[HAYABUSA link]: Press Conference at 16:50 on 7th Dec. JST
Following is the transration by Mr.zunda. Thank you!
Quick update from the press conference:
It seems unlikely that the bullet has been shot during the landing on Nov. 26th. (Comment by PAKU: To be precise, the JAXA www page says that the operation team has not confirmed data that shows a shot in the downloaded telemetry.) Chemical thrusters have not recovered yet. Altitude of the vehicle has been controlled with the ion engine. (Note by zunda: the JAXA www page says that they are using xenon gas for the ion engine as propellant.)
Hayabusa will leave Itokawa later than Dec. 14th. Journey plan is still being built.
Details will be posted here after the press conference.
Following is the transration by Mr.RogueEngineer. Thanks a lot!
Rough translation to English (briefing part only, no Q and A session):
The report from the press conference on 4:50 PM, attended by Project Manager Junichiro Kawaguchi and Professor Matogawa.
Briefing from Project Manager Kawaguchi:
As already reported, the recover operation from the safe mode is not going well. On November 19th, we established beacon communication with low-gain antenna.
From November 30th, we started communication with on/off radio signal (1-bit communication).
On December 1st, intermittent communication of 8bits/sec with low-gain antenna was established.
From that, we found out:
As a result of attitude control on November 27th, it seems that electricity loss has occurred due to great change in attitude or other cause.
Vaporization of the fuel that leaked inside of the probe might have caused drop of temperature of significant number of equipments. At the same time, loss of electric power caused deep discharge of battery. These seems to have resulted in resetting of electrical module in the system. We are still analyzing the details.
On December 2nd, we tried restarting chemical engine (thruster), but we had marginal thrust, and it was not fully operational.
On December 3rd, we confirmed that misalignment of the direction of high-gain antenna and the Sun-Earth was getting larger, that was, 20 to 30 degrees. As a emergency attitude control, we decided to use xenon gas, which was normally used for ion engine operation, and started writing software for that.
On December 4th, we executed attitude control with xenon gas emission.
On December 5th, the alignment of high-gain antenna and Sun-Earth has recovered to 10 to 20 degrees, and we are having communication of 256bits/sec with medium-gain antenna. However, the probe is slowly rotating, and we are only having intermittent communication, once in 6 minutes.
As of December 6th, Hayabusa is at 550km from Itokawa. The distance from the Earth is 290,000,000km. Currently we are reactivating the only remaining reaction wheel, and it is running at 1000rpm.
Mainichi: Does it mean the bullet was fired, but the data was lost?
Kawaguchi: The data from firing equipment cannot be replayed unless we set the probe to launch mode. We did not have the time to switch the mode. Because the data could be lost if the firing equipment is reset due to loss of electricity, on Nov. 26th, we sent a command to transfer the data to data recorder and write protect it.
However, on 27th, we had loss of electricity and equipment reset of large scale. We lost the absolute time data of DHU (Data Handling Unit) and partition data of data recorder (DRAM). That means, we can replay data recorder, but we don't have the data that we fired the bullet.
But we still could replay the command sequence during the descent. According to that, in the sequence prior to the touchdown, there was a command to inhibit firing of the bullet by switching the bullet firing equipment back to safety mode. We are still investigating why such a command was included in the sequence.
The data we gained so far is spotty, but all the data we have suggests that "the bullet was not fired". Our take is there is 80 percent chance that the bullet was not fired.
Yomiuri: When will you be able to say anything conclusive from the analysis of data?
Kawaguchi: We are having hard time interpreting some of the data. On the first landing, the probe was exposed to high temperature from Itokawa, but the temperature of bullet firing equipment was higher on the second landing, suggesting that the bullet was fired. That is inconsistent with other data.
With current communication speed, we cannot download the image data. Once we could download the image, we'll be able to see the touchdown attitude and more detailed information could be drawn.
Before we start the operation of ion engine, we wish to download as much data as possible, and when we have sufficient data, we would like to hold a press conference for debriefing.
Anyway, the amount of data is scarce and they are inconsistent. We cannot draw any conclusion yet.
Kyodo Tsuusin: Of the record kept in the data recorder, some is lost and some is still there?
Kawaguchi: Data recorder uses DRAM and we lost partition information. That usually means all the data is lost. But when we tried download small amount of data, we could retrieve what looks like valid information.
Kyodo Tsuusin: As for the safety mode of the bullet firing equipment, did you send wrong command, or was there an error in writing inside the probe?
Kawaguchi: We don't know yet.
Following is the transration by Mr. nao. Thank you for your.effort.
Rough translation (cnt'd). Sorry for my poor English.
Kyodo Tsushin: Can the vehicle return to Earth by departure after 14th Dec?
Kawaguchi: That schedule is based on the case that we can fix the vehicle with the quickest process. We have prepared a orbit plan to start the return on 14th or 15th and reach the Earth in June 2007.
However, the thrusters are yet in bad condition. Without thruster recovery, the vehicle cannot keep the attitude. From now on, we try to recover the thrusters by rebooting powers or changing temperature of the thruster system.
If thrusters don't recover, the vehicle will return using attitude control by emitting xenon jet for the ion engines. In this case, if the attitude falls down, we have to stop the ion engines, restore the attitude by xenon jet, and then boot the ion engines again. Because the booting process of the ion engine takes considerable time, there is a risk for lacking enough running time for the engines to return to the Earth, which indicates an emerging alternative way to extend the return timing.
Kyodo Tsushin: Is there a possibility to change the pickup point in Australia to somewhere?
Kawaguchi: Indeed, the extension of return timing will increase the re-entry speed or the re-entry angle of the capsule, leading to larger risks for the capsule.
NHK How is the attitude control by xenon gas, concretely?
Kawaguchi: The vehicle has four ion engines, and the orifice of each engine has a neutralizer with four nozzles per engine in order to neutralize the jet gas electrically. The nozzles are openable and closable. By opening or closing the nozzles to emit neutralized xenon gas jets, we are controlling the attitude. Its propulsion force is very small.
Following is the transration by Mr.volunteer . Thank you!
Nikkei Science: Are the posture control on 11/27 and the power loss that followed related, or are they two independent events?
Kawaguchi: It is highly probable that the two events are related. Back in the operation on 27, thruster output was very small. So we restarted the spin which was once stopped, and at the same time sent commands to take more distance from Itokawa since it was getting closer to the asteroid.
Asahi: What do you think of the possibility that the sample were stirred up by the landing and actually gathered? And your comment on this turn of the situation where you couldn't retrieve the sample at the rate of 80%?
Kawaguchi: Escape velocity from Itokawa is equivalent to the speed of a pencil dropped from 0.5 millimeter height. It would only bounce up 0.5mm on earth, but on Itokawa where the gravity is small it would jump up more than 10 meters. Buton the second touchdown, the vehicle actually touched the ground for only a second and ascended back, so the sampler horn ascended with the sample, thus the sample would not have reached the capsule. In the touchdown on 20th the vehicle landed on the surface for substantially long time, so we think it is highly probable that the sample that were stirred up have entered the capsule.
We were able to take all the technical procedures aimed for collecting the sample. In that sense, we think that this landing has not lost its significance. Of course we're very determined to retrieve the sample. This is already an area beyond engineering demonstration. The fact that the projectile did not fire is, in a word, discouraging. We think it is essential for us to keep up our motivation for the return flight.
Following is transration by Mr.nao. Thank you very much.
Tokyo Shimbun: What is the neutralizer of the ion engines? And I'd like to know how the disorder in the thrusters is related the A/B dual systems mentioned in the last conference.
Kawaguchi: When the vehicle emits the cations, it gets charged negatively. Then the cations are attracted the negative charges and cannot leave it. So, the cations are needed to be neutralized electrically by anions. The neutralizer emits the negatively-charged gas to neutralize the jet plasma.
The disorder of thrusters is due to the movement failure of latching valves. We are trying to manage to move the latching valves by restarting the power for the valves or changing the temperature of the valves.
Yomiuri: Can the situation change if captured images are downloaded?
Kawaguchi: Yes, but here I cannot assure the success of download.
Space Authors Club: Do you mean that the latching valves of both A and B systems are stuck in with the closing state?
Kawaguchi: Yes. It seems that, on 27th Nov, several kilograms of the fuel was leaked inside the vehicle. The temparature dropped by vaporization. It is not the oxidant but the hydrazine that is leaking. On 2nd Dec, we sent commands to open the A/B latching valves, but they didn't move. It may be caused by problems in the power or wiring on the valve driving system. Freeze of valves or pipes is unlikely because we are now heating each parts in order to release the out gas. Open of the valves might cause the leakage again, but with comprehension of such risks, we are trying to move the valves.
Aviation Week: How is the operation by utilizing NASA DSN?
Kawaguchi: We are provided the usage of 70m antenna for 2 hours per day till tomorrow, by the kindness of NASA. In addition we are going to request support by the 34m antenna for one more week.
Aviation Week: You said that the reaction wheel are rotating with 1000 rpm. How is it with respect to the rated value?
Kawaguchi: We'd like to use it with 2000-3000 rpm in consultation with the vendor. They are designed for about 5000 rpm in max.
Jiji Tsushin: Did the leakage occurred inside the vehicle?
Kawaguchi: We confirmed from acceleration data on 26th that it leaked also outside through the top side.
When communication was disrupted by the large attitude disorder on 27th, there was a leakage of several kilograms, though we do not know if it is outside or inside. Its ground is the event that there occurred the downward propulsion force and the spinning speed decreased on 30th. It can be explained by our speculation that the fuel leaking inside the vehicle evaporated and blew outside.
Jiji Tsushin: Are the xenon or the thruster fuel enough for return to the Earth?
Kawaguchi: I think xenon lasts enough if there are no more disturbance.
Unknown: Is the leakage inside the vehicle stopping?
Kawaguchi: Stopping. If it continued, the vehicle temperature would decrease by vaporization heat. Now we are heating the vehicle to vaporize and eject the leaked fuel remaining inside.
Unknown: Are you stopping the leakage, or did it stop by itself?
Kawaguchi: I think that we stopped it. Now the both latching valves are closed and the leakage is stopped.
Sky Traveler (Gekkan Temmon): In the case of missing the return chance by 15th Dec, supposing we'll wait for three years for its return, then will Hayabusa travel along with Itokawa?
Kawaguchi: I think it will go away sufficiently from Itokawa. It will go further and further off Itokawa. FYI, the three-years waiting is just a candidate, and a pattern with three-and-half years is also possible. At this moment we focus on June 2007.
Mainichi: Is the reason of the thruster leakage unknown?
Kawaguchi: Yes. The touchdown itself is unlikely to cause it because the leakage occurred on the top side of the vehicle. The temperature dropped down due to vaporization on 27th, but on the contrary, the temperature increased on 26th. We have to give a consistent explanation after analyzing such data.
Tokyo Shimbun: Did the success of attitude control by the ion engines increase the chance for the return to the Earth?
Kawaguchi: We had no way in the last press conference, but now the situation got better than that. But we cannot evaluate definitely whether it is sufficient for the return.
Tokyo Shimbun: You concluded the success by finish of the sequence on 26th. Does the sequence finish even with a wrong command inserted?
NHK: As for scientific data, Have you already downloaded the data up to 25th? And is there possibility to download the current data during the return cruise?
Kawaguchi: (The data up to 25th is) Already downloaded. We will download the data at the touchdown before starting the return cruise. After cruising phase starts, it will be difficult to make enough time for download.
NHK: Is the battery charged now?
Kawaguchi: It has restored again. Hayabusa is designed to work without the battery as long as its attitude is normal. I think that it has no obstacle for the cruise. The battery of Hayabusa has a capacity only for 40-min operation of the whole system.
NHK: How long can it be extended to achieve the return in June 2007?
Kawaguchi: We aim the return start by the mid of December, understanding some disadvantages in re-entry. If it is extended to the late December, the return on June 2007 will be harder.
Unknown: When did you confirm that the bullet did not fire?
Kawaguchi: Around 3:00pm on 6th. It was a deep shock to me, too. I told it to Ministry of Education, Culture, Sports, Science and Technology in this morning.
Sky Traveler (Gekkan Temmon): Were you unable to confirm the bullet firing on the finish of the sampling sequence?
Kawaguchi: In order to confirm the action of firing equipment, we have to switch the operation mode of the vehicle to the another one, the lift-off mode. On 26th we considered that it worked because the sequence worked well.
Akahata: Did you assume the attitude control by the xenon gas in advance?
Kawaguchi: No, we didn't assume it. This idea was proposed by the ion engine team when the thrusters did not move on 2nd Dec.
I myself was planning to control the attitude by operating the ion engines. But the ion engine team comprehended well the movement range of the nozzles, and gave me a proposal that the jet by the neutralizer can change the attitude.
At that time, the attitude of the vehicle was sliding by 1 degree per day, and without the proposal what we could do would be almost only to watching the dying vehicle.
Nikkei: Is the replacement of the sequences an artificial error?
Kawaguchi: The detail is unknown in the current situation. Let us keep it "No comment" now.
Unknown: You said that the data might be lost by the battery discharge. Which date have you already downloaded the data for, and which date is the data stored in the DRAM for?
Kawaguchi: First, the reason is not the battery discharge, but the decrease of power output; the battery team would get angry (to hear that).
The DRAM must keep a few megabytes data around the touchdown, but we could download only a slight part. The images with high-reso have large sizes.
Sky Traveler (Gekkan Temmon): We already got an image picturing the target marker on the descending phase. Did you obtained any images after that?
Kawaguchi: That image is the latest.
Sankei: Did you confirm whether the command to switch the firing equipment to the safety mode executed?
Kawaguchi: We have to confirm it by data to be downloaded.
Aviation Week: Which do you set a priority on, the return to the Earth or download of the data?
Kawaguchi: Not decided yet. It depends.
Weekly Post: How do you keep motivation during such critical situation?
Kawaguchi: Because our final goal is to return to the Earth, of course.
Prof. Matogawa: No other vehicles in the past have ever been so robust as Hayabusa. It overcomes 8 times even after experiencing 7 failures (a Japanese proverb). I think the belief by Project Manager (Prof. Kawaguchi) is keeping the team up.
- 【宣伝】4月15日(日曜日)、 『飛べ！「はやぶさ」小惑星探査機60億キロ奇跡の大冒険』朗読会があります。(2012.04.05)
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