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TOPIC: HAYABUSA (MUSES-C) mission
Blobrana


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Itokawa
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Itokawa`s surface is devoid of craters.
One possibility for the lack of craters is that asteroid Itokawa is a rubble pile -- a collection of rocks and ice chunks loosely held together by their low gravity. If so, craters might be filled in whenever the asteroid gets perturbed by a passing planet -- Earth in this case.
Alternatively, surface particles may become electrically charged by the Sun, levitate in the microgravity field, and move to fill in craters.


Image taken on November 1st 2005.
Credit: ISAS/JAXA

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RE: HAYABUSA (MUSES-C) mission
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Location of the Usuda Deep Space Centre



Usuda Deep Space Centre.kmz (1kb, Google Earth file)

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A garbled image from the JAXA `Live` webpage captured at 4:58 JST
(see other back posts here for better picture)



Image Credit: JAXA/ISAS

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2005.11.20: Landing not be confirmed, but succeeded at dropping target marker with 880 thousand people's signatures

16:00 (JST):
Project Manager, Prof. Junichiro Kawaguchi: Hayabusa started descending at 21:00 JST, Nov 11. In fact the descending had been started before and we proclaimed "start descending" when the altitude from Itokawa's surface became 1km. We could aim the probe to the destination much more precisely than the past rehearsals. Finally we entered the "vertical descend" phase at 4:30 JST Nov 12 at the altitude of 400-500m, descending with the velocity 10cm/s along the line from the Earth to Itokawa. Everything worked well in this phase and I think we could keep Hayabusa's speed within 1cm/s during this descend.

Hayabusa continued descending 1 hours and reached to 54m. At 4:55 JST in this descending, we made decision to GO the landing.
We had preset the altitude to drop the target marker at 54m and we released the binding of the marker there, cutting the wire holding the marker. After that, Hayabusa decelerated 6cm/s at the alt.40m and released the target marker. We suppose the marker landed to Itokawa's surface after about 400 seconds.

At the alt. 35m we switched the altitude control system from rider(?) to the laser range finder. We use the laser range finder for the first time for altitude control, but it worked well.

After that Hayabusa took the image of the target marker and descended to it autonomously. This also worked well.

At the alt.55m, Hayabusa hovered using the laser range finder. Then it again descended slowly and we operated Hayabusa to keep its attitude along the surface of Itokawa. After this we intermitted the communication by the high-gain antenna and changed to the beacon mode, in which we can only monitor the altitude through the Doppler shift of the signal.

So far we have only the data of the Doppler shift to know what happened after that.

We think that Hayabusa descended at the speed of 2-3cm/s and entered the orbit that drift horizontally along the surface of Itokawa. Judging by this and another data, Hayabusa seemed not to touched down.
When Hayabusa stays long time at near the surface of Itokawa, its temperature would be high by the radiation from Itokawa, so we send command to ascend at 7:00 JST from NASA's station.

At that moment, Hayabusa entered the safe mode because the angle between the solar cell paddles and the Sun became too large. The reason why this happened is unknown so far.
After that we've succeeded to stop the spin of Hayabusa using the whole time we can see Hayabusa from Usuda Station, but we have not recover 3-axial attitude control yet. We are going to recover the attitude after tomorrow. So we have not download the data of Hayabusa's data recorder yet.

Moreover, Hayabusa left Itokawa with fairly large speed, so it seems Hayabusa to be at the distance of 100km from Itokawa now. We will take several days to take back Hayabusa at the previous position again.

It also needs checking whether the on-board devices get damaged by the heat as Hayabusa stayed long time near the surface of Itokawa. We'll checkout that devices tomorrow and the day after.
We pressed hard on the target and we could operate Hayabusa at very high precision from far distance in spite of the loss of reaction wheels. This is a great step for us. We are also very happy to deliver the target marker signed by many people successfully to the asteroid.

The next in our schedule is a test of the probe first. If that's OK, we'll try to get the sample of Itokawa again as the target marker still remained on it.


English translation of the Blog by Matsuura-san

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Mission control room.
Image from smatsu.air-nifty.com

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The spacecraft released the landing target ball 40 meters away from Itokawa asteroid at 5:30 am (2030 GMT) as planned and then moved to 17 meters from the surface.

"We don't know whether the target marker landed on the surface. But we believe it did because Hayabusa moved to the 17-meter point from Itokawa after the release." - Toshihisa Horiguchi, JAXA spokesman.

At that point, Hayabusa suffered a glitch and was not able to confirm its altitude, and ground control lost contact with the probe for about three hours
The spacecraft resumed its signal transmission at 9:30 am (0030 GMT), but the agency could not confirm its position.

"Hayabusa reached extremely close, but could not make the landing" - Toshihisa Horiguchi.

"From an engineering point of view, we see this as a success. We definitely want to try again" - Junichiro Kawaguchi, project leader.

The agency said it hoped to make a second attempt to land the craft.

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Hayabusa Press Briefing
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Control Room Screen

15:46 Prof. Matogawa says the project manager Kawaguchi will show up at 4pm. Regaining the 3-axis attitude control seems not completed in time during the Usuda station communication.
Press briefing will start at 4pm.

16:00 Hayabusa project manager prof. Kawaguchi entered into the press room.
Kawaguchi: "Hayabusa started descent operation at 9pm last night. It actually started the decent long before but we declared at 9pm at the altitude of 1km.
We successfully aimed the probe to the target, better than our last rehearsals.
Around 4:30 this morning we started the "perpendicular descent " phase, at altitude of 400 to 500 m, along the line between Earth and Itokawa. The velocity was about 10 cm/s.
It had been very smooth. We presume we had controlled the spacecraft at an order of 1 cm/s precision.
It took about an hour to the altitude 54 m. We send GO at 4:55. This was the prescheduled altitude. We cut the wire which hold the target marker. At the altitude of 40 m the spacecraft braked by 6 cm/s, which released the target marker. We calculated the marker reached onto the surface of Itokawa 400 seconds later.
At 35 m we switched the altitude monitor from radar? to the laser range finder. It was first time for us to use the laser range finder, but it worked pretty well.
The spacecraft then took pictures of the marker and it followed the marker autonomously, which also went very well.
At 55 m Hayabusa went into hovering mode using the laser range finder.
Then it went down slowly until 17 m, when the spacecraft aligned itself
to the surface of Itokawa. The communication with the high gain antenna was stopped at that point. We switched to the beacon mode and watched the altitude with Doppler information.
After that point we only have Doppler information at hand now.
We speculate the spacecraft had descended at 2 to 3 cm/s with the trajectory parallel to the surface of Itokawa. We observe it stayed at 10 m for about a half hour. Combined with other data, we do not think Hayabusa had touched down.
Staying longer near the surface of Itokawa, the temperature of the spacecraft goes up due to the sun light reflection from the surface. We sent ascent command at 7am from NASA station.
At this point the angle between the Sun and the solar array went too large and this caused the Hayabusa to go into safe mode. We don't know why at this point.
We tried every effort during the communication time window from the Usuda station to stop the spin of the spacecraft but we still do not regain the 3-axis control. We will try again tomorrow. As a consequence, we still not downloaded the data in the data recorder.
The spacecraft evacuated from Itokawa at rather high speed, so it is now about 100 km away from Itokawa. It will take several days to bring it back near Itokawa.
We need to check the status of the sensors because the spacecraft stayed longer near the surface. We will check them in a couple of days.
We were so close to the success but we maintained the spacecraft in a deep space at a very high precision without the (reaction) wheels. This is a very big step forward.
We are also pleased that we successfully delivered the target marker, which carries the names of so many people.
We plan to test the probe. Then we'd like to try the touch down again to get the sample of the surface. We have another target marker on board."

Mainichi: "Tell us the reason you don't think there was a touch down."
Kawaguchi: "The spacecraft has a software which will be triggered by the distortion of the sampler horn. We know this has not been triggered based on the telemetry received at Usuda.
However the spacecraft went into ascent mode autonomously, so there had been some turbulence such as some part of the spacecraft touched the surface of Itokawa. We don't not precisely at this point."
Kyoko: "What is the reason for the horizontal drift?"
Kawaguchi: "It is a speculation at this point that the spacecraft had drifted horizontally. At very low altitude it does not follow the target marker. It free-falls onto the surface. There is a possibility that the spacecraft may drift horizontally when it cuts the chasing of the target marker, which is an expected operation. We thought it should then in a free fall"
Tokyo: "You think the spacecraft was in visual contact with the target marker?"
Kawaguchi: "We think so. We think this is a smoking gun evidence that the target marker has landed. We still do not declare until the data is downloaded.
The separation of the marker, descent speed, the marker being photographed and tracked, were all monitored in real time."
NHK: "You say it did not touched down. How about the altitude?"
Kawaguchi: "By integrating the descent rate, the amount of the descent looks like the spacecraft went inside Itokawa. This is a tentative number and not conclusive. It actually did not go inside Itokawa. There is a possibility as the spacecraft moves horizontally with the rotation of Itokawa that we might have this kind of data. Rationally."
NHK: "The software was not triggered means the impactor was not ejected. Are you really sure the spacecraft did not touch down?"
Kawaguch: "You are right. Even if some portion of the spacecraft touched the surface of Itokawa, I do not want to declare it as a 'touch down'."
NHK: "Why you think the altitude was 10 m?"
Kawaguchi: "Actual measurement we had was 17 m. We also know that the spacecraft was in descent after this measurement. We speculate it was at about 10 m."
NHK: "Why it lost the attitude?"
Kawaguchi: "We don't know yet. While it aligns to the surface, the logic to go into safe mode because of the angle between the solar arrays and the Sun was tuned off. Afterwards we turned off the logic. We still don't know what happened in between."
NHK: "You did not receive the status of ascent in real time. Did it go in the safe mode?"
Kawaguchi: "It was just at the handing over from the NASA DSN and the Usuda station. We realized these events when we received the signal at Usuda."
Gekkan Tenmon: "How long was it during the horizontal drift? You sent the ascent command from Earth, and you are supposed to send the stop command but you didn't. Why?"
Kawaguchi: "The duration of the drift was monitored to be about 30 minutes. Then we sent the ascent command and it arrived to the spacecraft 16 minutes later. So it should have been longer than 30 minutes.
We did not send the stop command because the recovery from the safe mode was our priority."
Gekkan Tenmon: "What about the remaining fuel?"
Kawaguchi: "We consumed fair amount. It is one of our concerns for the future operations. But we would like to try one more chance."
Jiji: "Would it be on time for the descent on November 25?"
Kawaguchi: "If we are to try again on the 25th, we need to hurry. There are so many things we need to consider. Also we can try the touch down operation only when the NASA DSN backup is available. There are not so many chances. We think we need to exploit the chances. But we also need to think again if there are damages in the spacecraft."
NHK: "The sensor for obstacles, which would trigger the abort, was not triggered?"
Kawaguchi: "No, it didn't."
Unknown: "The whole world is watching this operation. Do you have any comments for not being able to touch down, and for your intention to try again?"
Kawaguchi: "It was a pity. We need to check the status of the spacecraft with very limited chances. On the other hand we have firmly established the spacecraft manoeuvre which had not been possible during the last two rehearsals. Autonomous descent and the attitude control with the laser range finder was a big milestone.
We thought we had cleared all the technical challenges, but we encountered some unknown event. We think Hayabusa is a success as a robot probe. It did not actually touch down but it is a good mark as for the engineering. We strongly want to try again."
Unknown: "What was the impact of the reaction wheels?"
Kawaguchi: "We originally planned the last minutes descent without the attitude thrusters. Because of the malfunction of the reaction wheels, the spacecraft had to go through the small turbulence due to the thrusters. It affected today's event in some way. Pending on the analysis of today's data, we are even thinking to thrust the spacecraft downwards onto Itokawa."
Tokyo: "What temperature Hayabusa could endure? Do you have the data how hot it was?"
Kawaguchi: "We think the circuits which were turned on and generated heats were in critical condition. There may be some effect due to the temperature. We originally did not plan to stay near Itokawa for such long period of time. We still do not have the estimate of the temperature. Some circuits might be at 100 deg C because the surface was 100 deg C."
The microphone was handed to another press room in Tokyo.
Asahi: "What is your most worrisome point? Is the schedule of another touch down on 25th at this point? When do you plan to download the data? Is there any possibility that you find something tonight?"
Kawaguchi: "We need to analyse the phenomena at the final stage. We are not sure whether exactly what happened. We think we need to try again even if we need to thrust the spacecraft downwards. We think there would be no problem if the spacecraft acts as same as today.
On the other hand we would not be able to navigate the spacecraft to exactly the same point as today. There remains some uncertainty due to the different surface. We believe we can do it based on our experiences.
We still do not know if we can try again on the 25th. We want to keep the 25th as the target date.
We will not have another data until 2am tomorrow."
Asahi: "Are there any possibilities that some part of the spacecraft is damaged?"
Kawaguchi: "As of our knowledge we do not have a big damage. We need to analyse it in detail."
Asahi: "What was the time of the target marker reached to the surface?"
Kawaguchi: "Released at 5:46, separation at 40 m and at 10 cm/s, so it should land in 400 seconds. It should have been 5:50."
Mainichi: "You said the drift time was 30 minutes. What was your original plan?"
Kawaguchi: "8 minutes or so."

Yomiuri: "What do you mean by you cut the wire at 54 m and the separation of the target marker was at 40 m?"
Kawaguchi: "After the wire was cut, the marker did not separate until you slow down the spacecraft. At 40 m, it braked by 6 cm/s, then the marker was separated. We need this complicated procedure to release the marker at the exact velocity."
Yomiuri: "And it landed on the Muses see?"
Kawaguchi: "Yes."
Sankei: "What will be the next chance if you miss the 25th?"
Kawaguchi: "Hayabusa must leave Itokawa in early December. So we need to seek for candidates during the end November and early December. We are not able to decide on our own."

The microphone returned to Sagamihara, ISAS.

NHK: "Was it a speculation that the spacecraft had drifted on the surface? Were there any possibilities it stayed near the surface?"
Kawaguchi: "It is a speculation. To give a reasonable explanation of the negative altitude, we need some movement while it had not touched the surface. Only the rational explanation is the movement horizontal to the surface."
NHK: "Was it a free fall after 17 m? Were the thrusters not used?"
Kawaguchi: "It was a free fall with attitude control with the thrusters."
NHK: "You told us several abort conditions at the last briefing. At this point were there any possibilities of abort due to the loss of the signal from the laser range finder? Were there no obstacles on the surface?"
Kawaguchi: "No. It does not mean there were no obstacles but it did not sense the obstacles. At the time of releasing Minerva, the obstacle sensor actually sensed Minerva. We think the sensor is functional."
NHK: "Am I correct there would be no reason that Hayabusa gets abort near the surface?"
Kawaguchi: "It might have gone into the safe mode due to some other reason which is not so obvious."
NHK: "Didn't the laser range finder record the angle of the plane it observed?"
Kawaguchi: "No."
Sankei: "Both the ascent due to entering the safe mode and the ascent command sent from Earth were in effect?"
Kawaguchi: "That is correct."
NHK: "Which direction did Hayabusa move away from Itokawa?"
Kawaguchi: "We don't know. It should be along the line perpendicular to the Muses Sea. It depends on the surface condition. Also the safe modes points the attitude of the spacecraft towards the Sun, so we would not be able to stop the spacecraft with thrusters. Nevertheless we performed the reverse firing manoeuvre without knowing the precise orientation of the spacecraft, to stop drifting further away."
NHK: "You said the temperature rise you measured was about 20 deg C. How long did it take?"
Kawaguchi: "About 20 minutes. We had the similar condition for another 30 minutes, so we think the temperature was more than 80 deg C, 40 to 50 deg C increase in total."
NHK: "Wasn't it dragged on the surface of Itokawa?"
Kawaguchi: "We have no direct evidence that it touched the obstacle. Even if there were such contacts, we won't call it 'landing'."
NHK: "Wasn't the free fall of 30 minutes enough time for touch down?"
Kawaguchi: "It should be. It may be possible that it followed onto some slope."
Kyodo: "When would you decide you might have another try on the 25th?"
Kawaguchi: "It may be the late that week. We will not postpone the decision until the very day."
Kyodo: "You said you will be able to touch down next time, given the same condition as today. What does that mean? Will you change some criteria?"
Kawaguchi: "We did not expect the final stage such hard, so we are somewhat curious. If the analysis does not come to conclusion, we would take a risk with downward acceleration to touch down. In other words, we would change the criteria."

The microphone turned back to Tokyo.

Unknown: "The fuel consumption seems very tight. Are there any possibilities that you scrap the returning to Earth and perform the sampling manoeuvre?"
Kawaguchi: "I think the possibility is remote. The mission includes the retrieval of the asteroid sample. Getting the sample and retrieving it are coupled."
Mainichi: "You said you made a good score in robotics. What is your score in 500 mark?"
Kawaguchi: "We are still in the middle of the mission. I would avoid answering that question. But I feel a kind of satisfaction on the outcome of the robotics manoeuvre."
Yomiuri: "Could you remind us what are the two engineering points?"
Kawaguchi: "In one phrase it is the navigation and guidance. We performed the operation with high precision, given the feedback from the past rehearsals. The newly achieved two are 1) the attitude and altitude control using the laser range finder, and 2) guidance of the spacecraft based on the image processing of the picture of the target marker."
Yomiuri: "That means once you download the data, you have quite high resolution images, don't you?"
Kawaguchi: "We are not sure because the spacecraft entered into the safe mode. But if successful, we should have the high resolution images."

The microphone returned to Sagamihara again.

Fuji TV: "When did you realize you did not have chance for touch down? What was your feelings?"
Kawaguchi: "At around 7am when we sent the ascent command, we felt we do not come to touch down. The atmosphere at the operation room was that they were curious for not having touch down at the final stage thus far. I myself was thinking 'this is a kind of difficult situation.'"
Gekkan Tenmon: "The remaining fuel at the arrival of Itokawa was 50 kg. When would you able to estimate the possibility of returning to Earth? How do you estimate the amount of the remaining fuel?"
Kawaguchi: "We can calculate the rough amount of the fuel based on the temperature and the pressure reading of the tank. There is a method of extremely low fuel consumption but it depends on the conditions of Hayabusa and the manoeuvre of returning to Earth. Whether it can return to Earth depends on how we choose the safety factors. We need to evaluate.
It is not whether we can bring Hayabusa back to Earth or not. It is how we restrict our fuel consumption.
I myself feel it is very critical at this point."
Gekkan Tenmon: "What are the house keeping data?"
Kawaguchi: "Readings of the temperature, pressure of the fuel tank, currents and voltages of the circuits, for example."
Matogawa: "I would like to thank Hayabusa team for delivering the target marker ball with about 880,000 names of people on it, to Itokawa. It was me who proposed this PR event. It is kind of strange to thank to the colleague. I've been watching various exploration missions, but this one gives me the firm impression that we have entered into a new horizon of the solar system exploration since the comet Halley mission.
The team members may not be aware now, but looking closely from behind, I think Japanese space exploration is really moving into the new chapter."
Unknown: "When would be the next press conference?"
Matogawa: "We don't know at this point. We will schedule. I would like the operation team to have some rest. It would not be today. Maybe tomorrow or some time later."

Prof. Kawaguchi returned to the operation without answering to further questions. The time slot opened for the Madrid station and the team need to establish the 3-axis control anytime soon.


Source Mr. Matsuura, journalist in the press room of JAXA/ISAS.

All timeline are in JST (GMT+9), as he wrote his blog, not the timeline of the event itself.

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RE: HAYABUSA (MUSES-C) mission
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Source Mr. Matsuura, journalist in the press room of JAXA/ISAS.


All timeline below is in JST (GMT+9), as he wrote his blog, not the timeline of the event itself.

04:54 JAXA confirmed Hayabusa received the decent command. Altitude 370m.
05:20 Altitude 250m. Hayabusa goes into autonomous operation mode.
05:30 Altitude 170m, velocity 10cm/s.
05:37 114m from the surface.
05:45 70m from the surface. Prof. Matogawa calls press room intermittently.

06:03 Hayabusa released the target marker, a bright small ball with about 880,000 names of people.

06:09 Hayabusa turned into ascent. Details unknown. Telemetry will arrive to Earth at 06:20. It was a miscommunication. It was a time Hayabusa might have turned into ascent.

06:37 Telemetry still not received. Parabola is now being switched from NASA DSN Gold Stone station to JAXA/ISAS Usuda station.

07:23 Prof. Matogawa addresses the media. The target marker has been released. It was confirmed Hayabusa went down to the altitude 17m with the autonomous mode. Shortly after, Hayabusa seems locked, not descending nor ascending (no Doppler shift in its beacon signal). Altitude of this event is unknown. Usuda station sent ascent command shortly after 7 o'clock, followed by the command to enter "Safe mode". No ascent observed as of this writing.

08:44 Situation not clear. Media briefing may be held around 9 o'clock.

08:51 Prof. Matogawa addressed the media. "Situation not improved. There were no responses to the ascent and safe mode commands sent from Usuda. No Doppler shift was observed. It requires two way link. The landing site rotated away to the far side of the Earth but we still receives the beacon from Hayabusa, so the possibility of Hayabusa being stucked on the surface of Itokawa is out. We keep receiving the beacon but it does not respond to the command from Usuda. We are trying to establish two way link using Hayabusa's low gain antenna. We just sent another command to switch to telemetry mode. We will know the result in 32 minutes."

09:36 Prof. Matogawa to the pressroom. They are now speculating the possibility of Hayabusa being stuck on the North Pole of Itokawa. JAXA released interim timeline. The operator confirmed the release of the target marker at 05:46. Reading of the laser range finder was 17 m at 05:55.

09:45 The two-way communication link was re-established at 09:32 using the low gain antenna. Hayabusa is not in safe mode now.

10:28 Prof. Matogawa addresses media again. "In about 10 minutes we expect the first telemetry data from Hayabusa. The press conference originally scheduled at noon would have to be cancelled. The project manager prof. Kawaguchi would also like to postpone it until tomorrow."
The media wanted to hold the press conference anyway.
"The result of the analysis of what happened has to wait until tomorrow. Once we receive the telemetry, we will know whether it touched down, impactor has been ejected, and such. We will let you know the status immediately. I would like prof. Kawaguchi to concentrate on his operation. Telemetry will arrive in every 40 minutes. I think I will give you the briefing in every hour or so. There were some speculations about why Hayabusa did not go into safe mode. While it was trying to touch down, it somehow hovered at a certain altitude (about 10 m) for a half-hour. Hayabusa's movement was closely monitored by two-way Doppler signal but no shift has been observed. We speculated the temperature of Hayabusa went up considerably. The communication circuit might have experienced some kind of anomaly. It seems reasonable we re-established the communication once Hayabusa moved away from Itokawa."
About the velocity monitoring with Doppler shift. "There are two methods, one is one-way Doppler shift using Hayabusa's signal, and two-way Doppler shift by measuring the response to the signal sent from Earth. Frequency of the signal from Hayabusa varies as the temperature of the communication circuit changes. Therefore we could not precisely measure the velocity without calibrations in one-way Doppler. To measure the velocity at a few cm/s, we need two-way Doppler."

12:12 Prof. Matogawa again. "Now we keep contact with Hayabusa with medium gain antenna. We started the communication with low gain antenna and enabled the medium gain. We will receive the house keeping data such as whether the impactor has been ejected, around 1 o'clock. We will also know whether Hayabusa touched down. I will come back immediately when I know."
The media: "Then we will have a lunch break until 1 o'clock..."
Matogawa: "No, I won't take a break. I don't know the entire picture but they (operation team) knows the whereabouts of Hayabusa. It's not returned to the home position yet."
He is still being interviewed by media as of 12:23.

13:42 Prof. Matogawa into the press room. "We still don't know whether it touched down or not. Hayabusa did go into the safe mode. We also know it now hovers further away from the home position. Hayabusa is now in safe mode, stabilizing itself with a gentle spin, with its solar array facing to the sun. Medium gain antenna transmits signal with an 18 degrees cone. We receive the house keeping data only when the Earth is within its cone. Hayabusa is broadcasting its house keeping data with medium gain antenna repeatedly.
We don't know why it entered into the safe mode. It is not clear whether it received the safe mode command from Earth or not. Hayabusa has an option of going into the safe mode from its autonomous mode. This could also be the case.
Low gain antenna transmits the signal into every direction. So we didn't know Hayabusa was rotating. It was not before we received the signal from medium gain antenna that we realized it is rotating.
Usuda station ends contact with Hayabusa around 14:55. We plan to establish the 3-axis altitude control before the contact through Usuda ends.
We hold the next DSN station, Madrid, Spain, from 17:25 to 22:00. After the next is Usuda, from 08:30 tomorrow morning to 14:55. We would like to establish the attitude control this afternoon.
Our current goals are 1) establish the attitude control and 2) attempt to go back to Itokawa again. We are evaluating which goal to perform and when."
Next briefing will be around 16:00, when Usuda station ends contact with Hayabusa.

14:40 Mr. Matsuura's personal speculation based on the press briefings by JAXA/ISAS: "I got the impression that we did not experience such a strange hovering nor going into safe mode during the last three descent operations.
It may as well be the consequences of the event specific to this operation, namely the touch down!?
It could be due to the touch down that Hayabusa lost the attitude and entered into the safe mode??
Safe mode means the probe is safe. Anyway we are not in the worst situation."

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The Japanese research probe moved within metres of an asteroid Sunday but hours later officials were still analysing its data and it remained unclear whether it had successfully landed to collect surface samples.

The Hayabusa probe, which botched a rehearsal earlier this month, is on a mission to collect samples from the asteroid during a brief landing and then bring them back to Earth.
Hayabusa moved to 40 metres above the potato-shaped asteroid Itokawa and then dropped a small ball-shaped telemeter as a touchdown target before descending further to 17 metres - the last point at which JAXA has confirmed its location.

"We are able to exchange signals with Hayabusa, so we will be able to confirm the results as soon as we go over more data and analyse it" - Tatsuo Oshima, JAXA spokesman said.

A rehearsal was aborted earlier this month when the spacecraft had trouble finding a landing spot and a small robotic lander deployed from the probe was lost. Hayabusa also had an earlier problem with one of its three gyroscopes which was later repaired.

Hayabusa was launched in May 2003 and has until early December before it must leave orbit and begin its 290-million-kilometre journey home. It is expected to return to Earth and land in the Australian Outback in June 2007.
The asteroid is named after Hideo Itokawa, father of rocket science in Japan, and is orbiting the sun between Earth and Mars. It is 690 metres long and 300 metres wide and has a gravitational pull of only one-one-hundred-thousandth of Earth's, which makes landing a probe difficult.

Japan was the fourth country to launch a satellite, in 1972, and announced earlier this year a major project to send its first astronauts into space and set up a base on the moon by 2025.

Examining asteroid samples is expected to help unlock secrets of how celestial bodies were formed because their surfaces are believed to have remained relatively unchanged over the eons, unlike those of larger bodies such the planets or moons.

Adapted from source.

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Usuda Deep Space Centre
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The Usuda Deep Space Centre was established in Usuda Town, Nagano Prefecture (Now Saku City from Apr. 2005), in 1984, as an affiliated facility of the former Institute of Space and Astronautical Science (ISAS).



The Centre sends command operations and receives data from Hayabusa. The remote location of the Centre was chosen carefully to reduce noise from towns, allowing for the reception of faint and subtle signals from space.
The main facility is a large parabolic antenna (64m-dia., 1980t.).
X-band communications (8 GHz) are used for with deep space probes, while S-band (2 GHz) and X-band (for receiving only) are used for other probes.

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