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2005.12.16

[Hayabusa link]: Press Conference on 14th Dec.

Following is transration by JSpace http://mole.den.hokudai.ac.jp/jspace/ Thank you for their effort.


Here are details of the press conference. Prof. Junichiro Kawaguchi (Project Manager) and Prof. Yasunori Matogawa attended.

Explanation by PM Kawaguchi:

During the operation via Usuda station at around 1:15pm on 8th Dec, we had decrease both in signal level and the range rate from Hayabusa. Because they are decreasing slowly, we suspect it was caused by attitude disorder occurred from blowout of leaking gas.

At that time on 8th Dec, Hayabusa was in the state waiting for recovery of chemical propulsion system. It was in the spinning state with the period of about 6-min in order to help the operation to stabilizate its attitude.

The capability of attitude control with xenon jets for the ion engines was not sufficient. The disturbance torque is larger than the capability of xenon jets, and we could not stop the loss of attitude balance.

It seems that the vehicle is now in coning motion surpassing the critical nutation angle (If the vehicle in coning motion surpasses that angle, the attitude changes drastically and the vehicle turns "upside down").

Since 9th Dec, communication to Hayabusa has been stopped. According to our analysis, however, there is a 60% chance for the recovery.

From now on, we have to switch the operation policy from the regular operation to the salvation mode. We will continue the salvation mode for one year. If we can recover the vehicle by the beginning of 2007, the ion engines will ignite from that time and it will return in 2010.

Hayabusa is designed to stabilize passively, and the current coning motion will eveutually converge to the rotation around the Z axis (around the parabola axis).

It may be difficult to maintain both of the power and communication line concurrently at this moment, from the disturbance on 8th Dec.

Presently, Hayabusa is in almost the same position as Itokawa. Uncertainty of the orbit (note by translator: snipped in the original article. According to JAXA press release, I suppose "Even if supposing the uncertainty of the orbit, we can track the vehicle by orienting the Usuda antenna to Itokawa, and the risk of losing Hayabusa will be minimal.")

According to our analysis results, the possibility to satisfy the condition among the sun and the earth is relatively high after convergence of coning motion. The possibility of recover by Dec 2006 is 60%, and that by the spring of 2007 is 70%.

If we could re-ignite the ion engines by the 2007 spring, the vehicle will be able to return to the earth on June 2010.

Questions and answers session:

Kyodo Press: Was the disturbance torque caused by fuel leak? Is it the same leak occur on November 26th and 27th?

Dr.Kawaguchi: Fuel leaked twice on November was pooled in the pipes and insulation blankets. We presume that the pooled fuel blew out on December 8th. Blown fuel was very little as just 10ml or 8ml. However Xenon jet could not control the disturbance.

Mainichi Shimbun Press: I would like to confirm present communication status. And what do you think about recovery of thruster system after recovery of position?

Dr. Kawaguchi: We need directional medium-gain and high-gain antenna, to receive any signal from the probe. That is, we need good convergence of the radio beam. High-gain antenna cannot be used with very little attitude alignment mismatch. On December 8th, we lost connection while we were still in medium-gain antenna mode. So we need to send a command from the earth to switch to low-gain antenna operation through low-gain antenna. However, the wave-receiving range of the low-gain antenna is approximately 60 degree. With very unstable axis coning movement, it is impossible to keep receiving command from the earth even using low-gain antenna. The coning movement takes about one month to be stabilized enough to regain communication. Now we are waiting for that.

In this status, the probe’s communication computer enters stand-by mode by shutting down the power. This probe is designed to restart from the mode with the commands from the earth. Thus, unless the equipments are broken from lower temperature, the probe should be recovereable with commands from the earth.

Thruster system has not recovered on December 8th. It is just a speculation, but wiring to drive shutting valve could be broken by fuel leak. On the other hand, another wiring for thermometer running the same place is still working. Something may be happening.

Mainichi Shimbun Press: Is there possibility for the recovery of thruster system?

Kawaguchi: We'd like to try recovering it. After recovery of communication, we'd like to start recovery for the thruster system. But there is a risk of total loss of the vehicle during the recovery process. We must get things going carefully considering the risk.

Tokyo Simbun Press: Is the coning motion converging? On what do you base the recovery chance of 60% over the coming year?

Kawaguchi: Convergence is based on the physical law. The direction of the rotation axis after convergence is a crucial key for the recovery; it's a matter of probability. The probability of communication recovery by Dec 2006 is 60%, and that by the 2007 spring is 70%.

Asahi Shimbun Press: Is there a possibility for failures of other equipments from three-year extension? And what about the running cost during the extension?

Kawaguchi: Of course, the probability of equipment failures will increase. We have to restart them from the almost freezing state. The figures I put before does not mean that "it can return to the earth with 70% probability"; it means that "for the 70% probability of communication recovery, we will continue the operation."

It costs, of course. If the government and citizens think it's not worth their money, we have to abandon the operation. But the JAXA committee on yesterday did not say we should give up. For details, please ask the JAXA officers.

Yomiuri Shimbun Press: Please tell us your impression about extension of return.

Kawaguchi: Very depressing for me. I expected the achievement of the mission in good condition; the 3-years extension will increase risks and make the operation harder.

However, we think we can recover with good reason. Still, even if it's recovered, the probe is fill of wound now and the return trip will be very hard. Yet, if there is any chance, we have a will to give it a try.

Nikkei Science: How will the recovery of the thruster system affect the return?

Kawaguchi: Currently, the recovery of the thruster system is not the requirement for the return trip to the earth. We have a plan of return trip by controlling the attitude with xenon jets after we get the leaked gas out of the probe by heating the vehicle. It is still in the planning phase, and we are studying its viability.

(Next from the Sagamihara campus...)

Astronomy Monthly(Gekkan Tenmon): Are there any change in your view on the sample retrieval after these events? How much scientific discovery could you make out at this point? You're experiencing another difficult situation now, what is the biggest lesson you've learned in these troubleshooting experience?

Kawaguchi: We haven't been able to download any new data, so our view is still unchanged. Status of the vehicle did change, and there are possibility of data being lost. If minimum power supply is available the data will hold, but we can't tell for sure at this point.

As for scientific discovery, we still have undisclosed informations, but the science community plans to open them to the public as soon as possible.

There are considerable amount of information that only Hayabusa could gather. We won't be repeating on its content for today. At some future date we will publish a formal summary. I consider that these results funded by national taxes should be primarily available to this country. We fear that if these data spread, any researcher from other countries could release a paper as first author. And of course contribution to the world must be considered, too.

As for achievements in engineering, we think that achievements in overall operations have a prominent importance, not only in troubleshooting.

We attempted the first sample return in this world. Space development in the past was nervously carrying out projects with solid chance of success under close watch by the mass media. But we think it is also neccesary to take risks and go on forward for the space development to progress.

If you build a hight tower and climb it you will see a new horizon. Hayabusa has inspired the morale toward building such tower on our own, and I think Hayabusa was meaningful on that account.

I suppose that neither NASA nor ESA can issue a proposal on sample return right now. At least they have to have success to the level of Hayabusa for that. So if there is Hayabusa 2, it would be something that only Japan can do. We look forward to it by all means.

Astronomy Monthly: Are there any similar plans outside Japan after Hayabusa?

Kawaguchi: Numerous project proposals like sample return or ion engines have emerged after the launch. Maybe Hayabusa did touch these off. We're receiving proposals for joint operation. This is because they fear there is too much risk to do this alone, they have to have us involved. But I think we can take the lead on the next plan, rather than just to be in part of the plans from other countries. This is my personal opinion, not of JAXA as a whole. I'll get in trouble if you get this as a consensus in JAXA.(laughter in the audience)

Tokyo Simbun Press: Does the return method without the thruster system utilize xenon jets?

Kawaguchi: Yes.

Tokyo Simbun Press: Can the xenon jets generate sufficient power in the return phase?

Kawaguchi: First, the attitude control and the orbit control are different matters. Operation of the ion engines has no problem now. But in order to operate them, the attitude has to be maintained properly. We will use xenon jets for that. We think we can do it.

Kyodo Tsushin Press: What will happen when convergence of coning motion stops?

Kawaguchi: It has two alternatives, whether the power can be provided to the solar batteries or not, and whether the communication can be established or not; The possibility that both conditions are satisfied is 60-70%. Hayabusa has quite large solar battery paddles for its ion engines. When it does not use the ion engines, they can generate power enough for recovery, even if the direction of the sun is not aligned considerably.

Sankei Shimbun Press: Are you going to wait for stabilization of the attitude in the operation over the next several months?

Kawaguchi: By the beginning of February, the attitude will be stabilized and we can decrease the frequency of the operation, to two or three days in a week. Then it will recover by the autumn. That's our estimation.

Currently, there is a possibility that fragments of commands reach the vehicle. So we are automatically and continuously transmitting commands.

Nature: Please tell me details about that NASA and ESA cannot provide such proposals like yours.

Kawaguchi: I have no intention of picking a quarrel with NASA or ESA (laughter in the audience) ... You may have seen the demo of running ASIMO, but if you ask if we could pull off that kind of stunt, we can't, at least in a short period of time. We have to consider political context in space programs. We are required to pursue the matters with high feasibility because they are tax-supported. Please note it's just my personal opinion. (laughter in the audience)

But, this tendency leads to the mainstream of the space development combining established technologies, called "off-the-shelf technology". Stardust by NASA is one example.

This plan is very easy to consider from the administrative view; Cheap and safe. Highly effective if it matches to the scientific purpose.

However, off-the-shelf way has no future, if there exist no more ready-made technologies on the shelf.

When such time comes, can NASA or ESA really shift their policy from combination of ready-made technologies? I think it will be hard. The more capable a bureaucrat is, the more hesitation he feels, I think.

But, because we have experienced the Hayabusa mission, we can say distinctly, for example, that "we can do at least the landing on an asteroid." A large number of application of research collaboration for us indicates the background that we are the one who can declare "we can do it".

Again, let me make sure that I don't intend to speak against NASA or ESA.

Mainichi Shimbun Press: How much is the chance of succeeding to return to the earth?

Dr. Kawaguchi: If Hayabusa is healthy, I will be confident of the return. But present condition of the probe is like a ill person that could be drop dead with a sneeze. Returning to the earth is like telling serious ill person to go to a postbox far away and drop a mail. Fortunately just one of four ion engines is enough to bring Hayabusa back to the earth. The condition is not very strict. To be back in 2007, all ion engines had to be healthy. But changing the plan to 2010 made requirment for power from ion engines much smaller. Of course, long term flight increase the possibility of failure.

Mainichi Shimbun Press: Is it getting worse than the situation on 7th December?

Kawaguchi: I think it stays unchanged. Drop of the temperature freezes the thruster oxidant. It causes the decrease of its volume, increasing the risk for another leakage. There are various factors and prediction is difficult. But it does not mean more difficulty in the return, for there are no new troubles.

NHK: Is the communication suspended currently, including the beacon mode? Isn't there any problem by complete discharge of the batteries?

Kawaguchi: it is suspended including the beacon. The batteries are of no concern to the return. As long as the attitude is proper and the solar batteries can generate the power, it can return to the earth.

NHK: Is the vehicle temperature OK, though the power is completely down?

Kawaguchi: It's unexpected. Because the heaters are off, the inside of the vehicle is in the temperature unexpected in advance. No doubt it's severe.

NHK: From which direction did the gas blow out on 8th December?

Kawaguchi: We don't know now.

X-Knowledge: I'd like to ask you what kind of unreleased data will be released from now on, as far as you know.

Kawaguchi: High-resolution images, of course. Gravity mapping with high precision, results of infrared and X-ray spectrographs ... the genre is as explained so far. Results of initial analysis will be corrected in the beginning of next February. A large-scale conference on the moon and planets will be held at Johnson Space Center in next March. We will release results there.

Monthly Star Navigation (Hoshi Navi): On the JAXA's website, success criteria for Hayabusa mission is 200 points now. How is the current rating?

Kawaguchi: Only the reentry of the capsule remains. As for big factors, four of them have finished ... I'd like to say so, but sampling result is now quite ambiguous. I think 70% has been completed. Once the rating as defined prior to launch reached 100 points, the succeeding points acquired are the same to me. I'll be satisfied if you evaluate it in good-mark system.

Aviation Week: In return to the earth, do you go through the procedure of stopping the ion engines, attitude modification by xenon jets, and restart of the ion engines? And can the xenon freeze?

Kawaguchi: Exactly for the operation procedure. While xenon freezes at -110 degrees Celsius, we think the temperature will not decrease that far because the sunlight always shines it.

Astronomy Monthly: Even on the return in 2010, will the return point be Woomera, Australia? And what is the most difficult in the return?

Kawaguchi: The return point is Woomera. The most difficult thing is sustenance of the attitude. It is almost a miracle that we can keep operation even though the wheels and thrusters have troubles. The thruster system have to be recovered after enough and serious consideration on risks. Attitude control by xenon jets is sufficient in usual situation, but now it's also severe under the situation to be almost in critical condition by just one sneeze.

NHK: Won't the designed life be expired in more than 7 years of operation?

Kawaguchi: The designed lifespan of the vehicle is four years. This operation exceeds it.

Yomiuri Shimbun Press: Is there any influence on other probes from now on?

Kawaguchi: In some projects in the developing phase now, there may occur the interference in utilization time of Usuda Station; SELENE, the moon probe, at this situation. I think it can share the time successfully. After that, it will be all right up to 2010.

Prof. Matogawa: Final word. Thank you very much for your media coverage. The coverage will converge for a while, but anyway thank you for your all-night coverage. This time we had the largest coverage system since the "Ohsumi" (the first Japanese satellite launched in 1970) mission. Yesterday I had a meeting with newspaper editors, and I felt a significant temperature difference from frontline press reporters. I thought that your enthusiasm in frontline reporters is not spread to the higher level. Please propagate it above (laughter in the audience).

This time, Hayabusa team have grown greatly in a few months, and some young members have proposed new mission ideas. Among JAXA executives, an atmosphere that "we must support them" have been coming up.

We will continue releasing our news frequently.

We appreciate your continued understanding and cooperation.

( Translated by JSpace http://mole.den.hokudai.ac.jp/jspace/ )
よろしくお願いいたします.

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