Edit of LbyD/20071005 - Space Development and Exploration in Japan

[[LbyD]]

** Original [#n5337b7e]
Original text - http://smatsu.air-nifty.com/lbyd/2007/10/post_9ab0.html

** Translation [#fd016aff]
//コメントの書き方
//こんな感じでコメントを入れてください。

Kaguya was successfully injected into the lunar orbit.

A press conference was held at ISAS in Sagamihara on 9:00am.

Attendants are Dr. Yoshisada Takizawa (Project Manager), Prof. Susumu Sasaki, Prof. Seiichi Sakamoto.

Photo: Project Manager Takizawa gesticulating the configuration of the moon and Kaguya in lunar orbit injection.

Takizawa read out the press release.  Lunar orbit injection (LOI) was successful.  
Apocynthion altitude is 11,741 km, pericynthian altitude 101 km and the period  	16 hours 42 minutes.

*** Q&A [#cc61255b]

''NHK broadcasting'': What is the significance of LOI for start of observation?  I'd like to ask you what you felt in injection.

''Takizawa'': Kaguya must orbit the moon anyhow for observation.  Critical maneuvers are essentially needed for orbiting the body with gravity.  The timing of maneuvers is very severe and any failure would yield a loss in the mission.  We now have made much progress toward the execution of observation by Kaguya.

Past events were all fine and the satellite was healthy, so we were confident, though it was a critical maneuver.  Nevertheless, the 25-minute firing was felt very long to me.

''NHK'': I'd like to know what "critical" means.

''Takizawa'': Timing is very severe.  LOI must be executed unfailingly with a certain timing.  If we missed this timing, Kaguya could not enter the lunar orbit.

If we failed the maneuver, Kaguya would be disturbed by the lunar gravity and enter another orbit where LOI is difficult.  It was important to inject it into the lunar orbit even if not accurate, but as a result, we succeeded in very accurate LOI.

''Asahi Shimbun Press'': Did the firing continue for 25 minutes?  Kaguya decelerated toward the moon; does it mean Kaguya changed the attitude before firing?  How much did it decelerate?

''Takizawa'': It continued firing for 25 minutes after attitude change.  Roughly speaking, the moon is moving at 1km/s or more with respect to the earth, and Kaguya at around 0.1km/s.  Because Kaguya is gravitated by the moon in its approach, we suppressed the over-approaching by reversed firing for LOI.

''Sakamoto'': It is a little complicated, for it depends on where to set the coordinate.

''Aoki (freelance journalist)'': Are upcoming maneuvers to lower the altitude safer than LOI?

''Takizawa'': The risk is less, for the timing margin is larger.

''Aoki'': I'd like to know details of orbits of the relay and VRAD satellites at the separation.  How much error in the apocynthion altitude is estimated?

''Takizawa'': As for the relay satellite, apocynthion altitude is 2400 km and the period is 6 hours.  For the VRAD satellite, apocynthion altitude is 800 km and the period is 3 hours.  The final Kaguya orbit is circular with 100-km radius and 2-hours period.  The apocynthion altitude error of around 100km is permissible.

The released diagram shows only the orbits at separation, but in actual maneuvers the thruster will fire several times for gradual lowering of altitude.  During this process, the satellites will be separated when the altitude becomes appropriate.

''Akahata Press'': Please tell us more details about the schedule ahead toward the observation phase.

''Takizawa'': After injection into the 100-km circular orbit, we'll take around one and a half months to check observation equipment.  It will be mid to late December that the actual data will begin to come.

''Akahata Press'': When will the HDTV video of the earthrise be published?

''Takizawa'': It will be acquired during the checkout of HDTV camera.  Because we have to download a huge amount of data, we'll judge the timing for download in consideration of checkout for other equipment.

''Matsuura (Space Authors' Club)'': You released the success the next day of the maneuver (today).  In fact, when did you feel secure of the "success" ?  And please tell us what you felt when you went to bed last night, if you would.

''Takizawa'': I felt it in the operation room during the firing of the 500N thruster.  The monitor was showing the acceleration and velocity of the satellite in realtime.  The values were nominal as estimated, so after the finish of firing I felt convinced that things went well.  Then we obtained the result of subsequent orbit determination at around 5am this morning, followed by this press conference.

''Sasaki'': I was watching the same data, and felt sure of the success in finish of firing.  The SELENE mission three big steps; the launch, LOI, and startup of observation equipment.  Now we've succeeded in the first two, but the equipment startup lies ahead.  We must keep watching out, but we are relieved now.

''Takizawa'': Indeed I felt relieved.  During the maneuver I was under tension, and kept my fingers crossed hoping everything goes well.

''Aviation Week'': Tell us the exact time of the manuever.

''Takizawa'': Started at 5:55am and finished at 6:20am.

(Next from the Tokyo Office)

''Kyodo Tsushin Press'': The apocynthion altitude was originally planned to be around 13000 km.  How will the difference affect the schedule ahead?  And is the satellite already in the polar orbit?

''Takizawa'': That value is the semi-major axis, including the radius of the moon.  So please subtract the moon radius from that.  The satellite is already in the polar orbit.

''Jiji Tsushin Press'': How much propellant did you consume?

''Takizawa'': We have consumed around 400kg in past maneuvers.  It's nominal.  The margin of the propellant has been little used.

(Next from the Sagamihara Campus)

''Aoki'': Can the surplus of the propellant lengthen the observation period?

''Takizawa'': The prolongation of observation depends on how the orbit of Kaguya is affected by the moon's gravity field.  The distribution of the moon's gravity field is one of the Kaguya's target, and not understood yet.  It will influence on if the life can be extended or not.

''Aoki'': How long will you observe the gravity field?

''Sasaki'': We'll keep observation during the one-year period.  We'll obtain the first result around two months after, and improve the accuracy afterward.  The two-month length is nothing physically significant; just means we consider around two months as a unit for organizing the data.

(From Tokyo)

''Newton Magazine'': You published the HDTV image of the earth.  We are looking forward to the publication of the moon image.  Is there a possibility that the HDTV image will be published before starting the observation?

''Takizawa'': We'll shoot HDTV images after entering the 100-km circular orbit on 19th this month (Note by translator: It means "take a picture no earlier than 19th October", not "take a picture on 19th October".  19th Oct. is the day for entering the circular orbit, but I am not sure if it will take a picture.  Sorry for misleading translation).  Our team will discuss what image to shoot.

''Kyodo Tsushin Press'': Would you please give us some explanation about the configuration of the moon and the Kaguya in LOI with gestures or something?

''Takizawa'': It goes this way and that way ... (gesticulating)

(Back To Sagamihara)

''Aoki'': Will the data other than HDTV images be published within this year?

''Sasaki'': We'll check each equipment after entering the regular orbit.  Significant care must be taken because some of equipment need high voltage.  Several image sensors will be checked out early, so we'll obtain image data before mid-December.  Small calibration is indispensable for image data.  If calibration goes well, we can publish the data early, but there is no guarantee.  So, we cannot affirm when to publish at this time.

''Aoki'': What equipment will publish images early?

''Sasaki'': We'd like to release images comprehensible to the public.  We would like to, and must, publish major data by early the next year.  It will be early the next year that data will be increasingly released.

(At the private conversation after the conference)

''Sakamoto'': The reason why the success was released the next day is that we decided to release it after orbit determination.  The orbit was determined early this morning, because the positions were measured at several points on the orbit with over-16-hour period for determination.

Though we felt it went well just after the maneuver, we cannot declare that we have surely injected the messages gathered in the "Wish upon the Moon" campaign into the lunar orbit, without knowing the orbit information.  Besides, we thought that also the media will prefer a single conference rather than several small releases over two days.

Yesterday I gave a lecture in the monthly talk event held at JAXAi (JAXA exhibition center), and I was asked a lot of tough questions.  Their deep interests make me so glad.

''Sasaki'': If the one-year observation goes well and we have remaining propellants, we consider even lowering the altitude down to 50km.  Since the precision of magnetometry is inversely proportional to the cube of the distance, the half altitude will give us eight fold precise data.

The delta-V of LOI was 300m/s.

** Request for comments [#h7f31b89]
#comment(below)

- 松浦さんから御快諾頂きましたのでお知らせしておきます。英語の方、適宜修正頂ければ幸いです。今回勢いで勝手に動いてしまい大変失礼しました＞三嶋さん・皆様 -- [[nao]] &new{2007-10-07 (Sun) 19:38:18};
- すみません、ガイドラインの存在をすっかり忘れておりまして（汗）、現在松浦さんに事後承諾を確認しているところです。大変申し訳ありません -- [[nao]] &new{2007-10-07 (Sun) 17:52:31};
- 皆様ご無沙汰してます．勝手にページ立てさせていただきました．今回私はあまり時間が取れないのですが，翻訳にご協力くださる方はよろしくお願いします． -- [[nao]] &new{2007-10-06 (Sat) 01:32:26};

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