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Press conference from 19:00, 2006-03-07 Original †Original text - http://smatsu.air-nifty.com/lbyd/2006/03/7_8c16.html Translation †2006.03.07 Press conference from 19:00 A press conference was held from 19:00 on 7 Mar 2006, with the Project Manager Prof. Jyun-ichiro Kawaguchi. Here is a brief summary. An official annoucement can be found in the JAXA webpage (http://www.jaxa.jp/press/2006/03/20060307_hayabusa_j.html , in Japanese). Please refer to that announcement in parallel. Kyodo News: (In the official announcement,) it says that almost all of the chemical propellant is lost, but possibly a considerable amount still remains. How should we understand this expression? It also says that the transfer of the sample case to the recovery case is planned. Is it for protecting the sample from the baking procedure? Kawaguchi: What that means is, the remaining propellant is not in the tank, but possibly inside Hayabusa or the thermal insulaters. Being not in the tank, it cannot be used as propellant. Also, we don't want propellant in the recovery- or sample-capsules. We'll bake it out first, and then close the capsule. Kyodo News: Then, the attitude cannot be controlled by the chemical thrusters. Kawaguchi: We had been tring since last November to open the latching valve, but was not successful. Currently, the fuel gauge for the oxidizer also indicates zero. At this point, we're not sure if this is a sensor failure or a real leakage. If it's a sensor failure, and if we could open the latching valve, maybe we can use the oxidizer jet for attitude control. In the worst case, we'll consider using the Xenon gas of the Ion engines for attitude control. 42-44kg of Xenon is remaining. By calculation, it's still possible to return by using Xenon for attitude control in parallel. But it's only a calculation. Besides, we haven't yet checked if the ion engines work. Unknown: Is it possible to regain the power supply? Kawaguchi: Maybe the explanation was not so good. At the beginning of December, when the attitude went out of order, the solar panels could not receive the sunlight, resulting in power failure. At 23rd January, (Hayabusa was) spinning around an axis which was 70 degrees away from the Earth and Sun. Hayabusa has large solar panels for driving the ion engines. As it's gradually facing the sun now, the available power is increasing. The power for baking can be maintained. The Mainichi Newspapers: When will be the deadline for the return in 2010? Kawaguchi: When we start in early 2007, 2 working ion engines would be enough. If three are alive, we can start more than a year later. The Mainichi Newspapers: Were the data around the touchdown collected? Kawaguchi: At this point, no data are found in the data recorder. They are estimatedly lost due to power failure. However, if we continue to check in details, it still might be possible to salvage. Tokyo Shimbun: Did the preparation for the return trip become easier by gaining the telemetry, or did it worsen even more, by ascertaining the conditions. How do you think? Kawaguchi: Compared to the beginning of last December, the situation worsened. At that time, it was still possible to return in 2007. Looking on the bright side, however, we regained communications we once lost, and that's a difference between heaven and hell. The probability of communication recovery for these February and March was only about 40%. Tokyo Shimbun: Are the batteries competely out of order? Kawaguchi: Now the batteries have developed shunts. We'll risk explosion if we charge them. We won't use it anymore. As long as the solar panels are in appropriate orientations, planet probes do not have to worry about shading and losing control. However, it cannot perform operations that leaves small power margins anymore. Kyodo News: From where did the propellant leak? Can you know from the telemetry? Kawaguchi: The spin and velocity change that occered at the end of November do not match with those measured in this communication recovery process. We estimate that a different part have broken and caused a different leak. It's hard to know the broken part. We don't have the information that tells us "Here is the broken part". The Sankei Shimbun: When will we know, whether the attitude control computers and the star-tracker work or not? Kawaguchi: Concerning the atittude control computers, we'll know in 2 or 3 weeks. As three systems of different types of attitude controlling computers are onboard, we think that we'll have a backup even if some are malfunctioned. For the Star-tracker, we can't know until we stop the spin. This would be at the end of this year. Even if all of these were lost, still, it can be possible to use alternative means, such as using the wide-angle camera instead of the star-tracker. Nikkei Science: Does the attitude control by Xenon mean that it's necessary for igniting the ion engines? Kawaguchi: Wrong. It means to jet the Xenon gas from the neutralizer of the ion engines, and use the reaction for controlling the attitude. Nihon Keizai Shimbun: Is the situation hard for the return to earth? Kawaguchi: The necessary condition have been satisfied by gaining the telemetry. There are still more barriers to get over for returning. We have to check the status of the ion engines and so on, and if all of them works, then it can return to earth. Practically, it's hard. Please consider that it's already a miracle that the probe is still being alive. Kyodo News: Will the spinning continue until the baking is over? Kawaguchi: Yes. The baking will take place while it's still spinning. Before firing the ion engines, we'll secure three axial control. That means, we'll use the ion engines for both attitude control and normal operation. Whether to jet the raw Xenon gas from the neutralizer for attitude control or not is under examination. While the ion engines are not operating, we'll use the raw gas jet from the neutralizer for attitude control. We have made this news public today, because from now we'll start operations with new risks. If we don't announce it now, we might never have a chance to say "We've made a recovery". (twitter) The Weekly Post: Please tell us how you were delighted at the news. At the moment when you got the beacon on January 23rd, and when you got the telemetry. Kawaguchi: Incredible. The signal was quite stronger than expected. Even the operator reported me that 'I couldn't be sure. So I sweeped the ground antenna to different angles, and confirmed that it's truly coming from the direction of Hayabusa'. On that day we were still half in doubt. On the next day, once again it was confirmed, and then we exchanged e-mails, everyone filled with delight. The spin period was about 50sec to 1min, accompanied with the fading of the signal. Hayabusa accepted our commands for only 20sec within every 1min. We made some tricks on the earth side to make the command reach within those 20 seconds. The Mainichi Newspapers: For how long did the power failure last? Kawaguchi: When not controlled, the attitude changes about 0.7 degrees per day. Thus the sunlight must had been coming from the (wrong) side for a considerable number of days. Jiji Press: What is the aim of the baking, and the temperature? Kawaguchi: To evacuate the gas away. Raising the temperature to the upper limit of the operating temperature would be enough. However, it will take time. At about 50 degrees. NHK: Will the situation worsen, if the ejection of the gas by baking causes disorder in the attitude? Kawaguchi: If we lose control of the attitude again, we'll basically return to the situation of this January. However, that can break something else. When the temperature goes too low, something can happen -- for example, the circuit boardsmay crack or peel off due to the different thermal expansion coefficient. The baking heaters are attached to each part of the body. NHK: It says that the attitude can be controlled by the ion engines. Does it mean the ion engines have gimbals? Kawaguchi: We'll test the gimbals in the coming days. It's the same to the gimbal of the mid-gain antenna. Space Authors Club: If the oxydizer had also leaked out, what do you think about the possiblility of explosion? Kawaguchi: We must first check if it had really leaked out. At least, it would mean that the oxidizer and the fuel did not mix. The Weekly Post: When will be the next press conference? Kawaguchi: That would be around when we start the return trip. For the recovery of each onboard equipments, I think annoucements on the internet will be sufficient. JAXA PRO: Please let us discuss with that issue later. (laughter) From the comments after the conference: Estimatedly, the coning had stopped before the recovery of communication in January. The Mainichi Newspapers: In December, you have told us that it's like 'Asking a seriously ill person to go to the post and sendout a mail'. Now, did Hayabusa become able to go to the post? Kawaguchi: It's even more seriously ill. However, it might be coming along with walking sticks. URL of this translation: http://jspace.misshie.jp/index.php?cmd=read&page=LbyD%2F20060307-2 Comments †
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