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00:00From the beginnings of our solar system four and a half billion years ago, there
00:05remain tantalizing clues to its evolution. Remnant debris, asteroids and
00:11comets. They vary in size from grains of dust to mountainsides, from footballs to
00:17planetoids. They were the building blocks of the planets and perhaps carry the
00:22origins of life itself. Now within our grasp, these rocks of ice and dust are
00:27ready to give up their secrets.
00:57Asteroids are believed to be made of chondrels, flash-heated grains of rock
01:15within the stellar disk of our forming solar system. These chondrels cluster
01:21together, forming the first asteroids and the building blocks of the planets.
01:26Once the solar system had evolved, there was a lot of asteroid material left over.
01:32They cover a broad spectrum of types. The largest of these are minor planets or
01:38planetoids, large enough to have an ovoid shape. This category took the previous
01:43planet Pluto off the major list and onto the minor. The smallest remnants of debris
01:49are often called meteoroids. There are in fact several minor planets. Some have been
01:56seconded into planetary orbit and become moons. The traditional asteroid belt between Mars and
02:02Jupiter has one called Ceres, the largest and the first to be detected.
02:09Our first close-up of an asteroid was courtesy of Galileo on its flight through the main asteroid belt
02:15towards Jupiter. It photographed 951 Gaspra, an S-type asteroid with an average diameter of just
02:23over six kilometers. The S stands for stony composition. Galileo then photographed the larger 243
02:31Ida at 15 and a half kilometers wide, revealing that it has its own moon named Dactyl. Asteroids are not
02:38limited to the asteroid belt between the orbits of Mars and Jupiter. Many orbit much closer to Earth
02:45and are known as near-Earth objects or NEOs. Radar is a very powerful instrument that we use to study
02:53near-Earth asteroids. Asteroid Teutatis was millions of kilometers away and we were able to resolve
03:00surface rocks. We could see boulders. There are currently only two radar facilities in the world that
03:05have sufficient sensitivity for doing regular observations of near-Earth objects. Arecibo and
03:10Goldstone. Even the most powerful optical telescopes, and I'm talking even, you know, Hubble telescope,
03:15they can only see this asteroid as a point of flight. It is just too far and too small. It provides an
03:21extraordinary opportunity to get very detailed radar images. You are transmitting microwaves. It's
03:26propagating at the speed of light toward the asteroid. It is bouncing back and this radar echo is
03:33containing surface features of the asteroid. It's telling us about its rotation and it's very
03:38precisely pinpointing its distance from the radar. These asteroids were imaged with crown-based radar.
03:47BL-86 revealed it has its own moon and asteroid HQ-124 passed very close to Earth, some three and a
03:55quarter times the distance to the moon. It is due to return sometime in the 24th century.
04:03Scientists are looking much more closely at these objects for their potential to pass through Earth's
04:08orbital plane and perhaps pose a threat.
04:16The most common type of asteroid is the C-type carbonaceous, accounting for about 75% of known asteroids.
04:25The probe near Shoemaker was the first dedicated asteroid probe launched by NASA.
04:36It photographed 253 Mathilde, a C-type, then moved on to 433 Eros, the largest visited at the time,
04:44where it orbited, took extensive measurements and, more by accident than good planning,
04:50landed on the asteroid, the first probe to do so.
05:02Deep Space 1, an experimental NASA probe, was sent to investigate an asteroid, 9969 Braille.
05:10Technical errors returned poor imagery. However, the probe continued on to its second rendezvous,
05:16for the first time with a comet, 19p Borrelli.
05:21Comets are closely related to asteroids, but originate from the cold, dark outer boundaries of our solar system.
05:28Comets are bodies in our solar system that have been left over ever since the solar system formed,
05:35some 4.5 billion years ago. And therefore, when we look into comets, we look into the past of our
05:41solar system. And so, by investigating the details of comets, how they formed, how they evolved,
05:47we can actually have a glimpse into how our solar system formed, and in the end, how the Earth formed, and why we are here.
06:10Comets have been recorded throughout history, as they are easily observed when close to the Sun,
06:15often considered an omen. One comet of note was Halley's.
06:27In 1986, Halley's comet returned once again, and this time it was met with a veritable armada of space probes.
06:34The first attempt at a space rendezvous was with the International Comet Explorer, or ICE. It passed through
06:46the tail of comet 21B-Giacobini-Zinnah on its way to meet Halley. The European Space Agency sent Giotto.
06:55The Russian and French sent two probes via Venus, Vega 1 and Vega 2. Japan sent Suisei and Sakikage,
07:04that country's first deep space probes. Their measurements went on to refine the targeting for Giotto,
07:10to make a much closer pass of the comet's nucleus than first planned. In 1994, astronomers and
07:17scientists were given an unexpected treat. Comet Shoemaker-Levy broke apart and struck Jupiter
07:24in a spectacularly violent fashion. Comets required more study. The Stardust probe was dispatched to
07:32investigate 5535 Anne Frank, Wild 2, and then the Temple 1 comet. It returned a sample of cometary tail to Earth.
07:44Our biggest discovery that we did was looking at this cometary material that was returned from
07:48NASA's Stardust mission. And the Stardust mission went up, rendezvoused with the comet, brought back
07:54very small amounts of material, comet material and comet exposed material. We had basically one shot at
08:00looking at this and it was really pushing our limits of detection. So I spent about two years
08:04optimizing our technique, you know, really rehearsing, practicing, getting everything as
08:10as perfect as possible before the one day of doing measurements. It's sort of all leading up to one
08:15big, one big game, one big day. And also just working with meteorites and working with the cometary
08:20material, I'm working with something that's four and a half billion years old that very few people ever
08:24get to play with. And the few days of being able to do the actual measurements make up for all of the
08:31rehearsals that it takes.
08:42JAXA launched Hayabusa to study asteroid 25143 Itokawa and to retrieve a sample from the surface
08:49in a touch-and-go maneuver. The mission took a total of seven years to accomplish with the sample
08:55return pod retrieved from the Australian Outback in 2010.
09:08Launched a year earlier by the European Space Agency was a very ambitious spacecraft called Rosetta.
09:14It's goal? To land a probe on a comet, 67P Churyumov-Gerasimenko. Just getting there was
09:22to prove a challenge in astro-navigation.
09:26But when you want to rendezvous with a comet, you have to accelerate the spacecraft and
09:31match the same velocity that the comet has around the sun. So this is the problem, not only the distance,
09:37but also the velocity. There is no rocket that can give us the velocity needed to be as fast as
09:44the comet. I close to a planet and you use the gravitational attraction of the planet to
09:50actually accelerate your spacecraft.
09:58It passed by asteroids 2867 Steins and 21 Lutetia.
10:03Lutetia is a very strange target, a very strange asteroid. We believe that it may be a C-class asteroid,
10:13which means that it is very primitive. However, it shows from ground-based and also space-borne
10:19observations that Lutetia does not look completely like a C-type asteroid and we are really puzzled about
10:26what it really may be. The spacecraft then moved on to its primary target, Comet 67P.
10:33The nucleus is pulling the spacecraft out of its planned orbit and that can be seen as a
10:42shift in frequency of the transmitted radio signal from the spacecraft. And the extent of this frequency
10:51shift is a measure of the mass of the comet nucleus, so we are able to weigh the nucleus here.
11:00There is no ice at the top, so it's covered by a mantle that we consider is essentially made of
11:06organic material, that's why it's very dark. And this material is one of the key things we would like to
11:10explore and analyze. These organics may hold the secret to life on Earth.
11:16What it's all about is the carbon chemistry. How much did the comets bring to Earth? So was it just
11:25the right elements, the right building blocks, or was there more information in it when these comets
11:32already arrived? To try and answer these questions, ESA attempted one of the most daring missions mankind
11:38has ever undertaken, to land a probe on the surface of the comet.
11:53Landing on a comet is one of the hardest things that has ever been done by the human species.
12:01This is the comet. It's roughly a one in thousand model, so the real thing is thousand times bigger.
12:06The landing site is roughly here, which we are aiming for to deliver the lander. It's the
12:11flattest part we could find. What we are studying at the comet with the instruments are basically what
12:16are the ingredients, which materials are present, and coming back to one of the objectives of the
12:21mission, how complex are the materials present at the comet. Landing means flying very, very slowly over the
12:31comet, and then gently pushing away the lander. It's not a landing like you can imagine on the moon,
12:37where you come with rockets and you have to break. Here the problem is the opposite. You have to really
12:43touch gently the comet. The forces in board are very small. If I get meaningful data, that would be just
12:50marvelous. If the descent works, the landing is okay, we receive a sample, and the whole thing runs smoothly,
12:56that would be just great. But we need a lot of luck, really. And we had a lot of luck already.
13:03So we are sitting on the surface. Phila is talking to us. More data to come and to be analyzed right now.
13:20Going down, which it should do, of course. We are there. It's done its job. We are on the comet.
13:27The science has started now. We have the first results that give us the first comprehension of what
13:32we think the comet is, where it started from. Now, for the rest of the year, we'll watch how the
13:37comet evolves. We'll unlock how the comet works. We're looking at where the gas and the dust start
13:43to accelerate from the surface, and how that beginning of the coma, that birth of the coma, works.
13:48So how the coma develops as it does to higher altitudes. This region has only ever been theoretically
13:55constrained or modeled. These will be the first measurements we make in this area or this region,
14:00and that's a really big, important target for us. Eventually, the tiny probe shut down.
14:10Having Phila reactivated is not so likely, but it's not impossible. Phila was designed to hibernate,
14:16was designed to switch off and be able to reactivate itself. Of course, we expected this to be a
14:22duration of a few days or a few weeks, not a few months. But okay, we'll see. Maybe we are lucky,
14:28and the units have survived these months, and we'll reactivate in June, July.
14:35While observing the asteroids, scientists were surprised to find one with what looked like a cometary tail.
14:42After careful study, scientists realized they were observing the results of the impact of two asteroids.
14:48596 Shela had been struck at high speed by a small asteroid. The impact hit with the force of a 100-kiloton nuclear bomb.
15:04NASA had done something similar with Deep Impact, a probe sent to comet Temple 1, where it dispatched a
15:10kinetic impactor, which struck the comet to study the impact and the debris thrown up as a consequence.
15:29NASA launched another small ion-powered probe, Dawn, which also had an extraordinary mission.
15:59to travel deep into the asteroid belt between Mars and Jupiter.
16:16Its target, two of the largest asteroids in the solar system.
16:20Dawn rendezvoused with Forvesta and orbited it for over a year, returning a wealth of data.
16:38Dawn then departed and cruised towards Siris, the largest of the asteroids, a planetoid,
16:43premiered it for over a year, when it has obtained orbit and begun its study.
16:51coaster, L
16:58chicos
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17:03australian
17:05Jaxa, the Japanese space agency, has recently launched a second Hayabusa probe.
17:34This one with many improvements over the first.
17:38Its target is the C-type asteroid, 1999 JU3.
17:47It's expected to reach its destination in three years, collect samples, and return to
17:52Earth by 2020.
18:12NASA has announced the OSIRIS-REx sample return mission to asteroid 1999 RQ-36, better known
18:19as Bennu.
18:33It's expected to launch sometime in the near future, and after a two-year journey, orbit
18:38and map the surface before touching down to retrieve two kilograms of material.
18:44The probe samples return is expected in 2023.
18:51It's expected to be a trip to the USIRIS-REx sample share once the national login becomes
19:00installed in 2022, the ability to compute and use the current aircraft.
19:04The space called an international aircraft carrier, and if you did, you would need to
19:07get the nearest vehicle to the USIRIS-REx sample.
19:12The next source is taken to the ANTRUES-REx sample.
19:46There is also a practical reason to study asteroids.
20:02In 2013, an asteroid with a mass of about 9,100 tons exploded over Chelyabinsk, Russia,
20:09with the force of 20 Hiroshima bombs, causing 1,500 injuries and damaging 7,000 buildings.
20:16It isn't the first asteroid strike on Earth, as the dinosaurs can attest to, and probably
20:36not the last.
20:46Through the United Nations, ESA and other major space agencies have established a safeguard
20:51program.
20:54The NEOWISE data have returned two very important findings.
21:01First, we've been able to determine that we've found 93 percent of all the near-Earth asteroids
21:05that are out there that are larger than one kilometer.
21:08We've also been able to tell that there are somewhat fewer near-Earth asteroids that are
21:12larger than 100 meters than were previously thought.
21:15However, fewer does not mean none.
21:17That leaves about 15,000 asteroids larger than 100 meters that remain to be found.
21:23This advisory group is also planning intervention missions if needed.
21:29We think that we can cope with deflecting an asteroid with two different technologies mainly.
21:37One is what we call kinetic impactor, hitting the asteroid and pushing it out of the way.
21:42The second one is take a heavy spacecraft and use it as, say, a gravity tractor, so by the
21:48mass of the spacecraft you pull the asteroid away.
21:58There is one project in the planning stage to snag a small asteroid in the near-Earth region
22:03and drag it into a lunar orbit.
22:26There it can be met by astronauts aboard an Orion capsule who will study the asteroid first-hand,
22:49take extensive samples, and return to Earth.
22:52For the more we know, the better prepared we are to protect our place in the solar system.
23:21The solar system.
23:51Transcription by CastingWords