- 4359 - LIFE - arrives in space dust? Research shows how life, or at least its building blocks, could escape from planets and survive the interstellar journey to another world. If it’s true, and panspermia can account for life appearing on Earth so soon after it formed and cooled, then it changes our understanding of our origins and even the rest of the Universe.
----------------------------- 4359 - LIFE - arrives in space dust?
- OSIRIS-REx spacecraft returned a final haul
of 121.6 grams from asteroid Bennu. The
mission successfully collected this
almost 4.3 ounces, of rock and dust. The OSIRIS-REx was launched in September,
2016. It reached its target, the carbonaceous Apollo group asteroid “101955
Bennu” in December, 2018.
-
- After spending months studying the
asteroid and finding a suitable sampling location, it selected one in December,
2019. After two sampling rehearsals, the spacecraft gathered its sample on
October 20th, 2020.
-
- In September 2023, the sample finally
returned to Earth. For OSIRIS-REx to be
successful, it had to collect at least 60 grams of material. With a final total
that is double that, it should open up more research opportunities and allow
more of the material to be held untouched for future research. NASA says they
will preserve 70% of the sample for the future, including for future
generations.
-
- The next step is for the material to be put
into containers and sent to researchers. More than 200 researchers around the
world will receive samples.
-
- Asteroid Bennu was chosen because it’s close
to Earth and has been observed extensively. It’s a carbonaceous asteroid, which
make up about 75% of asteroids. But it’s also a sub-type of carbonaceous
asteroids called a B-type. These are much more uncommon than other carbonaceous
asteroids, and scientists think they’re very primitive and contain volatiles
that date back to the early Solar System.
-
- Bennu is a natural time capsule that holds
clues to how the Solar System formed, including Earth. It’s also a rubble pile
asteroid, and OSIRIS-REx showed that Bennu has over 200 boulders on its surface
that are larger than 10 meters. Some of these boulders have veins of carbonate
minerals that predate the formation of the asteroid.
-
- Bennu is a rubble pile asteroid that was
likely part of a much larger parent body at one time in the distant past. NASA/University of Arizona.
-
- The “O” in OSIRIS-REx stands for
Origins. Will the sample contain any
organic compounds that could’ve played a role in the appearance of life? If so,
that supports the “panspermia theory”.
-
- The main scientific value in the Bennu
sample concerns what the samples will tell us about the asteroid’s origins.
Scientists think that Bennu broke off from a much larger parent body before
migrating to the inner Solar System. It could hold clues to that journey and
how it changed over time.
-
- Astronomers suspect that Bennu is actually
older than the Solar System itself. It could hold important clues to the gas
and dust in the solar nebula that eventually formed the Sun and all the
planets.
-
- Initial observations showed that the
asteroid contains carbon and water. Carbon wasn’t unexpected since the asteroid
is a carbonaceous one. Neither was water surprising since scientists have long
thought that asteroids were one of the main ways that Earth got its water.
-
- While the OSIRIS-REx sampling mission is
over, the spacecraft is still going. It’s in its extended mission now. Its target is the asteroid Apophis, which
will have a close encounter with Earth in 2029. The mission will study how the
close encounter affects the asteroid, including its orbit and trajectory, and
any surface changes that Earth’s gravity might trigger, like landslides.
-
- Once scientists get their hands on the
samples, we can expect a stream of fascinating results. Who knows which of our
ideas about the Solar System will be confirmed and which ones will be
discarded? No matter what we learn, it’s guaranteed to be interesting.
-
- Cosmic dust could spread life from world to
world across the Galaxy. Does life
appear independently on different planets in the galaxy? Or does it spread from
world to world? Or does it do both? New
research shows how life could spread via a basic, simple pathway: cosmic dust.
-
- One thing scientists have learned in the
past few decades is that life on Earth might have had an early start. The Earth
is about 4.53 billion years old, and some evidence shows that simple life
existed here at least 3.5 billion years ago. Some evidence suggests life was
here even before that, only about 500 million years after Earth formed when it
had cooled down. The life would have been extremely simple, but it may have
been there.
-
- But life may not have originated here.
Researchers question if there was enough time for life to appear spontaneously
in early Earth conditions. New research
examines the idea that cosmic dust could be responsible for spreading life
throughout the galaxy by “panspermia”. Life arose elsewhere, and was delivered
to the young Earth.
-
- No matter how much we ponder and investigate
the origins of life, we don’t know how it starts. We have an idea about the
type of environment that could spawn it, but even that is an idea obscured by
billions of years. But it started somehow.
-
- By obtaining the assumption that planetary
dust particles can escape from the gravitational attraction of a planet, we
consider the possibility for the dust grains to leave the star’s system by
means of the radiation pressure.
-
- The idea that life itself could travel
through space on comets and asteroids is familiar to many people. When these
objects crash into planets, the thinking goes, hitchhiking life is delivered,
and if there’s a niche it can exploit, it will. But how could simple dust
accomplish the same thing?
-
- For dust to carry life, it must originate
from a planet that hosts life. This can happen in specific circumstances.
Research shows that dust particles from Earth in the planet’s high-altitude
atmosphere can scatter against cosmic dust grains. Hypervelocity space dust can
interact with this Earth dust, creating powerful momentum flows. A small
fraction of the planetary dust particles can be accelerated enough to escape
the planet’s gravity.
-
- Once free of its planet’s gravity, dust is
then at the mercy of stellar radiation pressure. The planetary dust particles, being already
free from the planet’s gravitational field, might escape from the star’s system
by means of the radiation pressure and initial velocity, spreading life into
the cosmos.
-
- Life would need to be very hardy to survive
on a dust grain as it travels through interstellar space. It would have to
avoid hazards like radiation and heat. If life itself couldn’t do it, maybe
complex molecules that lead to life could.
-
- It has been shown that, during 5 billion
years, the dust grains will reach 100,000 stellar systems, and by taking the
Drake equation into account, it has been shown that the whole galaxy will be
full of planetary dust particles.
-
- By means of the solar radiation pressure,
small dust grains containing live organisms can travel to the nearest solar
system, Alpha Centauri, in nine thousand years. Our powerful rockets, like the
Space Launch System and the Falcon Heavy, would take over 100,000 years to make
the journey.
-
- “Panspermia” is the idea that life is
spread throughout the galaxy, or even the Universe, by dust, asteroids, comets,
and even minor planets. It’s an
intriguing idea. A significant number of
dust grains will survive interstellar space with life or complex molecules
intact.
-
- Working with a statistical approach to the
Drake Equation the number of planets that developed life is on the order of
30,000,000. This value is so huge that
if dust particles can travel a distance of the order of several hundred light
years, one can conclude that the MilkyWay, with a diameter of 100,000
light-years, should be full of complex molecules distributed throughout the
whole galaxy. Even if we assume that
life is destroyed during this time, the vast majority of complex molecules will
remain intact.
-
- If we’re fortunate to find solid evidence
of life on Mars, for instance, then this type of research it spawns will take
on a new luster. The theory claims that
the number of planets with primitive life is enormous. We don’t know that.
Planets are extraordinarily complex, and there are a bewildering number of
variables.
-
-
February 17, 2024 LIFE -
arrives in space dust?
4359
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------ “Jim Detrick” -----------
--------------------- --- Sunday, February 18,
2024
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