Akatsuki Venus Climate Orbiter |
Akatsuki Venus Climate Orbiter |
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 ![]() |
I thought it was time to start a separate thread on this mission, launching soon
some good medium-resolution images of the spacecraft are available on JAXA digital archives http://jda.jaxa.jp/jda/p3_e.php?time=N&...mp;mission=4066 |
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#2
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![]() Director of Galilean Photography ![]() ![]() ![]() Group: Members Posts: 896 Joined: 15-July 04 From: Austin, TX Member No.: 93 ![]() |
Like in Akatsuki, sometimes the rockets for the attitude thrusters and the main thrusters use the same fuel system, with the attitude thrusters using the fuel as a monopropellant (one-part) (like in the Martian, where Watney drips the fuel on a catalyst) but the main thrusters using the fuel together with an oxidizer as a bipropellant (two-part), typically hypergolic (self-igniting when mixed). When used as a bipropellant, the reaction is much more energetic, and provides greater thrust. When used as a monopropellant, the reaction is less energetic, but only requires pumping one liquid. The simplicity of only having to pump one fluid matters when you have multiple attitude thrusters around a probe. The thrust bipropellant provides is worth the additional weight and complexity if the delta-V required is high enough, like orbit insertion.
-------------------- Space Enthusiast Richard Hendricks
-- "The engineers, as usual, made a tremendous fuss. Again as usual, they did the job in half the time they had dismissed as being absolutely impossible." --Rescue Party, Arthur C Clarke Mother Nature is the final inspector of all quality. |
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#3
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Member ![]() ![]() ![]() Group: Members Posts: 817 Joined: 17-April 10 From: Kamakura, Japan Member No.: 5323 ![]() |
Page-9
(page title): Engines to be used (inside red framed box): Attitude control engine/top side (23N), used for orbit insertion (inside blue framed box): Attitude control engine/down side (23N) (character set at very bottom): In order to make the craft into VOI-R1 orientation (sun is in the jet direction) on one day before (6 December 2015) VOI-R1 firing will be conducted using the top side (+Z) attitude control engine which can best tolerate the solar beam input. Page-10 (page title): Attitude changes before and after VOI-R1 (on the left hand orbit diagram): (A)+X Sun ( ![]() © VOI-R1c attitude (D) Venus observing attitude (yellow stars indicate attitude change positions) (upper left arrows): sun direction in red, earth direction in blue at time of VOI-R1 operation (on the right hand 4 blocks): (character set just above these 4 blocks): craft attitude as seen from earth (4 blocks clockwise are): Blk1: (A)+Z Sun attitude Blk2: (B)VOI-R1 attitude Blk3: (D) Venus observing attitude Blk4: © VOI-R1c attitude P |
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