- 4082 - “EUCLID'S” - space mission, 2023? July 1st, 2023 the ESA’s Euclid space telescope lifted off from Cape Canaveral in Florida. This next-generation astrophysics mission will spend the next few weeks flying to the Earth-Sun L2 Lagrange Point, where it will spend the next six years observing one-third of the sky.
---------------------------- 4082 - “EUCLID'S” - space mission, 2023?
- During that time,
Euclid will observe billions of galaxies to a distance of 10 billion
light-years, leading to the most extensive 3D map of the Universe ever created.
This map will help astronomers and cosmologists resolve the lingering mystery
of Dark Matter and Dark Energy.
-
- Using its
600-megapixel camera, near-infrared spectrometer, and photometer (that measures
the redshift of galaxies), Euclid will chart how the Universe has expanded over
the past 10 billion years (3 billion years since the Big Bang) to the present.
This coincides with the beginning of the “Dark Energy–dominated era,” when the
Universe began expanding at a gradually-accelerating rate.
-
- By mapping the
large-scale cosmic structure of the Universe and how it has changed since then,
Euclid will reveal more about the role of gravity, Dark Matter, and Dark Energy
have played across space and time.
-
- Understanding the
interplay of these forces is vital to resolving the current “Crisis in
Cosmology.” This includes the rotational curves of galaxies and how it doesn’t
conform to the amount of visible (“luminous”) matter they contain. Scientists
noticed this during the 1960s, which gave rise to the theory that 85% of a
galaxy’s mass was made up of a mysterious, invisible matter (hence the term
“dark”). Speculation about the existence of Dark Energy began in the 1990s.
-
- As scientists
peered farther out into the cosmos , back in time, they noticed that cosmic
expansion has been speeding up for the past four billion years. Combined with
the unresolved mystery of Dark Matter, this suggested that either our theories
regarding gravity (as described by General Relativity) are wrong or that an
unknown force is responsible for counteracting gravity on the largest of
scales.
-
- Based on the most
widely-accepted cosmological model – the Lambda Cold Dark Matter (LCDM) model –
cosmologists estimate that Dark Energy accounts for roughly 72% of the
mass-energy density of the Universe.
-
- By measuring the
influence of Dark Matter and Dark Energy, Euclid will help put to rest the
ongoing debate regarding prevailing cosmological theories. Once Euclid reaches
L2, where it will join the James Webb Space Telescope (JWST), the mission
controllers will begin verifying all functions on the spacecraft, test the
telescope, and finally turn the instruments on.
-
- This will be
followed by a two-month phase where they will test and calibrate each of
Euclid’s scientific instruments and prepare for the telescope’s first
observations. Three months after launch, the mission controllers will commence
with the early phase of Euclid’s cosmic survey.
-
- By 2027, it will be
joined by the Nancy Grace Roman Space Telescope (RST), which will assist in the
hunt for Dark Energy by providing more detailed analyses of objects mapped by
Euclid.
-
- There is a problem
with our understanding of the universe: It doesn't make sense if we account
only for the matter and energy that we can see, measure or detect. Albert Einstein's famous general theory of
relativity, which describes the physical 'rules' of the universe in a series of
equations only adds up on cosmic scales if there is five times as much matter
dispersed throughout the cosmos than what we can see and detect.
-
- This invisible
matter, or dark matter, together with another invisible entity, dark energy,
form the biggest mystery in cosmology, the study of the origins of the
universe. While dark matter pulls stuff together with the force of gravity, the
elusive dark energy seems to be doing the exact opposite, pushing things apart
and causing the acceleration of the expansion of the universe that was first
discovered in 1998. Together, dark energy and dark matter account for a
mind-boggling 95% of the "stuff" in the universe, and we know close
to nothing about this "stuff."
-
- Dark matter is
something that gravity works on in the same way as normal matter, but it
doesn't interact with any light or any anything so we only know it's there by
the effect it has on the movements of galaxies and stars. Whereas dark energy is something we found
out about more recently when we discovered that the expansion of the universe
seems to be getting faster with time. That doesn't make any sense if you think
there's just gravity there. It should be slowing down.
-
- The new European
Euclid telescope might bring that answer a little closer into view. The
spacecraft, fitted with a 3-foot-11 inch (1.2 meters) telescope, will also help
map the distribution of dark matter across spacetime in three dimensions for
the first time ever.
-
- But how exactly is
Euclid going to "reveal" the existence of the invisible universe when
it cannot see and measure it? The telescope, fitted with sensors capable of
detecting visible and infrared light, will join the famed James Webb Space
Telescope at Lagrange Point 2. In this region some 900,000 miles (1.5 million
kilometers) away from Earth, the gravitational forces of the planet and the sun
are equal, keeping the spacecraft in a stable location relative to Earth.
-
- Here, shielded
from the glare of the star at the center of our solar system, Euclid will look
into the depths of the cosmos, 10 billion years back in time, to map the
distribution of galaxies across one third of the sky outside our Milky Way
galaxy. It will take over six years for the $660 million telescope to complete
its survey.
-
- If you've got a
very large clump of matter, any sort of matter, not necessarily dark matter, it
will bend the light rays. Which means
that anything behind that type of matter will look distorted. These distortions, also known as the gravitational
lensing effect, are minuscule, so minuscule in fact, that they can't be
accurately measured by ground-based telescopes due to the blurring caused by
Earth's atmosphere.
-
- The effect is very
tiny, less than 1%. To detect this tiny
effect is very difficult. We need to be very, very precise with our image
quality and measure many, many galaxies to be able to deduce anything. By using some rather complicated math,
astronomers will be able to use these gravitational lensing measurements to
calculate the amount of dark matter between Euclid and each distorted galaxy,
allowing them to create the first ever 3D map of the dark matter's distribution
in the universe.
-
- There is evidence
of dark matter in so many ways that it is quite unlikely that Euclid could find
evidence through measuring the gravitational lensing that it does not
exist. But, dark matter must exist because there is
simply not enough normal matter to grow [galaxy] structures, to have them
assemble the way they are.
-
- The existence of
“dark energy”, on the other hand, is less certain and it's in this area where
Euclid scientists expect the biggest surprises. At stake is the ultimate
validation of Albert Einstein's famous and widely accepted theory of
relativity, which claims to capture what is supposed to be the universal rules
of the behavior of all matter and energy in the cosmos.
-
- It could be simply
that general relativity doesn't really work at cosmic scale, and therefore dark
energy is not needed. We need dark
energy now if we assume that general relativity works. Dark energy is not
needed to grow the cosmic structures, to grow stars and galaxies.
-
- Many experiments
and observations made at smaller distances have confirmed the theory of general
relativity over the years. If Euclid's measurements were to take this theory
into question, it would be "an absolute discovery,"
-
- Astronomers want
to find evidence for the existence of dark energy in the distribution of
galaxies and galaxy clusters across spacetime. They believe this distribution
is not random, but a reflection of soundwaves that bounced around the ancient
universe.
-
- In the wake of
these soundwaves, regions of denser gas emerged that later gave rise to
galaxies. Astronomers can observe these patterns in the cosmic microwave
background, the remnants of the first light that spread through the emerging
universe in the first hundreds of thousands of years after the Big Bang and
that can still be detected today.
-
- In the cosmic
microwave background, we can see this pattern as it looked in very early
times. With Euclid, we will be able to
measure it much closer to us now in time in the pattern of galaxies in the sky.
We will see this imprint in the scale that galaxies like to cluster, in their
preferred distance separation.
-
- By comparing the
ancient imprints with the newer ones, scientists will be able to see how much
the universe has expanded since its earliest days and what role dark energy may
have played in this process.
-
- Because the dark energy pushes the universe
apart, if there's a lot of dark energy, we'll see that that scale is much
larger than we would have otherwise. It
could take years before there is something really new to be announced.
-
- For now, all models
point to the existence of dark energy that is constant and spread uniformly
throughout the cosmos. Some evidence, however, suggests that things may not be
all that simple. The Hubble constant that describes the rate of the universe's
expansion doesn't appear to be the same in the nearby observable cosmos as it
is in the early universe, a possible sign that something might not be right
with the cosmology models.
-
-
July 7, 2023 “EUCLID'S” -
space mission, 2023?
4082
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