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Hayabusa 2 (Хаябуса-2), Procyon – H-IIA F26 – Танэгасима – 03.12.2014 04:22:04 UTC, (успешно)
Nov. 13, 2018

★ Hayabusa2 status (the week of 2018.11.05) ★

After completing important operations such as TD1-R3 and BOX-C2, the spacecraft returned to the home position at an altitude of 20km. This week, we performed a health check for the optical navigation cameras (ONC), the thermal infrared imager (TIR) and the near infrared spectrometer (NIRS3). Although we normally image Ryugu, for these tests we changed the spacecraft attitude to intentionally remove the asteroid from the field of view and image deep space (a so-called ‘dark observation’). Observing dark deep space allows us to investigate the level of noise in the observation equipment. This will be the third dark observation after arriving at Ryugu.

2018.11.13 N. S.
Nov. 20, 2018

★ Hayabusa2 status (the week of 2018.11.12) ★

This week, Hayabusa2 performed the necessary range measurements and ΔV adjustments to maintain an altitude of 20km from the asteroid while preparing for the approaching solar conjunction operation next week. We also conducted science observations with the ONC, TIR and NIRS3, downloaded the acquired data and checked the health of the spacecraft bus equipment. In particular, the RCS (chemical propulsion system), TCS (temperature control system) and AOCS (altitude control system) were checked for use during the operation preparation phase next week. Since the spacecraft will take observations during the period when communication with Japan's Usuda ground station is not possible, the data download will be performed by the overseas groundstations at midnight. As the spacecraft is now in the same direction as the Sun, Hayabusa2 will be followed by the dayside country on Earth. This is like the poem by Shuntaro Tanikawa, entitled “Morning Relay”:
“We are relaying morning, from longitude to longitude, taking turns protecting the spacecraft”.

2018.11.20 S.H. & M.A.
HAYABUSA2@JAXA‏ @haya2e_jaxa 3:41 - 23 нояб. 2018 г.

[Conjunction] Today (Nov 23), ΔV (acceleration) was changed to move away from Ryugu: the solar conjunction operation has begun. Hayabusa2 started moving from the home position away from Ryugu direction of the Sun) at ~12 cm/s to begin an orbit that will extend out to 100km.

3:47 - 23 нояб. 2018 г.

[Conjunction] This operation reminded us of the approach to Ryugu. After the successful ΔV, the declaration of success was announced in the control room by the project member in charge of the solar conjunction orbit planning and there was applause.

4:03 - 23 нояб. 2018 г.

[Conjunction] ΔV is based on a trajectory that was finely tuned by the orbit and navigation teams during the conjunction orbit evaluation meeting yesterday (November 22).

4:04 - 23 нояб. 2018 г.

[Conjunction] Whether the spacecraft flies as planned depends on how accurately solar radiation pressure, asteroid gravity and solar tidal forces can be determined. We plan to make a ΔV adjustment around November 30.
Nov. 27, 2018

★ Hayabusa2 status (the week of 2018.11.19) ★

Hayabusa2 has entered the conjunction period where the spacecraft is very close to the Sun as seen from Earth. In preparation for conjunction in the first half of this week, range and DDOR (Delta Differential One-way Range) measurements were performed for the orbital determination, and attitude control was also done. After rotating the spacecraft attitude by 180 degrees on the z-axis, Ryugu seen with the onboard ONC turned upside down. On Labor Thanksgiving Day (23rd) thrusters were used to put the spacecraft safely into the orbit planned for conjunction. We conducted further range and DDOR measurements and we will verify the precision of the orbit and make fine adjustments. Next week, the angle between Hayabusa2 and the Sun will decrease further and telemetry data can no longer be transmitted.

2018.11.27 R.T.
Dec. 7, 2018

★ Hayabusa2 status (the week of 2018.11.26) ★

To guarantee the safety of the mission during the period of solar conjunction, the spacecraft was ins erted into a “conjunction trajectory” last week on 2018.11.23. Hayabusa2 will reach its maximum distance of 110km from Ryugu on 2018.12.11 and return to the home position at an altitude of 20km on 2018.12.29. Since even small errors from the designated trajectory may result in an undesired close approach or —in the worst case— a collision with Ryugu, we have carefully measured and evaluated the spacecraft's trajectory after insertion. On 2018.11.30, Hayabusa2 reached a distance of around 75km from Ryugu and the first Trajectory Control Manoeuvre (TCM01) was performed. TCM01 was a ΔV of 3.8 mm/s given along the z-direction (towards Earth). The effect of the solar corona made the resultant ΔV difficult to assess with the two-way doppler measurement compared with past operations. Despite this difficulty, we could confirm the actual ΔV was successfully given with an estimated val ue of 3.77 mm/s (99.21% of the designated ΔV). Next orbital manoeuvre is scheduled after the end of the deep conjunction phase on Christmas Day (2018.12.25). During deep conjunction, only attitude manoeuvres are scheduled — one every few days— to ensure the Earth is tracked. Although it will be difficult to obtain telemetry data from the spacecraft during deep conjunction, we will take the chance to gain and accumulate valuable experience from the conjunction operation by performing radio science and communication tests. We will utilize the Ka-band capability as well as introduce “Beacon Operations” to obtain the needed minimum amount of spacecraft data on the ground.

2018.12.03 Y.T.2 & S.S.
HAYABUSA2@JAXA‏ @haya2e_jaxa 20:15 - 9 дек. 2018 г.

We are now approaching the time during the solar conjunction where Hayabusa2 will be furthest fr om Ryugu. Today’s distance fr om Ryugu is about 109km. The spacecraft is moving away at about 6mm/s, but will change to begin the approach back toward Ryugu soon.

20:19 - 9 дек. 2018 г.

This is a diagram of the trajectory during solar conjunction. It is drawn in the Hill coordinate system; think of this as the coordinate system wh ere the Sun is in the negative x-axis direction. (1/2)

20:20 - 9 дек. 2018 г.

Hayabusa2 departed from the home position (altitude 20km) on November 23 and will pass the furthest point from Ryugu tomorrow (December 11). Red dots on the previous image show wh ere a trajectory control manoeuvre was performed. (2/2)
Dec. 13, 2018

★ Hayabusa2 status (the week of 2018.12.03) ★

We are continuing operations for the solar conjunction period, and full scale “Beacon Operations” have begun. This made us realise we are approaching the deepest part of solar conjunction. When the angle between Hayabusa2 and the Sun as seen fr om the Earth becomes 3 degrees or less, the radio waves transmitted by the spacecraft are affected by plasma near the solar surface. As a result, the intensity of the radio field received on Earth from Hayabusa2 fluctuates greatly and the telemetry which tells us about the state of the spacecraft may not be received. In this case, the “Beacon Operations” become a powerful tool. Information about whether the state of the spacecraft is normal (such as voltage and similar conditions) are represented like a binary number wh ere the “1” and “0” are replaced by the intensity of the transmitted radio waves from Hayabusa2. Therefore, even if the received radio field intensity on Earth is changing, the “1” or “0” can still be read by eye (in fact, we also make it possible to analyse this on a computer). As a result, Hayabusa2 was able to communicate “I am fine”. With this, we are ready to pass through the midst of solar conjunction!

2018.12.12. T.I.
Naming our MINERVA-II1 rovers

On September 21, 2018 (JST), the two MINERVA-II1 rovers (Rover-1A and Rover-1B) separated fr om the Hayabusa2 spacecraft to land on the surface of asteroid Ryugu, wh ere they successfully imaged and hopped across the asteroid surface autonomously. These two rovers have now been given names.

In Roman mythology, Minerva is the goddess of music, poetry, medicine, wisdom, commerce, weaving, crafts and magic. Works of art of the goddess frequently show her with an owl, which is considered her sacred creature and a symbol of wisdom. We therefore named our rovers after Minerva’s symbol of the owl. As the two rovers are slightly different from one another, we named them after the owl and the horned owl :

Horned owl from the French word:
Highly Intelligent Bouncing Observation Unit

Owl from English:
Observation unit with intelligent Wheel Locomotion

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Figure: The two overs of MINERVA-II1 and their names.

Dec. 20, 2018

★ Hayabusa2 status (the week of 2018.12.10) ★

In this week, we passed through the middle of solar conjunction on 12.12 and performed three pass operations (periods of connection opportunity with Hayabusa2) from the Usuda ground station and two using overseas stations. At the Usuda station, a telemetry operation was attempted after the “beacon operation”, but only three packets of data could be received. When the Sun moves in-between the spacecraft and Earth, communication is tough! From the overseas stations (Madrid and Goldstone) a ranging operation was performed that used Ka band radio waves. After this we tried to acquire telemetry, but this proved to be impossible. However, we were able to confirm that the command send from the ground reached Hayabusa2 which then operated as instructed. We have now passed through the toughest period and will be able to receive telemetry next week.

2018.12.19. M.H.
HAYABUSA2@JAXA‏ @haya2e_jaxa 8 ч. назад

The solar conjunction operation for Hayabusa2 is continuing and today (December 21), the distance to Ryugu is about 82km. The spacecraft is approaching Ryugu at about 6cm/s.

А чего это с миневр и маскота почти нету фоток, развернутых репортов о перемещениях с привязкой и прчих грунтозпмеров?

Жизнь - это падение в пропасть неизвестной глубины и заполненную туманом.
sol пишет:
А чего это с миневр и маскота почти нету фоток, развернутых репортов о перемещениях с привязкой и прчих грунтозпмеров?
Маскот давно не работает. Он ~16 часов отработал и теперь вечным сном спит (солнечных батарей у него нет).
А с Минервами недавно была пресс-конференция (на ютубе JAXA запись есть, если знаете японский :)), немножко новых фотографий показали... Но не выкладывают на сайте, да. Но Минервы сейчас тоже спят. Предположительно в тени.  
13 декабря прошёл очередной пресс-брифинг по работе зонда. Материалы брифинга опубликованы 25 декабря.

Hayabusa2_Press20181213_verK_EN2.pdf - 2.2 MB, 33 стр, 2018-12-25 11:34:29 UTC

Скрытый текст
Astrodynamics and the Gravity Measurement Descent Operation

Until now, “astrodynamics” has been one of the less frequently reported operations for Hayabusa2. In space engineering, the movement, attitude, trajectory and overall handling of the flight mechanics of the spacecraft is referred to as “astrodynamics”. For example, astrodynamics played an active role in the gravity measurement descent operation in August 2018. While this was a short time ago, let’s look at a few of the details.

From August 6 - 7, 2018, the “Gravity Measurement Descent Operation” was performed to estimate the strength of asteroid Ryugu’s gravity. Hayabusa2 initially descended from the home position at an altitude of 20km to an altitude of 6100m. Orbital control was then temporarily stopped to allow the spacecraft to “free-fall” towards Ryugu, moving due to the gravitational pull of the asteroid alone. When the altitude decreased to about 850m, the thrusters were instantaneously fired to give the spacecraft an upward velocity, whereupon Hayabusa2 performed a “free-rise” to an altitude of about 6100m (the spacecraft’s movement here is similar to throwing a ball vertically upwards).

From the spacecraft’s motion during the free-fall and free-rise, the strength of Ryugu’s gravity could be measured and the mass of the asteroid obtained. As a result of this measurement, the mass of Ryugu was calculated to be about 450 million tons.

The shape and volume of Ryugu are known thanks to the construction of the three-dimensional shape model (article on July 11: http://www.hayabusa2.jaxa.jp/topics/20180711bje/index_e.html). Using this volume and the measured mass of Ryugu from the gravity measurement descent operation, the average density of the asteroid can be calculated. The average density and shape of Ryugu could then be used to find the gravitational strength (gravitational acceleration) on the surface of Ryugu, which was found to have the following distribution:

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Figure 1: Distribution of the gravitational acceleration on the surface of asteroid Ryugu (image credit: JAXA).

The gravitational acceleration on the surface of Ryugu is approximately 0.11~0.15 mm/s2, which is about eighty thousandths (~ 1/80000th) the strength of the Earth’s gravity and a few times stronger than that of Itokawa. We can additionally see that the gravity near the poles of Ryugu is stronger than near the asteroid’s equator. This is due to the equatorial ridge protruding from the surface.

The information on the asteroid’s gravitational acceleration obtained through this method has been used for operations that approach close to the surface of Ryugu. Of course, it will also be used during touchdown. The gravity measurement descent operation described here is one application of astrodynamics. The astrodynamics team for Hayabusa2 use a variety of similar methods to estimate the trajectory of the spacecraft and Ryugu, and to evaluate the dynamic environment for operating around Ryugu.

Hayabusa2 project
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