designed
to look at many of the same things JWST will:
the early universe, dust and gas formation
in solar systems and early star formation.
So does JWST have to worry about running out
of liquid helium?
No, it has a closed-cycle refrigerator using
helium gas sealed into the equipment.
So, the limiting factor for keeping JWST alive
is fuel for station-keeping, not helium.
So goodbye Herschel and thanks for all the
infrared fish!
We look forward to hearing about more discoveries
from your data as astronomers comb through
it in the years to come.
Next, astronomers using ESO's Very Large Telescope
Interferometer have made the most detailed
observations ever of the dust around the huge
black hole at the center of an active galaxy.
Astronomers have known for almost 20 years
now that most galaxies have a supermassive
black hole at their centers.
Some of the ones actively drawing in material
from its surroundings are gobbling it up so
fast that they are creating powerful jets
that shoot out into space as some of the most
energetic objects we've ever seen.
The central regions of these brilliant powerhouses
are ringed by doughnuts of cosmic dust dragged
from the surrounding space, similar to how
water forms a small whirlpool as it drains
from a sink.
But new observations of a nearby active galaxy
called NGC 3783, have given a team of astronomers
a surprise.
Although the hot dust which is around 700
to 1000 degrees Celsius, is indeed in a torus
as expected, they found huge amounts of cooler
dust above and below this main torus.
The newly-discovered dust forms a cool wind
streaming outwards from the black hole and
this wind must play an important role in the
complex relationship between the black hole
and its environment.
The black hole feeds from the surrounding
material, but the intense radiation this produces
also seems to be blowing the material away.
It is still unclear how these two processes
work together and allow supermassive black
holes to grow and evolve within galaxies,
but the presence of a dusty wind adds a new
piece to this picture.
These new observations may lead to a paradigm
shift in the understanding of active galactic
nuclei.
They are direct evidence that dust is being
pushed out by the intense radiation.
Models of how the dust is distributed and
how supermassive black holes grow and evolve
must now take into account this newly-discovered
effect.
Finally, the James Webb Space Telescope reaches
a new construction milestone: the backplane
support frame, a fixture that will be used
to connect all the pieces of the telescope
together is complete.
This is the part that will hold the telescope's
primary mirror segments and is one of the
most important on the telescope.
The backplane support frame will bring together
Webb's center section and wings, secondary
mirror support structure, aft optics system
and integrated science instrument module.
This frame also will keep the light path aligned
inside the telescope during science observations.
Measuring 11.5 feet by 9.1 feet by 23.6 feet
and weighing 1,102 pounds, it is the final
segment needed to complete the primary mirror
backplane support structure.
This thing will support the observatory's
weight during its launch from Earth and hold
its18-piece, 21-foot-diameter primary mirror
nearly motionless while Webb peers into deep
space.
It consists of more than 10,000 parts and
must operate at temperatures from minus 406
degrees to minus 343 degrees Fahrenheit.
The next step for the backplane is it will
undergo extremely cold, or cryogenic, thermal
testing at NASA's Marshall Space Flight Center
in Huntsville, Ala.
Well, that's it for this week Space Fans,
thank you for watching and as always, Keep
Looking Up!
