When we imagine aliens visiting Earth,
we often picture an evil crew on a
spaceship. Scary, threatening, and
weirdly humanoid. But what if aliens end
up slipping onto our planet in much
smaller and subtler ways on a
microscopic scale, unnoticed?
Now, flip that question. When we send
spacecraft across the solar system, land
on distant asteroids, and bring pieces
of them home, how can we be sure we
aren't leaving traces of ourselves
behind? Traces that future scientists
might one day misinterpret as something
alien.
That's one of the reasons sample return
missions are so fascinatingly delicate.
When we venture out there to bring a
piece of the universe back here, we need
to touch without leaving fingerprints.
And in the case of asteroid Ryugu, what
came back to Earth wasn't just a handful
of ancient dust, but a lesson in just
how easy it is to confuse what's truly
alien with what's all too familiar.
I'm Alex Mccoan and you're watching
Astramm. Join me today as we explore why
asteroids like Ryugu are so
scientifically valuable, how the
Hayobusa 2 mission successfully brought
home a piece of it, and the hidden
threat right here at home that almost
ruined the whole thing.
Why study asteroids in the first place?
Far more than lifeless rocks, they're
really more like time capsules. You see,
our solar system was created over 4.5
billion years ago. Its planets, moons,
and all other celestial bodies are
thought to be made from some primordial
material. But it's hard to tell what
that material may have been just by
studying Earth rocks. On Earth, erosion,
tectonic activity, and the weather
modify the material's physical and
chemical properties beyond recognition.
That's not the case with asteroids where
this material remains largely
unperturbed by time, like a window into
the earliest days of our solar system.
There's also evidence to suggest
asteroid collisions with Earth might
have delivered organic compounds to our
planet when the conditions for life were
just starting to emerge. Asteroids might
hold insights we can't get elsewhere
about the origins of the solar system
and the life in it. Yet, getting to
asteroids isn't easy. Most of them are
found in the asteroid belt, circling the
sun in an orbit between Mars and
Jupiter. A trip out there, though it has
been done before, would take a long
time. Not worth it just to collect a
small sample. It is much more efficient
to send a spacecraft to an asteroid that
crosses Earth's orbit. So that's exactly
what the Japanese Aerospace Exploration
Agency or JAXA did. In 2010, the
Hayabusa mission returned the first ever
asteroid samples to Earth. Taken from
asteroida
and weighing less than a gram, it set
the stage for the sequel mission
Hayabusa 2.
On the 3rd of December 2014, Hayabusa 2
spacecraft launched from the Tanagashima
Space Center in Japan. The mission aimed
to gain insight into the origin and
evolution of the solar system, including
the beginnings of life. It would do this
by collecting samples from the near
Earth asteroid Ryugu. Discovered in
1999, it measures 900 meters across and
comes within 195 million km from the sun
or 45 million km of Earth's orbit, a
quarter of the distance to the asteroid
belt. After almost 4 years of travel,
Hayabusa 2 arrived at Ryugu on the 27th
of June 2018.
The spacecraft consisted of an orbiter
equipped with instruments including
optical navigation cameras, a near
infrared spectrometer, a thermal
infrared imager, and a liar. These tools
mapped Ryugu's surface composition and
thermal properties from an orbital
altitude of 20 km.
Soon after arrival, Hayabusa 2 deployed
two small Manurva 2 rovers. the first to
successfully land on an asteroid. Rover
1A and Rover 1B used internal rotating
masses to hop in Ryugu's low gravity,
capturing images and temperature data of
the surface. Soon after, the mascot
lander was released. Because Rayugu's
gravity was too weak to pull Mascot
toward it, the lander was pushed out of
the spacecraft by a spring and then free
fell from a height of 51 m.
6 minutes later, it touched down on the
asteroid, bouncing several times before
coming to a halt. It operated on Ryugu's
surface for 17 hours, collecting
magnetic, thermal, and spectroscopic
data. A third rover, Manurva 22, was
released in October 2019, but failed
before deployment. Instead, it was
released into orbit as a gravitational
experiment before crashing into Ryugu 5
days later.
Hibusa 2 retrieved samples from Ryugu
during two brief touchdowns in 2019. The
first touchdown gathered surface samples
close to the equatorial ridge by firing
a small projectile. The impact ejected
surface material into the sampler horn,
which then funneled it into sealed
containers with the spacecraft's return
capsule. The second sample came from
firing a small carry-on impactor on
touchdown to create an artificial crater
and expose subsurface material. The
reasoning behind the two sample types
was that the surface samples had been
exposed to the regular radiation,
micrometeoroid impacts, and temperature
cycles of space, whereas the subsurface
material had been shielded from this
cosmic weathering, providing a more
comprehensive picture of Ryugu's
composition.
By November 2019, the spacecraft had
everything it needed. With its precious
cargo loaded, it wrapped up its time at
Ryugu and started the return journey
home. Over a year later, in December
2020, Hayabusa 2 emerged above our pale
blue dot. As it soared past us, it
dropped a landing capsule containing the
5.4 g of asteroid sambble, which
parachuted down to a soft landing in
South Australia.
NASA and JAXA are sharing samples
between the higher booster 2 mission and
the similar Osiris Rex mission which
returned samples of the Bennu asteroid
in 2023 maximizing research potential
and opportunities for peer review. As
the spacecraft continued on its extended
mission to another smaller asteroid,
scientists on Earth scrambled to extract
and analyze this little piece of our
universe's history.
The heavy weight of hope was placed on
this tiny asteroid sample and it didn't
disappoint. We already knew that Rayugu
belonged to the sea type or carbonacious
asteroids which tend to be found in the
outer regions of the asteroid belt and
contain similar materials to those from
the time our solar system was formed.
But what we didn't know, and to
researchers delight, Ryugu's composition
was found to be very similar to a rare
class of meteorites known as C1
condrites.
C1 condrites are the most chemically
primitive meteorites known and are
characterized by the presence of
carbonatous material other than pure
carbon like diamond or graphite. They
contain condrils, which are small round
grains that formed in the solar nebula
when our son was still very young. It
seemed Jaxa had hit the nail on the
head. Their mission had gotten them up
close and personal with the birth of the
solar system, just as they had aimed
for. Today, Rayuku orbits our sun
relatively close to Earth, scraping by
at a distance of just 114,000 km at its
closest. But it didn't always call this
galactic neighborhood home. Using an
X-ray technique called Muzbau
spectroscopy, the team put together a
timeline of Ryugu's past by meticulously
analyzing minute chemical changes in
each sample particle fragment. What they
found is convincing enough to place
Ryugu's origins in the outer solar
system. The asteroid surface properties
support this theory. If Ryugu had
originated closer to the sun, where
temperatures are higher, researchers
would expect to see coarser grains.
Additionally, the grain fragments are
porous. This is exactly what you'd
expect to see in asteroids that once
held water and carbon dioxide ice. In
order for those compounds to be solid,
Ryugu's parent body would have been
three to four times farther from the sun
than Earth is. Research places Ryugu's
formation about two million years after
the solar system itself. Over the next
three million years, its parent body
lost its ice, leaving behind a hydrated
interior and dry surface. About 1
billion years later, a cosmic impact
fragmented it. Those fragments
eventually coalesed into today's Ryugu.
Sample analysis also showed the asteroid
contains a rich mix of organic
molecules. This is huge as it implies
that the fine grain surface of an
asteroid as old as Ryugu is able to
shield organic molecules from the harsh
environment of interstellar space.
Hiroashi Naroka of Kaushu University in
Japan confirms that these molecules
could be transported through the solar
system and even be potentially dispersed
as interplanetary dust by impacts that
eject the uppermost layer of the
asteroid. It seems to add weight to the
hypothesis that abiotic chemical
reactions on asteroids might play a role
in creating some of life's ingredients.
But beyond just organic molecules, one
research team at Imperial College London
also found something a lot more
exciting. Organic matter. Not exactly
life, but rods and filaments similar to
the size and shapes of microorganisms
here on Earth. If these were true
extraterrestrial organisms, it would
finally prove that the idea of
panspermia, aka that life originating
from elsewhere in the universe can
survive the transfer between planetary
bodies is possible.
But before they shouted alien, the team
did what any good scientist would do.
They double-cheed their work.
Space agencies have very tight protocols
when it comes to preventing
contamination. The Ryugu sample traveled
to Earth in a hermetically sealed
chamber and was opened in a class 10,000
clean room using sterilized tools before
being stored in airtight containers
under nitrogen. When scientists went to
retrieve the sample to begin testing,
they first performed an X-ray
nanotomography analysis. Basically X-ray
on steroids. It allows researchers to
image internal structures at scales
smaller than a micrometer without
sectioning or damaging the specimen.
This was to check that Ryugu's sample
didn't fall prey to any contamination in
the process of transferring it from the
landing capsule into its storage
facility. The results came in. Ryugu's
sample was clean. So where did the
microorganisms come from?
Upon arrival on Earth, the primary
rayugu samples were carefully subdivided
into multiple portions in Jax's
specialized facility. Some remained
sealed in their pristine state for
future analysis, while others were
distributed to different research teams
worldwide for immediate study. This
standard practice allows scientists to
maximize research potential while
preserving portions of the irreplaceable
material. Subsample A0180
measuring just 1 by 0.8 mm traveled to
Imperial College London where despite
the meticulous protocols and cuttingedge
containment systems, the impossible
happened.
During their first observation by
scanning electron microscopy, the
researchers noticed something strange.
rods and filaments of organic matter
scattered across the sample. Cylindrical
and carbonri, these specimens were
mainly observed on the surface of the
sample, though 28% were found within
porous cavities. They counted 11 rods
and filaments in total, a number which
rose to 147 at the second scanning
electron microscopic examination 19 days
later. Just to be sure, they surveyed
common fabrics and fibers in the lab to
compare them to these filaments. Hair,
clothing, wipes, nothing seemed to
match. They paid close attention to the
rate of population growth and decline
and concluded that based on population
statistics, the specimens were living
and had infiltrated the Ryugu rock after
sample preparation.
In order to examine a rock under a
microscope, the sample must first be
cut, ground, and polished to create a
flat mirror-like surface for
examination, also known as preparation
of the polish block. The research team
deduced it was at this point that the
rods and filaments appeared, a
conclusion supported by the earlier
findings of the nano X-ray tomography,
which came out clean. This pointed to
one explanation. The rods and filaments
were likely microorganisms of
terrestrial origin. Earthly bacteria had
contaminated our pristine asteroid
sample. The team didn't attempt to
sequence the bacteria's DNA, so we don't
know exactly what species it was, but it
was likely a single spore of some kind
of procariote, probably a basillus, that
started forming a colony. Luckily, the
team was able to control the spread.
Once they repolished the block, the
microorganism population disappeared for
good, and analysis could go on as
planned. Despite the contamination
setback, Ryugu's sample had proven
incredibly valuable. Combined with
NASA's much larger sample from Bennu,
which weighed 121.6 6 g and arrived in
2023. It had given us a glimpse into the
early days of the solar system and new
findings about both asteroids are still
coming to light.
As we prepare for more ambitious sample
return missions, including potential
trips to Mars, the stakes get even
higher. If we're looking for signs of
life, we need to be completely certain
we're not finding hitchhikers from our
own planet.
Space agencies do have planetary
protection guidelines in place to
minimize the risk of forward
contamination, us taking microbes to
other planets, and back contamination,
setting alien life loose on our planet.
And Hayabusa 2 is a great example of how
space exploration is as much about the
challenges here on Earth as it is about
the challenges out there in space. Each
mission teaches us something new about
our target subjects as well as our own
methods. And despite the unexpected
hiccup, Ryugu's ancient material
continues to improve our understanding
of celestial origins. I'm excited to see
what new findings will come out in the
next 5 to 10 years. Until then, we'll
just have to sit tight. Thanks for
watching. If you enjoyed this video, you
might want to check out my other videos
on asteroid Bennu. Until next time.
Does life originate from stardust?
Interestingly, this is something the
ably named Stardust spacecraft did not
originally set out to discover, but it's
a question that its findings have
provoked, and it's all thanks to
including the lightest substance in the
world on board.
The Stardust spacecraft is known for its
involvement with the Deep Impact NASA
mission to the comet Temple 1. However,
this was not Stardust first mission, nor
its primary one. Before Temple One,
Stardust was out collecting data on
another comet by doing something that no
other probe before it had done. Its
mission was to travel to the comet V 2,
collect some of the material from his
coma, and then deliver the sample intact
back to Earth. And given that this would
involve catching particles that were
moving at over 23,000 kmh, all without
damaging them, this was no easy task.
I'm Alex Mccoan and you're watching
Astramm. Join with me today as we
explore how Stardust managed to
accomplish this incredible feat and
uncover what Stardust findings taught us
about commentary origins as well as our
own.
In the late 1990s, cometry science was
still in the early stages. Although we
had sent six probes up to visit these
enigmatic celestial bodies, not very
much was known about their origins. It
was believed at the time that comets
were foreign visitors to our solar
system older than the sun, having been
formed from the loose pre-olar grains of
dust that orbit other stars before
drifting through space towards us, only
to be caught up in the sun's
gravitational pull. It was believed that
this theory could be confirmed by
traveling to one of these comets and
picking up some of this loose dust or
star dust that surrounds them in space.
By examining the isotopic composition,
scientists would be able to tell if it
was unusual when compared to the dust
given off by our own star.
However, this was a challenging mission.
As is often the case, it came down to a
question of speed and energy. Comets
travel through the inner solar system at
speeds reaching 160,000 kmh.
While it was possible for a probe to try
and match that speed and come up
alongside it, this had to be done
without needing too much fuel or the
weight of the craft would be too heavy
and thus too expensive to get into space
in the first place. For this mission,
scientists selected a comet known as V
2. They believed that they would be able
to get stardust alongside Vil 2 at a
relatively low velocity. However, this
velocity would still be around 6.5 km/s
or 23,400
km/h.
As you can imagine, catching even
particles at that speed would be
extremely challenging. Although
particles would likely not do too much
damage to Stardust, being too small to
really impact it, it would do
irreparable damage to the particles
themselves. When an object crashes at
23,400
km/h into a surface, the odds of it
keeping its original shape and structure
are incredibly small. Scientists would
not learn much about the structure of
these particles if they smash those
particles into pieces. Not to mention
the warping effect all that kinetic
energy being suddenly converted into
thermal would have on the molecular
bonds involved. So what was their
solution? What was their mechanism for
catching objects traveling at those
speeds? Well, much like how an airbag
softens the blow for you if you are
involved in a car crash, scientists
realized that they would need an airbag
of their own. Something that would not
halt the particle all at once, but would
reduce its speed over a longer distance,
thus reducing the amount of crushing
deceleration involved. For this, they
found an incredible material that was
basically air, solid air. They decided
to use aerogel.
Aerogel is a fascinating substance that
was discovered in 1931 by Samuel Kisler
when he made a bet with fellow scientist
Charles Learned about jelly. As you've
probably seen if you've ever made it
yourself, jelly is formed of two parts.
Firstly, a relatively solid structure
that acts like a kind of sponge and
secondly, water. When you add water to
solid cubes of dense jelly, it absorbs
the water and expands into the wobbly
substance we are familiar with. If you
were to extract the water, the solid
part of the jelly would normally
contract again. Kissler's bet with
Learned was to be the first one to
remove all of the liquid from the jelly
without making it shrink. In short, to
make a jelly that was entirely filled
with air, an air jelly. Without going
into all the details, Kisler won his bet
and at the same time invented the first
aerogel. Aerogel is a fascinating
substance as it is usually over 99% air
and yet has the structural strength to
support bricks. Nowadays, it tends to be
made from silica composites rather than
jelly, but can be made from a wide range
of materials. It is incredibly light and
is, strangely enough, an even better
insulator than regular air. And most
importantly for stardust, when particles
hit it, it would offer just the right
amount of resistance to slow down the
particle without denaturing or
destroying it. The trails left behind in
the aerogel would also be useful for
scientists to spot where a particle had
been captured.
Stardust was fitted with a tennis
racket-sized aerel collector tray made
up of 90 blocks of aerajel 3 cm thick
with over 1,000 square cm of surface
area which would be deployed from inside
the main body whenever sampling was to
take place. Stardust would also capture
from the interstellar medium to allow
comparisons and to learn more about the
dust in our own solar system. Once it
had collected these samples, it would
store them on a sample return capsule,
which would be fired back towards the
Earth for re-entry and collection. This
SRC was 80 cm x 50 cm, weighed 45 kg,
and came fitted with an aeros shield,
navigation recovery aids, and a
parachute. Also on board Stardust was a
navigation camera, a cometry and
interstellar dust analyzer, and a dust
flux monitoring system among other
scientific devices. The probe launched
on the 7th of February 1999 and spent
the next 5 years traveling through
space, passing the asteroid 5535 anfrank
along the way, which it took some photos
of. But on the 2nd of January 2004, it
finally arrived at its target, Comet V
2. And what it found was immediately
extraordinary. Scientists had not
expected much from V 2. Some NASA
scientists described their expectation
of it to be a rather bland object
looking somewhat like a black potato.
However, this is not what they found.
Instead, the surface of V 2 was covered
with spiky pinnacles hundreds of meters
tall, cliffs, massive holes jettting
dust and gas out into space, even on
parts of the comet that were pointed
away from the sun, and thus were
expected to be less reactive. In short,
the surface of the comet was
unexpectedly alive and self-renewing.
Something else was just as notable for
its absence. Craters.
Unlike almost every other body in our
solar system with surfaces exposed to
space, there were no craters on the
surface of Vil 2. This puts it in stark
contrast to places like Mars or our own
moon. Given the period of time V 2 is
thought to have existed, it surely must
have encountered other objects which
impacted with it. So where had these
craters gone?
It shows that the comet's surface can
either be self-renewing or active,
reducing signs of visible craters over
short time frames, astronomically
speaking.
And of course, during this flyby,
Stardust had its aerogel collector
exposed and it was rapidly collecting
dust samples. Just listen to the
frequency in which dust struck the
spacecraft.
The samples were carefully stowed away
and upon reaching the vicinity of Earth,
Stardust ejected the SRC. The angle of
approach had to be just right as it was
traveling at tremendous speed. If the
approach angle was too low, it would
just skim off the atmosphere and fly
back into space. If the angle was too
high, the heat would disintegrate the
capsule. So, it was with great relief
that the DC8 NASA airplane monitoring
the sky saw it approaching at just the
right second and just the right angle.
The SRC landed in the Utah desert where
it was recovered. Everything having
worked and deployed just as it was
designed to. And taking the samples back
to the lab, scientists learned another
completely unexpected fact about
Cometville 2. It was not a visitor to
our solar system at all. Unlike what had
previously been believed, Cometville 2
had not originated from another star. It
had been born from our own. By comparing
the isotopic composition of the
particles Stardust collected with the
samples from our own solar system, it
was proven that Cometville 2 originated
from the solar system. And contrary to
what all the ice on its surface might
lead you to believe, the rock at its
center was formed under white hot
conditions.
Trules and calcium aluminium inclusions
were both found among the samples
Stardust collected. These are structures
that only form under incredibly hot
conditions and can be found in other
asteroids between Mars and Jupiter. So
scientists had to rethink their theory
that comets formed in cold conditions at
the edge of solar systems, even if they
do spend some time there. Both fire and
ice go into making comets. And thanks to
the careful, delicate way that the
particles had been collected, scientists
were able to find out one last
surprising thing. The amino acid
glycine.
Amino acids are the building blocks that
make up proteins that are vital for all
living things. Although this does not
mean that there was anything alive on
Cometville 2, this does lend weight to
the idea that it was from comets such as
this crashing into our Earth millions of
years ago that life's first building
blocks found their way to our planet,
which I'm sure you all agree offers a
tantalizing glimpse into our own
origins.
What happened next for Stardust? As only
the SRC was sent back to Earth, Stardust
remained in space and had enough fuel to
visit another object, Comet Temple 1,
which is just as well as the Deep Impact
mission there didn't go as planned. And
you can find out more about Stardust's
involvement with that mission here.
After this extended mission, with all
its fuel used up, it sent one last
transmission to Earth to acknowledge
that it was being turned off for good.
Comets are truly fascinating things, and
it was thanks to the incredible work of
the Stardust Probe and all those who
worked on it that we could make these
discoveries. Who would have expected
that as we looked out across the wide
universe, we would discover things that
would help us understand ourselves
better? But thanks to them, we now know
life's origins might just lie in
stardust.
The Rosetta fillet spacecraft that
visited 67P Churimov Gerisenco was
perhaps ESA's most ambitious mission.
Launched in 2004 and arriving in 2014,
it spent two informative years around
the very interesting looking comet.
Although not everything went to plan,
the data that Rosetta and Phile were
able to collect about comets has changed
our perspective of what we understand
about the formation of the solar system
and even about our home planet Earth.
The data will continue to be examined
for years to come.
But what have we learned so far?
I'm Alex Mccoan and you're watching
Astramm. and together we will uncover
what the Rosetta filt mission discovered
around 67P Churimov Gerisenco.
67P is currently a Jupiter family comet,
meaning its orbit doesn't take it much
further out than Jupiter anymore,
although it was once a Kyper belt
object, which means it originated beyond
the orbit of Neptune.
Arriving at this comet was a revelation
to mission planners by itself. So far,
nothing in the solar system that has
been examined closely looks anything
like 67P.
It's about 5 km across at its longest
point and has two loes which are joined
by a narrow stretch of material in the
middle. This by itself was somewhat
unusual, but it is also very jagged.
Unlike a lot of asteroids that we
visited
during the course of the mission, it was
discovered that the surface of this
comet is quite changeable.
If we look closely at the neck
connecting the two loes, it becomes
apparent that this section is under
mechanical stress.
If we look at these rocks, we can see
that there are fracture lines running
through them. Fracture lines are also
apparent from a different angle.
Scientists have used models based on
fracture lines found all around the neck
region to determine that these fractures
permeate deeply inside the comet up to
500 m below the surface.
It seems that as the comet rotates about
its axis, the two loes are pulling away
from each other, thinning the neck
region gradually over time.
Huge 10 m boulders were observed being
displaced by this mechanical stress as
well as from the volatility on the
surface sometimes by up to 100 m due to
the comet's weak gravity.
This also implies that the comet is
really quite brittle and porous which is
something that wasn't known about comets
before this mission.
as well as fracture lines. Layers can
also be seen, implying that during its
formation, this comet was built up
gradually over time.
However, although it is brittle, the
surface of the comet is a lot harder
than expected.
Scientists thought that the initial
landing site for file would almost be
soft and fluffy, kind of like a dirty
snow, but this was not the case. As felt
came to land on 67P to directly interact
with the comet, it found that its final
resting location was solid, thought to
be water ice with a thin layer of dust.
Mission controllers for FEL tried to get
a sample of the soil, but as you can
see, FEL ended up at an awkward angle
and wasn't able to get its drill into
the surface.
However, readings were still able to be
obtained by examining the material on
the craft itself which had ended up on
felt after the bounces.
Of the surface material examined, it was
determined that there were 16 different
organic compounds, four of which had
never been detected on a comet before.
While organic compounds do not mean
life, life is based on organic
compounds.
While Fel wasn't able to get too many
readings from the surface, Rosetta was
able to get some samples of the comet by
collecting some of the dust snow that
was ejected away from the comet into
space.
One of the most impressive shots Rosetta
was able to take is this video of dust
particles and cosmic rays shooting off
in all directions with background stars
moving in the background. All the
particles are visible here because
Rosetta is looking at the night side of
the comet, meaning increased exposure
can pick up these interesting visual
elements.
Throughout the mission, Rosetta
collected roughly 31,000 dust particles.
And interestingly, their composition
didn't change much throughout the course
of the mission, even as the comet became
more active, meaning that the whole
nucleus of the comet is likely to be
consistent throughout.
The dust particles consisted of complex
organic carbonatous material mixed in
with sodium, magnesium, aluminium,
silicon, calcium, and iron.
What separates this material from an
asteroids, however, is the presence of
an abundance of hydrogen and oxygen. It
is theorized that asteroids have been
heated a lot longer than comets have due
to their closer proximity to the sun,
which has stripped the hydrogen from
their compositions.
Comets, however, have been kept away
from the inner solar system for much of
their lives, meaning these dust samples
are pristine relics from the formation
of the solar system and potentially even
the molecular cloud the sun would have
originated from.
Oxygen was an unexpected find as it's
highly reactive and if there is hydrogen
around it will usually bind together to
form H2O.
Carbon and hydrogen were also detected
in the comet's tenuous atmosphere by
filt.
The dust particles you see here are
tiny. The biggest that was collected was
only 2 mm across.
But interestingly, it is particles just
like these ones that light up the sky
during a meteor shower.
What these views do give us though are
an insight to the material that formed
the solar system so that we can see
where the solar system evolved from.
Comets tend to be very dark, only
reflecting 3 to 4% of the sunlight that
falls on them, which you wouldn't expect
from something considered to be icy. But
actually, not a lot of the ice in a
comet is exposed to the surface
directly. Most of the comet is coated in
this layer of complex carbonatous dust,
which is darker than asphalt.
Light that isn't reflected is instead
absorbed, heating the volatile material
beneath the dust layer, causing
outgassing of water and carbon dioxide,
which also blasts the tiny dust
particles Rosetta picked up into space.
These colored sections in the time lapse
show exposed water ice. And as you can
see, it's not a very big percentage of
the comet itself.
Zooming out a little bit and looking at
comets generally, this is why comets
have two tails. One tail follows the
orbit of the comet. This tail is the
dust tail. The dust tail is illuminated
as it reflects sunlight.
The other tail consists of the volatile
material, the water and carbon dioxide
that outgassed from the comet. This tail
follows the direction of the solar wind
and these particles are illuminated
through ionization and interactions with
the charged particles from the sun.
It is often hard to see comets with your
naked eye on Earth, but every so often a
comet will outgass enough material that
it is visible. In the northern
hemisphere, the last one I saw was
Hailbop in 1997 when I was just a kid.
What an amazing sight it was.
You guys in the southern hemisphere have
been a bit luckier with comets. You've
had comet McNort in 2007
and comet Lovejoy in 2011.
Going back to 67P, there was one other
very big reason why the Rosetta Filt
mission happened in the first place and
that was to see if water on comets is
the source of water on Earth.
Before this mission, the theory was that
Earth was bombarded by comets early in
its development back when the solar
system was a lot more chaotic.
Considering a large portion of comets
are water ice, these could have given
the surface of Earth the water we enjoy
today.
But as it turns out from Fel's findings,
this was not the case.
Scientists were able to determine this
from the water vapors dutyium ratio to
hydrogen which is significantly
different from Earth's.
Dutyium is an isotope of hydrogen with
an added neutron. The ratio of dutarium
to hydrogen in water is key to
determining where in the solar system an
object originated.
Here's Earth's ratio. And here is 67Ps.
As you can see, they are very different.
Only two comets have had their water
vapor measured for detium directly. 67P
and Haley's comet. And neither suggest
that comets were the source of water on
Earth.
Instead, this data gives more weight to
models that suggest asteroids are the
source of water on Earth, even though
their water content is generally very
low. If this is the case, Earth had a
rough time during its formation.
Rosetta and Fel were also equipped to
detect if the comet had a magnetic
field. Initially, scientists thought
they had discovered the presence of a
magnetic field on the comet, the hum of
which they converted to audio sound. And
this is what it sounds like.
However, it turns out that this was not
the result of a magnetic field as felt
could not detect the presence of a
magnetic field on the surface, but
rather this sound is the solar wind's
interaction with the comet's atmosphere.
In fact, because of this interaction,
the atmosphere and comet nucleus are
completely devoid of any magnetic field,
which is called a diamagnetic cavity.
Rosetta finished its mission by crashing
into the surface of the comet.
As the comet was going further away from
the sun, there was no guarantee it would
have enough power for its heaters. So in
order to maximize the science gained,
mission controllers commanded it to
perform a controlled descent into the
comet.
During this descent, it took multiple
images which you can see in this time
lapse, providing better resolution
images of the comet than ever before
until finally it hit the surface and all
communication was lost.
Between Rosetta and Felt, they have
opened our eyes to what the solar system
was like during its formation and have
provided data that has and will yet lead
to many discoveries. Here's hoping for
many more missions like this one in the
future. Space exploration is getting
exciting.
When it comes to astronomy, the approach
of poke it with a stick is usually not a
very viable option. You cannot poke
stars with a stick and not much can
normally be learned by poking planets.
However, if your stick is actually a
high tech sample collection device and
you target a cosmological time capsule
composed of loose regalith and dust,
suddenly we have the setting for the
largest and most scientifically advanced
stick poking in human history. And with
the Osiris Rex spacecraft's mission to
the Bennu asteroid, that's exactly what
happened.
I'm Alex Mccoan and you're watching
Astramm. And today we continue with our
third look at the Osiris Rex program. In
this video, we explore the moment of
truth, the culmination of a journey that
spanned four years, the first time in
history a US spacecraft poked an
asteroid.
If you watched my other videos on this
topic, you will remember that the Osiris
Rex or the origins spectral
interpretation resource identification
security regalith explorer is a NASA
developed spacecraft that was launched
in 2016 with the mission of collecting
and then bringing home to Earth a sample
from the near earth asteroid known as
101955
Bennu. This mission is an important one
as Bennu is an extremely old asteroid.
It is thought to have been around since
the birth of the solar system and as
such is a treasure trove of information
about the solar systems formation and
maybe even the origins of life. However,
while missions have photographed
asteroids before and have even collected
stardust from the tails of comets, this
was the first time a US spacecraft would
have ever traveled to an asteroid to
physically collect a sample from its
surface. NASA's goal was to collect a 60
g sample of Regalithan dust from Bennu's
surface. It would do that by entering
Bennu's orbit and slowly descending. It
would be careful not to disturb or
contaminate the asteroid surface by
using its thrusters, but would drift
gently down, extending its long
touchandgo sample acquisition mechanism,
or tag SAM as it did so. Then, at the
moment it touched the surface of the
asteroid, it would release a burst of
nitrogen gas from its arm, kicking up
dust and materials, which would be
captured in its sampler. Osiris Rex
would then return home with its sample.
However, that mission was not as simple
as it may sound. Bennu is a relatively
small asteroid, only about 490 m in
diameter, which meant that there was
very little gravity. While scientists
had previously mapped out the rough
shape of Bennu to a surprisingly high
degree of accuracy using radar imaging,
this low gravity had led them to believe
that Bennu would be made of relatively
fine materials.
This was not the case. Bennu was covered
in large boulders, some of which were 58
m across. As such, there were limited
places where Osiris Rex would be able to
touch down to collect its sample. And
so, Osiris Rex spent over a year, 505
days, circling Bennu and mapping out its
surface, choosing the best location for
its system spanning pogo stick hop.
After careful deliberation, NASA had
decided on potentially four sites for
the sample collection. Osprey,
Kingfisher, Nightingale, and Sunpiper.
You might notice a bird theme here.
Bennu itself was named as the result of
a contest run by the University of
Arizona, the Planetary Society, and the
Linear Project in 2012. In it, more than
8,000 students submitted name ideas. The
winner was a third grade student who
wanted to name the asteroid after the
Egyptian mythological bird Bennu because
he thought that the Osiris Rex's Tagsam
arm looked like the graceful extension
of a heron's neck just like the Egyptian
god Bennu, meaning it was named after
the craft visiting it rather than the
shape of the asteroid itself. NASA seems
to have kept with this birdlike naming
convention.
In the end, NASA chose the Nightingale
site for Osiris's landing. The site was
set in a crater that seemed to be
relatively young and clear of rocks,
which came with numerous benefits. Not
only would landing be easier, but the
recently exposed material beneath
Bennu's surface would likely be an
accurate reflection of the asteroid's
internal workings.
With the site selected, Osiris began its
slow descent.
However, it did not rush in with a
single try. Instead, it did practice
runs. The first took place on the 15th
of April, 2020. Osiris Rex approached
the asteroid to a distance of 65 m
before activating its thrusters and
rising again. Everything worked
perfectly and its thrusters worked just
as intended. Satisfied with this run,
scientists sent it in again. On the 11th
of August, Osiris Rex approached at a
distance of 40 m before once again
rising, slowly darting forwards and
backwards, but drawing ever closer. And
on the 20th of October, this heron
lookalike went in to strike.
using onboard computer systems to plan
its trajectory and perform its
operations. As the lag time for signals
from Earth rendered real-time remote
control of the spacecraft impossible,
Osiris slowly reached out to touch the
surface of the asteroid.
It raised its solar panels in a Y shape
to keep them out of the way and protect
them from any loose dust that was about
to go flying. It reached out its arm to
land. it touched the surface and then
surprisingly it kept going.
When I think of the surface of asteroids
and comets, I imagine them as firm and
hard enough to stand on as you might see
in films such as Armageddon. But the
truth is that particularly for small
asteroids like Bennu, their low gravity
means that their mass is only loosely
held together. What looks like a stable
surface is actually loosely held
material interspersed with pockets of
nothingness. Gaps that mean Bennu is so
easy to sink into, if you stepped on it,
you'd likely vanish inside of it.
Like stepping into foam, Osiris Rex's
arm sank almost half a meter into the
surface of Bennu before the thrusters
arrested its fall. Furiously activating
its nitrogen gas burst, Osiris blasted a
hole in the side of the asteroid. What
was expected to kick up a little
regalith dust displaced over six tons of
loose rock as all that material so
loosely held together under Bennu's tiny
gravity was catapulted in all
directions.
Osiris Rex's thrusters went into
overdrive, burning the most they had
ever burned on this trip to pull them
away from the expanding cloud of dust.
Of course, this was all pre-programmed.
NASA had planned for this, although
perhaps not to this extreme. Osiris Rex
had just made a new massive crater in
Bennu.
Upon getting away from the asteroid
surface, Osiris Rex checked its hall. It
had hoped for 60 g of material. Instead,
it found it had collected somewhere
between 400 g and over 1 kg of material.
So much material had been collected that
a rock got stuck in the flap that closed
the sampler's head, causing some small
amount of the material to get lost.
However, Osiris Rex succeeded in
transferring the sampler head to a
sealed container built into it. Its
mission had been a huge success.
For a time, Osiris Rex stayed watching,
flying over the asteroid to image it and
see the outcome of what it had done. The
surface of Bennu was different now. Even
larger materials had moved far. Just
look at how far this boulder was thrown.
Around 12 m across Bennu's surface.
However, Osiris Rex couldn't linger
forever. Its sample needed to get back
to Earth. And so after performing one
last flyby on April 7th, 2021, it began
a long journey home.
And there we have it. Right now, as of
the release of this video, Osiris Rex is
making its way back through the void of
space. It is thought that it will arrive
back around Earth by September 2023.
Once it reaches Earth's orbit, it will
release its sample, which will fall
through our atmosphere to land in the
Utah desert, where it will be collected
and examined. This will mark the
culmination of an incredible scientific
exercise, collecting a sample of an
asteroid and returning it back in
pristine condition to Earth.
But as for Osiris Rex itself, this
mission was only the beginning. Having
captured a sample of Bennu, this
Egyptian heron will be off to slay a new
beast, Apopus, the Egyptian serpent of
chaos, destroyer of light and order, or
more accurately, the Apopus asteroid, a
370 m diameter asteroid that is believed
to be passing within 50,000 km of Earth
in 2029.
Let's hope that the asteroid does not
behave in a way that's too in keeping
with its Egyptian namesake. Either way,
Osiris will be heading off to
investigate it. Once again, using its
thrusters to kick up material from the
asteroid surface for analysis. To
reflect this extension of the mission,
Osiris has been given a new name. No
longer is it Osiris Rex. It is now
Osiris Apopus Explorer or Osiris Apex.
With a name like that, perhaps its
greatest discoveries are yet to come.
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