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Raumfahrt - JAXA´s Asteroid Explorer Hayabusa-2 auf Asteroid 1999 JU3 gelandet-Update-14

6.04.2019

The Crater Search Operation
(Pre-SCI): CRA1

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Figure 1: Area to observe during the CRA1 operation (image credit: JAXA).

Currently, we have scheduled the small carry-on impactor operation (SCI operation) for the first week in April. The purpose of the SCI operation is to create a crater on the surface of Ryugu, and it is important to be able to compare the asteroid surface before and after the SCI operation. Before performing the SCI operation, we therefore decided to observe the area where the crater is likely to be generated. This is the “Crater Search Operation (Pre-SCI)” (CRA1). The same observational procedure will be performed after the SCI operation and denoted “Crater Search Operation (Post SCI)” (CRA2).

The CRA1 operation will take place between March 20 – 22, 2019. Descent preparation work will start on the 20th and the descent will begin from the 21st. Observations at the lowest altitude reached (approximately 1.7km) will be from the 21st to 22nd and the spacecraft will ascend on the 22nd. Figure 1 shows the site that will be observed. This area includes the SO1 region that was observed during the Descent Observation Operation (DO-S01) conducted between March 6 – 8.

The operation schedule is known in Figure 2. Hayabusa2 begins its descent on March 21 at 08:57 JST (onboard time) with a speed of 0.4 m/s. On the same day at around 19:17 JST, the speed will be reduced to about 0.1 m/s. The spacecraft will continue to descend and reach the lowest point (altitude approximately 1.7km) on March 22 at around 03:32 JST and continuously observe at that altitude for a while. Hayabusa2 will begin to ascend at 05:08 JST and return to the home position. Note that the times listed here are the planned values and the actual operation times may differ.

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Figure 2: Schematic diagram of the CRA1 operation (image credit: JAXA).
Note: times listed here may differ from the actual operation.

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Revised illustrations of Hayabusa2

At the beginning of the Hayabusa2 Project, realistic illustrations were drawn by Akihiro Ikeshita. These illustrations have now been revised to match the actual asteroid Ryugu. These illustrations show our arrival at Ryugu and the first touchdown.

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SCI (Small Carry-on Impactor)
Operation Schedule

The Small Carry-on Impactor (SCI) operation will take place between April 3 – 6. This is an impact experiment to create an artificial crater in a designated area. Please see the table and figure below for information regarding the operation schedule.

SCI operation main schedule

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Notes:

  • Time: Approximate scheduled time. UTC is Universal Time, JST is Japan standard time. There is a possibility that this may change during operation.
  • Spacecraft line-of-sight velocity: This is the speed along the line-of-sight relative to the asteroid (minus is towards the asteroid, positive is away). Numerical value is displayed only when speed control is performed. After a speed control operation, the speed changes due to the gravitational force of Ryugu and other celestial bodies.
  • Altitude: Approximate distance from the surface of Ryugu
  • Since the spacecraft line-of-sight velocity and altitude become complicated after the SCI separation, they were omitted here.

 

Schematic of the SCI operation

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Figure 1: Schematic diagram of the SCI operation part #1. The operation from the home position to SCI separation is shown here. The graph on the left shows the change in the spacecraft position with time. On the right, the spacecraft position is shown in the x-z coordinate system (home position coordinate system). The times listed are the scheduled time and may differ from actual operations. (Image credit: JAXA.)

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  • Figure 2: Schematic diagram of the SCI operation part #2. The operation from SCI separation to the return to the home position is shown. In this figure, the position of the spacecraft in the x-z coordinate system is shown schematically. The time is the scheduled time and may differ from actual operations. (Image credit: JAXA.)

 

Crater generation area

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Figure 3: Area selected for creating the artificial crater during the SCI operation. The yellow ellipse in the left figure described as the “CRA1 operation observation area” roughly corresponds to the crater generation area (blue circle in the right figure). (Image credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST.)

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Navigation Images from the SCI
operation

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Operational Status of Asteroid Explorer Hayabusa2's SCI

National Research and Development Agency
Japan Aerospace Exploration Agency (JAXA)

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An image of separated SCI taken with the Optical Navigation Camera - Wide angle (ONC-W1) on April 5, 2019 at an onboard time of around 10:56 JST
Photographed from approximately 500 meters above Ryugu
Image credit: JAXA, The University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, The University of Aizu, AIST

 

The National Research and Development Agency Japan Aerospace Exploration Agency (JAXA) has carried out operations to separate the SCI (Small Carry-on Impactor) onboard the asteroid explorer Hayabusa2 for deployment to the asteroid Ryugu.

The SCI separation has been confirmed using Hayabusa2’s Optical Navigation Camera-Wide (ONC-W1), it is our assessment that separation of the SCI went as planned.

In order to avoid the impact given by the operation of the small carry-on impactor (SCI), Hayabusa2 was moved to the safety zone on the backside of the asteroid before the SCI began to be operated. Hayabusa2 is operating normally.

We will be providing further information once we have confirmed whether the SCI is operating and whether a crater has been created on Ryugu.

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Asteroid Explorer Hayabusa2’s SCI Put into Operation

April 5, 2019 (JST)

National Research and Development Agency
Japan Aerospace Exploration Agency (JAXA)

The National Research and Development Agency Japan Aerospace Exploration Agency (JAXA) separated the SCI (Small Carry-on Impactor) onboard the asteroid explorer Hayabusa2 for deployment to Ryugu and put the SCI into operation.

After the start of the operation, the camera (DCAM3) separated from Hayabusa2 captured an image that shows ejection from Ryugu’s surface, which implies that the SCI had functioned as planned.
Hayabusa2 is operating normally. We will be providing further information once we have confirmed whether a crater has been created on Ryugu.

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This image captured by the camera separated from Hayabusa2 (DCAM3) shows ejection from Ryugu’s surface, which was caused by the collision of the SCI against Ryugu.

Image taken at 11:36 a.m., April 5, 2019 (Indicated by the camera, Japan time)
Image credit: JAXA, Kobe University, Chiba Institute of Technology, The University of Occupational and Environmental Health, Kochi University, Aichi Toho University, The University of Aizu, and Tokyo University of Science

Quelle: JAXA

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Update: 7.04.2019

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How Hayabusa2 made history with man-made crater attempt on asteroid

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Yuichi Tsuda, who leads the Hayabusa2 project at the Japan Aerospace Exploration Agency, speaks at a press conference in Sagamihara, Kanagawa Prefecture, on Friday.

Space explorer Hayabusa2’s successful operation on Friday to create a crater by striking the asteroid Ryugu with a lump of copper, when confirmed, will mark the first such achievement in the world.

The mission is considered to be one of the most difficult for the probe to accomplish.

The Japan Aerospace Exploration Agency (JAXA) designed a new impactor specifically for Hayabusa2 to shoot the copper lump at the asteroid, demonstrating the high technology Japan has developed for space exploration.

 

Going beyond Hayabusa

“We successfully established new means of space exploration,” said Yuichi Tsuda, JAXA’s Hayabusa2 project leader, at a press conference on Friday evening, stressing the significance of the latest achievement which built on the foundations laid down by its predecessor, the original Hayabusa.

 

The first Hayabusa probe landed on the asteroid Itokawa in 2005. Hayabusa2, which was built using the same basic design, shares its purpose of bringing back samples of rocks, among other materials, from asteroids to Earth.

But if Hayabusa2 was just a rehash, it would be hard to gain public support for injecting a total of about ¥29 billion (about $260 million) from the state’s coffers into the project.

Taking this into consideration, Hayabusa2 was additionally given the unprecedented task of using an impactor to create a crater on an asteroid’s surface to enable it to collect samples from the asteroid’s interior that have not deteriorated or been affected by such factors as sunlight.

The conical small carry-on impactor with a diameter of about 30 centimeters works by ejecting a copper plate attached to its base. The impactor ejects the copper plate, which is about five millimeters thick and weighs about two kilograms, using explosive power to accelerate its speed to two kilometers per second and strike it against the asteroid’s surface. As the impactor was built specifically for this task, an explosives manufacturer took part in its development.

Aiming and firing the impactor at a point on the asteroid’s surface required meticulous accuracy. It was “like shooting an arrow on horseback while blindfolded,” according to a person close to the project.

From analysis of images taken by an observation camera, it is likely that the impactor operated as planned, and it is thought a crater was created on the asteroid’s surface as a result.

The U.S. National Aeronautics and Space Administration has in the past struck a comet with a lump of metal, but Friday’s attempt is the first such achievement on an asteroid.

“The significance of Hayabusa2’s exploration has grown greater. The rest of the world will look to emulate this achievement,” said Junya Terazono, associate professor at the University of Aizu.

 

A space odyssey

One major struggle for the project team scientists in the latest mission was how to protect Hayabusa2’s body from debris from the explosion to catapult the copper lump, as well as fragments ricocheting from the asteroid.

Hayabusa2 is located about 310 million kilometers from Earth, and it takes about 17 minutes for a signal to reach it, or vice versa, making it impossible to send commands instantaneously.

For that reason, the team decided to carry out the mission using an automatically controlled system. The complicated movement, in which Hayabusa2 evacuates while changing its direction a number of times between horizontal and vertical after releasing the impactor and an observation camera, was all programmed into the system in advance.

In February, Hayabusa2 touched down precisely on the planned landing site, which is 6 meters in diameter, on Ryugu.

The team members were able to draw from this experience an understanding of the tendencies of each of 12 altitude-controlling reaction wheels installed on Hayabusa2, building up their confidence in probe-control technology.

Stressing that they learned from the touchdown experience, Takashi Kubota, a member of the team, said, “With the technology that enables the probe to move freely, it can expand the possibilities of exploration in outer space.”

 

Careful consideration

Hayabusa2 will take about two weeks to return to its home position at a 20-kilometer altitude from Ryugu. Then after that, from April 22 or later, it will descend to the asteroid to confirm whether a crater has been formed on the surface. At some time as early as May, it will again land on the crater or its vicinity on the asteroid to start collecting samples of fragments.

But whatever happens next, the team believes Hayabusa2 has already managed to collect enough samples from its first landing on the asteroid in February.

It will also be able to gain scientific findings by observing the vicinity of the crater from above. A senior JAXA scientist said, “If there’s a risk that the body of Hayabusa2 may get damage by landing on the asteroid again, it will not be necessary for us to press ahead with it.”

JAXA will weigh up the pros and cons of landing the probe again after carefully assessing the safety of doing so.

Quelle: The Japan News

 

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