The Weirdest Things NASA Found On Space Rocks

0:00 When we imagine aliens visiting Earth,

0:03 we often picture an evil crew on a spaceship,

0:06 scary, threatening, and weirdly humanoid.

0:10 But what if aliens end up slipping onto

0:12 our planet in much smaller and subtler ways, on a microscopic scale, unnoticed?

0:20 Now, flip that question.

0:22 When we send spacecraft across the solar system, land on distant asteroids,

0:28 and bring pieces of them home,

0:30 how can we be sure we aren't leaving traces of ourselves behind?

0:35 Traces that future scientists might one day misinterpret as something alien.

0:42 That's one of the reasons sample return missions are so fascinatingly delicate.

0:48 When we venture out there to bring a piece of the universe back here,

0:52 we need to touch without leaving fingerprints.

0:55 And in the case of asteroid Ryugu,

0:58 what came back to Earth wasn't just a handful of ancient dust,

1:02 but a lesson in just how easy it is

1:05 to confuse what's truly alien with what's all too familiar.

1:11 I'm Alex Mikalogan, and you're watching Astrium.

1:14 Join me today as we explore why

1:16 asteroids like Ryugu are so scientifically valuable,

1:20 how the Hayabusa 2 mission successfully brought home a piece of it,

1:24 and the hidden threat right here at home that almost ruined the whole thing.

1:33 Why study asteroids in the first place?

1:37 Far more than lifeless rocks, they're really more like time capsules.

1:43 You see, our solar system was created over 4.5 billion years ago.

1:47 Its planets, moons, and all other celestial bodies

1:51 are thought to be made from some primordial material,

1:54 but it's hard to tell what that material

1:56 may have been just by studying Earth rocks?

2:00 On Earth, erosion, tectonic activity, and the weather modify the material's

2:05 physical and chemical properties beyond recognition.

2:09 That's not the case with asteroids, [music]

2:11 where this material remains largely unperturbed by time,

2:15 like a window into the earliest days of our solar system.

2:19 There's also evidence to suggest asteroid collisions

2:22 with Earth might have delivered organic compounds

2:25 to our planet when [music] the conditions for life were just starting to emerge.

2:30 Asteroids might hold insights we can't get elsewhere about

2:33 the origins of the solar system and the life in it.

2:36 Yet, getting to asteroids isn't easy.

2:39 Most of them are found in the asteroid belt

2:41 circling the Sun in an orbit between Mars and Jupiter.

2:45 A trip out there, though it has been done before, would take a long time.

2:51 Not worth it just to collect a small sample.

2:54 It is much more efficient to send

2:56 a spacecraft to an asteroid that crosses Earth's orbit.

3:00 So, that's exactly what the Japanese Aerospace Exploration Agency, or JAXA, did.

3:07 In 2010, the Hayabusa mission returned the first ever asteroid samples to Earth.

3:13 Taken from asteroid Itokawa and weighing less than a gram,

3:17 it set the stage for the sequel mission, Hayabusa 2.

3:25 On the 3rd of December, 2014,

3:27 Hayabusa 2 spacecraft launched from the Tanegashima Space Center in Japan.

3:32 The mission aimed to gain insight

3:34 into the origin and evolution of the solar system,

3:37 including the beginnings of life.

3:40 It would do this by collecting samples from the near-Earth asteroid Ryugu.

3:45 Discovered in 1999, it measures 900 m across and comes within 195

3:52 million kilometers from the Sun or 45 million kilometers of Earth's orbit,

3:57 a quarter of the distance to the asteroid belt.

4:01 After almost 4 years of travel,

4:04 Hayabusa 2 arrived at Ryugu on the 27th of June, 2018.

4:10 The spacecraft consisted of an orbiter

4:12 equipped with instruments including optical navigation cameras,

4:16 a near-infrared spectrometer, a thermal infrared imager, and a lidar.

4:22 These tools mapped Ryugu's surface, composition,

4:26 and thermal properties from an orbital altitude of 20 kilometers.

4:31 Soon after arrival, Hayabusa 2 deployed two small Minerva 2 rovers,

4:38 the first to successfully land on an asteroid.

4:42 Rover 1A and Rover 1B used internal

4:45 rotating masses to hop in Ryugu's low gravity,

4:49 capturing images and temperature data of the surface.

4:53 Soon after, the MASCOT lander was released.

4:57 Because Ryugu's gravity was too weak to pull MASCOT toward it,

5:01 the lander was pushed out of the spacecraft by a spring

5:05 and then free fell from a height of 51 meters.

5:09 6 minutes later, it touched down on the asteroid,

5:13 bouncing several times before coming to a halt.

5:17 It operated on Ryugu's surface for 17 hours,

5:20 collecting magnetic, thermal, and spectroscopic data.

5:24 A third rover, Minerva 2-2,

5:27 was released in October 2019 but failed before deployment.

5:32 Instead, it was released into orbit as a gravitational

5:35 experiment before crashing into Ryugu 5 days later.

5:40 Hayabusa 2 retrieved samples from Ryugu during two brief touchdowns in 2019.

5:47 The first touchdown gathered surface samples close

5:50 to the equatorial ridge by firing a small projectile.

5:54 The impact ejected surface material into the sampler horn,

5:58 which then funneled it into sealed

6:00 containers with the spacecraft's return capsule.

6:03 The second sample came from firing a small carry-on impactor

6:07 on touchdown to create an artificial

6:10 crater and expose [music] subsurface material.

6:13 The reasoning behind the two sample types was [music]

6:16 that the surface samples had been exposed to the regular radiation,

6:20 micrometeoroid impacts, and temperature cycles of space.

6:24 Whereas, the subsurface material had been shielded from this cosmic weathering,

6:29 providing a more comprehensive picture of Ryugu's composition.

6:34 By November 2019, the spacecraft had everything it needed.

6:39 With its precious cargo loaded,

6:41 it wrapped up its time at Ryugu and started the return journey home.

6:46 Over a year later, in December 2020, Hayabusa2 emerged above our pale blue dot.

6:54 As it soared past us,

6:56 it dropped a landing capsule containing the 5.4 g of asteroid sample,

7:01 which parachuted down to a soft landing in South Australia.

7:06 NASA and JAXA are sharing samples between

7:09 the Hayabusa2 mission and the similar OSIRIS-REx mission,

7:13 which returned samples of the Bennu asteroid in 2023,

7:17 maximizing research potential and opportunities for peer review.

7:22 As the spacecraft continued on its

7:24 extended mission to another, smaller asteroid,

7:27 scientists on Earth scrambled to extract and analyze

7:30 this little piece of our universe's history.

7:35 The heavy weight of hope was placed on this tiny asteroid sample,

7:41 and it didn't disappoint.

7:44 We already knew that Ryugu belonged to the C-type or carbonaceous asteroids,

7:48 which tend to be found in the outer regions of the asteroid belt,

7:52 and contain similar materials to those from the time

7:55 our solar system was formed.

7:57 But, what we didn't know, and to researchers' delight,

8:01 Ryugu's composition was found to be very similar

8:04 to a rare class of meteorites known as C1 chondrites.

8:10 C1 chondrites are the most chemically primitive meteorites known,

8:14 and are characterized by the presence

8:16 of carbonaceous material other than pure carbon, like diamond or graphite.

8:23 They contain chondrules, which are small,

8:26 round grains that formed in the solar nebula when our sun was still very young.

8:32 It seemed JAXA had hit the nail on the head.

8:35 Their mission had gotten them up close

8:37 and personal with the birth of the solar system, just as they had aimed for.

8:43 Today, Ryugu orbits our sun relatively close to Earth,

8:46 scraping by at a distance of just 114,000 km at its closest.

8:52 But, it didn't always call this galactic neighborhood home.

8:56 Using an X-ray technique called Mössbauer spectroscopy,

9:00 the team put together a timeline of Ryugu's past

9:03 by meticulously analyzing minute chemical

9:06 changes in each sample particle fragment.

9:09 What they found is convincing enough to place

9:12 Ryugu's origins in the outer solar system.

9:15 The asteroid's surface properties support this theory.

9:19 If Ryugu had originated closer to the sun,

9:22 where temperatures are higher, researchers would expect to see coarser grains.

9:27 Additionally, the grain fragments are porous.

9:31 This is exactly what you'd expect to see

9:33 in asteroids that once held water and carbon dioxide ice.

9:38 In order for those compounds to be solid,

9:40 Ryugu's parent body would have been three to four

9:43 times farther from the sun than Earth is.

9:46 Research places Ryugu's formation about 2

9:49 million years after the solar system itself.

9:52 Over the next 3 million years, its parent body lost its ice,

9:57 leaving behind a hydrated interior and dry surface.

10:02 About 1 billion years later, a cosmic impact fragmented it.

10:07 Those fragments eventually coalesced into today's Ryugu.

10:12 Sample analysis also showed the asteroid

10:14 contains a rich mix of organic molecules.

10:17 This is huge as it implies that the fine-grained surface of an asteroid as old

10:22 as Ryugu is able to shield organic

10:24 molecules from the harsh environment of interstellar space.

10:28 Hiroshi Naraoka of Kyushu University in Japan confirms

10:33 that these molecules could be transported through the solar system

10:37 and even be potentially dispersed as interplanetary dust

10:40 by impacts that eject the uppermost layer of the asteroid.

10:44 It seems to add weight to the hypothesis that abiotic chemical reactions

10:48 on asteroids might play a role in creating some of life's ingredients.

10:53 But beyond just organic molecules, one research team at Imperial College London

10:58 also found something a lot more exciting.

11:01 Organic matter.

11:04 Not exactly life, but rods and filaments similar

11:08 to the size and shapes of microorganisms here on Earth.

11:12 If these were true extraterrestrial organisms,

11:15 it would finally prove that the idea of panspermia,

11:19 aka that life originating from elsewhere in the universe

11:22 can survive the transfer between planetary bodies, is possible.

11:27 But before they shouted alien, the team did what any good scientist would do.

11:33 They double-checked their work.

11:36 Space agencies have very tight protocols

11:39 when it comes to preventing contamination.

11:41 The Ryugu sample traveled to Earth

11:43 in a hermetically sealed chamber and was opened

11:46 in a class 10,000 clean room using sterilized

11:50 tools before being stored in airtight containers under nitrogen.

11:54 When scientists went to retrieve the sample to begin testing,

11:57 they first performed an X-ray nanotomography analysis,

12:01 basically X-ray on steroids.

12:05 It allows researchers to image internal structures at scale

12:08 smaller than a micrometer without sectioning or damaging the specimen.

12:13 This was to check that Ryugu sample didn't fall prey to any contamination

12:17 in the process of transferring it

12:19 from the landing capsule into a storage facility.

12:23 The results came in.

12:24 Ryugu sample was clean.

12:27 So, where did the microorganisms come from?

12:32 Upon arrival on Earth, the primary Ryugu samples were carefully subdivided

12:37 into multiple portions in JAXA's specialized facility.

12:41 Some remained sealed in their pristine state for future analysis,

12:45 while others were distributed to different

12:47 research teams worldwide for immediate study.

12:50 This standard practice allows scientists to maximize research

12:53 potential while preserving portions of the irreplaceable material.

12:58 Subsample A0180, measuring just 1 by 0.8 mm,

13:05 traveled to Imperial College London,

13:07 where, despite the meticulous protocols and cutting-edge containment systems,

13:12 the impossible happened.

13:15 During their first observation by scanning electron microscopy,

13:19 the researchers noticed something strange.

13:22 Rods and filaments of organic matter scattered across the sample.

13:27 Cylindrical and carbon-rich,

13:29 these specimens were mainly observed on the surface of the sample.

13:33 Though, 28% were found within porous cavities.

13:38 They counted 11 rods and filaments in total,

13:42 a number which rose to 147 at the second

13:45 scanning electron microscopic examination 19 days later.

13:50 Just to be sure, they surveyed common fabrics and fibers

13:53 in the lab to compare them to these filaments.

13:56 Hair, clothing, wipes, nothing seemed to match.

14:00 They paid close attention to the rate of population growth and decline,

14:04 and concluded that, based on population statistics,

14:08 the specimens were living and had

14:11 infiltrated the Ryugu rock after sample preparation.

14:15 In order to examine a rock under a microscope,

14:18 the sample must first be cut, ground,

14:21 and polished to create a flat, mirror-like surface for examination,

14:25 also known as preparation of the polished block.

14:29 The research team deduced it was

14:31 at this point that the rods and filaments appeared,

14:34 a conclusion supported by the earlier findings of the nano X-ray tomography,

14:39 which came out clean.

14:41 This pointed to one explanation.

14:44 The rods and filaments were likely microorganisms of terrestrial origin.

14:50 Earthly bacteria had contaminated our pristine asteroid sample.

14:56 The team didn't attempt to sequence the bacteria's DNA,

14:59 so we don't know exactly what species it was,

15:03 but it was likely a single spore of some kind of prokaryote,

15:08 probably a bacillus, that started forming a colony.

15:13 Luckily, the team was able to control the spread.

15:16 Once they repolished the block,

15:18 the microorganism population disappeared for good,

15:21 and analysis could go on as planned.

15:24 Despite the contamination setback,

15:27 Ryugu's sample had proven incredibly valuable.

15:30 Combined with NASA's much larger sample from Bennu,

15:33 which weighed 121.6 g and arrived in 2023,

15:38 it had given us a glimpse into the early days of the solar system,

15:42 and new findings about both asteroids are still coming to light.

15:48 As we prepare for more ambitious sample return missions,

15:52 including potential trips to Mars, the stakes get even higher.

15:57 If we're looking for signs of life, we need to be completely certain we're

16:02 not finding hitchhikers from our own planet.

16:05 Space agencies do have planetary protection guidelines

16:08 in place to minimize the risk of forward contamination,

16:11 us taking microbes to other planets, and back contamination,

16:16 setting alien life loose on our planet.

16:19 And Hayabusa 2 is a great example of how space exploration is as much about

16:24 the challenges here on Earth as it is

16:26 about [music] the challenges out there in space.

16:30 Each mission teaches us something new about our target subjects,

16:33 as well as our own methods.

16:36 And despite the unexpected hiccup, Ryugu's ancient material continues to improve

16:41 our understanding of celestial origins.

16:44 I'm excited to see what new findings will come out in the next 5 to 10 years.

16:48 Until then, we'll just have [music] to sit tight.

16:52 Thanks for watching.

16:53 If you enjoyed this video,

16:55 you might want to check out my other videos on asteroid Bennu.

16:58 Until next time.

17:02 Does life originate from stardust?

17:06 Interestingly, this is something the aptly named Stardust

17:10 spacecraft did not originally set out to discover,

17:13 but it's a question that its findings have provoked.

17:16 And it's all thanks to including the lightest substance in the world on board.

17:23 The Stardust spacecraft is known for its involvement

17:26 with the Deep Impact NASA mission to the comet Temple 1.

17:30 However, this was not Stardust's first mission, nor its primary one.

17:35 Before Temple 1, Stardust was out collecting data on another comet

17:39 by doing something that no other probe before it had done.

17:42 Its mission was to travel to the comet Wild 2,

17:46 collect some of the material from its coma,

17:48 and then deliver the sample intact back to Earth.

17:52 And given that this would involve catching

17:54 particles that were moving at over 23,000 km/h,

17:58 all without damaging them, this was no easy task.

18:02 I'm Alex McConaughey, and you're watching Astrium.

18:05 Join with me today as we explore

18:07 how Stardust managed to accomplish this incredible feat,

18:10 and uncover what Stardust's findings taught us

18:13 about cometary origins, as well as our own.

18:20 In the late 1990s, cometary science was still in the early stages.

18:25 Although we had sent six probes up to visit these enigmatic celestial bodies,

18:29 not very much was known about their origins.

18:32 It was believed at the time that comets were

18:35 foreign visitors to our solar system, older than the Sun,

18:38 having been formed from the loose pre-solar grains of dust

18:41 that orbit other stars before drifting through space towards us,

18:46 only to be caught up in the Sun's gravitational pull.

18:50 It was believed that this theory could be confirmed by traveling

18:53 to one of these comets and picking up some of this loose dust,

18:56 or stardust, that surrounds them in space.

19:00 By examining the isotopic composition,

19:02 scientists would be able to tell if it was unusual

19:05 when compared to the dust given off by our own star.

19:09 However, this was a challenging mission.

19:12 As is often the case, it came down to a question of speed and energy.

19:16 Comets travel through the inner solar system at speeds reaching 160,000 km/h.

19:22 While it was possible for a probe to try

19:24 and match that speed and come up alongside it,

19:27 this had to be done without needing too much fuel or the weight of the craft

19:31 would be too heavy and thus too expensive to get into space in the first place.

19:36 For this mission, scientists selected a comet known as Wild 2.

19:40 They believed that they would be able to get

19:42 Stardust alongside Wild 2 at a relatively low velocity.

19:46 However, this velocity would still be around 6.5 km/h or 23,400 km/h.

19:54 As you can imagine, catching even particles

19:57 at that speed would be extremely challenging.

20:00 Although particles would likely not do too much damage to Stardust,

20:04 being too small to really impact it,

20:06 it would do irreparable damage to the particles themselves.

20:11 When an object crashes at 23,400 km/h into a surface,

20:16 the odds of it keeping its original shape and structure are incredibly small.

20:21 Scientists would not learn much about the structure

20:23 of these particles if they smashed those particles into pieces,

20:26 not to mention the warping effect all that kinetic energy being

20:30 suddenly converted into thermal would have on the molecular bonds involved.

20:35 So, what was their solution?

20:37 What was their mechanism for catching objects traveling at those speeds?

20:41 Well, much like how an airbag softens the blow

20:44 for you if you're involved in a car crash,

20:47 scientists realized that they would need an airbag of their own.

20:50 Something that would not halt the particle all at once,

20:53 but would reduce its speed over a longer distance,

20:56 thus reducing the amount of crushing deceleration involved.

21:00 For this, they found an incredible material that was basically air, solid air.

21:05 They decided to use aerogel.

21:09 Aerogel is a fascinating substance that was discovered in 1931 by Samuel

21:14 Kistler when he made a bet with fellow scientist Charles Learned about jelly.

21:19 As you've probably seen if you've ever made it yourself,

21:22 jelly is formed of two parts.

21:24 Firstly, a relatively solid structure that acts like a kind of sponge,

21:28 and secondly, water.

21:31 When you add water to solid cubes of dense jelly,

21:34 it absorbs the water and expands into the wobbly substance we are familiar with.

21:39 If you were to extract the water,

21:41 the solid part of the jelly would normally contract again.

21:44 Kistler's bet with Learned was to be the first one to remove

21:47 all of the liquid from the jelly without making it shrink.

21:52 In short, to make a jelly that was entirely filled with air, an air jelly.

21:57 Without going into all the details,

21:59 Kistler won his bet and at the same time invented the first aerogel.

22:04 Aerogel is a fascinating substance as it is usually over

22:07 99% air and yet has the structural strength to support bricks.

22:13 Nowadays, it tends to be made from silica composites rather than jelly,

22:17 but can be made from a wide range of materials.

22:21 It is incredibly light and is strangely

22:23 enough an even better insulator than regular air.

22:27 And most importantly for Stardust, when particles hit it,

22:30 it would offer just the right amount of resistance

22:33 to slow down the particle without denaturing or destroying it.

22:37 The trails left behind in the aerogel would also be

22:40 useful for scientists to spot where a particle had been captured.

22:45 Stardust was fitted with a tennis racket-sized

22:47 aerogel collector tray made up of 90

22:49 blocks of aerogel 3 cm thick with over 1,000 square centimeters of surface area,

22:55 which would be deployed from inside the main

22:57 body whenever sampling was to take place.

23:00 Stardust would also capture from the interstellar medium to allow comparisons

23:04 and to learn more about the dust in our own solar system.

23:07 Once it had collected these samples,

23:09 it would store them on a sample return capsule,

23:12 which would be fired back towards the Earth for re-entry and collection.

23:16 This SRC was 80 cm by 50 cm, weighed 45 kg,

23:22 and came fitted with an aero shield, navigation recovery aids, and a parachute.

23:27 Also on board Stardust was a navigation camera,

23:30 a comet trajectory and interstellar dust analyzer,

23:33 and a dust flux monitoring system, among other scientific devices.

23:39 The probe launched on the 7th of February 1999

23:41 and spent the next 5 years traveling through space,

23:45 passing the asteroid 5535 Anne Frank along the way,

23:48 which it took some photos of.

23:50 But on the 2nd of January 2004, it finally arrived at its target, comet Wild 2.

23:57 And what it found was immediately extraordinary.

24:01 Scientists had not expected much from Wild 2.

24:04 Some NASA scientists described their expectation of it to be

24:07 a rather bland object looking somewhat like a black potato.

24:11 However, this is not what they found.

24:13 Instead, the surface of Wild 2 was

24:15 covered with spiky pinnacles hundreds of meters tall,

24:19 cliffs, massive holes jetting dust and gas out into space,

24:23 even on parts of the comet that were pointed away from the sun,

24:27 and thus were expected to be less reactive.

24:30 In short, the surface of the comet was unexpectedly alive and self-renewing.

24:37 [music]

24:37 Something else was just as notable for its absence, craters.

24:42 Unlike almost every other body in our solar

24:44 system with surfaces exposed to space,

24:47 there were no craters on the surface of Wild 2.

24:50 This puts it in stark contrast to places like Mars or our own moon.

24:55 Given the period of time Wild 2 is thought to have existed,

24:58 it surely must have encountered other objects which impacted with it.

25:02 So, where had these craters gone?

25:05 It shows that a comet surface can either be self-renewing or active,

25:10 reducing signs of visible craters over short time frames,

25:13 astronomically speaking.

25:16 And of course, during this flyby, Stardust had its aerogel collector exposed,

25:21 and it was rapidly collecting dust samples.

25:24 Just listen to the frequency in which dust [music] struck the spacecraft.

25:33 The samples were carefully stowed away.

25:36 And upon reaching the vicinity of Earth, Stardust ejected the SRC.

25:41 The angle of approach had to be just

25:43 right as it was traveling at tremendous speed.

25:47 If the approach angle was too low,

25:49 it would just skim off the atmosphere and fly back into space.

25:53 If the angle was too high, the heat would disintegrate the capsule.

25:57 So, it was with great relief that the DC-8 NASA airplane monitoring the sky

26:02 saw it approaching at just the right second and just the right angle.

26:07 The SRC landed in the Utah desert, where it was recovered,

26:10 everything having worked and deployed just as it was designed to.

26:14 And taking the samples back to the lab,

26:16 scientists learned another completely unexpected

26:19 fact about comet [music] Wild 2.

26:21 It was not a visitor to our solar system at all.

26:24 Unlike what had previously been believed,

26:27 comet Wild 2 had not originated from another star.

26:30 It had been born from our own.

26:32 By comparing the isotopic composition of the particles Stardust

26:36 collected with the samples from our own solar system,

26:39 it was proven that comet Wild 2 originated from the solar system.

26:44 And contrary to what all the ice on its surface might lead you to believe,

26:47 the rock at its center was formed under white-hot conditions.

26:52 Chondrules and calcium aluminum inclusions were

26:55 both found among the samples Stardust collected.

26:58 These are structures that only form under incredibly hot conditions

27:02 and can be found in other asteroids between Mars and Jupiter.

27:06 So, scientists had to rethink their theory that comets

27:08 formed in cold conditions at the edge of solar systems,

27:11 even if they do spend some time there.

27:14 Both fire and ice go into making comets.

27:18 And thanks to the careful, delicate way that the particles had been collected,

27:22 scientists were able to find out one last surprising thing,

27:26 the amino acid glycine.

27:29 Amino acids are the building blocks that make

27:32 up proteins that are vital for all living things.

27:35 Although this does not mean that there was anything alive on comet Wild 2,

27:39 this does lend weight to the idea that it was from comets such as this crashing

27:43 into our Earth millions of years ago that life's

27:46 first building blocks found their way to our planet,

27:49 which I'm sure you will agree offers a tantalizing glimpse into our own origins.

27:55 What happened next for Stardust?

27:57 As only the SRC were sent back to Earth,

28:00 Stardust remained in space and had enough fuel to visit another object,

28:05 comet Tempel 1, which is just as well

28:07 as the Deep Impact mission there didn't go as planned.

28:10 And you can find out more about Stardust involvement with that mission here.

28:15 After this extended mission, with all its fuel used up,

28:19 it sent one last transmission to Earth to acknowledge

28:21 that it was being turned off for good.

28:26 Comets are truly fascinating things,

28:29 and it was thanks to the incredible work of the Stardust probe

28:32 and all those who worked on it that we could make these discoveries.

28:36 Who would have expected that as we looked out across the wide universe,

28:39 we would discover things that would help us understand ourselves better?

28:44 But thanks to them, we now know life's origins might just lie in stardust.

28:54 The Rosetta-Philae spacecraft that visited 67P

28:57 Churyumov-Gerasimenko was perhaps ESA's most ambitious mission.

29:04 Launched in 2004 and arriving in 2014,

29:08 it spent two informative years around the very interesting-looking comet.

29:14 Although not everything went to plan, the data that Rosetta and Philae were able

29:19 to collect about comets has changed our perspective of what

29:22 we understand about the formation [music] of the solar

29:24 system and even about our home planet Earth.

29:31 The data will continue to be examined for years to come.

29:35 But, what have we learned so far?

29:40 I'm Alex McConaughey and you're watching Astrum.

29:42 And together, we will uncover what

29:44 the Rosetta-Philae mission discovered around 67P Churyumov-Gerasimenko.

29:53 67P is currently a Jupiter family comet,

29:57 meaning its orbit doesn't take it much further out than Jupiter anymore.

30:02 Although it was once a Kuiper Belt object,

30:05 which means it originated beyond the orbit of Neptune.

30:09 Arriving at this comet was a revelation to mission planners by itself.

30:14 So far, nothing in the solar system

30:16 that has been examined closely looks anything like 67P.

30:21 It's about 5 km across at its longest point and has two lobes,

30:28 which are joined by a narrow stretch of material in the middle.

30:32 This by itself was somewhat unusual, but it is also very jagged.

30:37 Unlike a lot of asteroids that we visited, during the course of the mission,

30:43 it was discovered that the surface of this comet is quite changeable.

30:48 If we look closely at the neck connecting the two lobes,

30:52 it becomes apparent that this section is under mechanical stress.

30:57 If we look at these rocks,

30:58 we can see that there are fracture lines running through them.

31:02 Fracture lines are also apparent from a different angle.

31:07 Scientists have used models based on fracture lines found all around

31:11 the neck region to determine

31:13 that these fractures permeate deeply inside the comet,

31:16 up to 500 m below the surface.

31:20 It seems that as the comet rotates about its axis,

31:24 the two lobes are pulling away from each other,

31:26 thinning the neck region gradually over time.

31:31 Huge 10-m boulders were observed being displaced by this mechanical stress,

31:36 as well as from the volatility on the surface,

31:39 sometimes by up to 100 m due to the comet's weak gravity.

31:45 This also implies that the comet is really quite brittle and porous,

31:50 which is something that wasn't known about comets before this mission.

31:54 As well as fracture lines, layers can also be seen,

31:58 implying that during its formation, this comet was built up gradually over time.

32:04 However, although it is brittle,

32:07 the surface of the comet is a lot harder than expected.

32:11 Scientists thought that the initial landing site

32:13 for Philae would almost be soft and fluffy,

32:16 kind of like a dirty snow, but this was not the case.

32:21 As Philae came to land on 67P to directly interact with the comet,

32:26 it found that its final resting location was solid,

32:29 thought to be water ice with a thin layer of dust.

32:33 Mission controllers for Philae tried to get a sample

32:36 of the soil, but as you can see, Philae ended up at an awkward angle and wasn't

32:41 able to get its drill into the surface.

32:45 However, readings were still able to be obtained

32:48 by examining the material on the craft itself,

32:51 which had ended up on Philae after the bounces.

32:57 Of the surface material examined,

32:59 it was determined that there were 16 different organic compounds,

33:03 four of which had never been detected on a comet before.

33:07 While organic compounds do not mean life, life is based on organic compounds.

33:14 While Philae wasn't able to get too many readings from the surface,

33:18 Rosetta was able to get some samples of the comet by collecting some

33:22 of the dust snow that was ejected away from the comet into space.

33:28 One of the most impressive shots Rosetta was able to take is

33:31 this video of dust particles and cosmic rays shooting off in all directions,

33:36 with background stars moving in the background.

33:40 All the particles are visible here because Rosetta

33:42 is looking at the night side of the comet,

33:45 meaning increased exposure can pick up these interesting visual elements.

33:50 Throughout the mission,

33:52 Rosetta collected roughly 31,000 dust particles, and interestingly,

33:57 their composition didn't change much throughout the course of the mission,

34:01 even as the comet became more active,

34:03 meaning that the whole nucleus of the comet

34:05 is likely to be consistent throughout.

34:09 The dust particles consisted of complex

34:12 organic carbonaceous material mixed in with sodium,

34:16 magnesium, aluminum, silicon, calcium, and iron.

34:21 What separates this material from an asteroid's, however,

34:25 is the presence of an abundance of hydrogen and oxygen.

34:29 It is theorized that asteroids have been heated a lot longer

34:32 than comets have due to their closer proximity to the Sun,

34:36 which has stripped the hydrogen from their compositions.

34:40 Comets, however, have been kept away from the inner

34:43 solar system for much of their lives.

34:45 Meaning these dust samples are pristine relics

34:48 from the formation of the solar system.

34:51 And potentially even the molecular cloud the Sun would have originated from.

34:56 Oxygen was an unexpected find as it's highly reactive.

35:00 And if there is hydrogen around, it will usually bind together to form H2O.

35:06 Carbon and hydrogen were also detected

35:08 in the comet's tenuous atmosphere by Philae.

35:12 The dust particles you see here are tiny.

35:15 The biggest that was collected was only 2 mm across.

35:19 But interestingly, it is particles just like these ones

35:23 that light up the sky during a meteor shower.

35:27 What these views do give us though are an insight to the material that formed

35:31 the solar system so that we can see where the solar system evolved from.

35:37 Comets tend to be very dark,

35:38 only reflecting 3 to 4% of the sunlight that falls on them.

35:43 Which you wouldn't expect from something considered to be icy.

35:46 But actually, not a lot of the ice

35:48 in a comet is exposed to the surface directly.

35:51 Most of the comet is coated in this layer of complex carbonaceous dust,

35:55 which is darker than asphalt.

35:59 Light that isn't reflected is instead absorbed.

36:03 Heating the volatile material beneath the dust layer,

36:06 causing outgassing of water and carbon dioxide,

36:10 which also blasts the tiny dust particles Rosetta picked up into space.

36:15 These colored sections in the time-lapse show exposed water ice.

36:20 And as you can see, it's not a very big percentage of the comet itself.

36:27 Zooming out a little bit and looking at comets generally,

36:31 this is why comets have two tails.

36:33 One tail follows the orbit of the comet.

36:36 This tail is the dust tail.

36:39 The dust tail is illuminated as it reflects sunlight.

36:43 The other tail consists of the volatile material,

36:47 the water and carbon dioxide that outgas from the comet.

36:51 This tail follows the direction of the solar wind.

36:54 And these particles are illuminated through ionization

36:57 and interactions with the charged particles from the sun.

37:02 It is often hard to see comets with your naked eye on Earth,

37:06 but every so often a comet will outgas enough material that it is visible.

37:11 In the northern hemisphere,

37:12 the last one I saw was Hale-Bopp in 1997 when I was just a kid.

37:18 What an amazing sight it was.

37:21 You guys in the southern hemisphere have been a bit luckier with comets.

37:25 You've had Comet McNaught in 2007 and Comet Lovejoy in 2011.

37:33 Going back to 67P, there was one other very big

37:37 reason why the Rosetta Philae mission happened in the first place.

37:41 And that was to see if water on comets is the source of water on Earth.

37:47 Before this mission,

37:48 the theory was that Earth was bombarded by comets early in its

37:52 development back when the solar system was a lot more chaotic.

37:57 Considering a large portion of comets are water ice,

38:00 these could have given the surface of Earth the water we enjoy today.

38:05 But, as it turns out from Philae's findings, this was not the case.

38:11 Scientists were able to determine

38:13 this from the water vapor's deuterium ratio to hydrogen,

38:17 which is significantly different from Earth's.

38:21 Deuterium is an isotope of hydrogen with an added neutron.

38:25 The ratio of deuterium to hydrogen in water is key

38:29 to determining where in the solar system an object originated.

38:34 Here's Earth's ratio, and here is 67P's.

38:38 As you can see, they are very different.

38:40 Only two comets have had their water vapor measured for deuterium directly,

38:44 67P and Halley's Comet.

38:47 And neither suggests that comets were the source of water on Earth.

38:51 Instead, this data gives more weight to models

38:53 that suggest asteroids are the source of water on Earth,

38:57 even though their water content is generally very low.

39:00 If this is the case, Earth had a rough time during its formation.

39:05 Rosetta and Philae were also equipped to detect

39:08 if the comet had a magnetic field.

39:11 Initially, scientists thought they had discovered the presence

39:13 of a magnetic field on the comet,

39:15 the hum of which they converted to audio sound.

39:19 And this is what it sounds like.

39:26 [music] However, it turns out that this was not the result of a magnetic field,

39:34 as Philae could not detect the presence of a magnetic field on the surface,

39:38 but rather this sound is the solar

39:41 wind's interaction with the comet's atmosphere.

39:44 In fact, because of this interaction,

39:46 the atmosphere and comet nucleus are completely devoid of any magnetic field,

39:51 which is called a diamagnetic cavity.

39:58 Rosetta finished its mission by crashing into the surface of the comet.

40:03 As the comet was going further away from the sun,

40:06 there was no guarantee it would have enough power for its heaters.

40:09 So, in order to maximize the science gained,

40:12 mission controllers commanded it to perform a controlled descent into the comet.

40:20 During this descent, it took multiple images,

40:22 which you can see in this time-lapse,

40:25 providing better resolution images of the comet than ever before.

40:31 Until finally, it hit the surface and all communication was lost.

40:38 Between Rosetta and Philae,

40:39 they have opened our eyes to what the solar system was like during its

40:43 formation and have provided data that has and will yet lead to many discoveries.

40:49 Here's hoping for many more missions like this one in the future.

40:53 Space exploration is getting exciting.

41:01 When it comes to astronomy,

41:02 the approach of poke it with a stick is usually not a very viable option.

41:08 You cannot poke stars with a stick and not

41:11 much can normally be learned by poking planets.

41:14 However, if your stick is actually a high-tech sample collection device

41:19 and you target a cosmological time capsule composed of loose regolith and dust,

41:24 suddenly we have the setting for the largest

41:27 and most scientifically advanced stick poking in human history.

41:31 And with the OSIRIS REx spacecraft's mission to the Bennu asteroid,

41:35 that's exactly what happened.

41:38 I'm Alex McColgan and you're watching Astrium.

41:41 And today we continue with our third look at the OSIRIS REx program.

41:46 In this video, we explore the moment of truth,

41:49 the culmination of a journey that spanned 4 years,

41:52 the first time in history a US spacecraft poked an asteroid.

41:58 If you watched my other videos on this topic,

42:01 you will remember that the OSIRIS REx,

42:03 or the Origins Spectral Interpretation Resource is a NASA-developed

42:11 spacecraft that was launched in 2016 with the mission

42:15 of collecting and then bringing home to Earth

42:17 a sample from the near-Earth asteroid known as 101955 Bennu.

42:23 This mission is an important one as Bennu is an extremely old asteroid.

42:28 It is thought to have been around since

42:30 the birth of the solar system and as such

42:32 is a treasure trove of information about the solar

42:35 system's formation and maybe even the origins of life.

42:39 However, while missions have photographed asteroids before and have

42:43 even collected stardust from the tails of comets,

42:46 this was the first time a US spacecraft would have ever

42:49 traveled to an asteroid to physically collect the sample from its surface.

42:54 NASA's goal was to collect a 60 g

42:56 sample of regolith and dust from Bennu's surface.

42:59 It would do that by entering Bennu's orbit and slowly descending.

43:03 It would be careful not to disturb or contaminate

43:06 [music] the asteroid surface by using its thrusters

43:09 but would drift gently down extending its long touch-and-go

43:13 sample acquisition mechanism or [music] TAGSAM as it did so.

43:18 Then, at the moment it touched the surface of the asteroid,

43:21 it would release a burst of nitrogen gas from its arm

43:24 kicking up dust and materials which would be captured in its sampler.

43:29 OSIRIS REx would then return home with its sample.

43:33 However, that mission was not as simple as it may sound.

43:36 Bennu is a relatively small asteroid only about 490 m

43:41 in diameter which meant that there was very little gravity.

43:45 While scientists had previously mapped out the rough shape of Bennu

43:48 to a surprisingly high degree of accuracy using radar imaging,

43:53 this low gravity had led them to believe

43:55 that Bennu would be made of relatively fine materials.

43:59 This was not the case.

44:01 Bennu was covered in large boulders, some of which were 58 m across.

44:07 As such, there were limited places where Osiris Rex

44:10 would be able to touch down to collect its sample.

44:13 And so, Osiris Rex spent over a year, 505 days,

44:18 circling Bennu and mapping out its surface,

44:22 choosing the best location for its system-spanning pogo stick hop.

44:27 After careful deliberation,

44:29 NASA had decided on potentially four sites for the sample collection:

44:33 Osprey, Kingfisher, Nightingale, and Sandpiper.

44:37 You might notice a bird theme here.

44:40 Bennu itself was named as the result

44:42 of a contest run by the University of Arizona,

44:45 the Planetary Society, and the LINEAR project in 2012.

44:49 In it, more than 8,000 students submitted name ideas.

44:54 The winner was a third-grade student who wanted

44:56 to name the asteroid after the Egyptian mythological bird Bennu,

45:00 because he thought that the Osiris Rex's TAGSAM arm

45:04 looked like the graceful extension of a heron's neck,

45:07 just like the Egyptian god Bennu.

45:09 Meaning, it was named after the craft visiting it,

45:12 rather than the shape of the asteroid itself.

45:15 NASA seems to have kept with this bird-like naming convention.

45:20 In the end, NASA chose the Nightingale site for Osiris's landing.

45:25 The site was set in a crater that seemed

45:27 to be relatively young and clear of rocks, which came with numerous benefits.

45:32 Not only would landing be easier,

45:34 but the recently exposed material beneath Bennu's surface would

45:37 likely be an accurate reflection of the asteroid's internal workings.

45:43 With the site selected, Osiris began its slow descent.

45:48 However, it did not rush in with a single try.

45:51 Instead, it did practice runs.

45:54 The first took place on the 15th of April, 2020.

45:58 Osiris Rex approached the asteroid to a distance

46:00 of 65 m before activating its thrusters and rising again.

46:04 [music] Everything worked perfectly and its thrusters worked just as intended.

46:10 Satisfied with this run, scientists sent it in again.

46:14 On the 11th of August,

46:15 OSIRIS-REx approached at a distance [music] of 40 m before once again rising.

46:21 Slowly darting forwards and backwards, but drawing ever closer.

46:26 And on the 20th of October, this heron look-alike went in to strike.

46:32 Using onboard computer systems to plan its

46:35 trajectory and perform its operations as the lag

46:38 time for signals from Earth rendered

46:40 real-time remote control of the spacecraft impossible,

46:43 OSIRIS slowly reached out to touch the surface of the asteroid.

46:48 It raised its solar panels in a Y shape to keep them out

46:51 of the way and protect them from any loose dust that was about to go flying.

46:56 It reached out its arm to land.

46:58 It touched the surface and then, surprisingly, it kept going.

47:05 When I think of the surface of asteroids and comets, [music]

47:07 I imagine them as firm and hard enough to stand

47:10 on as you might see in films such as Armageddon.

47:14 But the truth is that, particularly for small asteroids like Bennu,

47:18 their low gravity means that their mass is only loosely held together.

47:23 What looks like a stable surface is actually

47:26 [music] loosely held material interspersed with pockets of nothingness.

47:30 Gaps that mean Bennu is so easy to sink into if you stepped on it,

47:35 you'd likely vanish inside of it.

47:38 Like stepping into foam,

47:40 OSIRIS-REx's arm sank almost half a meter into the surface

47:44 of Bennu before the thrusters arrested its fall.

47:48 Furiously activating its nitrogen gas burst,

47:51 OSIRIS blasted a hole in the side of the asteroid.

47:55 What was expected to kick up a little

47:57 regolith and dust displaced over 6 tons of loose

48:01 rock as all that material so loosely held together

48:05 under Bennu's tiny gravity was catapulted in all directions.

48:11 OSIRIS-REx's thrusters went into overdrive burning the most they had ever burned

48:16 on this trip to pull them away from the expanding cloud of dust.

48:21 Of course, this was all pre-programmed.

48:24 NASA had planned for this, although perhaps not to this extreme.

48:28 OSIRIS-REx had just made a new massive crater in Bennu.

48:33 Upon getting away from the asteroid surface, OSIRIS-REx checked its hole.

48:39 It had hoped for 60 g of material.

48:42 Instead, it found it had collected somewhere between

48:45 400 g and over 1 kg of material.

48:49 So much material had been collected that a rock got stuck in the flap

48:53 that closed the sampler's head causing some

48:55 small amount of the material to get lost.

48:58 However, OSIRIS-REx succeeded in transferring the sampler

49:01 head to a sealed container built into it.

49:04 Its mission had been a huge success.

49:08 For a time, OSIRIS-REx stayed watching flying over the asteroid

49:12 to image it and see the outcome of what it had done.

49:16 The surface of Bennu was different now.

49:18 Even larger materials had moved far.

49:21 Just look at how far this boulder was thrown,

49:24 around 12 m across Bennu's surface.

49:28 However, OSIRIS-REx couldn't linger forever.

49:31 Its sample needed to get back to Earth

49:33 and so after performing one last flyby on April 7th,

49:37 2021, it began a long journey home.

49:42 And there we have it.

49:43 Right now, as of the release of this video,

49:46 OSIRIS-REx is making its way back through the void of space.

49:50 [music] It is thought that it will arrive back around Earth by September 2023.

49:56 Once it reaches Earth's orbit, it will release its sample,

49:59 which will fall through our atmosphere to land in the Utah desert,

50:02 where it will be collected and examined.

50:06 [music] This will mark the culmination of an incredible scientific exercise,

50:09 collecting a sample of an asteroid and returning

50:12 it back in pristine condition to Earth.

50:16 But, [music] as for OSIRIS-REx itself, this mission was only the beginning.

50:21 Having captured a sample of Bennu,

50:23 this Egyptian heron will be off to slay a new beast,

50:26 Apophis, the Egyptian serpent of chaos,

50:29 destroyer of light and order, or more accurately, the Apophis asteroid,

50:35 a 370-m diameter asteroid that is believed to be

50:39 passing within 50,000 km of Earth in 2029.

50:44 Let's hope that the asteroid does not behave

50:46 in a way that's too in keeping with its Egyptian namesake.

50:50 Either way, OSIRIS will be heading off to investigate it,

50:54 once again using its thrusters to kick

50:56 up material from the asteroid's surface for analysis.

51:00 [music]

51:00 To reflect this extension of the mission, OSIRIS has been given a new name.

51:04 No longer is it OSIRIS-REx, [music]

51:06 it is now OSIRIS Apophis Explorer, or OSIRIS APEX.

51:13 [music] With a name like that, perhaps its greatest discoveries are yet to come.

51:19 You may have noticed this video didn't have any sponsors,

51:22 and that's because it was brought to you by our astronauts on Patreon.

51:27 Consider joining our Patreon to keep these videos thriving,

51:30 even when they're sponsor-free.

51:32 It's the reason we can research deep into the topics we love,

51:35 without cutting corners or chasing clicks.

51:38 Every new astronaut allows us to explore bigger ideas,

51:42 and make every upload even better than the last.

51:45 So, if you've ever thought about being a bigger part of this channel,

51:48 join the crew to power Astrium and keep space curiosity alive.