YM COLUMN ARCHIVE
June 11, 2008
HAYABUSA, Hoshide and Astronomy Satellite
If we could see the area very near the sun now, we will find HAYABUSA close-in there. At the end of May this year, HAYABUSA was cruising at an angle of twelve degrees away from sun as viewed from earth, which means that earth, sun and HAYABUSA were aligned almost on the same straight line. As distance from earth to sun is 1 astronomical unit (AU), HAYABUSA is away from earth by 2.5 AU now, for it is located at 1.5 AU beyond the sun, which means HAYABUSA has reached the furthest distance from earth. 2.5 AU takes forty minutes in communication to and from between earth and the spacecraft.
As I wrote in the column before, HAYABUSA was in resting phase of its ion engine injection and was keeping the attitude stabilization by spinning. Spinning axis was oriented toward sun to make solar battery panels faced to sun, because the spacecraft most needs energy power. Under such circumstances, however, antenna could not be directed toward earth all the time; therefore ground control center could receive radio waves only at the timing of antenna’s facing earth during ten minutes time cycle of spinning. As I said in the beginning of this column, earth and sun are aligned at such a low angle now, which enables HAYABUSA to direct its antenna constantly toward earth by keeping its attitude to receive sunlight on the battery panels so that the control center can continuously receive the radio waves. This situation is expected to last until early 2009. Around this time HAYABUSA team is to restart ion engine operation to enter the final stage of home stretch last spurt to bring the spacecraft back to earth in June 2010.
And now, Astronaut Hoshide and other crews, who successfully attached Experimental Module of Kibo to ISS and fixed up the Japanese-made robot arm, are preparing ready for return to earth. Astronaut Hoshide and his teammates will take some time in final preparation and move to space shuttle “Discovery” to close the hatch between the shuttle and ISS, and then bid “farewell” to ISS tonight (JST). They are expected to be back on earth on Saturday (US time).
One last news. GLAST (The Gamma Ray Large Area Space Telescope) that has been postponed of its launch due to various troubles will be carried to space by Delta 2 rocket on the midnight of June 11 (JST). GLAST will make a great contribution to clarify the mysteries of high-energy phenomena such as a black hole. Let us be looking forward to its achievements.
I welcome your opinions on this column to the following E-mail address.
matogawa@planetary.or.jp
(Translated by The Planetary Society of Japan)
Copyright (c) 2000 The Planetary Society of Japan. All rights reserved
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