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Hayabusa 2 (Хаябуса-2), Procyon – H-IIA F26 – Танэгасима – 03.12.2014 04:22:04 UTC, (успешно)
 
Опубликованы материалы пресс-брифинга 09.05.2019

Hayabusa2_Press20190509_ver6_en4.pdf - 4.2 MB, 31 стр, 2019-05-13 05:12:41 UTC

 
 
 
 
 
 
http://www.hayabusa2.jaxa.jp/en/topics/20190513e_Shape/
Цитата
Ryugu’s fast-spinning past shaped the asteroid’s western hemisphere!

The Astrophysical Journal Letters is an academic journal for research results in astronomy and astrophysics published in the United States. Our paper on the shape of asteroid Ryugu was recently included in the journal (publication date: March 26, 2019) entitled:

Hirabayashi, M., and 28 colleagues, “The western bulge of 162173 Ryugu formed as a result of a rotationally driven deformation process,” The Astrophysical Journal Letters, 2019, 874, 1, doi:10.3847/2041-8213/ab0e8b .
https://iopscience.iop.org/article/10.3847/2041-8213/ab0e8b

In this article, we will highlight our main findings fr om this research.

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Ryugu has the shape of an abacus bead, which was introduced in detail in three recent papers led by members of the Hayabusa2 team –Sei’ichiro Watanabe, Seiji Sugita and Kohei Kitazato—who published in the academic journal, Science Magazine.

Prior to the spacecraft arriving at Ryugu, the asteroid’s shape was known to be simply “round-ish” but the angular abacus bead structure was not yet seen. How did such a shape arise? In truth, while there are various hypotheses, no certain explanation has been found. The most prominent idea is the high-speed rotation theory, which was described in detail in the paper by Sei’ichiro Watanabe.

In this new paper, we focused on the fact that while at first glance, the shape of Ryugu is roughly axisymmetric about the rotation axis, a closer inspection shows this is not exactly true. As introduced in the paper led by Seiji Sugita, the surface layer of Ryugu differs between the east and west regions, bordered by the Tokoyo and Horai Fossae. The region to the west, commonly known as the western bulge, has fewer craters and a smoother surface than the region to the east. In addition, the Ryujin Dorsum (equatorial ridge) has a very steep inclination angle where it passes through the western bulge (figure 1).


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Figure 1: When viewed from a certain direction (90 degrees west), the angle of the equatorial ridge on Ryugu becomes very sharp. This feature is also discussed in the paper led by Sei’ichiro Watanabe. (Hirabayashi, M.+, 2019)

In this paper, we made a structural analysis of Ryugu to examine the formation of the western bulge. Using this, we could explore the result of structural relaxation that would occur after any changes to the shape of Ryugu that may have happened in the asteroid’s past. The detailed structural analysis suggested that the mysterious difference in surface properties between Ryugu’s east and west regions may have been due to structural changes (such as a landslide or internal alternations) during a period in Ryugu’s history when the asteroid was spinning at high speed (figure 2). This result supports the high speed rotation theory for explaining Ryugu’s odd shape.


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Figure 2: While Ryugu was rotating at high speed, part of the asteroid’s interior suffered structural collapse (yellow). There is no collapse in the green area. The region wh ere structural collapse did not occur overlaps with the region of the western bulge, indicated by the dashed line (Hirabayashi, M.+, 2019).

The ideas in this paper were triggered by the frequent discussions that were took place within the ONC (Optical Navigation Camera) and Science teams. After arriving at Ryugu, new images were sent from the spacecraft nearly daily and prompted a limitless series of questions that all began “why is this here?” Finding the answers to these questions was kind of like solving a puzzle.

Questions were discussed daily within the ONC and Science teams at regular meetings. “No – that can’t be it, lol!” was a key phrase for suggesting great ideas. Ideas can be hidden all over the place and tracking these down is fun. These active mid-summer discussions with the ONC team are all part of this paper.

Lastly, this paper should be considered to the beginning of further research, rather than a final outcome. It provides still more motivation to think about the new research that will come next. How was this abacus bead made in the Universe? We look forward to discovering more.

Masatoshi Hirabayashi (ONC Team Co-I、Auburn University)
Hayabusa2 Project
2019.05.13
 
https://ria.ru/20190513/1553443511.html
Цитата
Зонд "Хаябуса-2" сбросит "маяк" на астероид в середине недели
12:42

МОСКВА, 5 апр – РИА Новости. Зонд "Хаябуса-2" передал на Землю первые детальные фотографии рукотворного кратера, порожденного взрывом бомбы на астероиде Рюгю, куда он опустится в среду или четверг для установки своеобразного "маяка". Об этом сообщили участники миссии на пресс-брифинге в штаб-квартире JAXA.
Цитата
"Взрывное устройство упало на поверхность астероида почти идеально в той точке, куда мы планировали его сбросить. Его подрыв привел к тому, что на Рюгю возникла новая выемка диаметром в 20 метров, а соседние с ней булыжники были разбросаны по всем окрестностям нового кратера", — заявили исследователи.
Скрытый текст

В первых числах апреля пилоты и научная команда миссии успешно реализовали вторую фазу "бомбардировки" астероида – сброс на его поверхность достаточно увесистой "бомбы", чья масса составляет примерно 15 килограмм. Она содержала в себе 4,5 килограмма октогена и была устроена таким образом, что вся сила взрыва оказалась направлена вниз, в сторону поверхности астероида.

Последующий месяц зонд потратил на решение двух задач – он вернулся в исходное положение, которое он был вынужден покинуть ради защиты от взрыва, и после этого начал поиски кратера, возникшего на поверхности астероида после сброса бомбы.

Он был найден в конце апреля, и после этого "Хаябуса-2" совершила серию "нырков" в сторону поверхности Рюгю для получения детальных снимков этой выемки и оценки последствий взрыва. Как оказалось, подрыв этой бомбы привел к рождению крупного кратера, чья глубина составляла примерно 2-3 метра, и "катапультированию" большого числа булыжников и фрагментов пород в безвоздушное пространство.

Эти данные, как отмечает Сейдзи Сугита (Seiji Sugita) из университета Токио (Япония), были критически важны для оценки возраста поверхности Рюгю. Дело в том, что ученые оценивают время формирования астероидов по числу и размерам кратеров. Они, в свою очередь, сильно зависят от того, как сильно частицы их "почвы" и пород сцеплены друг с другом.

По этой причине текущий облик Рюгю мог сформироваться как 9 миллионов лет назад, если его грунт отличается крайне высокой рыхлостью, так и более 180 миллионов лет назад в обратном случае. Наблюдения за последствиями взрыва, как отметил Сугита, уже помогли ученым заметно сузить разброс в значениях, однако максимально точные данные будут получены, если "Хаябуса-2" сможет выполнить "бонусную" часть миссии и забрать образцы материи из кратера.

Для решения этой задачи у японского зонда не так много времени. Сейчас Рюгю сближается с Солнцем, и в начале июля, как показывают расчеты пилотов миссии, его поверхность станет слишком горячей для безопасной посадки аппарата.

По этой причине первую посадку в зоне сброса бомбы "Хаябуса-2" проведет уже в середине этой недели. Завтра зонд начнет снижение, и в среду или в четверг он сблизится с поверхностью астероида рядом с той точкой, где возник кратер. Помимо получения новых детальных снимков этой выемки, японский аппарат сбросит туда специальный светоотражающий маячок, который поможет ему осуществить посадку в кратер в конце мая или в июне.

Пока ученые не приняли окончательного решения насчет того, куда именно сядет "Хаябуса-2" и стоит ли проводить эту опасную процедуру в принципе. Как надеются исследователи, новые снимки и другие данные, которые зонд соберет в ближайшие дни, помогут им определиться с этим выбором и избежать потенциально фатальных проблем в будущем.
 
Цитата
Hayabusa2 SCI tests

The Planetary Society

Опубликовано: 5 апр. 2019 г.

WARNING: LOUD. This video shows two camera angles from a test of Hayabusa2's SCI experiment on Earth in 2011. The copper projectile fires from a concrete bunker, penetrates several gridded targets, and hits a mound of dirt simulating asteroid Ryugu 100 meters away. For more, visit http://www.planetary.org/explore/spac.... Credit: JAXA / Jason Davis / The Planetary Society
https://www.youtube.com/watch?v=4IsTheUJbgk (0:13)
 
Цитата
HAYABUSA2@JAXA‏ @haya2e_jaxa 7 ч. назад

[PPTD-TM1] May 15, 2019 at 11:00 JST: the first shift for the PPTD-TM1 has begun, which is an operation to drop a target marker for future touchdown. Preparation for the descent began yesterday, but at this time the spacecraft is at the home position (about 20km in altitude).


7 ч. назад

[PPTD-TM1] May 15 at 11:47 JST: Gate 1 check. We have confirmed both the spacecraft and ground system are normal. Work is progress for the spacecraft descent.
 
Цитата
HAYABUSA2@JAXA‏ @haya2e_jaxa 6 ч. назад

[PPTD-TM1] May 15, 12:47 JST. The control room has confirmed that the spacecraft began descent as scheduled. The descent speed is about 40 cm/s. The onboard time for the start of descent was 12:31 JST, with a propagation delay time less than 16 minutes.
 
http://www.hayabusa2.jaxa.jp/en/topics/20190515e_PPTD-TM1/
Цитата
The Pinpoint Touchdown – Target Marker 1 (PPTD-TM1) operation

While the decision to perform a second touchdown has not been finalized, preparation is underway. The first operation is to separate a target marker. This operation is denoted PPTD-TM1: Pinpoint Touchdown – Target Marker 1. The original mission plan was to perform a pinpoint touchdown when touching down near the crater generated by the Small Carry-on Impactor (SCI), which gives this operation its name. In fact, we have already used the pinpoint touchdown method during the first touchdown (February 22, 2019) but we retained this operation name.

This operation will attempt to deploy the target marker in the S01 area on the assumption that the S01 area is the region for touchdown. S01 has previously been observed during descent observation operations in March and April this year. Its location is shown in Figure 1.


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Figure 1: S01 area.
(Image credt:JAXA)


Figure 2 shows an enlarged image near the S01 area. The S01 area is near where the SCI impacted the surface of Ryugu, which is marked in Figure 2 as area C01. In the same figure, L14 is a newly sel ected area located near the SCI collision point as another candidate area for the second touchdown. All the touchdown candidate points are marked with yellow circles of size about 6 to 12m in diameter. During this operation, we choice S01 to drop the target marker.


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Figure 2: The SCI impact area and surrounding region (captured before the impact of the SCI).
(Figure credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagota University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST.)


The PPTD-TM1 operation will be performed from May 14 to 16, 2019. Descent preparation will take place on May 14. From 12:31 May 15 JST (on-board time), the spacecraft will begin its descent at 0.4 m/s. The speed will be reduced to 0.1 m/s at 22:51 on the same day and the descent will continue down to an altitude of approximately 35m at 11:25 on May 16 and an altitude of approximately 10m at 11:42, the lowest point. The target marker will be separated just before reaching the lowest altitude. The spacecraft will begin to rise shortly afterwards and return to the home position on May 17. The operation schedule is shown in Figure 3. Please be aware that the actual operation time may differ from the planned values shown here.


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Figure 3: Schematic of the PPTD-TM1 operation (figure credit: JAXA).
Note: times listed may differ fr om actual operation


Figure 4 shows the sequence at low altitude. At this time, the distance measurement to the surface of Ryugu is performed using the Laser Range Finder (LRF), but the LRF data is not used to control the spacecraft. After the first touchdown, the LRF performance may have changed and this will be first checked during the operation. Instead, the distance measurement will only be performed with the laser altimeter (LIDAR). The spacecraft will make a slight zig-zag while rising in order to obtain three-dimensional information about the surface through parallax.


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Figure 4: Sequence at low altitude (figure credit: JAXA).

Hayabusa2 Project
2019.05.15
 
Цитата
HAYABUSA2@JAXA‏ @haya2e_jaxa 2 ч. назад

[PPTD-TM1] May 15 at 17:20 JST: A briefing has taken place as the shift changes to shift 2. The altitude of the spacecraft has passed 13 km.
 
Цитата
HAYABUSA2@JAXA‏ @haya2e_jaxa 17 мин. назад

[PPTD-TM1] May 15 at 20:25 JST. The altitude of the spacecraft is about 8km. (The time stated in these tweets will be the time the altitude was confirmed in the control room.)
 
Цитата
HAYABUSA2@JAXA‏ @haya2e_jaxa 1 ч. назад

[PPTD-TM1] May 15 at 23:24 JST: Gate 2 check. Spacecraft is slowing down as planned and the state of both the spacecraft and ground system is confirmed to be normal. The altitude of the spacecraft is about 4500m.
 
Цитата
HAYABUSA2@JAXA‏ @haya2e_jaxa 2 мин. назад

[PPTD-TM1] May 16 at 07:37 JST: the altitude has passed 1500 m.
 
Цитата
HAYABUSA2@JAXA‏ @haya2e_jaxa 1 мин. назад

[PPTD-TM1] May 16 at 09:05 JST: the altitude of the spacecraft has reached 1000m.
 
Цитата
HAYABUSA2@JAXA‏ @haya2e_jaxa 3 мин. назад

[PPTD-TM1] May 16 at 09:50 JST: the altitude of the spacecraft is about 750m.
 
Цитата
HAYABUSA2@JAXA‏ @haya2e_jaxa 4 мин. назад

[PPTD-TM1] May 16 at 10:43 JST: spacecraft altitude is 400m.
 
Цитата
HAYABUSA2@JAXA‏ @haya2e_jaxa 6 мин. назад

[PPTD-TM1] May 16 at 11:02 JST: the spacecraft altitude has passed 300m. This navigation image was received at 10:48 JST. The shadow of Hayabusa2 is now visible towards the left.

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